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Sample records for austempered ductile iron

  1. Highsilicone Austempered Ductile Iron

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    Kochański A.

    2014-03-01

    Full Text Available Ductile iron casts with a higher silicone content were produced. The austempering process of high silicone ductile iron involving different austempering times was studied and the results presented. The results of metallographical observations and tensile strength tests were offered. The obtained results point to the fact that the silicone content which is considered as acceptable in the literature may in fact be exceeded. The issue is viewed as requiring further research

  2. Fracture toughness of austempered ductile iron

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    Srinivasan, M.N. [Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering; Komatsu, S. [Kinki Univ., Higashihiroshima (Japan). Dept. of Mechanical Systems Engineering

    1995-12-01

    The effect of austenitizing temperature, austempering temperature and austempering time on the fracture toughness of austempered ductile iron have been presented and discussed in this paper. Statistical design of experiments with a 2{sup 3} matrix was used to determine the effect of the individual variables and their interactions. The desirable combination of the three variables is suggested based on the analysis.

  3. Properties investigation of austempered ductile iron

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    Sudhanshu Detwal

    2016-03-01

    Full Text Available This work concerns microstructural and mechanical properties of an austempered ductile cast iron (ADI. The ductile iron material was produced by the sand mould casting technique. Afterwards, austempering heat treatment was applied to the specimens at two different temperatures of 250°C and 350°C. Austempered Ductile Irons (ADIs were produced successfully by different two-stage heat treatments, to obtain favorable microstructure and hardness. The microstructure and hardness obtained by such variable heat treatments were compared. The austempering temperature and time were found to be decisive parameters in obtaining a desired ADI microstructure.

  4. Multiphase Ausformed Austempered Ductile Iron

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    Soliman M.

    2017-09-01

    Full Text Available Ductile iron was subjected to a total true strain (φt of 0.3 either by applying φt in the austenite region or by apportioning it through applying a true strain of 0.2 in the austenite region before quenching to austempering temperature (TA of 375°C, where a true strain of 0.1 is applied (ausforming. Additionally, two types of matrices were produced in the ductile iron, namely ausferritic and ferritic-ausferritic matrices. The ferrite is introduced to the matrix by intercritical annealing after austenitization. Dilatometric measurements as well as microstructure examination showed a fast ausferrite transformation directly after applying φA and that the introduction of ferrite to the matrix resulted in a remarkable acceleration of the ausferrite formation. The transformation kinetics, microstructure evolution, hardness and compression properties are studied.

  5. Some mechanical properties of austempered ductile iron

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    Waanders, F.B.; Vorster, S.W.; Vorster, M.V. [Potchefstroom Univ. (South Africa). Dept. of Metall. Eng.

    1997-12-01

    In the present investigation the influence of the microstructure, obtained after an austempering treatment in a ``process window``, on the mechanical properties of austempered ductile iron has been investigated. These properties include tensile strength, elongation and hardness. Conversion electron Moessbauer spectra (CEMS) were measured, after heat treatment. (orig.). 7 refs.

  6. Some Mechanical Properties of Austempered Ductile Iron

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    Waanders, F.B.; Vorster, S.W.; Vorster, M.J. [Potchefstroom University, Department of Metallurgical Engineering (South Africa)

    1998-12-15

    In the present investigation the influence of the microstructure, obtained after an austempering treatment in a 'process window', on the mechanical properties of austempered ductile iron has been investigated. These properties include tensile strength, elongation and hardness. Conversion electron Moessbauer spectra (CEMS) were measured, after heat treatment.

  7. Thin Wall Austempered Ductile Iron (TWADI

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    M. Górny

    2009-07-01

    Full Text Available In this paper the analysis of thin walled castings made of ductile iron is considered. It is shown that thin wall austempered ductile iron can be obtained by means of short-term heat treatment of thin wall castings without addition of alloying elements. Metallographic examinations of 2 mm thin walled castings along with casting with thicker wall thickness (20x28 mm after different austempring conditions are presented. It has been proved that short-term heat treatment amounted 20 minutes of austenitizing at 880 oC followed by holding at 400 oC for 5 minutes causes ausferrite matrix in 2 mm wall thickness castings, while casting with thicker wall thickness remain untransformed and martensite is still present in a matrix. Finally there are shown that thin wall ductile iron is an excellent base material for austempering heat treatments. As a result high mechanical properties received in thin wall plates made of austempered ductile iron.

  8. Thin wall ductile and austempered iron castings

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    E. Fraś

    2010-07-01

    Full Text Available It has been shown that it is possible to produce thin wall castings made of ductile iron with wall thickness in the range of 1.2 to 2.9 mm(without chills, cold laps and misruns. Thin wall ductile iron castings can be lighter (380 g than their substitutes made of aluminium alloys (580g. The kinetics of austenitising transformation was studied in unalloyed ductile iron. The advance of transformations during austenitising was monitored by measurement the fraction of martensite and also by dilatometic studies. It has been shown that in thin wall ductile iron castings austenitising at 880 oC for 20 minutes is adequate to obtain the austenite matrix at the end of the first stage of austempering heat treatment cycle.

  9. Abrasive wear behaviour of as cast and austempered ductile irons

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    Baydogan, M.; Koekden, M.U.; Cimenoglu, H. [Istanbul Technical Univ., Dept. of Metallurgy and Materials Science Engineering Istanbul (Turkey)

    2000-07-01

    In this study, abrasive wear behaviour of as cast and austempered GGG 50 and GGG 80 quality ductile irons was investigated. In the as cast condition, GGG 50 and GGG 80 quality ductile irons were having ferritic and pearlitic matrix structures, respectively. Austempering at 250 C after austenitisation at 900 C for 100 minutes produced bainitic matrix structure in both of the investigated ductile irons. Abrasive wear tests performed by rubbing the as cast and austempered specimens on Al{sub 2}O{sub 3} abrasive bands, revealed that austempering treatment improves abrasion resistance about 10-70% depending on the abrasive particle size and composition of the base iron. In the as cast condition, pearlitic GGG 80 grade ductile iron, has higher wear resistance than ferritic GGG 50 grade ductile iron. In the austempered condition GGG 50 and GGG 80 grade ductile irons which have bainitic matrix structure, exhibit almost similar wear resistance. (orig.)

  10. The austempering study of alloyed ductile iron

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    Eric, Olivera [Institute of Nuclear Sciences ' Vinca' , P.O. Box 522, 11001 Belgrade (Serbia and Montenegro)]. E-mail: oliverae@vin.bg.ac.yu; Jovanovic, Milan [Institute of Nuclear Sciences ' Vinca' , P.O. Box 522, 11001 Belgrade (Serbia and Montenegro); Sid-baranin, Leposava [University of Novi Sad, Faculty of Technical Sciences, Novi Sad (Serbia and Montenegro); Rajnovic, Dragan [University of Novi Sad, Faculty of Technical Sciences, Novi Sad (Serbia and Montenegro); Zec, Slavica [Institute of Nuclear Sciences ' Vinca' , P.O. Box 522, 11001 Belgrade (Serbia and Montenegro)

    2006-07-01

    Austempered ductile iron (ADI) proved to be an excellent material as it possesses attractive properties: high strength, ductility and toughness are combined with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields optimum microstructure for a given chemical composition. In this paper an investigation has been conducted on ADI alloyed with 0.45%Cu and austempered in a range of times and temperatures. The microstructure and fracture mode developed throughout these treatments have been identified by means of light and scanning electron microscopy and X-ray diffraction analysis. It was shown that strength, elongation and impact energy strongly depend on amounts of bainitic ferrite and retained austenite. Based on these results an optimal processing window has been established.

  11. Calorimetric examinations of austempered ductile iron ADI

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    F. Binczyk

    2007-12-01

    Full Text Available The study presents the results of calorimetric examinations during heating and cooling of austempered ductile iron ADI after austempering at temperatures of 280, 330 and 380oC. The samples for examinations were taken from cast rods of 20 and 60 mm diameter. Examinations were carried out on a differential scanning calorimeter, type Multi HTC S60. During heating, on a DSC curve one strong exothermic effect has been noted to occur (it does not occur in the case of common-grade cast iron, accompanied by two endothermic effects. The exothermic effect occurs within the range of about 20oC. Depending on the temperature of austempering treatment, its beginning falls to the temperatures from 469 to 490oC. The heat of this effect is proportional to the austenite content in ADI matrix after austempering. The endothermic effects are related with decomposition of pearlite (or bainite and with phase transformation α → γ (ferrite as a constituent of ausferritic matrix.

  12. Stacking faults in austempered ductile iron

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    Hermida, J.D. [CNEA, San Martin (Argentina). Dept. de Materiales

    1996-06-01

    During last decade, Austempered Ductile Iron (ADI) has been successfully used as an acceptable replacement material for steel in many applications, due to the relatively high strength and reasonable ductility obtained. These properties are the result of the special microstructure exhibited by this material at the end of the upper bainite reaction: ferrite platelets surrounded by high carbon stabilized austenite. However, at the beginning of the austempering treatment, the existence of interdendritic low carbon austenite is revealed by its transformation to martensite when cooling the sample or during subsequent deformation. The completion of the upper bainite reaction is of decisive importance to mechanical properties because the remaining martensite reduces ductility. It was observed that the rate of the upper bainite reaction is governed by the carbon content difference between the low and high carbon austenites. The carbon content is obtained by the lattice parameter measurement, because there exists a known expression that relates both magnitudes. Several works have used X-ray diffraction to measure the lattice parameter and phase concentrations as a function of austempering time. In these works, the lattice parameters were obtained directly from the {l_brace}220{r_brace} and {l_brace}311{r_brace} peaks position. The purpose of this work is to show more precise lattice parameters measurement and, very closely related to this, the existence of stacking faults in austenite, even at times within the processing window.

  13. Wear resistance properties of austempered ductile iron

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    Lerner, Y.S. [Univ. of Northern Iowa, Cedar Falls, IA (United States); Kingsbury, G.R. [Kingsbury (G.R.), Lyndhurst, OH (United States)

    1998-02-01

    A detailed review of wear resistance properties of austempered ductile iron (ADI) was undertaken to examine the potential applications of this material for wear parts, as an alternative to steels, alloyed and white irons, bronzes, and other competitive materials. Two modes of wear were studied: adhesive (frictional) dry sliding and abrasive wear. In the rotating dry sliding tests, wear behavior of the base material (a stationary block) was considered in relationship to countersurface (steel shaft) wear. In this wear mode, the wear rate of ADI was only one-fourth that of pearlitic ductile iron (DI) grade 100-70-03; the wear rates of aluminum bronze and leaded-tin bronze, respectively, were 3.7 and 3.3 times greater than that of ADI. Only quenched DI with a fully martensitic matrix slightly outperformed ADI. No significant difference was observed in the wear of steel shafts running against ADI and quenched DI. The excellent wear performance of ADI and its countersurface, combined with their relatively low friction coefficient, indicate potential for dry sliding wear applications. In the abrasive wear mode, the wear rate of ADI was comparable to that of alloyed hardened AISI 4340 steel, and approximately one-half that of hardened medium-carbon AISI 1050 steel and of white and alloyed cast irons. The excellent wear resistance of ADI may be attributed to the strain-affected transformation of high-carbon austenite to martensite that takes place in the surface layer during the wear tests.

  14. Effect of fully and semi austempering treatment on the fatigue properties of ductile cast iron

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    Kim, Min Gun; Lim, Bok Kyu; Hwang, Jung Gak [Kangwon National Univ., Chuncheon (Korea, Republic of); Kim, Dong Youl [Samcheok National Univ., Samcheok (Korea, Republic of)

    2005-03-01

    Single phase bainite structure which is obtained by the conventional austempering treatment reduces the ductility of ductile cast iron. Because of the reduction of ductility it is possible to worsen the fatigue properties. Therefore, semi austempered ductile iron which is treated from {alpha}+{gamma} is prepared to investigate the static strength and fatigue properties in comparison with fully austempered ductile iron (is treated from {gamma}). In spite of semi austempered ductile iron shows the 86% increase of ductility. Also, semi austempered ductile iron shows the higher fatigue limit and lower fatigue crack growth rate as compared with fully austempered ductile iron. By the fractographical analysis, it is revealed that the ferrite obtained by semi austempering process brings about the plastic deformation (ductile striation) of crack tip and gives the prior path of crack propagation. The relatively low crack growth rate in semi austempered specimen is caused by above fractographical reasons.

  15. Thermomechanical treatment of austempered ductile iron

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    A. A. Nofal

    2007-11-01

    Full Text Available The production of lightweight ferrous castings with increased strength properties became unavoidable facing the serious challenge of lighter aluminum and magnesium castings. The relatively new ferrous casting alloy ADI offers promising strength prospects, and the thermo-mechanical treatment of ductile iron may suggest a new route for production of thin-wall products. This work aims at studying the influence of thermomechanical treatment, either by ausforming just after quenching and before the onset of austempering reaction or by cold rolling after austempering. In the first part of this work, ausforming of ADI up to 25% reduction in height during a rolling operation was found to add a mechanical processing component compared to the conventional ADI heat treatment, thus increasing the rate of ausferrite formation and leading to a much finer and more homogeneous ausferrite product. The kinetics of ausferrite formation was studied using both metallographic as well as XRD-techniques. The effect of ausforming on the strength was quite dramatic (up to 70% and 50% increase in the yield and ultimate strength respectively. A mechanism involving both a refined microstructural scale and an elevated dislocation density was suggested. Nickel is added to ADI to increase hardenability of thick section castings, while ausforming to higher degrees of deformation is necessary to alleviate the deleterious effect of alloy segregation on ductility. In the second part of this work, the influence of cold rolling (CR on the mechanical properties and structural characteristics of ADI was investigated. The variation in properties was related to the amount of retained austenite (γr and its mechanically induced ransformation. In the course of tensile deformation of ADI, transformation induced plasticity (TRIP takes place, indicated by the increase of the instantaneous value of strain-hardening exponent with tensile strain. The amount of retained austenite was found to

  16. Carbon content of austenite in austempered ductile iron

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    Chang, L.C. [Kuang Wu Inst. of Tech. and Commerce, Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering

    1998-06-05

    The development of austempered ductile iron (ADI) is a major achievement in cast iron technology. The austempering heat treatment enables the ductile cast iron containing mainly strong bainitic ferrite and ductile carbon-enriched austenite, with some martensite transforms from austenite during cooling down to room temperature. A key factor controlling the stability of the retained austenite can be evaluated soundly using the thermodynamics principles. It is the purpose here to demonstrate that the data of ADI from numerous sources have a similar trend.

  17. Microstructural characteristics of Al-alloyed austempered ductile irons

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    Kiani-Rashid, A.R.; Edmonds, D.V.

    2009-01-01

    Microstructural development after austempering ductile irons containing 0.48% and 4.88%Al has been studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental irons were made by green sand casting and gravity die casting. After austenitising at 920 deg. C for 90 min, an austempering treatment at 400 deg. C for times up to 100 min resulted in microstructures consisting of carbide-free bainitic ferrite with considerable amounts of high carbon retained austenite.

  18. Properties and Structure of High-Silicone Austempered Ductile Iron

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    Krzyńska A.

    2014-06-01

    Full Text Available The results presented in this paper are a continuation of the previously published studies. The results of hest treatment of ductile iron with content 3,66%Si and 3,80% Si were produced. The experimental castings were subjected to austempering process for time 30, 60 and 90 minutes at temperature 300°C. The mechanical properties of heat treated specimens were studied using tensile testing and hardness measurement, while microstructures were evaluated with conventional metallographic observations. It was again stated that austempering of high silicone ferritic matrix ductile iron allowed producing ADI-type cast iron with mechanical properties comparable with standard ADI.

  19. Influece of the austempering temperature on the tensile strength of the austempered ductile iron (ADI samples

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    S. Savićević

    2017-01-01

    Full Text Available Austempered Ductile Iron (ADI is a class of ductile iron subjected to a two-step heat treatment process – austenitization and austempering. The heat treatment gives to ADI a high value of tensile strength and an especially good strength-to-weight ratio. However, designers in most cases are unfamiliar with this material that can compete favorably with steel and aluminum castings, weldments and forgings. The high tensile strength of ADI is the result of its unique ausferrite microstructure. In this paper, an investigation of the influence of the austempering temperature on the tensile strength of the ADI samples is presented.

  20. The surface layer of austempered ductile iron investment castings properties

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    D. Myszka

    2009-01-01

    Full Text Available The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

  1. Wear and scuffing of austempered ductile iron gears

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    Magalhaes, L. [Departamento de Engenharia Mecanica, Instituto Superior de Engenharia, Instituto Politecnico do Porto (Portugal); Seabra, J. [Porto Univ. (Portugal). Dept. Engenharia Mecanica e Gestao Industrial

    1998-03-01

    This paper enhances actual knowledge of the properties of austempered ductile iron (ADI) as a gear material. Results from scuffing tests performed with ADI gears on a FZG test rig are presented and discussed. Contact condition analysis is done using elast-hydrodynamic theory along with several experimental techniques, as surface electronic scanning microscopy, metallurgical spectroscopy and lubricant ferrographic analysis. (orig.)

  2. APPLICATION OF AUSTEMPERED DUCTILE IRON TO RAIL WHEEL SETS

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    Sacit DÜNDAR

    2003-03-01

    Full Text Available Austempered Ductile Iron (ADI is made up of a composite structure of acicular ferrite and carbon-enriched austenite. The transformation of austenite to martensite under certain stress levels results in a material with a hard rim and a tough internal structure. These properties makes it an alternate material for the production of railcar wheelsets.

  3. Influence of microstructure on fracture toughness of austempered ductile iron

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    Rao, P.P.; Putatunda, S.K. [Wayne State Univ., Detroit, MI (United States). Dept. of Chemical Engineering and Materials Science

    1997-07-01

    An investigation was carried out to examine the influence of microstructure on the plane strain fracture toughness of austempered ductile iron. Austempered ductile iron (ADI) alloyed with nickel, copper, and molybdenum was austenitized and subsequently austempered over a range of temperatures to produce different microstructures. The microstructures were characterized through optical microscopy and X-ray diffraction. Plane strain fracture toughness of all these materials was determined and was correlated with the microstructure. The results of the present investigation indicate that the lower bainitic microstructure results in higher fracture toughness than upper bainitic microstructure. Both volume fraction of retained austenite and its carbon content influence the fracture toughness. The retained austenite content of 25 vol pct was found to provide the optimum fracture toughness. It was further concluded that the carbon content of the retained austenite should be as high as possible to improve fracture toughness.

  4. Dry sliding wear of Ni alloyed austempered ductile iron

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    E. Akbarzadeh Chiniforush

    2016-09-01

    Full Text Available Measurements of dry sliding wear are presented for ductile irons with composition Fe-3.56C-2.67Si-0.25Mo-0.5Cu and Ni contents of 0.8 and 1.5 in wt.% with applied loads of 50, 100 and 150 N for austempering temperatures of 270, 320, and 370 °C after austenitizing at 870 °C for 120 min. The mechanical property measurements show that the grades of the ASTM 897M: 1990 Standard can be satisfied for the selected austempering conditions. The results show that wear resistance is independent of austempering temperature with an applied load of 50 N, but there is a strong dependence at higher austempering temperatures with applied loads of 100 and 150 N. Observations indicate that wear is due to subsurface fatigue with cracks nucleated at deformed graphite nodules.

  5. Wear Resistance of Austempered Ductile Iron with Nanosized Additives

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    Kaleicheva, J. K.; Mishev, V.

    2018-01-01

    The wear resistance, microstructure and mechanical properties of austempered ductile iron (ADI) with nanosized additives of cubic boron nitride cBN are investigated. Samples of ductile iron are put under austhempering at the following conditions: heating at 900°С, 1 h and isothermal retention at 280оС, 2 h and 380°С, 2 h with the aim to achieve a lower bainitic structure and an upper bainitic structure. The experimental wear testing of austempered ductile irons is performed in friction conditions of a fixed abrasive by a cinematic scheme „pin - disc” using an accelerated testing method and device. The microstructure of the ADI is investigated by metallographic and X-Ray analyses. The Vickers hardness testing and impact strength examination are carried out. The influence of the nanosized additives of cBN on the wear resistance, microstructure, impact strength and hardness of the ADI is investigated.

  6. Wear Behavior of Austempered Ductile Iron with Nanosized Additives

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    J. Kaleicheva

    2014-03-01

    Full Text Available The microstructure and properties of austempered ductile iron (ADI strengthened with nanosized addtives of titanium nitride + titanium carbonitride (TiN + TiCN, titanium nitride TiN and cubic boron nitride cBN are investigated. The TiN, TiCN and cBN, nanosized particles are coated by electroless nickel coating EFTTOM-NICKEL prior to the edition to the melt. The spheroidal graphite iron samples are undergoing an austempering, including heating at 900 оС for an hour, after that isothermal retention at 280 оС, 2 h and 380 оС, 2h. The metallographic analysis by optical metallographic microscope GX41 OLIMPUS and hardness measurements by Vickers Method are performed. The structure of the austempered ductile iron consists of lower bainite and upper bainite.Experimental investigation of the wear by fixed abrasive are also carried out. The influence of the nanosized additives on the microstructure, mechanical and tribological properties of the austempered ductile irons (ADI is studied.

  7. Production of austempered ductile iron gears for transmission cases

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    Sagin, A. [Metallurgy Engineering Dept., Technical Univ. of Yildiz, Istanbul (Turkey); Topuz, A. [Chemical and Metallurgical Faculty, Technical Univ. of Yildiz, Istanbul (Turkey)

    2005-07-01

    The investigations presented in this contribution were targeted to replace a gear group made up of SAE 8620 steel in army jeeps with microstructural controlled austempered ductile iron, in order to reduce the manufacturing steps. Furthermore, the vibrations were also expected to decrease, due to the application of austempered ductile iron. The fatigue resistance of unalloyed and Ni alloyed austempered ductile iron have been investigated to see if some improvement as compared to steels with cementite could be achieved. The effect of the austenization heat treatment on the fatigue resistance was studied in metallographic investigations and it turned out that the alloying elements Cu, Ni and Mo have a beneficial effect. For economical reasons, the gears were fabricated of nodular iron containing 3.98% C, 1.89% Si, 0.269% Mn and 0.028% P. Considering the fatigue resistance, a Ni alloyed material with 3.66% C, about 1.81% Si, 0.134% Mn, 0.031% P and 1.51% Ni was chosen. The roundness of the graphites was about 93-100% and 80-85%. The gears were at first produced by austenization at 900 C for 3 hours and then by austempering at 235 C for 2.5 hours. The fatigue tests were performed at the maximum stresses to be expected. (orig.)

  8. Strain Induced Martensitic Transformation in Austempered Ductile Iron (ADI)

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    Li, X. H.; Saal, P.; Gan, W. M.; Landesberger, M.; Hoelzel, M.; Hofmann, M.

    2016-09-01

    The strain induced martensitic transformation in austempered ductile iron (ADI) has been investigated using high resolution neutron diffraction on samples compressed ex-situ to different plastic strains. In addition bulk texture measurements using neutron diffraction have been performed to calculate the orientation distribution of ferrite and austenite phases for different strain levels. Combing the detailed texture information with neutron diffraction pattern proved to be essential for quantitative phase analysis and extraction of martensite phase fractions. The martensite content induced by strain in ADI depends on austempering temperature and degree of deformation.

  9. Neural Network Analysis of Tensile Strength of Austempered Ductile Iron

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    Z. Ławrynowicz

    2007-07-01

    Full Text Available The neural technique was applied to the analysis of the ultimate tensile strength and additionally the yield strength of austempered ductile iron (ADI. Austempered ductile iron is an excellent material and it possesses attractive properties as high strength, ductility and toughness. This paper begins with an introduction to neural networks and demonstrates the ability of the method to investigate new phenomena in cases where the information cannot be accessed experimentally. The model allows the strength properties to be estimated as a function of heat treatment parameters and the chemical composition. A ‘committee’ model was used to increase the accuracy of the predictions. The model was validated by comparison its predictions with data of tensile tests experiments on austempered samples of ductile cast iron. The model successfully reproduces experimentally determined ultimate tensile strength and it can be exploited in the predictions of both ultimate and yield strength and in the design of chemical composition of cast irons and their heat treatments.

  10. Mechanical properties and structure of austempered ductile iron -ADI

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    Krzyńska A.

    2007-01-01

    Full Text Available The results of experimental study of austempered ductile iron are presented. The aim of the investigations was to look closer into the structure – mechanical properties relationships of this very attractive cast material. The experiment was carried out with 500 7 grade ductile iron, which was austempered using different parameters of heat treatment. The specimens were first solution treated 1 hour in 910oC and then isothermally quenched for different time in silicon oil bath of temperature 275, 325, 300 and 350oC. The mechanical properties heat treated specimens were tested in tensile to evaluate yield stress Re, 0.2, tensile strength Rm and elongation A10. Additionally hardness of heat treated samples was measured using Brinell-Rockwell hardness tester. Structure of the specimens was studied either with conventional metallography, scanning (SEM and transmission (TEM electron microscopy. It followed from the study that conventional grade ductile iron enabled to produce both low and high strength ADI, depend on heat treatment parameters. As expected the low temperature isothermal quenching produced higher strength ADI compare to the same ductile iron but austempered at 350oC. It was discovered however, that low yield strength ADI obtained for short time quenching at 275oC exhibited high strengthening effect while strained in tensile. So it was concluded that this had to by cause by large amount of untransformed austenite, which FCC lattice is characterized by high strengthening coefficient.

  11. Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry

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    Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry was studied as a function of the microstructure developed by austempering at 380 and 300°C for different exposure time in the slurry. The corrosion rates of the ADI balls immersed in the iron ore slurry was determined using weight loss method.

  12. Tensile properties of austempered ductile iron under thermomechanical treatment

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    Achary, J.

    2000-02-01

    A new processing method was investigated for improving the strength and elongation of austempered ductile iron (ADI) by grain refinement of parent austenite using thermomechanical treatment. The material was deformed at the austenitization temperature by single and multipass rolling before the austempering treatment. The effects of the amount of deformation, austenitization temperature, austempering temperatures, reaustenitization, and secondary deformation on the tensile properties were studied. The properties obtained using the method were compared with those of the ASTM standards. The effect of deformation on the graphite shape was also studied. Tensile strength/yield strength/elongation values were found to increase with increasing austenite deformation up to 40% and then to start decreasing. Tensile strength/yield strength and elongation values of 1,700 MPa/1,300 MPa/5% and 1,350 MPa/920 MPa/15% can be achieved with this method in the ranges of variables studied.

  13. An austempering study of ductile iron alloyed with copper

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    OLIVERA ERIC

    2005-07-01

    Full Text Available Austempered ductile iron (ADI has proved to be an excellent material as it possesses attractive properties: high strength, ductility and toughness are combined with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields the optimum microstructure for a given chemical composition. In this paper the results of an investigation the austempering of ADI alloyed with 0.45 % Cu for a range of times and temperatures are reported. The microstructure and fracture mode developed throughout these treatments have been identified by means of light and scanning electron microscopy and X-ray diffraction analysis. It was shown that the strength, elongation and impact energy strongly depend on the amounts of bainitic ferrite and retained austenite. Based on these results, and optimal processing window was established.

  14. Superior austempered ductile iron (ADI) properties achieved by prior hot isostatic pressing (HIP)

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    LaGoy, J.L.; Widmer, R.; Zick, D.H. [Industrial Materials Technology Inc., Andover, MA (United States)

    1996-12-31

    Ductile iron obtained from different foundries and cast by dissimilar methods has been successfully hot isostatically pressed (HIPed) before austempering to achieve substantially higher ductilities, without significant detriment to other properties, than those reached by austempering along. HIP was attempted to solve different mechanical deficiencies in austempered ductile iron (ADI) such as the lack of ductility in higher strength grades, inconsistent mechanical properties, and service life limitations. A variety of HIP temperatures were analyzed from near the austenitizing region up to within 56 C (100 F) of the melting point of ductile iron. Microporosity was eliminated by HIP at all temperatures, and subsequent austempering revealed a uniform ADI microstructure. HIP proved successful with both unencapsulated castings and those enclosed within steel canisters. Additional benefits caused by HIP processing of ductile iron castings without the austempering treatment include a significant decrease in mechanical property data scatter, high hardness at reasonable ductility levels, and a substantially reduced scrap rate.

  15. Microstructure evolution during surface alloying of ductile iron and austempered ductile iron by electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Gulzar, A. [Materials Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Akhter, J.I. [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Ahmad, M., E-mail: maqomer@yahoo.com [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Ali, G. [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Mahmood, M. [Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan); Ajmal, M. [Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore (Pakistan)

    2009-07-30

    Alloying and microstructural modification of surfaces by electron beam has become popular to tailor the surface properties of materials. Surface modification of as-received ductile iron, Ni-plated ductile iron and Ni-plated austempered ductile iron was carried out by electron beam melting to improve the surface properties. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the melted specimens enhanced considerably as compared to the as-received samples. However the microhardness of melted Ni-plated samples is lower than that of the unplated specimens. X-ray diffraction clearly revealed the formation of an austenite and Fe{sub 3}C phases in the electron beam molten zone. The broadening of peaks suggests refinement of the microstructure as well as internal stresses generated during electron beam melting.

  16. Neutron Diffraction Studies of Intercritically Austempered Ductile Irons

    Energy Technology Data Exchange (ETDEWEB)

    Druschitz, Alan [University of Alabama, Birmingham; Aristizabal, Ricardo [University of Alabama, Birmingham; Druschitz, Edward [University of Alabama, Birmingham; Hubbard, Camden R [ORNL; Watkins, Thomas R [ORNL

    2011-01-01

    Neutron diffraction is a powerful tool that can be used to identify the phases present and to measure the spacing of the atomic planes in a material. Thus, the residual stresses can be determined within a component and/or the phases present. New intercritically austempered irons rely on the unique properties of the austenite phase present in their microstructures. If these materials are to see widespread use, methods to verify the quality (behavior consistency) of these materials and to provide guidance for further optimization will be needed. Neutron diffraction studies were performed at the second generation neutron residual stress facility (NRSF2) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory on a variety of intercritically austempered irons. For similar materials, such as TRIP steels, the strengthening mechanism involves the transformation of metastable austenite to martensite during deformation. For the intercritically austempered ductile irons two different deformation/strengthening mechanisms, phase transformation and slip, dependent upon the iron chemistry, were observed. Lattice strain and phase fraction data as a function of applied stress are presented.

  17. A Microscale Model for Ausferritic Transformation of Austempered Ductile Irons

    Science.gov (United States)

    Boccardo, Adrián D.; Dardati, Patricia M.; Celentano, Diego J.; Godoy, Luis A.

    2017-01-01

    This paper presents a new metallurgical model for the ausferritic transformation of ductile cast iron. The model allows predicting the evolution of phases in terms of the chemical composition, austenitization and austempering temperatures, graphite nodule count, and distribution of graphite nodule size. The ferrite evolution is predicted according to the displacive growth mechanism. A representative volume element is employed at the microscale to consider the phase distributions, the inhomogeneous austenite carbon content, and the nucleation of ferrite subunits at the graphite nodule surface and at the tips of existing ferrite subunits. The performance of the model is evaluated by comparison with experimental results. The results indicate that the increment of the ausferritic transformation rate, which is caused by increments of austempering temperature and graphite nodule count, is adequately represented by this model.

  18. Effect of austempering time on mechanical properties of a low manganese austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Putatunda, S.K.; Gadicherla, P.K.

    2000-04-01

    An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were prepared from unalloyed ductile cast iron with low manganese content and with a ferritic as-cast (solidified) structure. These specimens were then austempered in the upper (371 C) and lower (260 C) bainitic temperature ranges for different time periods, ranging from 30 min. to 3 h. Microstructural features such as type of bainite and the volume fraction of ferrite and austenite and its carbon content were evaluated by X-ray diffraction to examine the influence of microstructure on the mechanical properties and fracture toughness of this material. The results of the present investigation indicate that for this low manganese austempered ductile iron (ADI), upper ausferritic microstructures exhibit higher fracture toughness than lower ausferritic microstructures. Yield and tensile strength of the material was found to increase with an increase in austempering time in a lower bainitic temperature range, whereas in the upper bainitic temperature range, time has no significant effect on the mechanical properties. A retained austenite content between 30 to 35% was found to provide optimum fracture toughness. Fracture toughness was found to increase with the parameter (X{gamma}C{gamma}/d){sup 1/2}, where X{gamma} is the volume fraction of austenite, C{gamma} is the carbon content of the austenite, and d is the mean free path of dislocation motion in ferrite.

  19. Development of austempered ductile iron timing gears; Austemper kyujo kokuen chutetsu timing gear no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, M.; Yamamoto, S.; Numajiri, S.; Nakajima, K. [Mitsubishi Motors Corp., Tokyo (Japan)

    1996-05-01

    To reduce vibration and noise of gears compared with ordinary steel gears for four cycle diesel engine of small commercial vehicles, austempered ductile iron (ADI) gears have been developed, which have excellent mechanical properties and vibration damping properties equivalent to steel gears. ADI is a material with tensile strength of 1,000 MPa, which is made by austempering the ductile iron to change matrix texture into tough bainite. For a new process method of ADI gears, austempering is conducted after gear cutting, and shaving is conducted, finally. Gear materials before austempering can be smoothly machined without deteriorating their machinability, to produce highly accurate gears. Fifteen percent of noise can be reduced for ADI gears during idling of engine, where 0.7 dB can be reduced in the noise level. The ADI gears provide superior pitting resistance to ordinary steel gears. They have nearly equivalent dedendum bending fatigue strength to ordinary soft nitrided steel gears. 6 refs., 12 figs., 2 tabs.

  20. Effects of various austempering temperatures on fatigue properties in ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Salman, S. [Marmara University, Technical Education Faculty, Istanbul (Turkey); Findik, F. [Materials Technology Department, Technical Education Faculty, Sakarya University, Sakarya (Turkey)]. E-mail: findik@sakarya.edu.tr; Topuz, P. [Yildiz Technical University, Department of Metallurgy and Material, Istanbul (Turkey)

    2007-07-01

    Austempering is an isothermal heat treatment which when applied to ferrous materials, produces a structure that is stronger and tougher than comparable structures produced with conventional heat treatments. In this paper, ductile iron specimens were applied to various austempering temperatures and interpreted fatigue properties. In this test, Denison 7615 fatigue machine was used for doing double sided bending stresses. The iron was austenitized at 900 deg. C and then austempered at 235, 300 and 370 deg. C for 2 h within a salt bath to obtain various austempered microstructures. Also, the fatigue properties of the bainitic structures which occurred by austempering are examined by scanning electron microscope.

  1. Effect of alloying elements on austempered ductile iron (ADI properties and its process: Review

    Directory of Open Access Journals (Sweden)

    Amir Sadighzadeh Benam

    2015-01-01

    Full Text Available Austempered ductile iron (ADI parts have a unique combination of high strength and toughness with excellent design flexibility and low cost. These excellent properties are directly related to its microstructure called "ausferrite" that is the result of austempering heat treatment applied to ductile irons. Alloying elements increase ADI austemperability and change speeds of austempering reactions. Thus, they can affect ADI resultant microstructure and mechanical properties. In this paper, the effects of alloying elements on ADI mechanical properties, microstructural changes, two-stage austempering reactions, processing windows, austemperability, and other aspects are reviewed.

  2. Austempered Ductile Iron (ADI: Influence of Austempering Temperature on Microstructure, Mechanical and Wear Properties and Energy Consumption

    Directory of Open Access Journals (Sweden)

    Prabhukumar Sellamuthu

    2018-01-01

    Full Text Available Alloyed Ductile iron, austenitized at 840 °C for 30 min in a special sealed austempering furnace, was austempered for 30 min in molten salt mixture at 4 trial temperatures of 300 °C, 320 °C, 340 °C and 360 °C. Tensile strength, yield strength, percentage elongation and impact energy were evaluated for the as-cast and austempered samples. Microstructures were investigated using microscopy, coupled with analyzing software and a scanning electron microscopy. The specific wear of samples was tested using pin-on-disc wear testing machine. X-ray diffraction was performed to calculate the amount of retained austenite present in the ausferrite matrix. As-cast microstructure consists of ferrite and pearlite, whereas austempered ductile iron (ADI contains a mixture of acicular ferrite and carbon enriched austenite, called “ausferrite”. Hardness and strength decreased, whereas ductility and impact strength improved with an increase in the austempering temperature. XRD analysis revealed that the increase in austempering temperature increased the retained austenite content. A decrease in wear resistance with austempering temperature was observed. Modified Quality Index (MQI values were envisaged, incorporating tensile strength, elongation and wear resistance. MQI for samples austempered at 340 °C and 360 °C showed a better combination of properties. About an 8% reduction in energy consumption was gained when the heat treatment parameters were optimized.

  3. Strain rate effects on fracture behavior of Austempered Ductile Irons

    Science.gov (United States)

    Ruggiero, Andrew; Bonora, Nicola; Gentile, Domenico; Iannitti, Gianluca; Testa, Gabriel; Hörnqvist Colliander, Magnus; Masaggia, Stefano; Vettore, Federico

    2017-06-01

    Austempered Ductile Irons (ADIs), combining high strength, good ductility and low density, are candidates to be a suitable alternative to high-strength steels. Nevertheless, the concern about a low ductility under dynamic loads often leads designers to exclude cast irons for structural applications. However, results from dynamic tensile tests contradict this perception showing larger failure strain with respect to quasistatic data. The fracture behaviour of ADIs depends on damage mechanisms occurring in the spheroids of graphite, in the matrix and at their interface, with the matrix (ausferrite) consisting of acicular ferrite in carbon-enriched austenite. Here, a detailed microstructural analysis was performed on the ADI 1050-6 deformed under different conditions of strain rates, temperatures, and states of stress. Beside the smooth specimens used for uniaxial tensile tests, round notched bars to evaluate the ductility reduction with increasing stress triaxiality and tophat geometries to evaluate the propensity to shear localization and the associated microstructural alterations were tested. The aim of the work is to link the mechanical and fracture behavior of ADIs to the load condition through the microstructural modifications that occur for the corresponding deformation path.

  4. CHOSEN FACTORS INFLUENCING MICROSTRUCTURE AND MECHANICAL PROPERTIES OF AUSTEMPERED DUCTILE IRON

    Directory of Open Access Journals (Sweden)

    Alan Vaško

    2009-10-01

    Full Text Available The paper deals with some factors influencing microstructure and mechanical properties of austempered ductile iron (ADI. Final structure and properties of ADI are obtained by exactly controlled process of heat treatment of nodular cast iron. The influence of conditions of isothermal heat treatment on microstructure and mechanical properties of austempered ductile iron, especially different temperature of isothermal transformation of austenite and different holding time at this temperature, is shown in the paper.

  5. FATIGUE CRACK PROPAGATION THROUGH AUSTEMPERED DUCTILE IRON MICROSTRUCTURE

    Directory of Open Access Journals (Sweden)

    Lukáš Bubenko

    2010-10-01

    Full Text Available Austempered ductile iron (ADI has a wide range of application, particularly for castings used in automotive and earth moving machinery industries. These components are usually subjected to variable dynamic loading that may promote initiation and propagation of fatigue cracks up to final fracture. Thus, it is important to determine the fatigue crack propagation behavior of ADI. Since fatigue crack growth rate (da/dN vs. stress intensity factor K data describe fatigue crack propagation resistance and fatigue durability of structural materials, da/dN vs. Ka curves of ADI 1050 are reported here. The threshold amplitude of stress intensity factor Kath is also determined. Finally, the influence of stress intensity factor amplitude to the character of fatigue crack propagation through the ADI microstructure is described.

  6. Effect of water on ductility and fatigue strength of austempered ductile cast iron (ADI)

    OpenAIRE

    Terutoshi, Yakushiji; W. George, Ferguson; Masahiro, Goto

    2006-01-01

    In order to study the mechanism of decreasing the tensile strength and elongation of Austempered Ductile Cast Iron (ADI) in the wet condition, various tension tests and impact test were carried out. And the three point bending fatigue tests were carried out on ADI and annealed 0.55% carbon steel to clarify the influence of water on fatigue strength. The main conclusions areas follows. Embrittlement by water begins when the plastic deformation start in tension test. The fatigue limit of ADI in...

  7. Dependence of fracture toughness of austempered ductile iron on austempering temperature

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P.P. [Karnatak Regional Engineering Coll. (India). Dept. of Metallurgical and Materials Engineering; Putatunda, S.K. [Wayne State Univ., Detroit, MI (United States)

    1998-12-01

    Ductile cast iron samples were austenitized at 927 C and subsequently austempered for 30 minutes, 1 hour, and 2 hours at 260 C, 288 C, 316 C, 343 C, 371 C, and 399 C. These were subjected to a plane strain fracture toughness test. Fracture toughness was found to initially increase with austempering temperature, reach a maximum, and then decrease with further rise in temperature. The results of the fracture toughness study and fractographic examination were correlated with microstructural features such as bainite morphology, the volume fraction of retained austenite, and its carbon content. It was found that fracture toughness was maximized when the microstructure consisted of lower bainite with about 30 vol pct retained austenite containing more than 1.8 wt pct carbon. A theoretical model was developed, which could explain the observed variation in fracture toughness with austempering temperature in terms of microstructural features such as the width of the ferrite blades and retained austenite content. A plot of K{sub IC}{sup 2} against {sigma}, (X{sub {gamma}}C{sub {gamma}}){sup 1/2} resulted in a straight line, as predicted by the model.

  8. Mathematical Model of Bainitic Transformation in Austempered Ductile Iron

    Directory of Open Access Journals (Sweden)

    Olejarczyk-Wożeńska I.

    2017-12-01

    Full Text Available A mathematical model of austenite - bainite transformation in austempered ductile cast iron has been presented. The model is based on a model developed by Bhadeshia [1, 2] for modelling the bainitic transformation in high-silicon steels with inhibited carbide precipitation. A computer program has been developed that calculates the incubation time, the transformation time at a preset temperature, the TTT diagram and carbon content in unreacted austenite as a function of temperature. Additionally, the program has been provided with a module calculating the free energy of austenite and ferrite as well as the maximum driving force of transformation. Model validation was based on the experimental research and literature data. Experimental studies included the determination of austenite grain size, plotting the TTT diagram and analysis of the effect of heat treatment parameters on the microstructure of ductile iron. The obtained results show a relatively good compatibility between the theoretical calculations and experimental studies. Using the developed program it was possible to examine the effect of austenite grain size on the rate of transformation.

  9. Microstructure transformation during plastic deformation of the austempered ductile iron

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2009-01-01

    Full Text Available Excellent properties of ADI (Austempered Ductile Iron are widely praised by the world technical literature. These properties depend onthe cast iron microstructure formed during the heat treatment process of a specific type. The matrix of ADI is a mixture of lamellar ferrite and high-carbon austenite. It seems, however, that it is the austenite that is responsible for the high strength and ductility of this material, although investigations and analyses have proved that it is not homogeneous. Various types of austenite found in the ADI matrix include unreacted austenite, stable austenite, and metastable austenite which will be transferred into martensite during machining of castings.In this study an attempt has been made to determine the fraction of metastable austenite and to evaluate its effect on ADI properties.The heat treatment enabled manufacturing ADI characterised by the following properties: T.S.>1000MPa, El.>10%, Y.S.>600MPa. As anext step, the controlled process of plastic deformation of the samples was carried out. Applying the new method it has been established that due to 15% cold work, the structure of the examined ADI contains 9% of martensite; this volume fraction goes up to 17% after 25% cold work. The results of the investigations were cofirmed by X-ray diffraction pattern analysis and magnetic measurements.Consequently, it has been proved that ADI characterised by properties satisfying the criteria of an international standard developed for this particular material contains a large amount of metastable austenite subject to the TRIP (Transformation Induced Plasticity effect.

  10. Microstructural and mechanical characteristics of low alloyed Ni-Mo-Cu austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Bosnjak, B.

    2000-12-01

    The present study investigated the effect of austempering temperature and austempering time on the microstructure and mechanical properties of low alloyed Ni-Mo-Cu ductile iron. The effect of austempering parameters and alloying additions on the austemperability of treated ductile iron has been estimated, too. Specimens were austenitised at 900 degree C for 120 mm, then austempered for 10, 30, 60, 120, 240 and 360 mm at 300, 350 and 400 degree C respectively, and examined by light and scanning electron microscopy. The structure consisted of bainitic ferrite containing retained austenite. the amount of which increased, and the carbon content of which decreased, with increasing austempering temperature. The carbon content of austenite has been evaluated by measuring the lattice parameter by X-ray diffraction. After short periods of austempering time in iron, the carbon content of the retained austenite decreases and on subsequent cooling to room temperature it transforms to martensite. The volume fractions of retained austenite, bainitic ferrite, martensite and austenite carbon content was correlated with microstructural changes and mechanical properties. Optimum properties are obtained at intermediate austempering periods (120-240 mm) when both the amount of retained austenite and austenite carbon content are maximum. (author)

  11. Investigations on the fracture toughness of austempered ductile irons austenitized at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P. Prasad; Putatunda, Susil K

    2003-05-25

    Ductile cast iron was austenitized at four different temperatures and subsequently austempered at six different temperatures. Plane strain fracture toughness was evaluated under all the heat treatment conditions and correlated with the microstructural features such as the austenite content and the carbon content of the austenite. Fracture mechanism was studied by scanning electron microscopy. It was found that the optimum austempering temperature for maximum fracture toughness decreased with increasing austenitizing temperature. This could be interpreted in terms of the microstructural features. A study of the fracture mechanism revealed that good fracture toughness is unlikely to be obtained when austempering temperature is less than half of the austenitizing temperature on the absolute scale.

  12. Microstructure and mechanical properties of CuNiMo austempered ductile iron

    Directory of Open Access Journals (Sweden)

    Erić Olivera

    2004-01-01

    Full Text Available Microstructure and mechanical properties of Cu, Ni and Mo alloyed cast ductile iron have been investigated after austempering. Samples were austenitised at 860oC for 1h and then austempered at 320oC and 400oC in the interval from 0,5 to 5h. The X-ray diffraction technique and the light microscopy were utilized to investigate the bainitic transformation, while tensile and impact tests were performed for characterization of mechanical properties. By austempering at 320oC in the range between 2 and 5h, a microstructure typical for austempered ductile iron was produced, i.e. a mixture of free bainitic ferrite and highly carbon enriched retained austenite. The characteristic of the whole range of austempering at 400oC is the appearance of martensitic structure. The maximum impact energy (133 J coincides with the maximum value of volume fraction of retained austenite that was obtained after 2,5h of austempering at 320oC. The appearance of martensite during austempering at 400oC is the main cause for much lower tensile properties than at 320oC.

  13. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    Myszka D.

    2013-03-01

    Full Text Available The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found that the traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.

  14. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2013-01-01

    Full Text Available The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found thatthe traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.

  15. Assessment of the microstructure evolution of an austempered ductile iron during austempering process through strain hardening analysis

    Science.gov (United States)

    Donnini, Riccardo; Fabrizi, Alberto; Bonollo, Franco; Zanardi, Franco; Angella, Giuliano

    2017-09-01

    The aim of this investigation was to determine a procedure based on tensile testing to assess the critical range of austempering times for having the best ausferrite produced through austempering. The austempered ductile iron (ADI) 1050 was quenched at different times during austempering and the quenched samples were tested in tension. The dislocation-density-related constitutive equation proposed by Estrin for materials having high density of geometrical obstacles to dislocation motion, was used to model the flow curves of the tensile tested samples. On the basis of strain hardening theory, the equation parameters were related to the microstructure of the quenched samples and were used to assess the ADI microstructure evolution during austempering. The microstructure evolution was also analysed through conventional optical microscopy, electron back-scattered diffraction technique and transmission electron microscopy. The microstructure observations resulted to be consistent with the assessment based on tensile testing, so the dislocation-density-related constitutive equation was found to be a powerful tool to characterise the evolution of the solid state transformations of austempering.

  16. Influence of cooling conditions and amount of retained austenite on the fracture of austempered ductile iron

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    VYACHESLAV GORYANY

    2008-01-01

    Full Text Available SEM Analysis of fracture surfaces from tensile test specimens of thick-walled, austempered ductile irons (diameter 160 mm shows different fracture behavior depending on the austenite retained in the matrix. The results show ductile fractures only in areas containing retained austenite sections. In section areas without or with a very low content of retained austenite, only brittle fracture without any plastic deformation occurs. The content of retained austenite determines the amount of ductile fracture in the microstructure.

  17. Mechanical properties of a low alloyed austempered ductile iron in the upper ausferrite region

    Energy Technology Data Exchange (ETDEWEB)

    Wen, D.C.

    1999-05-01

    Microstructural observations, X-ray diffraction testing and measurements of mechanical properties were used to study the characteristics of austempering and the influence of tempered martensite on mechanical properties as a function of austempering time at 400 degree C after austenitising at 900 degree C for a 0.77%Cu-0.5%Ni ductile iron. The austempering times were derived from a resistivity curve measured by a vacuum heat treatment system. The experimental results show that the resistivity change curve could be used effectively for selecting the isothermal holding times of austempering treatment, with all The mechanical properties of ADI austempering at times corresponding to the processing window defined by the electrical resistance measurement satisfying the standard requirement. The formation of martensite in austempering reduced the mechanical properties of ADI but these properties could be increased by a treatment tempering at 200 degree C after cooling and to obtain more ductility and toughness as compared with that undergoing single heat treatment. This increase also extended the effective austempering time interval of ADI over which the ASTM standards were satisfied. (author)

  18. The effect of alloy elements on the microstructure and properties of austempered ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, B.Y.; Chen, E.T.; Lei, T.S. [National Taiwan Institute of Technology, Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering

    1995-05-01

    Ductile cast iron has already demonstrated excellent mechanical properties. If given proper austempering, it can exhibit even more outstanding characteristics. The process of austempering for ductile cast iron is similar to steel, and requires an adequate completely, and then rapidly quenching the austenitizing temperature allowing the matrix of ductile iron to be austenitized completely, and then rapidly quenching the austenitized ductile iron down to 300 C--400 C. Caution is required to prevent austenite from transforming into proeutectoid ferrite or pearlite. Finally, the ductile iron must be kept in an isothermal condition for a proper length of time. Many kinds of experimental techniques such as quantitative metallography, magnetic change, dilatometry, X-ray diffraction, electrical resistivity change etc., may be used to measure the phase transformation during the austempering of ductile irons. However, the method of measuring the change of electrical resistivity, not only provides continuous and complete data, but also the time to start and to finish for both stages of the reaction can be significantly determined. In this paper, the effect of alloy elements on the microstructure and property of ADI was investigated. First, the specimens containing Mn, Cu, Ni and Mo were made separately, then a PC-controlled vacuum heat treating system was used for the heat treatments.

  19. Effects Of 0.25 % Mo (Molybdenum Which Is Contained In The Ductile Cast Iron On Mechanical Properties Of Austempered Ductile Iron (ADI.

    Directory of Open Access Journals (Sweden)

    Nukman Nukman

    2010-10-01

    Full Text Available The aim of this research is to investigate the effects of 0.25 % Mo (Molybdenum which is contained in the ductile cast iron on mechanical properties of Austempered Ductile Iron (ADI. The various temperatures and the holding times are used in the heat treatment processes. Using a given 0.25 % Mo in the ductile iron, ADI's alloyed developes a higher ultimate tensile stress value and decreases the elongation if we compare with the as cast (non alloy ductile iron. The higher impact energy value obtained at 9000 C austenization and 375o C austempering temperatures during 60 minutes holding times. The structure changes into ausferrit.

  20. Influence of austempering heat treatment on mechanical and corrosion properties of ductile iron samples

    Directory of Open Access Journals (Sweden)

    M. Janjić

    2016-07-01

    Full Text Available Mechanical properties and corrosion resistance of metals are closely related to the microstructure characteristics of the material. The paper compares the results of these two sets of properties after investigating samples of base ductile iron and heat-treated samples of the base austempered ductile iron (ADI. The basic material is perlite ferritic iron alloyed with copper and nickel. To test the corrosion rate of the base material (ductile iron and the heattreated samples (ADI, electrochemical techniques of potentiostatic polarization were used (the technique of Tafel curves extrapolation and the potentiodynamic polarization technique.

  1. Austempering transformation kinetics of austempered ductile iron obtained by Mössbauer Spectroscopy

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2008-10-01

    Full Text Available The composition of metallic matrix in ductile iron as-cast and after austempering at temperatures of 280, 330 and 380oC (ADI wasexamined. The study presents the results of these examinations obtained by Mössbauer spectroscopy. The specimens were taken from castrods of 60mm diameter. Using calculated values of the parameters of hyperfine interactions (isomeric shift IS, quadrupole splitting QS andhyperfine effective magnetic field H, isolated by deconvolution of the experimental spectrum, the constituents of the metallic matrix were identified in terms of both quantity and quality. The measured values as well as the data compiled in literature indicate that component Z1 (the, so called, Zeeman spectrum sextet is related with 57Fe atoms present in the structure of ferrite α1 (I stage of o→α1 + st transformation, component Z2 is typical of ferrite α2 (II stage of st→α2 + carbides transformation, while component Z3 has its origin in 57Fe atoms seated in the structure of carbides (Fe3C, Fe2C or Fe2,4C. On the other hand, by analysis of the parameters of hyperfine interactions describing the non-magnetic components (L and Q it has been proved that they are typical of austenite.

  2. Effect of shot peening process on fatigue behavior of an alloyed austempered ductile iron

    Directory of Open Access Journals (Sweden)

    Amir Sadighzadeh Benam

    2011-08-01

    Full Text Available Shot peening is one of the most common surface treatments to improve the fatigue behavior of metallic parts. In this study the effect of shot peening process on the fatigue behavior of an alloyed austempered ductile iron (ADI has been studied. Austempering heat treatment consisted of austenitizing at 875℃ for 90 min followed by austempering at three different temperatures of 320, 365 and 400℃. Rotating-bending fatigue test was carried out on samples after shot peening by 0.4 – 0.6 mm shots. XRD and SEM analysis, micro hardness and roughness tests were carried out to study the fatigue behavior of the samples. Results indicate that the fatigue strengths of samples austempered at 320, 365 and 400℃ are increased by 27.3%, 33.3% and 48.4%, respectively, after shot peening process.

  3. The abrasion and impact-abrasion behavior of austempered ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.; Dogan, Omer N.; Lerner, Y.S. (University of Northern Iowa)

    1998-01-01

    Austempering of ductile irons has led to a new class of irons, Austempered Ductile Irons (ADIs), with improved mechanical strength and fracture toughness lacking in gray cast irons. Laboratory wear tests have been used to evaluate the abrasive and impact-abrasive wear behavior of a suite of ADIs. The use of high-stress, two-body abrasion, low-stress, three-body abrasion, and impact-abrasion tests provides a clear picture of the abrasive wear behavior of the ADIs and the mechanisms of material removal. When combined with hardness measurements, fracture toughness and a knowledge of the microstructure of the ADIs, the overall performance can be assessed relative to more wear resistant materials such as martensitic steels and high-chromium white cast irons

  4. Wear behavior of an austempered ductile iron containing Mo-Ni-Cu

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, S.; Rahimi, M.A. [Faculty of Materials Engineering, Sahand Univ. of Technology, Tabriz (Iran)

    2005-07-01

    The aim of the this investigation is to study the influence of Ni on tribiological behavior of an austempered ductile iron (ADI) containing Mo, Ni and Cu. Ductile irons with chemical composition Fe-3.56%C-2.67%Si -0.25%Mo-0.5%Cu and Ni contents of 0.8 and 1.5% were cast into standard Y-blocks. Wear test samples were machined off from the bottom section of blocks. Austenitizing heat treatment was carried out at 870 C temperature followed by austempering at 270, 320, and 370 C for 5-1140 minutes. The wear test was carried out by using block-on-ring test machine. Sliding dry wear behavior was studied under applied loads of 50, 100 and 150 N. The results show that wear resistance is independent of austempering temperature with an applied load of 50 N, but there is a strong dependence at higher austempering temperatures with applied loads of 100 and 150 N. Wear mechanism is described as being due to subsurface fatigue, with cracks nucleated at plastically, deformed graphite interfaces. The wear controlling mechanism is the crack growth when wear shows a dependence on applied load and austempering temperature. (orig.)

  5. Impact toughness and fracture toughness of austempered ductile iron

    Directory of Open Access Journals (Sweden)

    Jingcheng LIU

    2004-11-01

    Full Text Available The impact toughness and fracture toughness ofaustermpered ductile iron (ADI are described. The notched and un-notched charpy impact toughness of ADI at room temperature are somewhat lower than that of steel castings or forged steel pieces, however, they are approximately three times higher than that of mormal pearlitic ductile iron. The impact toughness of ADI decreases with decreasing temperature; but at -40 ℃ it still maintains about 70% of the value at room temperature. The properties of fracture toughness are important in safety design and failure analysis. In this study all fracture toughness data of ADI are higher than that of conventional ductile iron, and are equivalent to or better than that of steel castings o forged steel pieces with the tensile strength equivalent to ADI.

  6. Microstructural investigation of austempered ductile irons with ultrasonic method; Ultraschall-Gefuegeuntersuchungen von zwischenstufenverguetetem Sphaeroguss

    Energy Technology Data Exchange (ETDEWEB)

    Topuz, A. [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical Engineering Dept.; Topcu, E. [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical Engineering Dept.; Bakkaloglu, A. [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical Engineering Dept.; Marsoglu, M. [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical Engineering Dept.

    1997-06-01

    In this study, the relationship between the matrix structure and the sonic velocity of ductile iron in the as-cast and austempered heat treatment conditions was investigated. The sonic velocity in 12 different ductile irons (unalloyed, alloyed with Ni, Mo, Cu, Ni+Cu and Ni+Mo+Cu) has been measured in the as-cast condition and austempered conditions. The investigations have shown that cast iron that should meet the minimum specification of 90% nodularity requires the minimum velocity of 5680 m/s in the as-cast condition and 5450 m/s in the at 235 C austempered condition. From experimental data the equation CT{sup a}=B has been found for austempered conditions. (orig.) [Deutsch] In der vorliegenden Arbeit wurde der Zusammenhang zwischen dem Matrixgefuege und der Schallgeschwindigkeit von Sphaeroguss im Guss- und Zwischenstufenverguetungszustand untersucht. Die Schallgeschwindigkeit wurde in 12 verschiedenen Proben aus Sphaeroguss (unlegiert, legiert mit Ni, Mo, Cu, Ni+Cu und Ni+Mo+Cu) im gegossenen und vergueteten Zustand gemessen. Die Untersuchungen ergaben, dass Gusseisen mit einem Grad der Sphaerolitbildung von mindestens 90% die geringste Schallgeschwindigkeit von 5680 m/s im Gusszustand und 5450 m/s im zwischenstufenvergueteten Zustand erreichte. Aus den experimentellen Ergebnissen wurde die Formel CT{sup a}=B fuer den zwischenstufenvergueteten Zustand errechnet. (orig.)

  7. Investigations on the fracture toughness of austempered ductile iron alloyed with chromium

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P. Prasad; Putatunda, Susil K

    2003-04-15

    An investigation was carried out to examine the influence of chromium content on the plane strain fracture toughness of austempered ductile iron (ADI). ADIs containing 0, 0.3 and 0.5 wt.% chromium were austempered over a range of temperatures to produce different microstructures. The microstructures were characterized by optical microscopy and X-ray diffraction. Plane strain fracture toughness of all these materials was determined and correlated with microstructure and chromium content. The chromium content was found to influence the fracture toughness through its influence on the processing window. Since the chromium addition shifts the processing window to shorter durations, the higher chromium alloys at higher austempering temperatures tend to fall outside of the processing window, resulting in less than optimum microstructure and inferior fracture toughness. A small chromium addition of 0.3 wt.% was found to be beneficial for the fracture toughness of ADI.

  8. Thermal Stability of Austempered Ductile Iron Evaluated in a Temperature Range of 20-300K

    Directory of Open Access Journals (Sweden)

    Dawid MYSZKA

    2016-05-01

    Full Text Available The aim of this article was to determine through changes in magnetic properties the stability of the austempered ductile iron (ADI microstructure during temperature changes in a range of 20 – 300 K. The measurements were taken in a vibrating sample magnetometer (VSM using Fe27Ni2TiMoAlNb austenitic stainless steel and four types of austempered ductile iron obtained under various heat treatment conditions. The plotted curves showing changes in the magnetisation degree as a function of temperature had a number of characteristic points illustrating changes taking place in the microstructure. For each of the materials examined, the martensite start temperature Ms and the temperature range within which the martensitic transformation takes place were identified.

  9. Statistical Assessment of the Impact of Elevated Contents of Cu and Ni on the Properties of Austempered Ductile Iron

    Directory of Open Access Journals (Sweden)

    Nawrocki P.

    2016-12-01

    Full Text Available The article presents a statistical analysis of data collected from the observation of the production of austempered ductile iron. The impact assessment of the chemical composition, i.e. high contents of Cu and Ni on the properties of ductile iron isothermal tempered is critical to find the right chemical composition of austempered ductile iron. Based on the analyses range of the percentage of Cu and Ni which were selected in the cast iron to obtain material with high strength properties.

  10. Sensitivity of Austempering Heat Treatment of Ductile Irons to Changes in Process Parameters

    Science.gov (United States)

    Boccardo, A. D.; Dardati, P. M.; Godoy, L. A.; Celentano, D. J.

    2018-03-01

    Austempered ductile iron (ADI) is frequently obtained by means of a three-step austempering heat treatment. The parameters of this process play a crucial role on the microstructure of the final product. This paper considers the influence of some process parameters (i.e., the initial microstructure of ductile iron and the thermal cycle) on key features of the heat treatment (such as minimum required time for austenitization and austempering and microstructure of the final product). A computational simulation of the austempering heat treatment is reported in this work, which accounts for a coupled thermo-metallurgical behavior in terms of the evolution of temperature at the scale of the part being investigated (the macroscale) and the evolution of phases at the scale of microconstituents (the microscale). The paper focuses on the sensitivity of the process by looking at a sensitivity index and scatter plots. The sensitivity indices are determined by using a technique based on the variance of the output. The results of this study indicate that both the initial microstructure and the thermal cycle parameters play a key role in the production of ADI. This work also provides a guideline to help selecting values of the appropriate process parameters to obtain parts with a required microstructural characteristic.

  11. Rolling contact fatigue strength of successive austempered ductile cast iron; Chikuji austemper shori kyujo kokuen chutetsu no korogari hiro kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, T. [Yamaguchi University, Yamaguchi (Japan). Faculty of Engineering; Ogi, K. [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Sawamoto, A. [Yamaguchi Univ., Yamaguchi (Japan). Faculty of Education

    1998-04-25

    The holding time of austempered spheroidal graphite cast iron material is allowed to vary in heat treatment especially at the lower bainite transformation zone during the process for the preparation of specimens different from each other in the amount of {gamma}-pool, and the specimens are tested for their rolling contact fatigue strength. The effects of the amount of {gamma}-pool, roughness of the bainite structure, and work-hardening, on the rolling fatigue strength are also studied. Findings obtained as the result of experiment are stated below. In the case of an austempered ductile cast iron specimen containing a {gamma}-pool amount that occupies a high rate of 6.52%, the rolling fatigue withstanding limit exhibits a relatively high level of 1310MPa, which becomes approximately 1245MPa when the holding time is extended in the lower bainite transformation zone. The limit rises to approximately 1320MPa at a stage where the {gamma}-pool virtually disappears. In a successive austempering treatment process that aims at improving on machinability and at allowing sufficient fatigue strength to be maintained, it is necessary to allow the holding time in the bainite zone to be long enough for the {gamma}-pool to disappear and for the lower bainite structure to grow sufficiently. 5 refs., 10 figs., 4 tabs.

  12. In-situ measurement of phase transformation kinetics in austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Leopold, E-mail: leopold.meier@utg.de [Technische Universität München, Lehrstuhl für Umformtechnik und Gießereiwesen, Walther-Meißner-Straße 4, 85748 Garching (Germany); Hofmann, Michael, E-mail: michael.hofmann@frm2.tum.de [Technische Universität München, Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Lichtenbergstraße 1, 85748 Garching (Germany); Saal, Patrick, E-mail: patrick.saal@utg.de [Technische Universität München, Lehrstuhl für Umformtechnik und Gießereiwesen, Walther-Meißner-Straße 4, 85748 Garching (Germany); Volk, Wolfram, E-mail: wolfram.volk@utg.de [Technische Universität München, Lehrstuhl für Umformtechnik und Gießereiwesen, Walther-Meißner-Straße 4, 85748 Garching (Germany); Hoffmann, Hartmut, E-mail: hartmut.hoffmann@utg.de [Technische Universität München, Lehrstuhl für Umformtechnik und Gießereiwesen, Walther-Meißner-Straße 4, 85748 Garching (Germany)

    2013-11-15

    Austempered ductile iron (ADI) alloyed with 0.42% Mn and 0.72% Cu was heat treated in a mirror furnace and the phase transitions were studied in-situ by neutron diffraction. The heat treatment consisted of austenitisation at 920 °C and isothermal austempering at 400 °C, 350 °C and 300 °C, respectively. Due to the growth of ferrite platelets, the austenite content decreases rapidly at all temperatures within the first 15–20 min and reaches a stable plateau after 35 min (400 °C) to 80 min (300 °C). The carbon content of the residual austenite, which was monitored and characterised by the change of the lattice parameter, increases up to 1.6 wt.% caused by redistribution from the newly formed ferrite. While at higher austempering temperatures this takes place almost parallel to the phase transformation, at 300 °C the redistribution of carbon to austenite lags behind considerably. Furthermore the neutron data revealed an austenite peak asymmetry during austempering which is attributed to successive phase transformation. It results temporarily in two fractions of austenite, an initial low-carbon and an enriched high-carbon modification. - Highlights: • The heat treatment of ADI was studied in detail by in-situ neutron diffraction. • The phase fractions were monitored and evaluated quantitatively. • The austenite carbon content increased up to 1.6 wt.% during austempering. • Peak asymmetries indicate two austenite fractions during highest transformation rates.

  13. Effect of Cu, Mo, Si on the content of retained austenite of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Mi, Y. [Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering

    1995-05-01

    In this paper, the effects of Cu, Mo, Si contents on the volume fraction of retained austenite of austempered ductile iron (ADI) are analyzed exactly by X-ray diffraction, and the fracture modes of test samples with different volume fraction of retained austenite are investigated by SEM. It is shown that the retained austenite content increases with the content of copper, decreases with the content of molybdenum, and reaches the maximum with a certain content of silicon. When the retained austenite content decreases, the fracture modes of test samples change from ductile fracture to cleavage fracture.

  14. The bainite reaction kinetics in austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Taran, Yu.N.; Uzlov, K.I.; Kutsov, A.Yu. [State Metall. Acad., Dnepropetrovsk (Ukraine). Phys. Metall. Dept.

    1997-11-01

    Bainitic reaction kinetics in ductile iron contained according to Ukrainian standard (weight%) 3.60-3.80 carbon, 2.60-2.80 Si, {proportional_to}0.12 Mn, {proportional_to}0.60 Cu and additionally alloyed by Mo (0.15-0.20) has been studied. It was found that the overall transformation kinetics becomes slower as transformation temperature increase. This is because more intensive redistribution of carbon into austenite at higher temperatures. Two austenites with different carbon content have been fixed and kinetics of their lattices parameters has been studied. (orig.). 6 refs.

  15. Ameliorated Austenite Carbon Content Control in Austempered Ductile Irons by Support Vector Regression

    Directory of Open Access Journals (Sweden)

    Chan-Yun Yang

    2013-01-01

    Full Text Available Austempered ductile iron has emerged as a notable material in several engineering fields, including marine applications. The initial austenite carbon content after austenization transform but before austempering process for generating bainite matrix proved critical in controlling the resulted microstructure and thus mechanical properties. In this paper, support vector regression is employed in order to establish a relationship between the initial carbon concentration in the austenite with austenization temperature and alloy contents, thereby exercising improved control in the mechanical properties of the austempered ductile irons. Particularly, the paper emphasizes a methodology tailored to deal with a limited amount of available data with intrinsically contracted and skewed distribution. The collected information from a variety of data sources presents another challenge of highly uncertain variance. The authors present a hybrid model consisting of a procedure of a histogram equalizer and a procedure of a support-vector-machine (SVM- based regression to gain a more robust relationship to respond to the challenges. The results show greatly improved accuracy of the proposed model in comparison to two former established methodologies. The sum squared error of the present model is less than one fifth of that of the two previous models.

  16. Effect of heat treatment on the thermal expansion coefficient of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Tadayon saidi, M. [Dept. Metallurgy-Karaj Azad Univ.-Karaj (Iran); Baghersaie, N. [Tehran Center, Control Dept., Eng. Research Inst., Ministry of Jihad Agriculture (Iran); Varahram, N. [RAZI Metallurgical Research Inst.-Tehran (Iran)

    2005-07-01

    Austempered ductile iron provide a unique combination of strength and toughness coupled with excellent design flexibility for automotive application as compared to forged or cast steels. Some material properties such as thermal expansion coefficient and its influence in final machining tolerance is a matter of discussion in the automotive industry. In this study the effect of heart treatment cycle on the microstructure and thermal expansion of ADI was investigated. Samples were austempered at 275 C and 375 C for one hour and then dilatometric test carried out in the temperature range of 50 C to 350 C, then the result was compared with the thermal expansion coefficient of forged steel. Microstructure and mechanical investigations were used to the assurance of these results. The results indicate that replacing of forged steel with ADI due to lower cost production and reduction in weight is possible if the correct tolerance were selected. (orig.)

  17. Effects of boron addition and austempering time on microstructure, hardness and tensile properties of ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Guerra L, F.V. [Instituto de Inv. En Metalurgia y Materiales UMSNH, México (Mexico); Bedolla-Jacuinde, A., E-mail: abedollj@icloud.com [Instituto de Inv. En Metalurgia y Materiales UMSNH, México (Mexico); Mejía, I. [Instituto de Inv. En Metalurgia y Materiales UMSNH, México (Mexico); Facultad de Ingeniería Mecánica UAEH, México (Mexico); Zuno, J. [Facultad de Ingeniería Mecánica UAEH, México (Mexico); Maldonado, C. [Instituto de Inv. En Metalurgia y Materiales UMSNH, México (Mexico)

    2015-11-11

    The present work analyzes the effect of boron addition to an Austempered Ductile Iron, in amounts from zero to 120 ppm. It has been found that boron has a strong effect on the equivalent carbon content, resulting in an increase on the precipitated graphite volume and a decrease in the dissolved carbon content in the matrix. This in turn, increases the ferrite volume fraction in the as-cast conditions from 0.24 in the base alloy to 0.78 for the iron with 120 ppm of boron. Furthermore, a decrease in the nodularity from 100% in the base alloy to 83% with 120 ppm of boron has been observed. During austempering, the transformation to ausferrite was faster and lower volumes of martensite and unstable austenite were detected when boron increased; this promoted lower hardness values, 239 HV for the base iron and 189 HV for the 120 ppm boron alloy. The increase in hardness and strength, typical for the start of bainite formation, were not observed in the boron added irons, but just in the base alloy. Under this basis, it is assumed that at least the addition of 60 ppm of boron extended the optimal processing window. The higher values of strength and ductility were obtained for the alloy with 60 ppm of boron; these results are discussed in terms of the graphitizing effect of boron in these irons and the reduced amount of carbon dissolved in austenite.

  18. Effect of austempering parameters on microstructure and mechanical properties of horizontal continuous casting ductile iron dense bars

    Directory of Open Access Journals (Sweden)

    Chun-jie Xu

    2015-03-01

    Full Text Available In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters (i.e. austenitizing temperature and time, and austempering temperature and time on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting (HCC. The results show that the major factors influencing the hardness of austempered ductile iron (ADI are austenitizing temperature and austempering temperature. The fraction of retained austenite increases as the austenitizing and austempering temperatures increase. When austenitizing temperature is low, acicular ferrite and retained austenite can be efficiently obtained by appropriately extending the austenitizing time. The proper austmepering time could ensure enough stability of retained austenite and prevent high carbon austenite decomposition. The optimal mechanical properties of ADI can be achieved with the following process parameters: austenitizing temperature and time are 866 °C and 135 min, and austempering temperature and time are 279 °C and 135 min, respectively. The microstructure of ADI under the optimal austempering process consists of fine acicular ferrite and a small amount of retained austenite, and the hardness, tensile strength, yield strength, elongation and impact toughness of the bars are HBW 476, 1670 MPa, 1428 MPa, 2.93% and 25.7 J, respectively.

  19. Morphology and constitution of the phases in as-welded microstructure of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.Y.; Zhou, Z.F.; Sun, D.Q.

    2005-06-15

    It was found by optical and electron microscopic examination of the microstructure of as-weld austempered ductile iron that the weld matrix is composed of austenite and bainite, the volume fractions of which were determined. In addition, the carbon content of austenite was measured and therefore the average carbon content of the matrix was calculated. In the matrix of the weld metal two types of bainite, bainite ferrite and lower bainite, were found. According to the morphology and distribution of the bainite plates, the nucleation and growth modes of bainite was inferred. (author)

  20. Mathematical formalisms to represent knowledge concerning the production process of austempered ductile iron

    Directory of Open Access Journals (Sweden)

    D. Wilk-Kołodziejczyk

    2015-10-01

    Full Text Available The aim of this study is to develop computer tools for calculation of the Fe - Fe3C phase equilibrium diagram. The phase equilibrium diagram is of fundamental importance in materials science and heat treatment processes of ferrous alloys. It enables prediction of carbon steel microstructure in the annealed condition, and facilitates selection of proper temperature for the heat treatment process. Choosing the right values of the heat treatment process parameters is essential in the production of Austempered Ductile Iron (ADI.

  1. Effects of matrix structures on fracture mechanisms of austempered ductile cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Shigeru; Matsufuji, Kenichi [Oita Univ. (Japan); Mitsunaga, Koichi [Kagoshima Junior Womens College (Japan); Takahara, Masao [Isuzu Motors, Kawasaki, Kanagawa (Japan)

    1995-12-31

    On the fatigue behavior of Austempered Ductile Iron (so called ADI), rotating fatigue tests in very high cycle region were performed. The S-N curve represented the double bending. This behavior is caused by the high cycle (>10{sup 7} cycles) fracture, and called the complex three region fractures. The main reason is the work hardening in the surface layer. Therefore, it was removed by electropolishing the surface layer with work hardening. The S-N curve did not show the double bending mentioned above. The fatigue strength with bainitic structure of electropolished ADI was higher than those of mother pearlitic structure.

  2. Multi-Response Optimization of Carbidic Austempered Ductile Iron Production Parameters using Taguchi Method

    Science.gov (United States)

    Dhanapal, P.; Mohamed Nazirudeen, S. S.; Chandrasekar, A.

    2012-04-01

    Carbide Austempered Ductile Iron (CADI) is the family of ductile iron containing wear resistance alloy carbides in the ausferrite matrix. This CADI is manufactured by selecting and characterizing the proper material composition through the melting route done. In an effort to arrive the optimal production parameters of multi responses, Taguchi method and Grey relational analysis have been applied. To analyze the effect of production parameters on the mechanical properties signal-to-noise ratio and Grey relational grade have been calculated based on the design of experiments. An analysis of variance was calculated to find the amount of contribution of factors on mechanical properties and their significance. The analytical results of Taguchi method were compared with the experimental values, and it shows that both are identical.

  3. Influence of casting size and graphite nodule refinement on fracture toughness of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.C.; Hsu, C.H.; Chang, C.C.; Feng, H.P. [Tatung Inst. of Tech., Raipei (Taiwan, Province of China). Dept. of Materials Engineering

    1998-10-01

    Casting size affects the solidification cooling rate and microstructure of casting materials. Graphite nodules existing in the structure of ductile iron are an inherent and inert second phase that cannot be modified in subsequent heat-treatment processing. The matrix and the fineness of the second phase undoubtedly have some impact on the fracture toughness of the as-cast material, as does the subsequent heat treatment, as it alters the microstructure. This research applied austempering heat treatment to ductile iron of different section sizes and graphite nodule finenesses. The influence of these variables on the plane strain fracture toughness (K{sub IC}) of the castings so treated was compared to that of the as-cast state. Metallography, scanning electron microscopy (SEM), and X-ray diffraction analysis were performed to correlate the properties attained to the microstructural observation.

  4. In-Situ Studies of Intercritically Austempered Ductile Iron Using Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Druschitz, Alan [University of Alabama, Birmingham; Aristizabal, Ricardo [University of Alabama, Birmingham; Druschitz, Edward [University of Alabama, Birmingham; Hubbard, Camden R [ORNL; Watkins, Thomas R [ORNL; Walker, Larry R [ORNL; Ostrander, M [Rex Heat Treat, Anniston, AL

    2012-01-01

    Intercritically austempered ductile irons hold promise for applications requiring fatigue durability, excellent castability, low production energy requirements, reduced greenhouse gas emissions and excellent machinability. In the present study, four different ductile iron alloys, containing manganese and nickel as the primary austenite-stabilizing elements, were heat treated to obtain different quantities of austenite in the final microstructure. This paper reports the microstructures and phases present in these alloys. Further, lattice strains and diffraction elastic constants in various crystallographic directions and the transformation characteristics of the austenite as a function of applied stress were determined using in-situ loading with neutron diffraction at the second generation Neutron Residual Stress Facility (NRSF2) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL).

  5. Un-lubricated sliding wear performance of unalloyed austempered ductile iron under high contact stresses

    Energy Technology Data Exchange (ETDEWEB)

    Zimba, J.; Samandi, M.; Yu, D.; Chandra, T.; Navara, E.; Simbi, D.J

    2004-08-15

    The dry sliding wear behaviour of unalloyed austempered ductile iron (ADI) was studied in a reciprocating tribotester using contact loads in the range 40-140 N. The results obtained show that austempering in the temperature range 325-375 deg. C significantly improves the tribological properties of the unalloyed spheroidal graphite iron. The friction coefficient was reduced by a factor of ten (10) with the wear resistance increasing by several orders of magnitude. The improvement in wear performance was attributed to: the lubricity inherent the graphite nodules, the increase in initial hardness brought about by the ausferrite structure, and the work hardening of the surface as retained austenite is transformed to martensite by plastic deformation, and in the process reducing considerably the sensitivity of the specific wear rate to loading. Optical, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) results pertaining to the wear tracks suggest that two main wear mechanisms are responsible for material removal in the unlubricated sliding wear of ADI, namely, plastic yielding and oxidation, with the latter producing hard oxide particles that act as abrasives. Massive plastic yielding followed by delamination and sometimes oxidation accounts for material loss in the much softer as cast ductile spheroidal graphite iron.

  6. Effect of boron on the microstructure and mechanical properties of carbidic austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Peng Yuncheng; Jin Huijin [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu Jinhai, E-mail: pyc_wanhj@163.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Li Guolu [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China)

    2011-11-25

    Highlights: {yields} Boron are applied to carbidic austempered ductile iron (CADI). {yields} Boron microalloying CADI is a new high hardenability of wear-resistant cast iron. {yields} Addition of boron to CADI significantly improves hardenability. {yields} Effect of boron on the CADI grinding ball were investigated. {yields} Optimum property is obtained when boron content at 0.03 wt%. - Abstract: Carbidic austempered ductile iron (CADI) castings provide a unique combination of high hardness and toughness coupled with superior wear resistance properties, but their hardenability restricts their range of applications. The purpose of this study was to investigate the influence of boron on the microstructure and mechanical properties of CADI. The experimental results indicate that the CADI comprises graphite nodules, which are dispersive boron-carbides that are distributed in the form of strips, and the matrix is a typical ausferritic matrix. Microscopic amounts of boron can improve the hardenability of CADI, but higher boron content reduces the hardenability and toughness of CADI. The results are discussed in the context of the influence of boron content on the microstructure and mechanical properties of grinding balls.

  7. Influence of Casting Section Thickness on Fatigue Strength of Austempered Ductile Iron

    Science.gov (United States)

    Olawale, J. O.; Ibitoye, S. A.

    2017-10-01

    The influence of casting section thickness on fatigue strength of austempered ductile iron was investigated in this study. ASTM A536 65-45-12 grade of ductile iron was produced, machined into round samples of 10, 15, 20 and 25 mm diameter, austenitized at a temperature of 820 °C, quenched into an austempering temperature (TA) of 300 and 375 °C and allowed to be isothermally transformed at these temperatures for a fixed period of 2 h. From the samples, fatigue test specimens were machined to conform to ASTM E-466. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) methods were used to characterize microstructural morphology and phase distribution of heat-treated samples. The fatigue strength decreases as the section thickness increases. The SEM image and XRD patterns show a matrix of acicular ferrite and carbon-stabilized austenite with ferrite coarsening and volume fraction of austenite reducing as the section thickness increases. The study concluded that the higher the value of carbon-stabilized austenite the higher the fatigue strength while it decreases as the ausferrite structure becomes coarse.

  8. Study of high cycle fatigue of PVD surface-modified austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Feng, H.P.; Lee, S.C.; Hsu, C.H.; Ho, J.M. [Tatung Inst. of Technol., Taipei (Taiwan, Province of China). Dept. of Mater. Eng.

    1999-05-25

    Austempered ductile iron (ADI) is made from ductile iron by an austempering treatment, and its main microstructure is ausferrite that is composed of acicular ferrite and high carbon austenite. The purpose of this experiment is to investigate the influence of different coating layers and the size of casting (mass effect) on the high-cycle fatigue properties of ADI. Specimens in two casting sizes of the same chemical composition were subjected to a high-toughness austempering treatment, then coated with TiN or TiCN hard films by a physical vapor deposition (PVD) process. The results showed that the fatigue limit of the small casting size ADI is 292 MPa for ADI coated with TiN and 306 MPa for ADI coated with TiCN, which are 16% and 22%, respectively, higher than that of the ADI without coating (251 MPa). For the large casting size ADI, the fatigue limits are 200, 214 and 217 MPa for ADI without coating, ADI coated with TiN and ADI coated with TiCN, respectively. ADI coated with TiN and with TiCN are 7% and 9% better than the uncoated. Thus, it is concluded that TiN and TiCN coatings by PVD can improve the high-cycle fatigue strength of ADI. This is due to the high surface hardness and possibly the ADI surface compressive residual stress as well. For the small casting size ADI, TiCN-coated specimens have a bit higher fatigue strengths and this might be attributed to the higher hardness of TiCN than TiN films. As to the effect of mass, it is found that the small casting size has better fatigue properties and benefits more from the coating films. This could have stemmed from the higher nodule count and its associated benefits in thinner castings. (orig.) 24 refs.

  9. Effect of laser surface hardening on the microstructure, hardness and residual stresses of austempered ductile iron grades

    Energy Technology Data Exchange (ETDEWEB)

    Soriano, C., E-mail: csoriano@tekniker.es [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain); Leunda, J.; Lambarri, J.; Garcia Navas, V.; Sanz, C. [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain)

    2011-06-01

    A study of the laser surface hardening process of two austempered ductile iron grades, with different austempering treatments has been carried out. Hardening was performed with an infrared continuous wave Nd:YAG laser in cylindrical specimens. The microstructure of the laser hardened samples was investigated using an optical microscope, microhardness profiles were measured and surface and radial residual stresses were studied by an X-ray diffractometer. Similar results were achieved for both materials. A coarse martensite with retained austenite structure was found in the treated area, resulting in a wear resistant effective layer of 0.6 mm to 1 mm with a microhardness between 650 HV and 800 HV. Compressive residual stresses have been found at the hardened area being in agreement with the microhardness and microstructural variations observed. The achieved results point out that the laser surface hardening is a suitable method for improving the mechanical properties of austempered ductile irons.

  10. Effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron

    Directory of Open Access Journals (Sweden)

    M. Ardestani

    2007-05-01

    Full Text Available The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325! and 400℃ after austenitizing at 875℃ and 950℃. The sub-zero treatments were carried out by cooling down the samples to -30℃, -70℃ and -196℃. The changes in volume fraction of austenite and mechanical properties were determined after cooling to each temperature. The austenite volume fraction of samples which were austenitized at 875℃ and austempered at 325℃ remained unchanged, whilst it reduced in samples austenitized at 950℃ and 875℃ for austempering temperature of 400℃. In these specimens, some austenite transformed to martensite after subzero cooling. Mechanical property measurements showed a slight increase in strength and hardness and decrease in elongation and toughness due to this transformation behavior.

  11. Influence of a novel two-step austempering process on the strain-hardening behavior of austempered ductile cast iron (ADI)

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jianghuai; Putatunda, Susil K

    2004-09-25

    An investigation was carried out to examine the influence of a novel two-step austempering process on the strain-hardening behavior of austempered ductile cast iron (ADI). Strain-hardening exponent (n value) of specimens austempered by conventional single-step austempering process as well as the novel two-step process were determined over the entire plastic deformation regions of the stress-strain curves. Optical microscopy and X-ray diffraction analysis were performed to examine mechanisms of strain-hardening behavior in ADI under monotonic (tensile) loading. Test results show that this novel two-step process has resulted in improved microstructural variables in the ADI matrix, and higher hardness, yield strength and tensile strengths, but lower ductility and strain-hardening exponent values compared to the conventional single-step austempering process. Test results also indicate that strain-hardening exponent of ADI is a function of amount and morphology of microstructural constituents and interaction intensities between carbon atoms and dislocations in the matrix.

  12. Abrasive wear of ploughshare blades made of Austempered Ductile Iron

    Directory of Open Access Journals (Sweden)

    Jiří Votava

    2007-01-01

    Full Text Available The objective of this article consists in exhaustive monitoring of abrasive wear and subsequent evaluation of nodular cast iron with spheroidal graphite used as the base material for production of ploughshare blades. Nodular cast iron has a lot of convenient properties for production of these components. We have tested this material in field tests. For these tests there were manufactured ploughshare blades (directly according to original. These ploughshare blades were tested in practical conditions of agricultural company Farma Nedvězí Ltd. Three ploughshare blades were used in natural cast state and the others were heat-treated. During the test there were measured decreases of weights of the ploughshare blades and subsequently compared with decreases of original ploughshare blades, produced by company Opall Agri which are ordinarily available at our market.

  13. Comparing the possibilities of austenite content determination in austempered ductile iron

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2011-07-01

    Full Text Available The article presents various methods for assessment of the austenite volume fraction in Austempered Ductile Iron (ADI. Tests were carried out on two types of ADI, i.e. unalloyed and alloyed with the addition of 0.72%Cu and 0.27%Mo, heat treated under different conditions of isothermal transformation to obtain different austenite volume fractions. The test material was then subjected to metallographic examinations, X-ray diffraction (XRD analysis, an analysis using the author's genuine programme of artificial neural networks, image analysis and magnetic measurements. The results were compared with each other indicating the possibility of a quantitative measurement of austenite and other phases present in cast iron. It was found that different methods of measurement are not fully consistent with each other but show similar results of the austenite content.

  14. Effect of initial microstructure on the activation energy of second stage during austempering of ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Campos-Cambranis, R.E.; Narvaez Hernandez, L. [UASLP, San Luis Potosi (Mexico). Instituto de Metalurgia; Cisneros-Guerrero, M.M. [Inst. Tecnologico de Saltillo (Mexico). Dept. Metal-Mecanica; Perez-Lopez, M.J. [Inst. Tecnologico de Zacatecas (Mexico)

    1998-03-13

    The good balance among mechanical properties of austempered ductile irons (ADI) mainly depends on the matrix microstructure, which basically consists of acicular ferrite and carbon-enriched austenite. This structure is produced by isothermal transformation of the austenite over the temperature range of 523 to 673 K. It is well accepted that during the isothermal holding, the transformation takes place in two stages. In the first stage, the austenite decomposes into acicular ferrite and carbon-enriched austenite. When the austenite is transformed at temperatures higher than 623 K, the acicular ferrite is free of carbides; at temperatures below 623 K, besides the formation of the acicular ferrite and austenite, precipitation of carbides takes place over the plates of the acicular ferrite. The mixture of ferrite and austenite is known as ausferrite being the responsible for the good mechanical properties of ADI. In this work, the ausferrite obtained above and below 623 K will be termed high and low temperature ausferrite respectively. Although ausferrite does not transform at room temperature, it is not a thermodynamically stable structure. Consequently, if the isothermal holding is extended, or if ADI is heated at high temperatures (523 to 800 K), the second stage of the austempering reaction will occur. During this stage, the carbon rich austenite will decompose into ferrite and carbides. In order to establish the maximum working temperature of ADI, it is necessary to characterize the thermal stability of ausferrite microstructure, since once stage II takes place, the mechanical properties, in particular ductility and toughness, are adversely affected. In the present work the influence of previous ausferrite microstructure (that obtained during first stage) of an alloyed ductile iron (0.6%Ni, 0.15%Mo) on the empirical activation energy of stage II is studied.

  15. Mechanisms of poor machinability of austempered ductile iron; Austemper kyujo kokuen chutetsu no nansaku kiko

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, S.; Miyaji, H. [National Research Institute for Metals, Tsukuba (Japan); Nakajima, H. [Hosei University, Tokyo (Japan)

    1995-07-01

    For the purpose of high strength distempered ductile iron (ADD) has the potential to reduce the size and weight of automotive parts, however poor machinability has made it difficult to achieve broad commercial application. To clarify the mechanism of poor machinability of ADI, (1) the chips was analyzed by X-ray diffraction, (2) the cutting front was observed after instantaneously stopping using a quick stop device, (3) for the turning tool wear was measured and (4) sawability of material was compared using a saw test. The results were as follows: In the low cutting-speed range, it was fount teat strain induced transformation from retained austerity ({gamma}R) to martensite ({alpha}{prime}) occurred, and this corresponded to the poorest machinability in the saw test. In the high cutting-speed range. {gamma}R{yields}{alpha}{prime} transformation was limited to the damaged layer, because the temperature of chips exceeded Md point. The tool wear during turning of ADI was generated closer to the cutting edge, as compared with turning of steels. Observation of chip forming state showed that this phenomenon resulted from the following two factors: (a) the formation of saw-tooth like chips ant the decrease of the tool-chip contact length due to the spheroidal graphite, and (b) the increase of cutting force due to the high hardness of the bainitic phase and the damaged layer hardened by the {gamma}R{yields}{alpha}{prime} transformation. 24 refs., 9 figs., 3 tabs.

  16. Austempered Ductile Iron Manufacturing Data Acquisition Process with the Use of Semantic Techniques

    Directory of Open Access Journals (Sweden)

    Wilk-Kołodziejczyk D.

    2016-12-01

    Full Text Available The aim of this work was to propose a methodology supporting the task of collecting the comparative data on studies of the mechanical properties of ADI. Collecting of research data is an important step in the process of finding the optimum design solutions for newly made products - experimental data allow us properly calibrate the manufacturing process of ADI to let the final product achieve the required properties. Parameters of the ADI production process, i.e. the time and temperature of austenitising and austempering, as well as the alloying elements added to ductile iron affect the ADI properties. The design process can use research data collected, among others, from the Web. As stated in the article, the process of data acquisition can be supported by semantic technologies, including ontologies which are descriptive logic formalism.

  17. Design and control of chemical compositions for high-performance austempered ductile iron

    Directory of Open Access Journals (Sweden)

    Gong Wenbang

    2012-05-01

    Full Text Available This paper presents the effects of chemical compositions of austempered ductile iron (ADI on casting quality, heat treatment process parameters and mechanical properties of final products. Through experiment and production practice, the impacts of carbon equivalent on ADI and its mechanical properties have been studied. Proper content ranges for carbon and silicon have been obtained to avoid ADI casting shrinkage and graphite floatation, as well as to achieve the optimal mechanical properties. According to the impact of silicon content on austenite phase transformation, the existing form of carbon in ADI has been analyzed, and also the formula and diagram showing the relationship between austenitizing temperature and carbon content in austenite have been deduced. The chemical composition range for high performance ADI and its control points have been recommended, to serve as a reference for production process.

  18. Fatigue of Austempered Ductile Iron with Two Strength Grades in Very High Cycle Regime

    Science.gov (United States)

    Zhang, Jiwang; Li, Wei; Song, Qingpeng; Zhang, Ning; Lu, Liantao

    2016-03-01

    In this study, Austempered ductile irons (ADIs) with two different strength grades were produced and the fatigue properties were measured at 109 cycles. The results show that the S-N curves give a typical step-wise shape and there is no fatigue limit in the very high cycle fatigue regime. The two grades ADI have the similar fracture behaviors and fatigue failure can initiate from defects at specimen surface and subsurface zone. On the fracture surfaces of some specimens, the `granular-bright-facet' area with rich carbon distribution is observed in the vicinity of the defect. The microstructure affects the crack behaviors at the early propagation stage. The ADI with upper and lower bainite shows higher fatigue strength compared with the ADI with coarse upper bainite.

  19. Identification of Mg2Cu particles in Cu-alloyed austempered ductile iron

    Science.gov (United States)

    Górny, Marcin; Tyrała, Edward; Sikora, Gabriela; Rogal, Łukasz

    2018-01-01

    In the present work, the Mg2Cu precipitates in copper-alloyed austempered ductile iron (ADI) were identified by analyzing techniques such as TEM and SEM with EDS. It was revealed that, in castings made of ADI-containing copper, highly dispersed particles of Mg2Cu are formed, whose size does not exceed TEM. In addition to this, the exhibited impact properties of castings with Cu, Ni, and Cu+Ni were also determined. This study casts a new light on the formation of the structure of Cu-alloyed ADI. The highly-dispersive and brittle Mg2Cu particles that are located in the vicinity of the graphite nodules have a negative effect on the impact properties of ADI. It has also been shown that impact strength decreases from levels of 160-180 J (for copper-free ADI) to 90-120 J (for copper-and copper-nickel-alloyed ADI).

  20. Evaluation of Thermal Stability of Ausferrite in Austempered Ductile Iron Using Differential Scanning Calorimetry

    Science.gov (United States)

    Warsinski, Karl C.

    Austempered Ductile Iron (ADI) is prone to changes in microstructure and mechanical properties when exposed to elevated service temperatures. Differential Scanning Calorimetry has been used to evaluate the stabilizing effects of copper, nickel, molybdenum, and cobalt on the ausferrite structure. Previous studies have conflated the effects of various alloy additions, and little effort has been made to systematically catalog the effects of individual elements. The focus of the current research has been to identify alloying elements that more strongly stabilize the ausferrite structure in order to improve service life of ADI at elevated temperatures. Nickel has been shown to have a moderate stabilizing effect, while copper and molybdenum cause a much sharper increase in activation energy. Cobalt has a high stabilizing effect at 0.5% addition by weight, but a further increase to 2.36% results in a slight decrease in activation energy.

  1. Bainitic transformation in austempered ductile iron with reference to untransformed austenite volume phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadabadai, M.N. [Tehran Univ. (Iran, Islamic Republic of)

    1997-10-01

    Much interest has been focused on austempered ductile iron (ADI) because of its superior mechanical properties, which might be improved by further control of microstructure. It has so far been assumed that segregation of alloying elements in the intercellular region just delays bainitic reaction in these regions. However, the existence of bainite-free regions (UAV) even after 10,000 minutes at test temperature, e.g., 375 C, indicates something intrinsic to the mechanism of bainitic transformation. The bainitic transformation start (B{sub s}) temperature is a function of alloying elements; segregation of alloying elements can also alter the B{sub s} temperature. In other words, B{sub s} temperature in the region near graphite should be different from the intercellular region. Therefore, the intercellular region with higher concentration of alloying elements such as Mn should have a lower B{sub s} temperature, which leads to formation of UAV even after a long high-temperature austempering time (hereafter, this stable UAV will be named as the minimum UAV value). To examine this concept, theoretical and experimental procedures were employed.

  2. Effects of austempering heat treatment conditions on fracture toughness of austempered ductile cast iron; Kyujo kokuen chutetsu no hakai jinsei ni oyobosu austemper shori no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Y.; Arai, M. [Musashi Institute of Technology, Tokyo (Japan)

    1996-03-25

    Discussions were given in various manners to learn effects of treatment conditions with respect to fracture toughness of austempered ductile cast iron. Austenitizing temperature and isothermal transforming conditions that result in comprehensively most excellent fracture toughness including tensile strength were 1173 K and 648 K - 3.6 ks, respectively. The austenitizing temperature as low as 1123 K reduces quantity of residual austenite, resulting in residual inclusion of free ferrite in the structure. If as high as 1223 K, reduction in the fracture toughness is caused under any condition as a result of increase in unstable austenite and growth of austenite into coarse particles. With respect to the isothermal transforming conditions, high fracture toughness may be achieved at a relatively high temperature. However, a structure that has been transformed from austenite to bainite causes a secondary reaction in a short time, and deposits particulates of cementite and graphite, leading to a prediction of decrease in the fracture toughness. Therefore, it is preferable that the treatment time is decreased in order to suppress the secondary reaction. 9 refs., 10 figs., 7 tabs.

  3. Effects of subzero treatment on toughness of austempered ductile cast iron; Austemper kyujo kokuen chutetsu no jinsei ni oyobosu subzero shori no koka

    Energy Technology Data Exchange (ETDEWEB)

    Tsukahara, S.; Yamada, S. [Kanto Gakuin University, Yokohama (Japan)

    1998-04-25

    Specimens of austempered ductile cast iron (ADI) after constant temperature transformation at different temperatures are tested for tension, shock, and bending, and the effects of the testing methods and testing speeds on ADI strength and toughness are investigated. Specimens are made of an austempered Fe-Si-Mg alloy cast into 25mm-thick Y-shape blocks. Heat treatment is performed in the atmosphere for test pieces manufactured by machining. In the subzero treatment, the austempered pieces are cooled in water and then immediately placed in liquid nitrogen for rapid cooling. Findings obtained are mentioned below. A test piece austempered at 773K and then cooled in water retains 26% of austenite, and this disappears after a tension test. In a test piece given subzero treatment following the cooling in water, the residual austenite is found reduced from 20% to 13%. No change is observed in the amount of residual austenite before and after a bend test and impact test whether or not the test piece has been subjected to subzero treatment. 8 refs., 8 figs., 2 tabs.

  4. Influence of Heat Treatment Conditions on Microstructure and Mechanical Properties of Austempered Ductile Iron After Dynamic Deformation Test

    Directory of Open Access Journals (Sweden)

    Myszka D.

    2014-10-01

    Full Text Available In this article, an attempt was made to determine the effect of dynamic load on the austempered ductile iron resistance obtained under different conditions of heat treatment. Tests were carried out on six types of cylindrical ductile iron samples austempered at 320, 370 and 400oC for 30 and 180 minutes. For each type of material, two samples were collected. As a next step in the investigations, the samples were subjected to a Taylor impact test. The samples after striking a non-deformable, rigid target were deformed on their front face. After Taylor test, a series of material tests was performed on these samples, noting a significant increase of hardness in the deformed part. This was particularly well visible in the ductile iron isothermally quenched at higher temperatures of 370 and 400oC. Inthezone of sample deformation, an increase in the content of ferromagnetic phase was also reported, thus indicating the occurrence of martensitic transformation in the microstructure containing mechanically unstable austenite. A significant amount of deformed graphite was also observed, which was a symptom of the deformation process taking place in samples. The ductile iron was characterized by high toughness and high resistance to the effect of dynamic loads, especially as regards the grade treated at a temperature of 370oC.

  5. Effects of heat treatment on toughness of austempered ductile cast iron with Cu and Ni; Cu-Ni tenka osutenpa chutetsu no jinsei ni oyobosu netsushori no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, M.; Takatsu, M.; Takagi, H

    1998-08-25

    The alloying of ductile cast iron with Cu and Ni is effective for the structural control in austemper heat treatment. Use of this type of cast iron is provided to produce cast iron materials with extremely high toughness and strength. In this study, the effects of austempering conditions and the addition of Cu and Ni on toughness of ductile cast iron are investigated. In austemper heat treatment, impact absorbed energy is increased by raising the austempering temperature. However, at high austempering temperatures exceeding 3.6 ks at 673K, the formation of fine pearlite proceeded, resulting in a marked decrease in the impact absorbed energy. Addition of Cu-Ni in the cast iron resulted in greater impact absorbed energy and tensile strength at any temperature during the austempering treatment. It depends on the suppression of precipitation beginning of fine pearlite and the stabilization of retained austenite. Furthermore, this cast iron alloy reduced the change in impact absorbed energy and tensile strength, induced during the austempering time. 15 refs., 12 figs., 1 tab.

  6. Effect of holding time in the ({alpha} + {gamma}) temperature range on toughness of specially austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, T.; Yamada, S. [Toyohashi Univ. of Technology (Japan). Dept. of Production Systems Engineering

    1996-07-01

    Austempered ductile iron (ADI) finds wide application in the industry because of its high strength and toughness. The QB{prime} process has been developed to produce a fine microstructure with high fracture toughness in ADI. This process involves reaustenitizing a prequenched ductile iron in the ({alpha} + {gamma}) temperature range followed by an isothermal treatment in the bainitic transformation temperature range. In the present work, the effect of holding time in the ({alpha} + {gamma}) temperature range on the structure and un-notched toughness of ADI has been studied. Prior to the austempering treatment, the as-cast ductile iron was heat treated to obtain martensitic, ferritic, and pearlitic matrix structures. In the case of prequenched material (martensitic matrix), the un-notched impact toughness increased as a function of holding time in the ({alpha} + {gamma}) temperature range. The reaustenitization heat treatment also resulted in the precipitation of fine carbide particles, identified as (Fe,Cr,Mn){sub 3}C. It was shown that the increase in holding time in the ({alpha} + {gamma}) temperature range leads to a reduction in the number of carbide particles. In the case of a ferritic prior structure, a long duration hold in the ({alpha} + {gamma}) temperature range resulted in the coarsening of the structure with a marginal increase in the toughness. In the case of a pearlitic prior structure, the toughness increased with holding time. This was attributed to the decomposition of the relatively stable carbide around the eutectic cell boundary with longer holding times.

  7. Effect of nodule count and austempering heat treatment on segregation behavior of alloying elements in ductile cast iron

    Directory of Open Access Journals (Sweden)

    E. Akbarzadeh Chiniforush

    2016-05-01

    Full Text Available The equilibrium partition ratio, k, has been measured for Mn, Mo, Si, Ni and Cu in a ductile iron with composition (wt.%: 3.45C, 0.25Mn, 0.25Mo, 2.45Si, 0.5Ni and 0.5Cu with different nodule counts obtained from different section sizes of 13, 25, 75 mm in the as cast, austenitized (at 870 °C for times 1, 4 and 6 hours and austempered (at 375 °C for times 1 to 1,440 min samples. Results show that Mn and Mo segregate positively at cell boundaries, but Si, Ni and Cu concentrate in an inverse manner in the vicinity of graphite nodules and there is a depletion of these elements at cell boundaries. Segregation curves for Ni and Cu are more smooth than for Si. Carbide formation has been observed at cell boundaries. Based on the results, the partition ratios for all elements decrease with increasing the nodule count. More carbide with coarser morphology has been observed in the microstructure with a lower nodule count. Austenitization for a longer time can decrease partition ratio, but cannot eliminate it entirely. Increasing the austenitization temperature has the same effect. Austenitizing parameters have no significant effect on carbides volume fraction. The kinetics of austempering is faster in higher nodule counts and subsequently better mechanical properties including higher ductility, strength and toughness have been observed for all austempering conditions studied.

  8. Correlation of nodular austempered ductile iron (ADI) microstructural parameters and fatigue properties using an approach based on fracture mechanics

    International Nuclear Information System (INIS)

    Dias, Jose Felipe; Fonseca, Vinicius Rizzuti; Godefroid, Leonardo Barbosa; Ribeiro, Gabriel de Oliveira

    2010-01-01

    An investigation has been accomplished to check the effect of temperature and austempering time on austempered ductile iron (ADI) properties by means of fracture toughness (K C ) and fatigue threshold (∆K th ) tests. The correlation of ADI microstructural parameters and ADI two mechanical parameters: KC and Kth, is evaluated. Three sets of samples have ben extracted from ADI casting Y blocks produced in industrial conditions.and austenitized at 900°C for 1.5 hour. The austempering process has been performed in the following ways: the first set was austenitized at 300 deg C for 4 hours, the second set at 360°C for 1.5 hour and the third at 360°C for 0.6 hour. These distinct austempering processes have been adopted in order to obtain distinct microstructures containing austenite with two different carbon rates and two ferritic cell sizes. The materials have been characterized by means of optical and electronic microscopy, X-ray diffraction and mechanical tests. All materials have presented equivalent fatigue crack propagation rates, fracture toughness in the range between 94 and 128 MPa·m 1/2 and ∆K th in the range between 5,7 and 6,4 MPa·m 1/2 . The experimental results have confirmed the effect of microstructural properties (austenitic volumetric rate, austenitic carbon rate, ferritic cell size, total matrix carbon content) on fracture toughness (K C ) and fatigue threshold (∆K th ). Further, it was found that following parameters: fracture toughness (K C ), fatigue threshold ((∆K th ) and impact strength are correlated with the total matrix carbon content and ferritic cell size. (author)

  9. Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry

    African Journals Online (AJOL)

    austempered at lower temperature. 5. The complex nature of corrosion of ADI is influenced by contents of retained austenite, ferrite and the carbon content in a collective way. Acknowledgements. The author (PM) gratefully acknowledges the faculties and lab technicians of the Department of Metallurgy & Material Science,.

  10. Fatigue crack growth in austempered ductile and grey cast irons - stress ratio effects in air and mine water

    Energy Technology Data Exchange (ETDEWEB)

    James, M.N. [Plymouth Univ. (United Kingdom). Dept. of Mech. and Marine Eng.; Li Wenfong [Department of Mechanical Engineering, University of Sydney, Sydney, NSW 2006 (Australia)

    1999-06-15

    A study is presented of the effect of stress ratio on fatigue crack growth in grey (GI) and austempered ductile (ADI) cast irons in laboratory air and, for the ADI, in synthetic mine water. Fatigue crack closure was measured by compliance techniques and factored out of the applied {Delta}K values ({Delta}K=K{sub max}-K{sub min}) to give effective stress intensity values. Crack growth rate modelling was then attempted for the laboratory air data using a two-parameter approach ({Delta}K and K{sub max}). This worked well for the ADI, but not for the GI, probably due to the much larger scatter inherent in the fatigue crack growth rates in the latter alloy. Trends in the observed growth rate and closure data for the two alloys are explained in terms of mechanism changes arising from microstructural/crack tip plastic zone interactions, and K{sub max} effects. (orig.) 9 refs.

  11. Effect of austenitizing conditions on the impact properties of an alloyed austempered ductile iron of initially ferritic matrix structure

    Energy Technology Data Exchange (ETDEWEB)

    Delia, M.; Alaalam, M.; Grech, M. [Univ. of Malta (Malta). Dept. of Metallurgy and Materials

    1998-04-01

    The effect of austenitizing conditions on the microstructure and impact properties of an austempered ductile iron (ADI) containing 1.6% Cu and 1.6% Ni as the main alloying elements was investigated. Impact tests were carried out on samples of initially ferritic matrix structure and which had been first austenitized at 850, 900, 950, and 1,000 C for 15 to 360 min and austempered at 360 C for 180 min. Results showed that the austenitizing temperature, T{sub {gamma}}, and time, t{sub {gamma}} have a significant effect on the impact properties of the alloy. This has been attributed to the influence of these variables on the carbon kinetics. Microstructures of samples austenitized at 950 and 1,000 C contain no pro-eutectoid ferrite. The impact properties of the former structures are independent of t{sub {gamma}}, while those solution treated at 1,000 C are generally low and show wide variation over the range of soaking time investigated. For fully ausferritic structures, impact properties fall with an increase in T{sub {gamma}}. This is particularly evident at 1,000 C. As the T{sub {gamma}} increases, the amount of carbon dissolved in the original austenite increases. This slows down the rate of austenite transformation and results in coarser structures with lower mechanical properties. Optimum impact properties are obtained following austenitizing between 900 and 950 C for 120 to 180 min.

  12. Influence of the amount and morphology of retained austenite on the mechanical properties of an austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Aranzabal, J. [INASMET, San Sebastian (Spain); Gutierrez, I.; Rodriguez-Ibabe, J.M.; Urcola, J.J. [CEIT, San Sebastian (Spain). Dept. of Materials

    1997-05-01

    High Si contents in nodular cast irons lead to a significant volume fraction of retained austenite in the material after the austempering treatment. In the present work, the influence of the amount and morphology of this phase on the mechanical properties (proof stress, ultimate tensile strength (UTS), elongation, and toughness) has been analyzed for different austempering conditions. After 300 C isothermal treatments at intermediate times, the austenite is plastically stable at room temperature and contributes, together with the bainitic ferrite, to the proof stress and the toughness of the material. For austenite volume fractions higher than 25 pct, the proof stress is controlled by this phase and the toughness depends mainly on the stability of {gamma}. In these conditions (370 C and 410 C treatments), the present material exhibits a transformation-induced plasticity (TRIP) effect, which leads to an improvement in ductility. It is shown that the strain level necessary to initiate the martensitic transformation induced by deformation depends on the carbon content of the austenite. The martensite formed under TRIP conditions can be of two different types: autotempered plate martensite, which forms at room temperature from an austenite with a quasi-coherent epsilon carbide precipitation, and lath martensite nucleated at twin boundaries and twin intersections.

  13. Design and optimization of stepped austempered ductile iron using characterization techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Rivera, J.L., E-mail: jose.hernandez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados-Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, Z.C. 31109, Chihuahua (Mexico); Garay-Reyes, C.G.; Campos-Cambranis, R.E.; Cruz-Rivera, J.J. [Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, Lomas 2a. sección, Z.C. 78210, San Luis Potosí (Mexico)

    2013-09-15

    Conventional characterization techniques such as dilatometry, X-ray diffraction and metallography were used to select and optimize temperatures and times for conventional and stepped austempering. Austenitization and conventional austempering time was selected when the dilatometry graphs showed a constant expansion value. A special heat color-etching technique was applied to distinguish between the untransformed austenite and high carbon stabilized austenite which had formed during the treatments. Finally, it was found that carbide precipitation was absent during the stepped austempering in contrast to conventional austempering, on which carbide evidence was found. - Highlights: • Dilatometry helped to establish austenitization and austempering parameters. • Untransformed austenite was present even for longer processing times. • Ausferrite formed during stepped austempering caused important reinforcement effect. • Carbide precipitation was absent during stepped treatment.

  14. Fatigue properties of austempered ductile cast iron at room and elevated temperatures; Austemper kyujo kokuen chutetsu no chukoon ni okeru hiro tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Fukuyama, K.; Hasegawa, N.; Inaga, K. [Gifu University, Gifu (Japan)

    1995-06-15

    Austempered ductile cast iron (ADI) is used widely as a structural material with high strength and toughness. However, since few studies have been made on investigation of fatigue properties at medium to high temperatures, this paper describes rotating bending tests carried out in temperature range between room temperature and 400{degree}C to investigate the fatigue properties and the fatigue crack generating behavior. The following results were obtained: the fatigue limit (fatigue strength after 10{sup 7} bendings) showed a remarkable maximizing phenomenon at temperatures around 300{degree}C; micronization of the base structure caused by transformation of residual austenite was recognized above 300{degree}C, and so was rise in the hardness; heating to this temperature led to rise in the Ms point, making the transformation occur more easily; the effect of repetitive stress causes a processing induced transformation; the temperature at which the transformation and the micronization are completed declines by about 50{degree}C lower than in the non-transformed region; and the fatigue fracture at middle to high temperatures is caused more frequently by internally existing graphite and development of cracks from very small casting cavities. 31 refs., 10 figs., 7 tabs.

  15. Effect of Phenomena Accompanying Wear in Dry Corundum Abrasive on the Properties and Microstructure of Austempered Ductile Iron with Different Chemical Composition

    Directory of Open Access Journals (Sweden)

    Myszka D.

    2015-04-01

    Full Text Available The research described in this article is a fragment in the series of published works trying to determine the applicability of new materials for parts of the mining machinery. Tests were performed on two groups of austempered ductile iron - one of which contained 1.5% Ni and 0.5% Mo, while the other contained 1.9% Ni and 0.9% Cu. Each group has been heat treated according to the three different heat treatment variants and then the material was subjected to detailed testing of mechanical properties and abrasion wear resistance, measuring also hardness and magnetic properties, and conducting microstructural examinations. The results indicated that each of the tested materials was senstive to the surface hardening effect, which resulted in high wear resistance. It has been found that high temperature of austempering, i.e. 370°C, favours high wear resistance of ductile iron containing nickel and molybdenum. Low temperature of austempering, i.e. 270°C, develops high wear resistance in ductile iron containing nickel and copper. Both these materials offer completely different mechanical properties and as such can be used for different and specific applications.

  16. Corrosion behaviour and structure of the surface layer formed on austempered ductile iron in concentrated sulphuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, H. [AGH University of Science and Technology, Department of Foundry Engineering, ul. Reymonta 23, 30-059 Cracow (Poland)]. E-mail: krawiec@uci.agh.edu.pl; Stypula, B. [AGH University of Science and Technology, Department of Foundry Engineering, ul. Reymonta 23, 30-059 Cracow (Poland); Stoch, J. [Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences (PAS), ul. Niezapominajek 8, 30-239 Cracow (Poland); Mikolajczyk, M. [Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences (PAS), ul. Niezapominajek 8, 30-239 Cracow (Poland)

    2006-03-15

    The aim of this paper is to investigate the structure of the surface layer formed on austempered ductile iron (ADI) after exposure to hot concentrated sulphuric acid at the open circuit potential value (OCP). The results derived from polarization measurements carried out in sulphuric acid at a temperature of 90 deg. C show that anodic dissolution of ADI is divided into three stages (corresponding to three anodic dissolution peaks). The structure of the layer formed on alloys at 90 deg. C at OCP was investigated using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). SEM analysis shows that the main elements of the surface layer are iron, silicon, oxygen, sulphur, and carbon. The binding energy recorded in individual bands indicates that the surface layer includes mainly SiO{sub 2} and FeOOH. The presence of sulphur at the lower oxidation state (S{sup 2-}) indicates that sulphuric acid undergoes reduction during this process. The corrosion resistance of these alloys is connected with the presence of SiO{sub 2} in the surface layer.

  17. Effect of deep cryogenic treatment and tempering on microstructure and mechanical behaviors of a wear-resistant austempered alloyed bainitic ductile iron

    Directory of Open Access Journals (Sweden)

    Chen Liqing

    2015-01-01

    Full Text Available In this paper, the effect of deep cryogenic treatment in combination with conven- tional heat treatment process was investigated on microstructure and mechanical behaviors of alloyed bainitic ductile iron. Three processing schedules were employed to treat this alloyed ductile iron including direct tempering treatment, tempering.+deep cryogenic treatment and deep cryogenic treatment.+tempering treatments. The microstructure and mechanical behavior, especially the wear resistance, have been evaluated after treated by these three schedules. The results show that martensite microstructure can be obviously refined and the precipitation of dispersed carbides is promoted by deep cryogenic treatment at .−196 ∘C for 3 h after tempered at 450 ∘C for 2 h. In this case, the alloyed bainitic ductile iron possesses rather high hardness and wear-resistance than those processed by other two schedules. The main wear mechanism of the austempered alloyed ductile iron with deep cryogenic treatment and tempering is micro-cutting wear in association with plastic deformation wear.

  18. Comportamiento del hierro nodular austemperizado en condiciones de corrosión y desgaste // Behavior of austempered ductile iron under wear and corrosion conditions

    Directory of Open Access Journals (Sweden)

    L. Goyos Pérez

    1999-07-01

    Full Text Available Los hierros nodulares en general y los austemperizados en particular han sido usados con cada vez mayor frecuencia debido asus relevantes propiedades mecánicas en comparación con su costo.En el presente trabajo se valora el comportamiento del hierro nodular ante el trabajo en condiciones de desgaste y corrosión,luego de ser sometido a diferentes tratamientos de austemperizado.Fueron usados un hierro nodular aleado con níquel y molibdeno y otro no aleado. Ambos hierros fueron sometidos a diferentestratamientos de austemperización con mantenimientos isotérmicos a temperaturas entre 250°C y 425°C por tiempos entre 15 y180 minutos.Las muestras tratadas fueron sometidas a ensayos de desgaste por fricción en condiciones no lubricadas determinando laspendientes de desgaste uniforme para cada caso. La resistencia a la corrosión fue determinada mediante el métodopotenciométrico usando como medio el jugo de caña sintético.A partir de los resultados obtenidos se valora la influencia de los diferentes tratamientos sobre las propiedades estudiadas y sedeterminan los más efectivos desde el punto de vista técnico económico.Palabras claves: Hierro nodular, corrosión, desgaste, austemperizado.____________________________________________________________________________AbstractNodular irons and particularly austempered ductile iron has been used more and more due to their excellent mechanicalproperties in comparison with their cost.Presently work deals on behavior of nodular iron working under wear and corrosion conditions, after being submitted todifferent austempered treatments.A nodular iron alloyed with nickel and molybdenum were used as well as a not alloyed one. Both irons were treated underdifferent austempered treatment combinations using isothermal maintenance to temperatures between 250°C and 425°C andspending times between 15 and 180 minutes.Samples were submitted to non-lubricated wear using a “pin on disk” method evaluating the

  19. Processing, Mechanical Properties, and Ballistic Impact Effects of Austempered Ductile Iron

    Science.gov (United States)

    1998-08-01

    Preheat Stress Relief 5930 C, 105 min Austenitize 891 ° C, 100 min Quench and Hold 3270 C, molten salt , hold 100 rmin Final Hardness 302 Brinell or 32...Rockwell C (HRC)* Process, Grade 2 Preheat Stress Relief 5930 C, 120 min Austenitize 8850 C, 150 mrin Quench and Hold 316’ C, molten salt , hold 150...Iron." American Foundry Society Transactions, vol. 99, pp. 281-286, 1991. Lee, Sunghak, Kyung- Mox Cho, Chang Sun Lee, and Wung Yong Choo

  20. Study of the influence of Cu and Ni on the kinetics of strain-induced martensite in austempered ductile cast iron; Estudio de la influencia del Cu y Ni en la cinetica de transformacion martensitica inducida por deformacion en fundiciones nodulares austemperadas

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D.; Navea, L.; Garin, J.; Aguilar, C.; Guzman, A.

    2013-09-01

    The objective of this work was to study the influence of copper and nickel on the kinetics of strain-induced martensite in austempered ductile cast iron. The austempered ductile cast irons were obtained from two ductile cast irons with different copper and nickel contents by means of austempering treatment. The deformation was carried out using a rolling mill. The quantification of the phases was obtained by means of X ray diffraction, while the microstructural characterization was carried out using optical and scanning electron microscopy. It was proved that the kinetics of strain-induced martensite in austempered ductile cast iron can be modeled using the equations proposed by Olson- Cohen and Chang et al. Based on the results obtained from these analyses, it is possible to conclude that the nickel and copper complicate the martensite transformation because these elements increase the staking fault energy of the austenite and its thermodynamic stability. (Author)

  1. The bainite transformation and the carbide precipitation of 4.88% aluminium austempered ductile iron investigated using electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kiani-Rashid, A.R. [Department of Materials Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad (Iran, Islamic Republic of)], E-mail: fkiana@yahoo.com

    2009-04-17

    The transformation to a bainitic microstructure during austempering under different conditions was examined for the most successful of the experimental casts. Austenitising temperature of 920 deg. C and austempering temperature of 350 deg. C for different holding times have been used. Microstructures have been examined by SEM and transmission electron microscopy (TEM). It was found that isothermal transformation at 350 deg. C for different soaking times gave a typical bainitic microstructure that increased with increasing austempering time. Extension of isothermal transformation time leads to precipitation of carbides which also depended on the bainitic phase transformation.

  2. Estudio experimental sobre el comportamiento del hierro austemperado nitrurado (adi a la fatiga de contacto. // Experimental study to contact fatigue behavior of nitrided-austempered ductile iron.

    Directory of Open Access Journals (Sweden)

    C. Figueroa

    2001-10-01

    Full Text Available En el presente trabajo se muestra un estudio sobre el hierro fundido austemperado nitrurado sometido a pruebas de fatiga decontacto. El mismo se austenitizó y austemperó a las temperaturas de 900 y 3800C respectivamente, seleccionándose enambos casos un tiempo de 2 horas. Después se le aplicó un proceso de nitruración gaseosa a 5700C durante 6 horas.Las experiencias fueron realizadas en una máquina para el ensayo de fatiga de contacto con discos. Las presionesHertzianas utilizadas fueron de 1.73, 1.78, 2.04, 2.41, 2.46 y 2.71 GPa.La composición de fases se determinó utilizando la difracción de rayos X, evidenciándose la presencia de los compuestos e(Fe2-3N y g¢ (Fe4N. Los defectos tales como: pittings spalls y grietas fueron observados por medio de la microscopíaelectrónica de barrido (SEM. Los resultados indicaron que la capa nitrurada entre 5 y 6 micras de espesor desaparece bajola acción de las presiones de contacto. Por otra parte se pudo detectar una disminución de la resistencia a la fatiga en el ADInitrurado cuando fueron utilizadas bajas presiones Hertzianas También se comprobó que los nódulos de grafito actúancomo barreras a la propagación de grietas.Palabras claves: Fatiga de contacto, Capa nitrurada, hierro dúctil austemperado, máquina de fatiga condiscos, rayos X._____________________________________________________________________AbstractThis paper presents a study on the behavior of nitrided austempered ductile iron (ADI under contact fatigue tests. ADI wasaustenitized at 9000C for 2 hours and austempered at 380oC for 2 hours. Later, the ADI was nitrided at 570oC for a periodof 6 hours.The contact fatigue tests were carried out using a disc test machine. Hertzian pressures of 1.73, 1.78, 2.04, 2.41, 2.46 and2.71 were used during the tests.The phase composition of nitride layer was determined using X-ray analysis, which detected the presence of the e and g¢phases. The pitting, spalls and cracks that appeared

  3. Caracterización de la capa de boruros formada durante la austenización de un hierro nodular austemperizado//Characterization of borides coating formed during austenitization of an austempered ductile iron

    Directory of Open Access Journals (Sweden)

    Urbano Ordóñez‐Hernández

    2015-01-01

    Full Text Available En este trabajo se ha investigado el efecto de la austenitización y el borurado simultáneos, a 950 ºC, en la microestructura, la microdureza Vickers y el espesor de la capa borurada en medio líquido de un hierro nodular austemperizado no aleado. Se demostró que es posible obtener una capa de boruros de hierro muy bien estructurada con la microdureza Vickers suficientemente alta (1400 HVy con adecuado espesor de capa de 67 μm, sobre un sustrato de ausferrita típico de las fundiciones nodulares austemperizadas. Por medio de un ensayo pin on disc modificado, se comprobó la superior resistencia al desgaste abrasivo de la capa de boruros depositada durante la austenización del ADI, comparada con la máxima obtenida durante el austempering de éste sin aplicar el recubrimiento.Palabras claves: hierro nodular, borurado, austenización, austemperizado.______________________________________________________________________________AbstractThe effect of simultaneous austenitization and boriding at 950 ºC, on microstructure, Vickers hardness and boronized layer thickness of a non alloyed austempered ductile iron has been investigated. It was demonstrated that it is possible to obtain a well formed boronized layer with a Vicker hardness sufficiently high (1400 HV, and with an appropriated 67μm layer thickness, on a typical ausferrite ADI substrate. By using a modified pin on disc test, it was demonstrated the higher abrasion wear resistance of borides layer deposited during ADI austenitization process, compared with Vickers hardness of low temperature noncoated austempered ductile iron.Key words: ductile iron, boriding, austenitization, austempering.

  4. The abrasion of austempered cast iron in laboratory and work conditions

    Directory of Open Access Journals (Sweden)

    Roman Březina

    2005-01-01

    Full Text Available Austempered ductile iron (ADI is nowadays used for machine parts, which used to be made of steel. It is suitable for abrasive conditions and cast irons exhibit sufficient strength and toughness. The paper deals with the possibility of manufacturing machine parts working in soil of austempered ductile iron. The authors find out the influence of heat treatment mode of ADI on wear resistance and compare it with formed steel.

  5. Characterisation of austempered spheroidal graphite aluminium cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Boutorabi, S.M.A. [Iran Univ. of Science and Technology, Tehran (Iran, Islamic Republic of). Dept. of Metallurgy and Materials

    1997-06-01

    The micro constituents of austempered spheroidal graphite aluminium cast iron were investigated. The heat tinting, special etching and microhardness measurement techniques were used. The results showed that the colour of each micro constituents and the hardness values in austempered ductile iron depend on the carbon content of each phase. The above techniques were supported by using an special etching which showed similar differences in each phase. It was shown that the heat tinting and special etching are reliable tools to characterise the complex matrix of ADI. The microhardness data supported interestingly the colour changes in above technique. (orig.)

  6. Recent development of ductile cast iron production technology in China

    Directory of Open Access Journals (Sweden)

    Cai Qizhou

    2008-05-01

    Full Text Available Recent progress in the production and technology of ductile cast iron castings in China is reviewed. The manufacture and process control of as-cast ductile iron are discussed. The microstructure, properties and application of partial austenitization normalizing ductile iron and austempered ductile iron (ADI are briefl y depicted. The new development of ductile iron production techniques, such as cored-wire injection (wire-feeding nodularization process, tundish cover ladle nodularizing process, horizontal continuous casting, and EPC process (lost foam for ductile iron castings, etc., are summarized.

  7. Effect of graphite nodule count and Mn content on successive austempering process of austempered ductile iron; ADI no chikuji austemper ho ni oyobosu kokuen tsubusu to Mn ryo no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Oide, T.; Ahmadabadi, M.; Saito, M. [Tohoku University, Sendai (Japan). Faculty of Engineering

    1995-02-25

    Shock test was executed for a test piece where the combination of a wide range of austempering conditions was selected and the effective graphite nodule count in the successive austempering process method, the range of Mn amount, etc. were discussed. The low and high graphite nodule counts of sample were 82 - 114 and 229 - 364 piece/mm{sup 2}, respectively. The low and high Mn were 0.26 - 0.65 % and 0.96 - 1.05 %, respectively. The heat treatment cycle was retained to be 1173K, 648K, and 588K in argon gas atmosphere. The Sharpy shock test and organization observation were performed for each test piece, thus revealing that a higher toughness value than that obtained by normal treatment could be obtained by the HLAT method; the better the graphite nodulation count was, the higher the toughness was; it was effective that the Mn was approximately 0.6 %; the influence given to the shock energy value was extremely larger by residual austenite volume than the untransformed austenite module. 7 refs., 12 figs., 2 tabs.

  8. Effect of austempering temperature and time on the kinetics and microstructure of austempered compacted graphite cast irons; Einfluss von Zwischenstufenverguetungstemperatur und -zeit auf die Kinetik und die Mikrostruktur von zwischenstufenverguetetem, Gusseisen mit Vermiculargraphit

    Energy Technology Data Exchange (ETDEWEB)

    Teymourian, Mehdi [LMI Co., Tehran (Iran, Islamic Republic of). Casting Dept.; Boutorabi, Seyed Mohammad Ali [Iran Univ. of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of). Center of Excellence for Advanced Materials

    2012-07-01

    After starting the austempering nucleation of bainitic ferrite was observed within a very short time. Samples that austempered for 2 min. showed martensite in the microstructure. By increasing the austempering time from 30 min to 90 min the retained austenite decomposes and X-ray diffraction observations revealed the greatest volume fraction of retained austenite up to 17.3 and 23.8 percent when austempered for 30 min. Micro-hardness of the bainitic Verbesferrite increased up to 370 and 500 HV and micro-hardness of the retained austenite increased up to 300 and 400 HV at the austempering temperatures of 300 C and 400 C respectively. In comparison to austempered ductile iron, the austempered compacted graphite cast iron shows higher rate of bainitic reaction. Bainite formation driving force and consequently the rate of austempering process are higher in compacted graphite cast irons. (orig.)

  9. Wear resistance studies of an austempered ductile iron with the aid of a single pass grooving pendulum; Estudo do comportamento em desgate de um ferro fundido nodular austemperado atraves da tecnica da tecnica de esclerometria pendular

    Energy Technology Data Exchange (ETDEWEB)

    Velez, J.M.; Tschiptschin, A.P. [Sao Paulo Univ., SP (Brazil). Escola Politecnica

    1995-12-31

    The abrasive wear resistance of an austempered ductile iron was studied with the aid of a single pass grooving pendulum. Specimens were austenitized at 860 deg C and austempered at 370 deg C for 30, 60, 90, 180 and 240 min. Austenite transformation kinetics was measured by quantitative metallography. Specimens for pendulum tests were gridded as squared based prisms (50 mm x 10 mm x 10 mm) and one of the faces submitted to metallographic polishing before the test. A hard metal cutting tool was used as abrasive. The absorbed energy as well as the loss of matter were measured. Scanning Electron Microscopy was used to analyze the surface topography of the scratched specimen. It was observed a maximum in the absorbed specific energy for the specimen treated for 60 min. with a microstructure of bainite ferrite plus plus 42% volume fraction of retained austenite. All other structures (ferrite plus carbides, ferrite plus lower contents of austenite and martensite plus austenite) gave lower values of absorbed specific energy. Observation of scratches and chips formed on the surface of the specimen can explain the above mentioned behaviour 12 refs., 11 figs., 2 tabs.

  10. Austenitization of FerriticDuctile Iron

    Directory of Open Access Journals (Sweden)

    Krzyńska A.

    2014-12-01

    Full Text Available Austenitization is the first step of heat treatment preceding the isothermal quenching of ductile iron in austempered ductile iron (ADI manufacturing. Usually, the starting material for the ADI production is ductile iron with more convenient pearlitic matrix. In this paper we present the results of research concerning the austenitizing of ductile iron with ferritic matrix, where all carbon dissolved in austenite must come from graphite nodules. The scope of research includedcarrying out the process of austenitization at 900° Cusing a variable times ranging from 5 to 240minutes,and then observations of the microstructure of the samples after different austenitizing times. These were supplemented with micro-hardness testing. The research showed that the process of saturating austenite with carbon is limited by the rate of dissolution of carbon from nodular graphite precipitates

  11. Characteristics of ADI Ductile Cast Iron with Single Addition of 1.56% Ni

    Directory of Open Access Journals (Sweden)

    Mrzygłód B.

    2017-12-01

    Full Text Available The results of examinations of microstructure and an analysis of its impact on selected mechanical properties of austempered ductile iron (ADI were presented in the paper. The ADI was produced from the ductile iron containing 1.56% Ni only alloying addition. The effect of the austempering time and temperature on the microstructure and mechanical properties of the examined cast iron was considered. Constant conditions of austenitizing were assumed and six variants of the austempering treatment were adopted. The studyof mechanical properties included a static tensile test, Charpy impact strength test and Brinellhardness measurement.

  12. Influencia de los factores microestructurales en la resistencia al desgaste por deslizamiento de las fundiciones nodulares austemperadas. // Influence of the microstructure factors in the sliding wear resistance of austempered cast ductile iron.

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2008-09-01

    Full Text Available Entre los materiales metálicos de mayor demanda, el hierro dúctil con grafito esferoidal o nodular ocupa en la actualidaduno de los lugares más importantes entre los hierros fundidos de alta resistencia. Desde hace unos veinticinco años laintroducción del hierro nodular austemperado significó de hecho una revolución en el campo de las aleaciones ferrosas. Enel presente trabajo se realiza un estudio de la influencia del conteo de nódulos de grafito del hierro nodular en el proceso deaustemperado, a partir de las características de las estructuras obtenidas, por la variación de la cantidad de nódulos degrafito y de las variables de tratamiento térmico. Dichas estructuras son sometidas a la acción del desgaste, en este caso aun desgaste por deslizamiento mediante un ensayo típico disco-zapata. Con los resultados obtenidos, se realiza un análisisestadístico de la influencia del conteo de nódulos en dichas propiedades y de las causas de este comportamiento, tomandoen consideración la interrelación del conteo de nódulos con las variables de tratamiento térmico utilizadas en las muestrasensayadas y su incidencia en el mecanismo de desgaste.Palabras claves: Hierro nodular, conteo de nódulos, austemperado, desgaste por deslizamiento.____________________________________________________________________________Abstract:A study about the influence of the graphite nodules quantity and some heat treatment parameters in the characteristic of castductile iron is presented. Experimental investigation of wear resistance by sliding is applied to specimens tested ofaustempered ductile irons using a test machine based in the disc- plate system. Statistical analysis about the influence of thegraphite nodule quantity in the wear resistance properties, so as well as, the causes of this behaviour taking into account thegraphite nodule count and some heat treatment variables is done.Key words: austempered ductile iron, graphite nodules, wear

  13. Correlation of nodular austempered ductile iron (ADI) microstructural parameters and fatigue properties using an approach based on fracture mechanics; Correlacao entre parametros microestruturais do ferro fundido nodular austemperado (ADI) com suas propriedades a fadiga utilizando uma abordagem baseada na mecanica de fratura

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Jose Felipe [Universidade de Itauna (UIT), MG (Brazil). Faculdade de Engenharia; Fonseca, Vinicius Rizzuti; Godefroid, Leonardo Barbosa [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Escola de Minas; Ribeiro, Gabriel de Oliveira [Universidade Federal de Minas Gerais (UFMG), MG (Brazil). Departamento de Engenharia de Estruturas

    2010-07-01

    An investigation has been accomplished to check the effect of temperature and austempering time on austempered ductile iron (ADI) properties by means of fracture toughness (K{sub C}) and fatigue threshold (∆K{sub th}) tests. The correlation of ADI microstructural parameters and ADI two mechanical parameters: KC and Kth, is evaluated. Three sets of samples have ben extracted from ADI casting Y blocks produced in industrial conditions.and austenitized at 900°C for 1.5 hour. The austempering process has been performed in the following ways: the first set was austenitized at 300 deg C for 4 hours, the second set at 360°C for 1.5 hour and the third at 360°C for 0.6 hour. These distinct austempering processes have been adopted in order to obtain distinct microstructures containing austenite with two different carbon rates and two ferritic cell sizes. The materials have been characterized by means of optical and electronic microscopy, X-ray diffraction and mechanical tests. All materials have presented equivalent fatigue crack propagation rates, fracture toughness in the range between 94 and 128 MPa·m{sup 1/2} and ∆K{sub th} in the range between 5,7 and 6,4 MPa·m{sup 1/2}. The experimental results have confirmed the effect of microstructural properties (austenitic volumetric rate, austenitic carbon rate, ferritic cell size, total matrix carbon content) on fracture toughness (K{sub C}) and fatigue threshold (∆K{sub th}). Further, it was found that following parameters: fracture toughness (K{sub C}), fatigue threshold ((∆K{sub th}) and impact strength are correlated with the total matrix carbon content and ferritic cell size. (author)

  14. Statistical fatigue properties of ductile cast irons; Kyujo kokuen chutetsu no hiro kyodo no tokeiteki seishitsu

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, N.; Nishikawa, Y.; Inaba, K. [Gifu University, Gifu (Japan). Faculty of Engineering; Fukuyama, K. [Gifu Prefectural Police Headquarters, Gifu (Japan)

    1995-09-15

    Rotating bending fatigue tests of smooth specimens were carried out at room temperature on a pearlitic ductile cast iron (PDI) and austempered ductile cast iron (ADI). No significant difference due to sampling position from cast blocks in both materials was found in fatigue limit and fatigue life distribution. Then, the statistical fatigue properties of ferritic (FDI), ferritic/pearlitic (FPDI), pearlitic and austempered ductile cast irons were investigated. The fatigue life distributions of all ductile irons were well represented by the three parameter Weibull distribution modified by the saturated probability of failure. The shape parameters of FDI, FPDI and PDI were in proportion to {sigma}/{sigma}w independent on micro structure, while the shape parameters of both stress levels in ADI were smaller than unity. The fatigue strength of ADI was highest, but the scatter of fatigue life was largest among the all cast irons. 13 refs., 15 figs., 7 tabs.

  15. Efecto del conteo de nódulos en la resistencia a la tracción de los hierros dúctiles austemperados. // Effect of nodules count in the tensile strength of austempered ductile irons.

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2004-01-01

    Full Text Available Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nódular ocupa uno de los lugaresmás importantes entre los hierros fundidos de alta resistencia y con la introducción del tratamiento térmico deaustemperado, aplicado a estas fundiciones, se da lugar a una nueva familia de materiales, caracterizados por su altaresistencia mecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de las fundicionesnodulares.Este trabajo, hace una valoración del comportamiento de hierros nodulares, con diferentes conteos de nódulos, a los que lesfue aplicado el tratamiento de austemperado y posteriormente se les sometió a ensayos de propiedades mecánicas detracción.Con los resultados obtenidos, se hace un análisis de la influencia del conteo de nódulos en dichas propiedades, así comotambién, de la interrelación del conteo de nódulos con las variables de tratamiento térmico utilizadas en las muestrasensayadas.Palabras claves: Hierro nódular, conteo de nódulos, austemperado.____________________________________________________________________________Abstract.At the present, iron production with nodular graphite, occupies one of the most important places in the production ofmetallic materials high resistance. The introduction of the austempered heat treatment, gives rise to a new family ofmaterials, characterized by its high mechanical resistance and elevated tenacity, this family maintain the economy andfacility of production of the smeltings nodules. This work, makes a valuation of the nodules iron behavior, with differentnumber of nodules, to which the austempered treatment was applied, in order to test mechanical properties. With theobtained results, an analysis is carriewd out to control the influence of the count of nodules in these properties, as well as,the interrelation of the count of nodules with the used heat treatment variables in the samples.Key words: nódular Iron, count of

  16. Intercritical heat treatments in ductile iron and steel

    Science.gov (United States)

    Aristizabal, Ricardo E.

    Materials such as dual phase (DP) steels, transformation induced plasticity (TRIP) steels and dual phase ductile irons are produced by intercritical heat treatments. These materials can provide significant weight savings in the automotive industry. The goal of this dissertation is to study intercritical heat treatments in ductile iron and steel to optimize the production parameters. Three different aspects were addressed. First, common steels were intercritically austenitized and austempered (intercritically austempered) under a variety conditions. The results showed that common grade steels that were intercritically austempered exhibited tensile properties in the same range as DP and TRIP steels. The second study consisted of determining the effect of heat treatment conditions on the tensile properties of intercritically austenitized, quenched and tempered ductile iron (IAQ&TDI). The results showed that (1) ultimate tensile strength (UTS) and yield strength (YS) were determined by the volume fraction of martensite, (2) tempering improved the elongation 1.7-2.5 times with only a slight decrease in strength, (3) the carbon in austenite formed during the intercritical heat treatment of ductile iron with a ferritic-pearlitic matrix came from the carbon available in the matrix and that carbon diffusion from the graphite nodules was restricted, and (4) limited segregation of substitutional elements occurred during intercritical austenitizing. Finally, intercritically austempered ductile iron (IADI) alloyed with different amounts of manganese and nickel was produced. Tensile properties and microstructure were determined. Also, the stability of the austenite during deformation and the lattice strains of the ferrite and the austenite phases were determined using x-ray diffraction (XRD) and neutron diffraction. The results indicated that: 1) high manganese concentrations produced materials with large blocky, low carbon austenite particles at the intercellular boundaries

  17. Influence of the Mn content on the kinetics of austempering transformation in compacted graphite cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Desimoni, J.; Gregorutti, R.; Laneri, K.; Sarutti, J.L.; Mercader, R.C.

    1999-11-01

    Moessbauer spectroscopy has been used to monitor the kinetics of austempering transformation in two compacted graphite (CG) cast irons alloyed with 0.11 and 0.58 wt pct of Mn, respectively. The phase relations were analyzed in terms of the Johnson-Mehl's equation, determining the kinetics parameters n (time exponent) and k (constant rate of the transformation). The values obtained were n = 1.4 and k = 7.47 x 10{sup {minus}3} s{sup {minus}1} for the low-Mn alloy, and n = 2.2 and k = 3.9 x 10{sup {minus}3} s{sup {minus}1} for the high-Mn alloy. These results, which reveal a faster kinetics for the low-Mn alloy, are coherent with metallographic observations, and the driving force obtained through the determination of the austenite carbon concentration that was determined from the Moessbauer data using the Genins model for the Fe-C configurations in the fcc lattice. The kinetics parameters are further compared to those obtained in austempered ductile iron (ADI), by analyzing the graphite morphology influence on the austempering transformation.

  18. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados. // Effect of nodules count in the waste by abrasion resistance for ductile austempering irons.

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2004-05-01

    Full Text Available Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular, ocupa en la actualidad unode los lugares más importantes entre los hierros fundidos de alta resistencia, y con la introducción del tratamiento térmicode austemperado aplicado a estas fundiciones, se da lugar a una nueva familia de materiales, caracterizados por su altaresistencia mecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de las fundicionesnodulares.Este trabajo, hace una valoración del comportamiento de hierros nodulares, con diferentes conteos de nódulos, a los que lesfue aplicado el tratamiento de austemperado y posteriormente se les sometió a ensayos de desgaste abrasivo.Con los resultados obtenidos se hace un análisis de la influencia del conteo de nódulos en dichas propiedades, así comotambién de la interrelación del conteo de nódulos con las variables de tratamiento térmico utilizadas en las muestrasensayadas.Palabras claves: Hierro nodular, conteo de nódulos, austemperado.____________________________________________________________________________Abstract.Between the metallic materials of greater demand, the iron production with nódular graphite occupies at the present time,one of the most important places between fused irons of high resistance, and with the introduction of the austempering heattreatment, applied to these meltings, brings a new family of materials, characterized by its high mechanical resistance andelevated tenacity, that maintain the economy and facility of production of the nodular smeltings.This work makes a valuation of the nodular irons behaviors, with different counts from nodules, to which the austemperingtreatment was applied, and later they were put under tests of abrasive wearing.Of the obtained results, takes control of the influence the nodules count in these properties, as well as, of the interrelation ofthe nodules count, with the used variables of heat

  19. Electron microstructure and mechanical properties of silicon and aluminum ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Sidjanin, L. (Univ. of Novi Sad (Yugoslavia). Dept. of Production Engineering); Smallman, R.E.; Young, J.M. (Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials)

    1994-09-01

    Samples of unalloyed silicon and aluminum spheroidal graphite cast iron have been studied in the austempered condition. Austempering times of up to 3 h at 400 C for Al SG and 1 h at 350 C for Si SG gives a typical ADI microstructure consisting of carbide-free bainitic ferrite and stable, high carbon enriched, retained austenite. This has an attractive combination of elongation and strength. For longer austempering times transition carbides are precipitated in the bainitic ferrite, [eta]-carbide in the upper bainitic range, i.e. 400 C for Al SG and 350 C for Si SG, and [epsilon]-carbide in the lower bainite range. Increasing amounts of transition carbide reduce the ductility and produce a mixed mode of fracture. For longer austempering times [chi]-carbide is precipitated at the ferrite/austenite boundaries leading to a more brittle fracture mode.

  20. Effects of Alloying Elements (Mo, Ni, and Cu on the Austemperability of GGG-60 Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    Erkan Konca

    2017-08-01

    Full Text Available The interest in austempered ductile irons (ADI is continuously increasing due to their various advantageous properties over conventional ductile irons and some steels. This study aimed to determine the roles of alloying elements Ni, Cu, and Mo, on the austemperability of GGG-60 ductile cast iron. Two different sets of GGG-60 (EN-GJS-600-3 samples, one set alloyed with Ni and Cu and the other set alloyed with Mo, Ni, and Cu, were subjected to austempering treatments at 290 °C, 320 °C, and 350 °C. A custom design heat treatment setup, consisting of two units with the top unit (furnace serving for austenitizing and the 200 L capacity bottom unit (stirred NaNO2-KNO3 salt bath serving for isothermal treatment, was used for the experiments. It was found that austempering treatment at 290 °C increased the hardness of the Ni-Cu alloyed GGG-60 sample by about 44% without causing a loss in its ductility. In the case of the Mo-Ni-Cu alloyed sample, the increase in hardness due to austempering reached to almost 80% at the same temperature while some ductility was lost. Here, the microstructural investigation and mechanical testing results of the austempered samples are presented and the role of alloying elements (Mo, Ni, and Cu on the austemperability of GGG-60 is discussed.

  1. Evaluation of Ductile Iron for Offshore Application

    OpenAIRE

    Jørgensen, Mats Røed

    2017-01-01

    Master's thesis in Mechanical engineering The possibility of using ductile iron as a construction material for offshore applications have been investigated. If ductile iron is considered as being a substitute material forwelded steel, it can create a larger freedom for engineers in a design process as well as provide benefits regarding strength and cost.The issue of getting ductile iron approved as a reliable substitute material for steel is a statement made by DNV GL, being that cast iron...

  2. A study on the effects of artifacts on fatigue limit of ductile cast iron with ferritic structure

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hak [Yeungnam Univ., Gyeongsan (Korea, Republic of); Kim, Min Gun [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2000-10-01

    In this study, fatigue tests were performed to examine the effects of micro drill hole on fatigue limit of as cast and Austempered Ductile cast Iron (ADI) using the rotary bending fatigue tester. As results, micro drill holes (diameter{<=}0.4mm) did not influence the fatigue limit of ADI, compared to annealed ductile cast iron; the critical defect size of crack initiation, in ADI was larger than as cast. If the {radical}areas of micro drill hole and graphite nodule in ADI are comparable, crack initiates at the graphite nodule. When the ruggedness develops through austempering treatment process, microstructure on crack initiation at micro drill hole is tougher than that of as cast ductile cast iron.

  3. Relationships between microstructure and mechanical properties in ductile cast irons: a review; Relaciones entre la microestructura y las propiedades mecanicas en fundiciones nodulares: revison bibliografica

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, R.; Bermont, V. [Universidad de La Serena. La Serena. Chile (Chile); Martinez, V. [Universidad de Santiago. Santiago Chile (Chile)

    1999-07-01

    The progress achieved in the understanding of the relationships between the microstructure and the mechanical properties of ductile cast iron is reviewed. It is also described the applications of heat treatment of austempered to ductile irons (ADI), which have allowed to improve substantially the mechanical properties of these materials. It is proposed a research program to obtain the crack growth resistance under corrosive atmospheres and to model the mechanical properties. (Author) 83 refs.

  4. The effects of boro-tempering heat treatment on microstructural properties of ductile iron

    International Nuclear Information System (INIS)

    Kayali, Yusuf; Yalcin, Yilmaz

    2011-01-01

    In this study, the effects of boro-tempering heat treatment on microstructural properties of ductile iron were investigated. Test samples with dimensions of 10 x 10 x 55 mm were boronized at 900 o C for 1, 3 and 5 h and then tempered at four different temperatures (250, 300, 350 and 450 o C) for 1 h. Both optical microscopy and scanning electron microscopy were used to reveal the microstructural details of coating and matrix of boro-tempered ductile iron. X-ray diffraction was used to determine the constituents of the coating layer. The boride layer formed on the surface of boro-tempered ductile cast iron is tooth shape form and consisted of FeB and Fe 2 B phases. The thickness of boride layer increases as the boronizing time increases and tempering temperature decreases. Tempering temperature is more effective than boronizing time on the matrix structure. Boro-tempering heat treatment reduces the formation of lower and upper ausferritic matrix temperature according to classical austempering. This causes formation of upper ausferritic matrix in the sample when tempered at 300 o C. This is in contrast to general case which is the formation of lower ausferritic matrix via austempering at this temperature.

  5. 46 CFR 56.60-15 - Ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Ductile iron. 56.60-15 Section 56.60-15 Shipping COAST... Materials § 56.60-15 Ductile iron. (a) Ductile cast iron components made of material conforming to ASTM A... (incorporated by reference; see 46 CFR 56.01-2). (b) Ductile iron castings conforming to ASTM A 395...

  6. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados. // Effect of nodules count in the abrasive wear of austempered ductile irons.

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2009-05-01

    Full Text Available Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular,ocupa en la actualidad, uno de los lugares más importantes entre los hierros fundidos de altaresistencia, y con la introducción del tratamiento térmico de austemperado, aplicado a estasfundiciones, se da lugar a una nueva familia de materiales, caracterizados por su alta resistenciamecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de lasfundiciones nodulares.Este trabajo, hace una valoración del comportamiento de hierros nodulares, con diferentes conteosde nódulos, a los que les fue aplicado el tratamiento de austemperado, y posteriormente se lessometió a ensayos de desgaste abrasivo.Con los resultados obtenidos, se hace un análisis de la influencia del conteo de nódulos en dichaspropiedades, así como también, de la interrelación del conteo de nódulos, con las variables detratamiento térmico utilizadas en las muestras ensayadas.Palabras claves: hierro nodular, conteo de nódulos, austemperado.__________________________________________________________________________AbstractBetween the metallic materials of greater demand, the iron production with nódular graphiteoccupies at the present time, one of the most important places between fused irons of highresistance, and with the introduction of the austemperado heat treatment of, applied to thesesmeltings, gives rise to a new family of materials, characterized by its high resistance mechanicaland elevated tenacity, that the economy and facility of production of the smeltings maintainnodulares. This work, makes a valuation of the iron behavior nodulares, with different counts fromnodules, to which the austemperado was applied treatment to them of, and later it was put underto them tests of abrasive wearing down. Of the obtained results, an analysis takes control of theinfluence of the count of nodules in these properties, as well as, of the interrelation of

  7. 49 CFR 192.373 - Service lines: Cast iron and ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the service...

  8. The influence of the hardening conditions on the mechanical properties of ductile cast iron

    Directory of Open Access Journals (Sweden)

    T. Giętka

    2010-01-01

    Full Text Available Ductile cast iron has been austempered according to two variants. The first treatment variant was austenitizing at a temperature tγ = 830, 860 and 900 0C and holding at a temperature tpi = 400 and 300 0C for 8 ÷ 64 min. Second variant treatment was two-phase austenitizing. Firstly, it was heated at a temperature tγ = 950 0C and after forecooling and chilling at a temperature tγ’ = 900, 860 and 830 0C isothermal process was conducted in the same conditions as in the first variant. The cast iron with ferritic matrix was austempered. After hardening the mechanical (Rp0,2, Rm and plastic (A5 properties were examined as well as the microstructure of matrix and hardness. It was noticed that the heat treatment carried out according to variants I and II lead to attaining cast iron of grade: ADI EN-GJS-800-8, EN-GJS-1200-2, EN-GJS-1400-1 according to PN–EN 1564 : 2000; in addition, ductility of these grades was 1,5÷4 times bigger than the mini-mum standard material requirements.

  9. Microstructure vs. Near-threshold Fatigue Crack Growth Behavior of an Heat-treated Ductile Iron

    Directory of Open Access Journals (Sweden)

    Radomila KONEČNÁ

    2012-03-01

    Full Text Available Perferritic isothermal ductile iron (IDI® is an intermediate grade between the low-strength grades of austempered ductile iron (ADI and pearlitic ductile iron (DI recently developed by Zanardi Fonderie Italy. IDI is produced by heat-treating an unalloyed nodular cast iron. The specific matrix microstructure is called “Perferritic” and consists predominantly of ferrite and pearlite. Compared to the pearlitic grades of nodular ductile iron, IDI combines similar strength with higher toughness as a result of the isothermal heat treatment. In this contribution the fatigue crack growth resistance and Kath of IDI are investigated and correlated to mechanical properties and microstructural features. The threshold Ka was determined using the load shedding technique as per ASTM Standard E-647 using CT specimens extracted from a cast block. Tensile specimens were extracted from the broken CT halves and used to determine the static mechanical properties. A metallographic investigation was carried out to correlate structural features and mechanical properties.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1336

  10. Study of the isothermal transformation of ductile iron with 0.5% Cu by electrical resistance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lin, B.Y.; Chen, E.T.; Lei, T.S. [National Taiwan Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering and Technology

    1995-10-01

    A computer-controlled system for measuring electrical resistance has been developed and used to study the isothermal transformation of austenite in a ductile iron (3.31% C, 3.12% Si, 0.22% mn, 0.55% Cu). The ability of the technique to follow the isothermal decomposition of austenite was established by measurements on an AISI 4340 steel. The times at which the austenite decomposed to primary ferrite, pearlite, and bainite were accurately detected. In the ductile iron, the formation of pearlite and of bainite was easily detected, and an isothermal transformation diagram was constructed from the results. The temperature range for the formation of bainite is especially important in producing austempered ductile iron (ADI) and was mapped. An initial stage of decomposition of austenite to ferrite and high-carbon austenite is followed by a time delay; then the high-carbon austenite decomposes to bainite. The formation of ADI requires austempering to a structure of ferrite and high-carbon austenite, then quenching to retain this structure, thus avoiding the formation of bainite. This is achieved by isothermal transformation into the time-delay region. For the ductile iron studied here, this time region was about 2.6 h at 400 C and increased to 277 h at 300 C.

  11. Modeling of Railway Wheels Made of Austempered Ductile Iron

    Directory of Open Access Journals (Sweden)

    Giętka T.

    2016-12-01

    Full Text Available A person is forced to travel constantly throughout its entire life. The more modern the society, the greater the pace of life, and the greater the need to be present in many places that are distant from each other. Rail transport occupies second place in this regard, after air transport. This means of transportation has many advantages, however the time of travel requires continuous improvement, in particular, to match the competition. One factor limiting the speed of travel is inter-operation between the wheels – rail kinematic pair. When rolling on a rail, a wheel is subject to wear, which unavoidably leads to its degradation. Frequent damage to both the wheel and the rail necessitates consideration of this problem. Because any changes to the rail are very expensive and time-consuming, this paper focuses on possible changes to the wheel.

  12. Analysis of nucleation modelling in ductile cast iron

    DEFF Research Database (Denmark)

    Moumeni, Elham; Tutum, Cem Celal; Tiedje, Niels Skat

    2012-01-01

    Heterogeneous nucleation of nodular graphite at inclusions in ductile iron during eutectic solidification has been investigated. The experimental part of this work deals with casting of ductile iron samples with two different inoculants in four different thicknesses. Chemical analysis, metallogra...

  13. The Performance Evalution of Ceramic And Carbide Cutting Tools In Machining of Austemepered Ductile Irons

    Directory of Open Access Journals (Sweden)

    Yahya IŞIK

    2014-12-01

    Full Text Available The aim of this research is to compare TiN (PVD coated Al2O3+Ti[C,N] mixed alumina-based (KY4400 ceramic and CVD coated carbide TiC+AI2O3+TiN (ISO P25 cutting tools in turning austempered ductile irons. Ductile cast iron samples were austenitized at 927°C and subsequently austempered for 1 hour at 400°C. The hardness of the workpiece material was measured and found to be 43.5 HRC. In the present work a series of tests were conducted in order to evaluate the tool performances by adopting tool life. In all experiments cutting forces, flank wear and surface roughness values were measured throughout the tool life. No cutting fluid was used during the turning operations. Study of the tool life and failure modes shows that tool life was determined by the flank wear and surface roughness generated on the workpiece. The main conclusion is that tool life of ceramic insert was longer than the coated carbide insert although much higher cutting speeds were used. 

  14. Transmission electron microscopy study of high temperature bainitic transformation in 1 wt.% Mn ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadabadi, M.N. [Tohoku Univ., Sendai (Japan); Niyama, E. [Tohoku Univ., Sendai (Japan); Echigoya, J. [Tohoku Univ., Sendai (Japan)

    1995-04-01

    A 1 wt.% Mn ductile iron austenitized at 900 C for 90 min and austempered at 375 C for different periods was used to study some aspects of bainitic reaction in high Mn austempered ductile iron with reference to carbide precipitation in bainitic ferrite. Transmission electron microscopy (TEM) energy-dispersive X-ray analysis (EDXA) study shows that precipitation of carbide in the ferritic component of bainite is a function of the local concentration of alloying elements. In other words, in the region near graphite where Si segregates and there is negative Mn segregation as well as carbon, the bainitic ferrite is carbide free. However, in the intercellular region where Mn segregates and Si is depleted, the ferritic component of bainite occurs together with very fine and almost uniformly distributed carbide. Furthermore, TEM-EDXA results show that the increase in Mn content not only delays stage I (the initial transformation of austenite to ferrite and retained austenite) of the bainitic reaction, but also delays stage II (decomposition of retained austenite to ferrite and carbide). ((orig.))

  15. Fatigue crack tip damaging micromechanisms in a ferritic-pearlitic ductile cast iron

    Directory of Open Access Journals (Sweden)

    Francesco Iacoviello

    2015-07-01

    Full Text Available Due to the peculiar graphite elements shape, obtained by means of a chemical composition control (mainly small addition of elements like Mg, Ca or Ce, Ductile Cast Irons (DCIs are able to offer the good castability of gray irons with the high mechanical properties of irons (first of all, toughness. This interesting properties combination can be improved both by means of the chemical composition control and by means of different heat treatments(e.g. annealing, normalizing, quenching, austempering etc. In this work, fatigue crack tip damaging micromechanisms in a ferritic-pearlitic DCI were investigated by means of scanning electron microscope observations performed on a lateral surface of Compact Type (CT specimens during the fatigue crack propagation test (step by step procedure, performed according to the “load shedding procedure”. On the basis of the experimental results, different fatigue damaging micromechanisms were identified, both in the graphite nodules and in the ferritic – pearlitic matrix.

  16. Effect of Heat Treatment Parameters on the Toughness of Unalloyed Ausferritic Ductile Iron

    Directory of Open Access Journals (Sweden)

    Guzik E.

    2016-06-01

    Full Text Available Studies were carried out to determine the effect of heat treatment parameters on the plastic properties of unalloyed ausferritic ductile iron, such as the elongation and toughness at ambient temperature and at – 60 °C. The effect of austenitizing temperature (850, 900 and 950°C and ausferritizing time (5 - 180 min. at a temperature of 360°C was also discussed. The next step covered investigations of a relationship that is believed to exist between the temperature (270, 300, 330, 360 and 390 °C and time (5, 10, 30, 60, 90, 120, 150, 180, 240 min. of the austempering treatment and the mechanical properties of unalloyed ausferritic ductile iron, when the austenitizing temperature is 950°C. The “process window” was calculated for the ADI characterized by high toughness corresponding to the EN-GJS-800-10-RT and EN-GJS-900-8 grades according to EN-PN 1564 and to other high-strength grades included in this standard. Low-alloyed cast iron with the nodular graphite is an excellent starting material for the technological design of all the ausferritic ductile iron grades included in the PN-EN-1624 standard. The examined cast iron is characterized by high mechanical properties stable within the entire range of heat treatment parameters.

  17. 49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Remedial measures: Cast iron and ductile iron... for Corrosion Control § 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to a...

  18. 49 CFR 192.369 - Service lines: Connections to cast iron or ductile iron mains.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Connections to cast iron or ductile... Customer Meters, Service Regulators, and Service Lines § 192.369 Service lines: Connections to cast iron or ductile iron mains. (a) Each service line connected to a cast iron or ductile iron main must be connected...

  19. Effect of Melting Techniques on Ductile Iron castings Properties

    Directory of Open Access Journals (Sweden)

    Bockus, S.

    2006-01-01

    Full Text Available The study was designed to investigate the effects of the charge, melting conditions, nodularizing and inoculation on the ductile iron castings properties. Results showed that the temperature and holding time of the melt in an induction furnace and the intensity of spheroidizing effect on the carbon and residual magnesium contents in the ductile iron castings. The same grade of ductile iron may be obtained using different chemical compositions. The castings of ductile iron will be ferritic as-cast only when large amount of pig iron in the charge and in addition some-steps inoculating treatment are used.

  20. 49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

    Science.gov (United States)

    2010-10-01

    ... cast iron or ductile iron lines. 192.487 Section 192.487 Transportation Other Regulations Relating to... iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... the purpose of this paragraph. (b) Localized corrosion pitting. Except for cast iron or ductile iron...

  1. SiMo Ductile Iron Crystallization Process

    Directory of Open Access Journals (Sweden)

    Stawarz M.

    2017-03-01

    Full Text Available The article presents crystallization process of silicon molybdenum ductile cast iron (SiMo. The alloy with 5% silicon content and with variable amounts of Mo in a range of 0-1% was chosen for the research. The carbon content in the analysed alloys did not exceed 3,1%. The studies of crystallization process were based on thermal - derivative analysis (TDA. Chemical composition of all examined samples was analysed with the use of LECO spectrometer. Additionally, the carbon and the sulphur content was determined basing on carbon and sulphur LECO analyser. For metallographic examination, the scanning electron microscopy (SEM with EDS analyser was used. Disclosed phases have been also tested with the use of X-ray diffraction. The results allowed the description of crystallization processes of silicon molybdenum ductile cast iron using thermal - derivative analysis (TDA. Conducted studies did not allow for the clear identification of all complex phases containing molybdenum, occurring at the grain boundaries. Therefore, the further stages of the research could include the use of a transmission electron microscope to specify the description of complex compounds present in the alloy.

  2. Solidification, processing and properties of ductile cast iron

    DEFF Research Database (Denmark)

    Tiedje, Niels Skat

    2010-01-01

    Ductile cast iron has been an important engineering material in the past 50 years. In that time, it has evolved from a complicated material that required the foundry metallurgist's highest skill and strict process control to being a commonly used material that can easily be produced with modern...... of the latest years of research indicate that ductile cast iron in the future will become a highly engineered material in which strict control of a range of alloy elements combined with intelligent design and highly advanced processing allows us to target properties to specific applications to a much higher...... and to illustrate how ductile iron's properties are optimised, the essentials of heat treatment are described too. It is the hope that researchers will find a comprehensive treatment of ductile cast iron metallurgy and that engineers and designers will be presented with the latest information on, and references to...

  3. Influence of Shot Peening on Abrasion Wear in Real Conditions of Ni-Cu-Ausferritic Ductile Iron

    Directory of Open Access Journals (Sweden)

    Wieczorek A. N.

    2016-12-01

    Full Text Available The paper presents results of the wear tests of chain wheels made of austempered ductile iron with various content of residual austenite. The aim of this study was to demonstrate the impact of the dynamic surface treatment (shot peening on wear properties of surface layers of the chain wheels tested that were subjected to the action of quartz abrasive. Apart from determining the value of the abrasive wear, examinations of the magnetic phase content in the microstructure were carried out and plots of hardness of the surface layer as a function of the distance from the surface and microstructure of the materials were prepared. Based on the results, the following was found: an increase in the abrasive wear and a reduction in the hardness of the surface layer of chain wheels subjected to shot peening, as well as reduction of susceptibility to negative action of the shot for cast irons with the structure of upper ausferrite.

  4. Friction welding of ductile cast iron using interlayers

    International Nuclear Information System (INIS)

    Winiczenko, Radoslaw; Kaczorowski, Mieczyslaw

    2012-01-01

    Highlights: → The results of the study of the friction welding of ductile cast iron using interlayers are presented. → The results of the analysis shows that the joint has the tensile strength compared to that of basic material. → In case of ductile cast iron, it is possible to reach the tensile strength equals even 700 MPa. → The process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the interface. -- Abstract: In this paper, ductile cast iron-austenitic stainless steel, ductile cast iron-pure Armco iron and ductile cast iron-low carbon steel interlayers were welded, using the friction welding method. The tensile strength of the joints was determined, using a conventional tensile test machine. Moreover, the hardness across the interface of materials was measured on metallographic specimens. The fracture surface and microstructure of the joints was examined using either light stereoscope microscopy as well as electron microscopy. In this case, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied. The results of the analysis shows that the joint has the tensile strength compared to that of basic material. In case of ductile cast iron, it is possible to reach the tensile strength equals even 700 MPa. It was concluded that the process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the ductile cast iron-stainless steel interface. This leads to increase in carbon concentration in stainless steel where chromium carbides were formed, the size and distribution of which was dependent on the distance from the interface.

  5. The effect of pearlite on the hydrogen-induced ductility loss in ductile cast irons

    Science.gov (United States)

    Matsuo, T.

    2017-05-01

    Hydrogen energy systems, such as a hydrogen fuel cell vehicle and a hydrogen station, are rapidly developing to solve global environmental problems and resource problems. The available structural materials used for hydrogen equipments have been limited to only a few relatively expensive metallic materials that are tolerant for hydrogen embrittlement. Therefore, for the realization of a hydrogen society, it is important to expand the range of materials available for hydrogen equipment and thereby to enable the use of inexpensive common materials. Therefore, ductile cast iron was, in this study, focused as a structural material that could contribute to cost reduction of hydrogen equipment, because it is a low-cost material having good mechanical property comparable to carbon steels in addition to good castability and machinability. The strength and ductility of common ductile cast irons with a ferritic-pearlitic matrix can be controlled by the volume fraction of pearlitic phase. In the case of carbon steels, the susceptibility to hydrogen embrittlement increases with increase in the pearlite fraction. Toward the development of ferritic-pearlitic ductile cast iron with reasonable strength for hydrogen equipment, it is necessary to figure out the effect of pearlite on the hydrogen embrittlement of this cast iron. In this study, the tensile tests were conducted using hydrogen-precharged specimens of three kinds of ferritic-pearlitic ductile cast irons, JIS-FCD400, JIS-FCD450 and JIS-FCD700. Based on the results, the role of pearlite in characterizing the hydrogen embrittlement of ductile cast iron was discussed.

  6. Engineered Cooling Process for High Strength Ductile Iron Castings

    Science.gov (United States)

    Lekakh, Simon N.; Mikhailov, Anthony; Kramer, Joseph

    Professor Stefanescu contributed fundamentally to the science of solidification and microstructural evolutions in ductile irons. In this article, the possibility of development of high strength ductile iron by applying an engineered cooling process after casting early shake out from the sand mold was explored. The structures in industrial ductile iron were experimentally simulated using a computer controlled heating/cooling device. CFD modeling was used for process simulation and an experimental bench scale system was developed. The process concept was experimentally verified by producing cast plates with 25 mm wall thickness. The tensile strength was increased from 550 MPa to 1000 MPa in as-cast condition without the need for alloying and heat treatment. The possible practical applications were discussed.

  7. Fracture toughness of borides formed on boronized ductile iron

    International Nuclear Information System (INIS)

    Sen, Ugur; Sen, Saduman; Koksal, Sakip; Yilmaz, Fevzi

    2005-01-01

    In this study, fracture toughness properties of boronized ductile iron were investigated. Boronizing was realized in a salt bath consisting of borax, boric acid and ferro-silicon. Boronizing heat treatment was carried out between 850 and 950 deg. C under the atmospheric pressure for 2-8 h. Borides e.g. FeB, Fe 2 B formed on ductile iron was verified by X-ray diffraction (XRD) analysis, SEM and optical microscope. Experimental results revealed that longer boronizing time resulted in thicker boride layers. Optical microscope cross-sectional observation of borided layers showed dentricular morphology. Both microhardness and fracture toughness of borided surfaces were measured via Vickers indenter. The harnesses of borides formed on the ductile iron were in the range of 1160-2140 HV 0.1 and fracture toughness were in the range of 2.19-4.47 MPa m 1/2 depending on boronizing time and temperature

  8. Solidification of Hypereutectic Thin Wall Ductile Cast Iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2006-01-01

    Hypereutectic ductile iron was cast in green sand moulds with four plates with thickness of 1.5, 2, 3 and 4 mm in each mould. Temperatures were measured in the 3 and 4 mm plate. The temperature curves showed that eutectic solidification was divided into two stages: primary and secondary eutectic...

  9. Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 8, No 3 (2016) >. Log in or Register to get access to full text downloads.

  10. Effect of austempering temperature on cavitation behaviour of unalloyed ADI material

    Energy Technology Data Exchange (ETDEWEB)

    Dojcinovic, Marina [University of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4, Belgrade (Serbia); Eric, Olivera [Innovation Centre, Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, Belgrade (Serbia); Rajnovic, Dragan; Sidjanin, Leposava [Department of Production Engineering, Faculty of Technical Sciences, University of Novi Sad, Trg Dositeja Obradovića 6, Novi Sad (Serbia); Balos, Sebastian, E-mail: sebab@uns.ac.rs [Department of Production Engineering, Faculty of Technical Sciences, University of Novi Sad, Trg Dositeja Obradovića 6, Novi Sad (Serbia)

    2013-08-15

    This paper provides an in-depth study and description of cavitation damage and microstructural changes in two types of unalloyed austempered ductile iron (ADI). ADI materials used were austempered at 300 and 400 °C having ausferrite microstructure with 16 and 31.4% of retained austenite, respectively. Metallographic examination was carried out to study the morphology of their cavitation-damaged surfaces. Cavitation damage was initiated at graphite nodules as well as in the interface between a graphite nodule and an ausferrite matrix. Furthermore, microcracking and ferrite/retained austenite morphology were proved to be of great importance for cavitation resistance. Mass loss rate revealed that ADI austempered at 400 °C has a higher cavitation resistance in water than ADI austempered at 300 °C. A higher amount of retained austenite in ADI austempered at 400 °C played an important role in increasing cavitation resistance. The good cavitation behaviour of ADI austempered at 400 °C was due to the matrix hardening by stress assisted phase transformation of retained austenite into martensite (SATRAM) phenomenon, as shown by X-ray diffraction analysis. - Highlights: • Cavitation rate of two ADI materials was tested. • ADI material with a lower hardness has had a lower cavitation rate. • The main reason is microstructural transformations during cavitation. • SATRAM phenomenon increases cavitation resistance.

  11. Thermo-Mechanical Processing and Properties of a Ductile Iron

    Energy Technology Data Exchange (ETDEWEB)

    Syn, C.K.; Lesuer, R.R.; Sherby, O.D.

    1997-07-14

    Thermo-mechanical processing of ductile irons is a potential method for enhancing their mechanical properties. A ductile cast iron containing 3.6% C, 2.6% Si and 0.045% Mg was continuously hot-and-warm rolled or one-step press-forged from a temperature in the austenite range (900{degrees}C-1100{degrees}C) to a temperature below the A, temperature. Various amounts of reduction were used (from 60% to more than 90%) followed by a short heat ent at 600`C. The heat ent lead to a structure of fine graphite in a matrix of ferrite and carbides. The hot-and- warm worked materials developed a pearlitic microstructure while the press-forged material developed a spheroidite-like carbide microstructure in the matrix. Cementite-denuded ferrite zones were developed around graphite stringers in the hot-and-warm worked materials, but such zones were absent in the press-forged material. Tensile properties including tensile strength and total elongation were measured along the direction parallel and transverse to the rolling direction and along the direction transverse to the press-forging direction. The tensile ductility and strength both increased with a decrease in the amount of hot-and-warm working. The press- forged materials showed higher strength (645 MPa) than the hot-and-warrn worked materials (575 MPa) when compared at the same ductility level (22% elongation).

  12. Solidification and microstructure of thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin

    2006-01-01

    In the recent years there has been an increasing interest in light constructions in order to save weight in e.g. cars. Ductile cast iron has good mechanical properties but it is necessary to re­duce the wall thicknesses of the castings in order to reduce the weight. Reducing the wall thicknesses...... of the casting will increase the cooling rates and by that change the conditions for nucleation and growth during solidification....

  13. Adhesion and wear properties of boro-tempered ductile iron

    International Nuclear Information System (INIS)

    Kayali, Yusuf; Yalcin, Yilmaz; Taktak, Suekrue

    2011-01-01

    Highlights: → In this study, the wear and adhesion properties of BDI were investigated. → Boro-tempering process under several heat treatment conditions was examined. → Optical microscope, SEM and XRD analysis were carried out to investigate the microstructure. → It was observed that boro-tempering process improves micro-hardness and wear properties of ductile irons. -- Abstract: In this study, adhesion and wear properties of boro-tempered ductile iron (BDI) were investigated. Boro-tempering was carried out on two stage processes i.e. boronizing and tempering. At the first stage, ductile iron samples were boronized by using pack process at 900 o C for 1, 3, and 5 h and then, secondly tempered at 250, 300, 350, and 400 o C for 1 h. X-ray diffraction (XRD) analysis of boro-tempered samples showed that FeB and Fe 2 B phases were found on the surface of the samples. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layer. Test result showed that adhesion decreased with increasing boriding time and increased with increasing tempering temperature. Dry sliding wear tests of these samples were performed against Al 2 O 3 ball at a constant sliding speed and loads of 5 and 10 N. Wear tests indicated that boro-tempering heat treatment increased wear resistance of ductile iron. In addition, it was found that while wear rate of boro-tempered samples decreased with increasing boriding time, there is no significant affect of tempering temperature on wear rate.

  14. Casting Ductile Iron in Layer Moulds Made from Ecological Sands

    Directory of Open Access Journals (Sweden)

    M. Rączka

    2012-09-01

    Full Text Available The article contains the results of tests performed under the target project in Hardtop Foundry Charsznica.The objective of the tests and studies was to develop a technology of making high-quality ductile iron castings, combined witheffective means of environmental protection. The studies presented in this article related to castings weighing from 1 to 300 kg made from ductile iron of grades 400-15 and 500-7, using two-layer moulds, where the facing and core sand was the sand with an alkaline organic binder, while backing sand was the sand with an inorganic geopolymer binder.A simplified method of sand reclamation was applied with possible reuse of the reclaim as an addition to the backing sand. The castiron spheroidising treatment and inoculation were selected taking into account the specific conditions of Hardtop Foundry. A pilot batch of castings was made, testing the gating and feeding systems and using exothermic sleeves on risers. The study confirmed the validity of the adopted concept of making ductile iron castings in layer moulds, while maintaining the content of sand with an organic binder at a level of maximum 15%.

  15. The Silumin Coat Structure on Alloy Ductile Iron

    Directory of Open Access Journals (Sweden)

    Szymczak T.

    2013-03-01

    Full Text Available The work presents the research results of the silumin coat structure applied on the carbidic alloy ductile iron with the metal matrix: pearlitic, bainitic and martensitic. The coats were made in the AlSi5 silumin bath at the temperature tk = 750±5°C. The holding time of cast iron element in the bath was τ = 180s. Irrespective of the kind of tested ductile iron the obtained coat consisted of three layers with a different phase composition. The first layer from the cast iron ground “g1`” is built from Fe4CSi carbide which contains selected alloy additives of the cast iron. On it the second layer “g1``” crystallizes. It consists of the AlFeSi inter-metallic phase which can appear in its pure form or contain a small quantity of the alloy additives of the cast iron. The last external part of the layer “g2” mainly consists of the hypo-eutectic phases of silumin. The AlFeSi inter-metallic phases in the form of free precipitations with a lamellar or faceted morphology can also appear there. These phases also can contain a small quantity of the alloy additives of the cast iron. More than that, in all the layers of the coat there are graphite precipitations. The phenomenon of graphite movement to the coat is caused by intensive dissolving of the cast iron element surface by the aluminum of the silumin bath.

  16. Mechanisms and mechanics of porosity formation in ductile iron castings

    Directory of Open Access Journals (Sweden)

    M. Perzyk

    2007-12-01

    Full Text Available Shrinkage defects in ductile iron castings can be of two basic types: shrinkage cavities associated with the liquid contraction prior to the expansion period of the iron as well as the porosity, which may appear even if the liquid shrinkage is fully compensated. In the present paper two possible mechanisms of the porosity are presented and analyzed. The first one is the Karsay’s mechanism based on the secondary shrinkage concept. The second one is the mechanism acting during the expansion period of the iron, first suggested by Ohnaka and co-authors and essentially modified by the present authors. The mechanical interactions between casting and mould are determined for the both mechanisms. Their analysis leads to the conclusion, that porosity forms during expansion period of the melt. The direct cause is the negative pressure which appears in the central part of the casting due to the differences in expansion coefficients of the fast cooling surface layer and slow cooling inner region. Observations concerning feeding behavior of ductile iron castings, based on this mechanism, agree well with industrial practice. The secondary shrinkage is not only needless to induce the porosity, but the corresponding mechanism of its occurrence, proposed by Karsay, does not seem to be valid.

  17. Some problems in the production of ductile irons by investment casting

    Directory of Open Access Journals (Sweden)

    Yu Bo

    2008-02-01

    Full Text Available Because of the excellent performance of ductile irons and the unique superiority of investment casting, the preparation of complicated and thin-wall ductile iron castings by investment casting shows a good development prospect. In this present work, combined with the actual product experiments, the characteristics of shell making, spheroidization, inoculation and defect prevention are presented, and some suggestions are given for investment casting of ductile iron.

  18. Effect of bainite transformation and retained austenite on mechanical properties of austempered spheroidal graphite cast steel

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Toshio; Abe, Toshihiko; Tada, Shuji [Tohoku National Industrial Research Inst., Sendai (Japan). Materials Engineering Div.

    1996-06-01

    Austempered ductile iron (ADI) has excellent mechanical properties, but its Young`s modulus is low. Austempered spheroidal graphite cast steel (AGS) has been developed in order to obtain a new material with superior mechanical properties to ADI. Its carbon content (approximately 1.0 pct) is almost one-third that of a standard ADI; thus, the volume of graphite is also less. Young`s modulus of AGS is 195 to 200 GPa and is comparable to that of steel. Austempered spheroidal graphite cast steel has an approximately 200 MPa higher tensile strength than ADI and twice the Charpy absorbed energy of ADI. The impact properties and the elongation are enhanced with increasing volume fraction of carbon-enriched retained austenite. At the austempering temperature of 650 K, the volume fraction of austenite is approximately 40 pct for 120 minutes in the 2.4 pct Si alloy, although it decreases rapidly in the 1.4 pct Si alloy. The X-ray diffraction analysis shows that appropriate quantity of silicon retards the decomposition of the carbon-enriched retained austenite. For austempering at 570 K, the amount of the carbon-enriched austenite decreases and the ferrite is supersaturated with carbon, resulting in high tensile strength but low toughness.

  19. Manufacture of Toothed Elements in Nanoausferritic Ductile Iron

    Directory of Open Access Journals (Sweden)

    Myszka D.

    2014-10-01

    Full Text Available The technology currently used for the fabrication of toothed wheels, gear couplings and chain drums involves the induction hardening process or hardening and tempering after carburising. All these processes take a long time and cause adverse changes in the dimensions and surface quality of products, requiring post-treatment machining to remove the resulting cavities. The paper proposes the implementation of gear elements made of ductile iron with nanoausferritic matrix obtained by a new appropriate heat treatment process. The new material offers good performance characteristics and nearly no need for the application of other technological processes commonly used in the manufacture of gears.

  20. Influence of isothermal transformation dwell on tensile and fatigue properties of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Vechet, S.; Hanzlikova, K. [Brno Univ. of Technology, Brno (Czech Republic); Kohout, J. [Military Academy in Brno, Brno (Czech Republic)

    2005-07-01

    Two ADI heats transformed at temperatures of 400 and 380 C during temporal range from 2 minutes to 9 hours were studied in details, with emphasis on structure composition and mechanical properties (tensile and fatigue properties were determined). In the case of the shortest dwells the level of mechanical properties is influenced by martensite, which occurs in the structure as a result of subsequent cooling. UTS and yield stress increase slightly with the dwell of isothermal transformation while the values of elongation to fracture as well as of fatigue limit are very closely dependent on the amount of the retained austenite in the microstructure. (orig.)

  1. Metallurgical Examination of Failed T-158 Cast Austempered Ductile Iron (CADI) Track Shoes

    Science.gov (United States)

    1994-06-01

    Qduedoa. A hiper tbla IIOIIIiaal silicon can1ellt is less tban optimal, since the fracture tauaflue•,..,.,.... ~CADI ctec::n.e widl the increae of silicon...bellllle~~meat. A hiper .._ optiiDII lilicoll content decleued tbe impact ,_.-.,of dae tact shoes. Moreover, tbe CADI tract lboes were fabricated

  2. Analysis of fatigue crack initiation in cycled austempered ductile cast irons

    Czech Academy of Sciences Publication Activity Database

    Petrenec, Martin; Beran, Přemysl; Dluhoš, J.; Zouhar, Michal; Ševčík, Martin

    2010-01-01

    Roč. 2, č. 1 (2010), s. 2337-2346 E-ISSN 1877-7058. [Fatigue 2010. Praha, 06.06.2010-11.06.2010] R&D Projects: GA ČR GAP108/10/2371; GA ČR GD106/09/H035 Institutional research plan: CEZ:AV0Z20410507; CEZ:AV0Z10480505 Keywords : Low cycle fatigue * ADI * Finite element modelling * Neutron diffraction Subject RIV: JL - Materials Fatigue, Friction Mechanics

  3. Performance of heavy ductile iron castings for windmills

    Directory of Open Access Journals (Sweden)

    Iulian Riposan

    2010-05-01

    Full Text Available The main objective of the present paper is to review the specific characteristics and performance obtaining conditions of heavy ductile iron (DI castings, typically applied in windmills industry, such as hubs and rotor housings. The requirements for high impact properties in DI at low temperatures are part of the EN-GJS-400-18U-LT (SRN 1563 commonly referred to as GGG 40.3 (DIN 1693. Pearlitic influence factor (Px and antinodularising action factor (K1 were found to have an important influence on the structure and mechanical properties, as did Mn and P content, rare earth (RE addition and inoculation power. The presence of high purity pig iron in the charge is extremely beneficial, not only to control the complex factors Px and K1, but also to improve the ‘metallurgical quality’ of the iron melt. A correlation of C and Si limits with section modulus is very important to limit graphite nodule flotation. Chunky and surface-degenerated graphite are the most controlled graphite morphologies in windmills castings. The paper concluded on the optimum iron chemistry and melting procedure, Mg-alloys and inoculants peculiar systems, as well as on the practical solutions to limit graphite degeneration and to ensure castings of the highest integrity, typically for this field.

  4. Approximate creep feed grinding of austempared ductile cast iron; Osutenpa kyujo kokuen chutetsu no kin`i kuripu fido kensaku

    Energy Technology Data Exchange (ETDEWEB)

    Nakamitsu, K.; Shimizu, K. [Oita National College of Technology, Oita (Japan)

    1996-10-01

    Austempered ductile cast iron (ADI) was subjected to approximate creep feed grinding to measure and observe the grinding ratio, hardness of ground surface, grinding resistance, production of burrs, roughness of ground surface, and grinding burn to investigate the best abrasive grains and grinding conditions. The grinding ratio of SiC grains was far better than that of Al2O3 grains, being about 10 times or more. Surface hardness of ADI ground by SiC grains changed little, but that ground by Al2O3 grains increased. As regards grinding resistance, that of Al2O3 grains have less slope and tangential component forces, but that of SiC grains increased with the increase in the ground volume. While burrs produced in grinding with SiC grains are secondary burrs, those produced in grinding with Al2O3 grains are primary burrs. In comparison with the normal grinding, grinding burn was produced on the ground surface, complicate striped patterns and grinding burns were produced by chattering particularly in grinding with Al2O3 grains. 10 refs., 11 figs., 2 tabs.

  5. Methodology of Fault Diagnosis in Ductile Iron Melting Process

    Directory of Open Access Journals (Sweden)

    Perzyk M.

    2016-12-01

    Full Text Available Statistical Process Control (SPC based on the Shewhart’s type control charts, is widely used in contemporary manufacturing industry, including many foundries. The main steps include process monitoring, detection the out-of-control signals, identification and removal of their causes. Finding the root causes of the process faults is often a difficult task and can be supported by various tools, including data-driven mathematical models. In the present paper a novel approach to statistical control of ductile iron melting process is proposed. It is aimed at development of methodologies suitable for effective finding the causes of the out-of-control signals in the process outputs, defined as ultimate tensile strength (Rm and elongation (A5, based mainly on chemical composition of the alloy. The methodologies are tested and presented using several real foundry data sets. First, correlations between standard abnormal output patterns (i.e. out-of-control signals and corresponding inputs patterns are found, basing on the detection of similar patterns and similar shapes of the run charts of the chemical elements contents. It was found that in a significant number of cases there was no clear indication of the correlation, which can be attributed either to the complex, simultaneous action of several chemical elements or to the causes related to other process variables, including melting, inoculation, spheroidization and pouring parameters as well as the human errors. A conception of the methodology based on simulation of the process using advanced input - output regression modelling is presented. The preliminary tests have showed that it can be a useful tool in the process control and is worth further development. The results obtained in the present study may not only be applied to the ductile iron process but they can be also utilized in statistical quality control of a wide range of different discrete processes.

  6. Comparative study of TIG and SMAW root welding passes on ductile iron cast weldability

    Directory of Open Access Journals (Sweden)

    J. Cárcel-Carrasco

    2017-01-01

    Full Text Available This work compares the weldability of ductile iron when: (I a root weld is applied with a tungsten inert gas (TIG process using an Inconel 625 source rod and filler welds are subsequently applied using coated electrodes with 97,6%Ni; and (II welds on ductile iron exclusively made using the manual shielded metal arc welding technique (SMAW. Both types of welds are performed on ductile iron specimen test plates that are subjected to preheat and post-weld annealing treatments. Samples with TIG root-welding pass shown higher hardness but slightly lower ductility and strength. Both types of welding achieved better ductile and strength properties than ones found in literature.

  7. Pearlitic ductile cast iron: damaging micromechanisms at crack tip

    Directory of Open Access Journals (Sweden)

    F. Iacoviello

    2013-07-01

    Full Text Available Ductile cast irons (DCIs are characterized by a wide range of mechanical properties, mainly depending on microstructural factors, as matrix microstructure (characterized by phases volume fraction, grains size and grain distribution, graphite nodules (characterized by size, shape, density and distribution and defects presence (e.g., porosity, inclusions, etc.. Versatility and higher performances at lower cost if compared to steels with analogous performances are the main DCIs advantages. In the last years, the role played by graphite nodules was deeply investigated by means of tensile and fatigue tests, performing scanning electron microscope (SEM observations of specimens lateral surfaces during the tests (“in situ” tests and identifying different damaging micromechanisms.In this work, a pearlitic DCIs fatigue resistance is investigated considering both fatigue crack propagation (by means of Compact Type specimens and according to ASTM E399 standard and overload effects, focusing the interaction between the crack and the investigated DCI microstructure (pearlitic matrix and graphite nodules. On the basis of experimental results, and considering loading conditions and damaging micromechanisms, the applicability of ASTM E399 standard on the characterization of fatigue crack propagation resistance in ferritic DCIs is critically analyzed, mainly focusing the stress intensity factor amplitude role.

  8. Thermomechanical Fatigue of Ductile Cast Iron and Its Life Prediction

    Science.gov (United States)

    Wu, Xijia; Quan, Guangchun; MacNeil, Ryan; Zhang, Zhong; Liu, Xiaoyang; Sloss, Clayton

    2015-06-01

    Thermomechanical fatigue (TMF) behaviors of ductile cast iron (DCI) were investigated under out-of-phase (OP), in-phase (IP), and constrained strain-control conditions with temperature hold in various temperature ranges: 573 K to 1073 K, 723 K to 1073 K, and 433 K to 873 K (300 °C to 800 °C, 450 °C to 800 °C, and 160 °C to 600 °C). The integrated creep-fatigue theory (ICFT) model was incorporated into the finite element method to simulate the hysteresis behavior and predict the TMF life of DCI under those test conditions. With the consideration of four deformation/damage mechanisms: (i) plasticity-induced fatigue, (ii) intergranular embrittlement, (iii) creep, and (iv) oxidation, as revealed from the previous study on low cycle fatigue of the material, the model delineates the contributions of these physical mechanisms in the asymmetrical hysteresis behavior and the damage accumulation process leading to final TMF failure. This study shows that the ICFT model can simulate the stress-strain response and life of DCI under complex TMF loading profiles (OP and IP, and constrained with temperature hold).

  9. Ductile cast iron obtaining by Inmold method with use of LOST FOAM process

    Directory of Open Access Journals (Sweden)

    T. Pacyniak

    2010-01-01

    Full Text Available The possibility of manufacturing of ductile cast iron castings by Inmold method with use of LOST FOAM process was presented in this work. The spheroidization was carried out by magnesium master alloy in amounts of 1% casting mass. Nodulizer was located in the reactive chamber in the gating system made of foamed polystyrene. Pretests showed, that there are technical possibilities of manufacturing of casts from ductile cast iron in the LOST FOAM process with use of spheroidization in mould.

  10. Effects of casting defects, matrix structures and loading conditions on the fatigue strength of ductile irons

    Directory of Open Access Journals (Sweden)

    Endo Masahiro

    2014-06-01

    Full Text Available A novel method is presented to estimate the lower bound of the scatter in fatigue limit of ductile iron based upon the information of microstructural in homogeneities and loading conditions. The predictive capability of the method was verified by comparing to the experimental data obtained by the rotating-bending, torsion and combined tension-torsion fatigue tests for ductile irons with ferritic, pearlitic and bulls-eye (ferritic/pearlitic microstructures.

  11. Thin wall ductile iron casting as a substitute for aluminum alloy casting in automotive industry

    Directory of Open Access Journals (Sweden)

    M. Górny

    2009-01-01

    Full Text Available In paper it is presented thin wall ductile iron casting (TWDI as a substitute of aluminium alloy casting. Upper control arm made of ductile iron with wall thickness ranging from 2 – 3.7 mm was produced by inmold process. Structure, mechanical properties and computer simulations were investigated. Structural analysis of TWDI shows pearlitic-ferritic matrix free from chills and porosity. Mechanical testing disclose superior ultimate tensile strength (Rm, yield strength (Rp0,2 and slightly lower elongation (E of TWDI in comparison with forged control arm made of aluminium alloy (6061-T6. Moreover results of computer simulation of static loading for tested control arms are presented. Analysis show that the light-weight ductile iron casting can be loaded to similar working conditions as the forged Al alloy without any potential failures.

  12. Influencing factors on as-cast and heat treated 400-18 ductile iron grade characteristics

    Directory of Open Access Journals (Sweden)

    I. Riposan

    2007-11-01

    Full Text Available As-cast and heat-treated 400-18 ductile iron (DI grade was obtained in different foundry conditions, as metallic charge, Mg-treatment alloy and inoculation. It was found that the Pearlitic Influence Factor (Px and Antinodulizing Complex Factor (K1 have an important influence on property of DI, depending on the Mn and P level, the metallurgical quality of iron melt, rare earth (RE and inoculation. It was also found that the influence of Mn is depended on the phosphorus and residual elements level in ductile iron. Less than 0.03%P and 0.2%Mn and Px2.0 determines presence of pearlite in as-cast structure, while ferrite structure is obtained after a short annealing heat treatment. Lower level of phosphorus (P1.2. Si has a significant influence on the mechanical properties of heat treated ductile irons: an important decreasing of elongation level and a moderate increasing of yield and tensile strength and their ratio in 150-170 HB typical hardness field. A typical final chemical composition for as-cast 400-18 ductile iron could include 3.5%-3.7%C, 2.4%-2.5%Si, max.0.18%Mn, max.0.025%P, max.0.01%S, 0.04%-0.05%Mgres. for Px<1.5 and K1<1.1. High purity pig iron, RE-bearing FeSiMg and powerful inoculant are also recommended.

  13. Influence of the section size and holding time on the graphite parameters of ductile iron production

    Directory of Open Access Journals (Sweden)

    S. Bockus

    2009-01-01

    Full Text Available This work was conducted to establish the conditions required to produce a desirable structure of the castings of various section sizes. This investigation was focused on the study of the influence of cooling rate or section size and holding time on graphite parameters of the ductile iron. Plates having thickness between 3 and 50mm were cast in sand molds using the same melt. The present investigation has shown that the section size of ductile iron castings and holding time had strong effect on the graphite parameters of the castings.

  14. Investigation of solidification of thin walled ductile cast iron using temperature measurement

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels

    2005-01-01

    Investigation of solidification of thin walled ductile cast iron can be improved using temperature measurement. This article includes some background of the precautions that have to be taken when measuring temperatures in thin walled castings. The aim is to minimize influence of temperature...... measurement on castings and to get sufficient response time of thermocouples. Investigation of thin wall ductile iron has been performed with temperature measurement in plates with thickness between 2,8 and 8mm. The cooling curves achieved are combined with examination of the microstructure in order to reveal...

  15. Examination and Elimination of Defects in Cone Casting Made of Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    Guzik E.

    2013-12-01

    Full Text Available In the scope of existing cooperation with the Foundry of Cast Iron ZM “WSK Rzeszów” Ltd. there was carried out research work of microstructure and mechanical properties in the walls of a cone casting made of ductile cast iron. The particular attention was being put to the search of the potential brittle phases which have deleterious effect on ductility and dynamic properties of highly strained use of the casting prone to the potential risk of cracks during the highly strained use.

  16. Assessment of ductile iron casting process with the use of the DRSA method

    Directory of Open Access Journals (Sweden)

    Kujawińska A.

    2016-01-01

    Full Text Available The paper introduces a concept of assessment of a ductile iron casting process with use of the rule-based approach, known as DRSA (dominance-based rough set approach. The research was conducted in a large Polish foundry. The collected data concern the chemical composition and mechanical properties of the used ductile cast iron. In the paper, a methodology of creating a rule-based moulding model for the tensile strength was proposed. The quality, sensitivity and accuracy of the model extracted from the data were examined. The studies proved its usefulness in the industrial practice and for aiding of the decision making process.

  17. Draft ASME code case on ductile cast iron for transport packaging

    Energy Technology Data Exchange (ETDEWEB)

    Saegusa, T. [Central Research Inst. of Electric Power Industry, Abiko (Japan); Arai, T. [Central Research Inst. of Electric Power Industry, Yokosuka (Japan); Hirose, M. [Nuclear Fuel Transport Co., Ltd., Tokyo (Japan); Kobayashi, T. [Nippon Chuzo, Kawasaki (Japan); Tezuka, Y. [Mitsubishi Materials Co., Tokyo (Japan); Urabe, N. [Kokan Keisoku K. K., Kawasaki (Japan); Hueggenberg, R. [GNB, Essen (Germany)

    2004-07-01

    The current Rules for Construction of ''Containment Systems for Storage and Transport Packagings of Spent Nuclear Fuel and High Level Radioactive Material and Waste'' of Division 3 in Section III of ASME Code (2001 Edition) does not include ductile cast iron in its list of materials permitted for use. The Rules specify required fracture toughness values of ferritic steel material for nominal wall thickness 5/8 to 12 inches (16 to 305 mm). New rule for ductile cast iron for transport packaging of which wall thickness is greater than 12 inches (305mm) is required.

  18. Development and Testing of a Linear Polarization Resistance Corrosion Rate Probe for Ductile Iron Pipe (Web Report 4361)

    Science.gov (United States)

    The North American water and wastewater community has hundreds of millions of feet of ductile iron pipe in service. Only a portion of the inventory has any form of external corrosion control. Ductile iron pipe, in certain environments, is subject to external corrosion.Linear Pola...

  19. Structure and mechanical properties of ductile iron GJS-500-7

    International Nuclear Information System (INIS)

    Kuryloa, P.; Tertela, E.

    2017-01-01

    The paper presents the results of research on mechanical properties (hardness distribution along the cross section towards the cast’s core) and on the structures of ductile iron GJS-500-7. The study defines the range and form of the surface layer of cast iron. It has been shown that the surface layer of the working surface of the cast may be shaped within its transition zone. [es

  20. Machinable, Thin-Walled, Gray and Ductile Iron Casting Production, Phase III

    Energy Technology Data Exchange (ETDEWEB)

    Charles Bates; Hanjun Li; Robin Griffin

    2003-12-08

    This report presents the results of research conducted to determine the effects of normal and abnormal processing and compositional variations on machinability (tool wear rate) of gray and ductile iron. The procedures developed allow precise tool wear measurements to be made and interpreted in terms of microstructures and compositions. Accurate data allows the most efficient ways for improving machinability to be determined without sacrificing properties of the irons.

  1. Hot Ductility and High Temperature Microstructure of High Purity Iron Alloys

    OpenAIRE

    Abiko, K.

    1995-01-01

    The inherent properties of metals are affected by impurity elements, sometimes strongly. There are many brittle phenomena in iron and its alloys due to the harmful effect of trace impurities such as sulphur, phosphorus, hydrogen and so on. On the other hand, a large number of alloying elements also embrittle iron due to the transformation and precipitation of secondary phase. For example, the ductility of Fe-Cr alloy decreases with the increase in chromium content, although the strength and t...

  2. Influence of rare earths on shrinkage porosity in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2009-01-01

    Ductile cast iron has been cast in test bars with thickness from 2 to 10 mm. The rare earth elements La and Ce have been added to some of the castings to evaluate their influence on microstructure and shrinkage tendency. Both La and Ce increased the graphite nodule count, especially for thickness...

  3. Undercooling, nodule count and carbides in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Ductile cast iron has been cast in plate thicknesses between 2 to 8 mm. The temperature has been measured during the solidification and the graphite nodule count and size distribution together with the type and amount of carbides have been analysed afterwards. Low nodule count gives higher...

  4. Numerical modelling of thin-walled hypereutectic ductile cast iron parts

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper Henri; Tiedje, Niels Skat

    2006-01-01

    Solidification of hypereutectic thin-walled ductile cast iron has been modelled in one dimension taking into account the precipitation of off-eutectic austenite dendrites during solidification. The simulations have been compared with casting experiments on plate geometries with plate thicknesses...

  5. Three-dimensional local residual stress and orientation gradients near graphite nodules in ductile cast iron

    DEFF Research Database (Denmark)

    Zhang, Yubin; Andriollo, Tito; Fæster, Søren

    2016-01-01

    A synchrotron technique, differential aperture X-ray microscopy (DAXM), has been applied to characterize the microstructure and analyze the local mesoscale residual elastic strain fields around graphite nodules embedded in ferrite matrix grains in ductile cast iron. Compressive residual elastic...

  6. Nucleation and solidification of thin walled ductile iron - Experiments and numerical simulation

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2005-01-01

    Investigation of solidification of thin walled ductile cast iron has been performed based on experiments and numerical simulation. The experiments were based on temperature and microstructure examination. Results of the experiments have been compared with a 1-D numerical solidification model...

  7. Synchrotron measurements of local microstructure and residual strains in ductile cast iron

    DEFF Research Database (Denmark)

    Zhang, Yubin; Andriollo, Tito; Fæster, Søren

    2017-01-01

    The local microstructure and distribution of thermally induced residual strains in ferrite matrix grains around an individual spherical graphite nodule in ductile cast iron (DCI) were measured using a synchrotron X-ray micro-diffraction technique. It is found that the matrix grains are deformed, ...

  8. Thermal distortion of disc-shaped ductile iron castings in vertically parted moulds

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Rasmussen, Jakob; Tiedje, Niels Skat

    2015-01-01

    A disc-shaped casting with an inner boss and an outer rim, separated by a thin walled section, was examined. This measurable deformation varied with the feeding modulus. The influence of alloy composition, particularly Si content, was examined with a pearlitic ductile iron (EN-GJS-500-7) and a fu...

  9. Effects of Silicon on Mechanical Properties and Fracture Toughness of Heavy-Section Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    Liang Song

    2015-01-01

    Full Text Available The effects of silicon (Si on the mechanical properties and fracture toughness of heavy-section ductile cast iron were investigated to develop material for spent-nuclear-fuel containers. Two castings with different Si contents of 1.78 wt.% and 2.74 wt.% were prepared. Four positions in the castings from the edge to the center, with different solidification cooling rates, were chosen for microstructure observation and mechanical properties’ testing. Results show that the tensile strength, elongation, impact toughness and fracture toughness at different positions of the two castings decrease with the decrease in cooling rate. With an increase in Si content, the graphite morphology and the mechanical properties at the same position deteriorate. Decreasing cooling rate changes the impact fracture morphology from a mixed ductile-brittle fracture to a brittle fracture. The fracture morphology of fracture toughness is changed from ductile to brittle fracture. When the Si content exceeds 1.78 wt.%, the impact and fracture toughness fracture morphology transforms from ductile to brittle fracture. The in-situ scanning electronic microscope (SEM tensile experiments were first used to observe the dynamic tensile process. The influence of the vermicular and temper graphite on fracture formation of heavy section ductile iron was investigated.

  10. The studies of mechanical properties and structure of ADI as function of austempering parameters

    Directory of Open Access Journals (Sweden)

    A. Krzyńska

    2010-10-01

    Full Text Available The results of study of ductile iron austempered using different parameters of austempering are presented. The aim of the investigations was to look closer into mechanical properties of this very attractive cast material. The experiment was carried out with commercial EN-GJS-500-7 grade ductile iron. The specimens were first solution heat treated 1 hour in 910oC and then isothermally quenched for different time in molten tin of different temperature. The mechanical properties heat treated specimens were tested using tensile test machine to evaluate Rp,0.2, Rm and A10. Moreover Brinell hardness tests were carried out for structure investigation conventional light microscopy only was used. It was discovered, that low yield strength ADI obtained for short time quenching at 275oC exhibited high strengthening effect while tensile strained. So it was concluded that this had to by cause by large amount of untransformed austenite, which FCC lattice providing large number of glide systems.

  11. Effect of phosphorus on hot ductility of high purity iron

    International Nuclear Information System (INIS)

    Abiko, K.; Liu, C.M.; Ichikawa, M..; Suenaga, H.; Tanino, M.

    1995-01-01

    Tensile tests on high purity Fe-P alloys with 0, 0.05 and 0.1 mass%P were carried out at temperatures between 300 K and 1073 K to clarify the intrinsic effect of phosphorus on the mechanical properties of iron at elevated temperatures. Microstructures of as-quenched, interrupted and ruptured specimens were observed. Experimental results show that the addition of phosphorus causes a remarkable increase in proof stress of high purity iron at 300 K, but the increase in proof stress by phosphorus decreases with increasing test temperature. The strengthening effect of phosphorus reduces to zero at 1073 K. High purity iron and Fe-P alloys rupture at almost 100% reduction in area at the whole test temperatures. However, Fe-P alloys show much larger elongation at test temperatures above 773 K than high purity iron. The increased elongation of high purity iron by addition of phosphorus was shown to be related to the effect of phosphorus on dynamic recovery and recrystallization of iron as its intrinsic effect. (orig.)

  12. Influence of cooling rate and antimony addition content on graphite morphology and mechanical properties of a ductile iron

    Directory of Open Access Journals (Sweden)

    Liu Zhe

    2012-05-01

    Full Text Available Cooling rate and inoculation practice can greatly affect the graphite morphology of ductile irons. In the present research, the effects of the cooling rate and antimony addition on the graphite morphology and mechanical properties of ductile irons have been studied. Three ductile iron castings were prepared through solidification under cooling conditions S (slow, M (medium and F (fast. The cooling rates around the equilibrium eutectic temperature (1,150 ℃ for these cooling conditions (S, M and F were set at 0.21 ℃·min-1, 0.32 ℃·min-1 and 0.37 ℃·min-1, respectively. In addition, four ductile iron castings were prepared by adding 0.01%, 0.02%, 0.03% and 0.04% (by weight antimony, respectively under the slow cooling condition. The results show that the nodularity index, tensile strength and hardness of the ductile iron castings without antimony addition are all improved with the increase of cooling rate, while the ductile iron casting solidified under the medium cooling rate possesses the largest number of graphite nodules. Furthermore, for the four antimony containing castings, the graphite morphology and tensile strength are also improved by the antimony additions, and the effect of antimony addition is intensified when the addition increases from 0.01% to 0.03%. Moreover, the rare earth elements (REE/antimony ratio of 2 appears to be the most effective for fine nodular graphite formation in ductile iron.

  13. Effect of Phosphorus on Hot Ductility of High Purity Iron

    OpenAIRE

    Abiko, K.; Liu, C.-M.; Ichikawa, M.; Suenaga, H.; Tanino, M.

    1995-01-01

    Tensile tests on high purity Fe-P alloys with 0, 0.05 and 0.1 mass%P were carried out at temperatures between 300 K and 1073 K to clarify the intrinsic effect of phosphorus on the mechanical properties of iron at elevated temperatures. Microstructures of as-quenched, interrupted and ruptured specimens were observed. Experimental results show that the addition of phosphorus causes a remarkable increase in proof stress of high purity iron at 300 K, but the increase in proof stress by phosphorus...

  14. Brittle-ductile behavior in 3D iron crystals

    Czech Academy of Sciences Publication Activity Database

    Pelikán, Vladimír; Hora, Petr; Machová, Anna; Spielmannová, Alena

    2005-01-01

    Roč. 55, č. 10 (2005), s. 1245-1260 ISSN 0011-4626 R&D Projects: GA AV ČR(CZ) IAA2076201 Institutional research plan: CEZ:AV0Z20760514 Keywords : cracks * dislocations * bcc iron Subject RIV: JG - Metallurgy Impact factor: 0.360, year: 2005

  15. Nondestructive characterization of ductile cast iron by magnetic adaptive testing

    Czech Academy of Sciences Publication Activity Database

    Vértesy, G.; Uchimoto, T.; Tomáš, Ivan; Takagi, T.

    2010-01-01

    Roč. 322, č. 20 (2010), s. 3117-3121 ISSN 0304-8853 R&D Projects: GA ČR GA101/09/1323; GA AV ČR 1QS100100508 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic NDE * magnetic adaptive testing * magnetic hysteresis * cast iron Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.689, year: 2010

  16. Numerical simulation of ductile-brittle behaviour of cracks in aluminium and bcc iron

    International Nuclear Information System (INIS)

    Zacharopoulos, Marios

    2017-01-01

    The principal aim of the present dissertation is to investigate the role of sharp cracks on the mechanical behaviour of crystals under load at the atomic scale. The question of interest is how a pure crystal, which contains a single crack in mechanical equilibrium, deforms. Two metals were considered: aluminium, ductile at any temperature below its melting point, and iron, being transformed from ductile to brittle upon decreasing temperature below T=77 K. Cohesive forces in both metals were modeled via phenomenological n-body potentials. A (010)[001] mode I nano-crack was introduced in the perfect crystalline lattice of each of the studied metals by using appropriate displacements ascribed by anisotropic elasticity. At T=0 K, equilibrium crack configurations were obtained via energy minimization with a mixed type of boundary conditions. Both models revealed that the crack configurations remained stable under a finite range of applied stresses due to the lattice trapping effect. The present thesis proposes a novel approach to interpret the intrinsic mechanical behaviour of the two metallic systems under loading. In particular, the ductile or brittle response of a crystalline system can be determined by examining whether the lattice trapping barrier of a pre-existing crack is sufficient to cause the glide of pre-existing static dislocations on the available slip systems. Simulation results along with experimental data demonstrate that, according to the model proposed, aluminium and iron are ductile and brittle at T=0 K, respectively. (author) [fr

  17. Experimental analysis of flow of ductile cast iron in stream lined gating systems

    DEFF Research Database (Denmark)

    Skov-Hansen, Søren; Green, Nick; Tiedje, Niels Skat

    2008-01-01

    Streamlined gating systems have been developed for production of high integrity ductile cast iron parts. Flow of ductile cast iron in streamlined gating systems was studied in glass fronted sand moulds where flow in the gating system and casting was recorded by a digital video camera. These results...... are compared with real time x-ray recordings of melt flow. Results show that flow patterns are the same using both techniques. The glass fronted moulds give global information on flow in the whole gating system and casting while the x-ray analysis gives detailed information on specific areas. The experiments...... show how the quality of pouring, design of ingates, design of bends and flow over cores influence melt flow and act to determine the quality of the castings....

  18. Numerical modelling of solidification of thin walled hypereutectic ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper; Tiedje, Niels

    2006-01-01

    Numerical simulation of solidification of ductile cast iron is normally based on a model where graphite nodules are surrounded by an austenite shell. The two phases are then growing as two concentric spheres governed by diffusion of carbon through the austenite shell. Experiments have however shown...... simulation of thin-walled ductile iron castings. Simulations have been performed with a 1-D numerical solidi¬fication model that includes the precipitation of non-eutectic austenite during the eutectic stage. Results from the simulations have been compared with experimental castings with wall thick...... the presence of austenite dendrites even in hypereutectic castings. In thin-walled castings the presence of austenite dendrites is even more pronounced, which increases the risk of shrinkage porosities. This off-eutectic austenite is therefore an important part that should be taken into account during...

  19. Effect of Reclamation on the Skin Layer of Ductile Iron Cast in Furan Molds

    Science.gov (United States)

    Dańko, R.; Holtzer, M.; Górny, M.; Żymankowska-Kumon, S.

    2013-11-01

    The paper presents the results of investigations of the influence of the quality of molding sand with furan resin hardened by paratoluenesulfonic acid, on the formation of microstructure and surface quality of ductile iron castings. Within the studies different molding sands were used: molding sand prepared with fresh sand and molding sands prepared with reclaimed sands of a different purification degree, determined by the ignition loss value. Various concentrations of sulfur and nitrogen in the sand molds as a function of the ignition loss were shown in the paper. A series of experimental melts of ductile iron in molds made of molding sand characterized by different levels of surface-active elements (e.g., sulfur) and different gas evolution rates were performed. It was shown that there exists a significant effect of the quality of the sand on the formation of the graphite degeneration layer.

  20. Graphite nodules and local residual stresses in ductile iron: Thermo-mechanical modelingand experimental validation

    DEFF Research Database (Denmark)

    Andriollo, Tito

    the theoretical predictions that local stresses up to approximately half the macroscopic yield strength may remain in the ductile iron microstructure after manufacturing. Needless to say, this new type of residual stresses is expected to play an important role in determining the properties of ductile iron....... In addition, it also indicates that the average thermal contraction of the nodules is likely 3 to 4 times smaller compared to that of the surrounding matrix, hence confirming the existence of a driving force for the formation of stresses at the local scale. In order to investigate this last aspect, the final...... in the matrix region close to the nodules, which are mainly deviatoric and strongly affected by the number of conical sectors forming the graphite particles. To support the numerical findings, whose relevance calls for an adequate experimental validation, two techniques are employed. The Oliver-Pharr nano...

  1. Fracture mechanics aspects in the safe design of ductile iron shipping and storage containers

    International Nuclear Information System (INIS)

    Sappok, M.; Bounin, D.

    1996-01-01

    Containers made of ductile cast iron provide a safe method for transport of radioactive material. Contrary to widespread opinion ductile cast iron is a very tough material and can be manufactured in heavy sections. The containers are designed to withstand the very high impact loads of accidents like free drops onto unyielding targets. The design is based on postulated undetected crack-like flaws at the highest stressed location. Design must show that applied stress intensities are smaller than fracture toughness and no crack initiation and therefore also no crack propagation can occur. The design procedure followed in this paper is given in a new guideline still being drafted by the International Atomic Energy Agency

  2. Influence of process parameters on the properties of austempered ductile iron (ADI examined with the use of data mining methods

    Directory of Open Access Journals (Sweden)

    D. Wilk-Kołodziejczyk

    2016-10-01

    Full Text Available The article presents opportunities offered by the data mining analysis as applied to studies of the effect of process parameters on the mechanical properties of ADI. The applied methods of regression trees and cluster analysis allow for the detection of relationships between parameters and also allow determination of strength and form of the impact of different factors. The results of this study allow the creation of knowledge bases for systems supporting the decision-making process in technology.

  3. Low cycle fatigue of austempered ductile cast iron alloyed with nickel at room and at depressed temperature

    Czech Academy of Sciences Publication Activity Database

    Petrenec, Martin; Beran, Přemysl; Šmíd, Miroslav; Roupcová, Pavla; Tesařová, H.

    2009-01-01

    Roč. 16, 3a (2009), s. 1-6 ISSN 1335-0803. [Degradácia konštrukčných materiálov 2009. Tatranská Lomnica, 02.09.2009-04.09.2009] R&D Projects: GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507; CEZ:AV0Z10480505 Keywords : Low cycle fatigue * ADI with nickel alloying * Neutron diffraction * Fatigue crack initiation * Depressed temperature Subject RIV: JL - Materials Fatigue, Friction Mechanics

  4. Effect of Cu on the microstructural and mechanical properties of as-cast ductile iron

    International Nuclear Information System (INIS)

    Tiwari, Siddhartha; Das, J.; Ray, K.K.; Kumar, Hemant; Bhaduri, A.

    2012-01-01

    The application of ductile cast iron in the heavy engineering components like, cask for the storage and transportation of radioactive materials, demands high strength with improved fracture toughness in as cast condition. The mechanical properties and fracture toughness of as-cast ductile iron (DI) is directly related to its structure property which can be controlled by proper inoculation, alloying elements and cooling rate during solidification. The aim of the present investigation is to study the effect of varying amount of Cu (0.07%, 0.11%, and 0.16%) with 1% Ni in the microstructural development of as-cast ductile iron with emphasis on its mechanical properties and fracture toughness. Three different ductile irons have been prepared using induction furnace in batches of 300 kg following industrial practice. Microstructural features (amount of phases, morphology, size and count of graphite nodules) and mechanical properties (tensile strength and hardness) of prepared DI were determined using standard methods. Dynamic fracture toughness was measured using instrumented Charpy impact test on pre-cracked specimens following the standard ISO-FDIS-26843. Additionally, fracture surfaces of broken tensile and pre-cracked specimens were observed by SEM to study the micro-mechanism of fracture. The pearlite fraction and the nodule count are found to increase with increasing amount of copper in ferritic-pearlitic matrix. The hardness and strength values are found to increase with increasing amount of pearlite whereas fracture toughness decreases. Fractographs of broken specimens exhibited decohesion of graphite, crack propagation from graphite interface and transgranular fracture of ferrite. (author)

  5. Comparison of low cycle fatigue of ductile cast irons with different matrix alloyed with nickel

    Czech Academy of Sciences Publication Activity Database

    Petrenec, Martin; Tesařová, H.; Beran, Přemysl; Šmíd, Miroslav; Roupcová, Pavla

    2010-01-01

    Roč. 2, č. 1 (2010), s. 2307-2316 E-ISSN 1877-7058. [Fatigue 2010. Praha, 06.06.2010-11.06.2010] R&D Projects: GA ČR GAP108/10/2371 Institutional research plan: CEZ:AV0Z20410507; CEZ:AV0Z10480505 Keywords : Low cycle fatigue * ferritic ductile cast iron * ADI * nickel alloying * neutron diffraction Subject RIV: JL - Materials Fatigue, Friction Mechanics

  6. Effect of Bi on graphite morphology and mechanical properties of heavy section ductile cast iron

    Directory of Open Access Journals (Sweden)

    Song Liang

    2014-03-01

    Full Text Available To improve the mechanical properties of heavy section ductile cast iron, bismuth (Bi was introduced into the iron. Five castings with different Bi content from 0 to 0.014 wt.% were prepared; and four positions in the casting from the edge to the center, with different solidification cooling rates, were chosen for microstructure observation and mechanical properties test. The effect of the Bi content on the graphite morphology and mechanical properties of heavy section ductile cast iron were investigated. Results show that the tensile strength, elongation and impact toughness at different positions in the five castings decrease with a decrease in cooling rate. With an increase in Bi content, the graphite morphology and the mechanical properties at the same position are improved, and the improvement of mechanical properties is obvious when the Bi content is no higher than 0.011wt.%. But when the Bi content is further increased to 0.014wt.%, the improvement of mechanical properties is not obvious due to the increase of chunky graphite number and the aggregation of chunky graphite. With an increase in Bi content, the tensile fracture mechanism is changed from brittle to mixture ductile-brittle fracture.

  7. Development of acceptance criteria and damage tolerance analyzes of the ductile iron insert; Framtagning av acceptanskriterier samt skadetaalighetsanalyser av segjaernsinsatsen

    Energy Technology Data Exchange (ETDEWEB)

    Dillstroem, Peter; Alverlind, Lars; Andersson, Magnus (Inspecta Technology AB (Sweden))

    2010-01-15

    SKB intends to qualify a test system for detection and sizing of defects deemed to be relevant to the ductile iron insert. In support of this qualification, a damage tolerance analysis indicating the current qualification targets, given assumed damage and failure modes. This report describes the damage tolerance analyzes of different types of defects that are considered relevant of the ductile iron insert. The results are reported separately for each test area (zone) and type of insert (BWRs and PWRs)

  8. On the isotropic elastic constants of graphite nodules in ductile cast iron: Analytical and numerical micromechanical investigations

    DEFF Research Database (Denmark)

    Andriollo, Tito; Hattel, Jesper

    2016-01-01

    A comprehensive description of the mechanical behavior of nodules in ductile iron is still missing in the published literature. Nevertheless, experimental evidence exists for the importance of such graphite particles during macroscopic material deformation, especially under compressive loading. I...... mesoscopic moduli in agreement with Young's modulus and Poisson's ratio recorded for common ferritic ductile iron grades. This suggests that graphite nodules may not be considered isotropic at the microscopic scale, at least from a mechanical viewpoint....

  9. The effect of austenitizing conditions in the ductile iron hardening process on longitudinal ultrasonic wave velocity

    Directory of Open Access Journals (Sweden)

    A. W. Orłowicz

    2014-04-01

    Full Text Available The paper presents results of a research on the effect of austenitizing temperature and time adopted in the hardening operation on the ultrasonic wave velocity in ductile iron. It has been found that with increasing austenitizing temperature and with the passage of the austenitizing time, a monotonic decrease of the ultrasonic longitudinal wave velocity value occurred. Implementation of ultrasonic testing of results obtained in the course of the cast iron hardening process both in production and as-cast conditions, requires development of a test methodology that must take into account the influence of base material structure (degree of nodularization, graphite precipitation count on the ultrasound wave velocity.

  10. Microstructure and Hot Oxidation Resistance of SiMo Ductile Cast Irons Containing Si-Mo-Al

    Science.gov (United States)

    Ibrahim, Mervat M.; Nofal, Adel; Mourad, M. M.

    2017-04-01

    SiMo ductile cast irons are used as high-temperature materials in automotive components, because they are microstructurally stable at high operating temperatures. The effect of different amounts of Si and Mo as well as the addition of 3 wt pct Al on the microstructure, high-temperature oxidation, and mechanical properties of SiMo ductile cast iron was studied. Dilatometric measurements of SiMo ductile iron exhibited obvious differences in the transformation temperature A 1 due to presence of Al and the increase of Si. The microstructure of the SiMo alloys without Al addition showed outstanding nodularity and uniform nodule distribution. However, by adding 3 wt pct Al to low Si-SiMo ductile iron, some compacted graphite was observed. The results of oxidation experiments indicated that high Si-SiMo ductile iron containing 4 and 4.9 wt pct Si had superior resistance to lower Si-SiMo and SiMo ductile iron containing 3 wt pct Al. The results showed also that with increasing Si up to 4.9 wt pct or by replacing a part of Si with 3 wt pct Al, tensile strength increased while elongation and impact toughness decreased.

  11. Modern Cored Wire Injection 2PE-9 Method in the Production of Ductile Iron

    Directory of Open Access Journals (Sweden)

    E. Guzik

    2012-04-01

    Full Text Available The results of studies on the use of modern two cored wires injection method for production of nodular graphite cast iron with use of unique implementation of drum ladle as a treatment/ transport and casting ladle instead vertical treatment ladle was described. The injection of length of Ø 9mm wires, cored: in FeSi + Mg nodulariser mixture and inoculant master alloy is a treatment method which can be used to produce iron melted in coreless induction furnace. This paper describes the results of using this method for possibility production of ductile iron under specific industrial conditions. In this case was taken ductile iron with material designation: EN-GJS-450- 10 Grade according PN-EN 1563:2000. Microstructure of 28 trials was controlled on internally used sample which has been correlated with standard sample before. The paper presents typical metallic matrix and graphite characteristic. Additionally, mechanical properties were checked in one experiment. Because of further possibility treatment temperature reduction only the rough magnesium recovery and cost of this new method are given.

  12. High-Temperature Low-Cycle Fatigue Property of Heat-Resistant Ductile-Cast Irons

    Science.gov (United States)

    Kim, Yoon-Jun; Jang, Ho; Oh, Yong-Jun

    2009-09-01

    This study examined the high-temperature degradation behavior of two types of heat-resistant Si-Mo ductile cast iron (Fe-3.4C-3.7Si-0.4Mo and Fe-3.1C-4.5Si-1.0Mo) with particular attention paid to the mechanical properties and overall oxidation resistance. Tension and low-cycle fatigue properties were examined at 600 °C and 800 °C. The mechanical tests and metallographic and fractographic analyses showed that cast iron containing higher Si and Mo contents had a higher tensile strength and longer fatigue life at both temperatures than cast iron with lower levels due to the phase transformations of pearlite and carbide. The Coffin-Manson type equation was used to assess the fatigue mechanism suggesting that the higher Si-Mo alloy was stronger but less ductile than the lower Si-Mo alloy at 600 °C. However, similar properties for both alloys were observed at 800 °C because of softening and oxidation effects. Analysis of the isothermal oxidation behavior at those temperatures showed that mixed Fe2SiO4 layers were formed and the resulting scaling kinetics was much faster for low Si-Mo containing iron. With increasing temperature, subsurface degradation such as decarburization, voids, and cracks played a significant role in the overall oxidation resistance.

  13. Machinability of clean thin-wall gray and ductile iron castings. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bates, C.E.; Littleton, H.E.; Eleftheriou, E.; Griffin, R.D.; Dwyer, Z.B.; DelSorbo, C.; Sprague, J.

    1997-02-01

    First phase was to develop a laboratory technique for evaluating the machinability of gray and ductile iron; longer term goal is to learn how to modify the foundry process to produce castings meeting all specified mechanical properties while providing improved machining behavior. Microcarbides present in the irons were found to dominate the machinability of iron. Pearlitic irons with acceptable machinability contain 8.9 to 10.5 wt% microcarbides. The weight fraction microcarbides in the iron is influenced by carbide forming element concentrations, presence of elements that retard carbon diffusion, and cooling rate from the eutectic through the eutectoid temperature range. Tool wear rate increased at higher surface machining speeds and fraction microcarbides; all irons containing above 11.5% microcarbides had poor machinability. Graphite size, shape, distribution, etc. had a lesser effect on machinability. Reducing the addition of a foundry grade Ca and Al bearing 75% FeSi inoculant from 0.5 to 0.2% increased the tool life 100%. Inoculation test castings were also poured in a class 40 gray iron; laboratory analysis is currently underway. Exploratory studies were conducted to determine if tool force could be used to predict tool life: torque and feed forces were found to correlate with machinability.

  14. On the brittle-ductile behavior of iron meteorites - New experimental constraints

    Science.gov (United States)

    Matsui, T.; Schultz, P. H.

    1984-01-01

    Impact trials were performed at the NASA vertical gun range to study low-temperature brittle-ductile transitions in meteoritic, steel and iron targets. The trials were performed to enhance the data base underlying the concept of formation of planetesimals in collisional coagulation. Impact velocities of 1.6-5.5 km/sec were used, as were temperatures from 100-300 K. Spallation was observed in the tests with meteorite samples, even at room temperature, and brittleness was enhanced at temperature below 200 C. Net mass losses were induced at the higher impact velocities. It is suggested that iron meteorite agglomerations could form in the inner solar region during nebular condensation, but would not form in farther-out regions such as the asteroid belt. The protoplanets could have an iron core, with metallicity decreasing with radius from the core, which may have happened with the earth.

  15. Application of 3-D numerical simulation software SRIFCAST to produce ductile iron castings

    Directory of Open Access Journals (Sweden)

    Junqing WANG

    2005-08-01

    Full Text Available Based on a method using numerical simulation equations and their solution schemes for liquid metal flows and heat transfer during mold filling and the solidification process of casting, 3-D numerical simulation software SRIFCAST was created. This includes enmeshment of casting; velocity and temperature fields calculation; displaying iso-temperature lines; velocity vectors and 3-D temperature fields on a Windows 9x operating system. SRIFCAST was applied to produce sound castings of automobile and diesel engines, and also to connect with microstructure simulation for ductile iron castings.

  16. Feeding Against Gravity with Spot Feeders in High Silicon Ductile Iron

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Tiedje, Niels Skat

    2014-01-01

    A test pattern, with three different moduli castings was developed to investigate methods to optimise feeding of high silicon ductile cast irons. Different feeder types, modulus, and locations were investigated using both an insulating and an exothermal sleeve material. Porosities were analysed......-hill against gravity. This effect may contribute to the thermal expansion created by the exothermal reaction. It was also found that the optimum feeder size does not scale linearly with the casting modulus but that larger casting modulus requires relatively smaller modulus feeders. The thermal gradient created...

  17. 3-D Analysis of Graphite Nodules in Ductile Cast Iron Using FIB-SEM

    DEFF Research Database (Denmark)

    D'Angelo, Luca; Jespersen, Freja N.; MacDonald, A. Nicole

    Ductile cast iron samples were analysed in a Focused Ion Beam Scanning Electron Microscope, FIB-SEM. The focussed ion beam was used to carefully remove layers of the graphite nodules to reveal internal structures in the nodules. The sample preparation and milling procedure for sectioning graphite...... nodules is described and ef-fects of preparation methods discussed. It was found that nodules contain different types of inclusions. These were analysed for chemical composition and crystallography using energy dispersive spectrometry (EDS) and electron back-scatter patterns (EBSP). Location of inclusions...

  18. SOIL-PIPE INTERACTION OF FAULT CROSSING SEGMENTED BURIED DUCTILE IRON PIPELINES SUBJECTED TO DIP FAULTINGS

    Science.gov (United States)

    Erami, Mohammad Hossein; Miyajima, Masakatsu; Kaneko, Shougo

    This study investigates the necessity of considering different soil resistance against pipeline relative movement in upward and downward directions. In this way, results of FEM analyses are verified by experimental tests on a segmented ductile iron pipeline with 93mm diameter and 15m length installed at a 60cm depth from the ground surface in the moderate dense sand backfill condition. Fault movement, totally 35cm, has three same steps occurring in reverse way and intersection angle of 60 degrees with the pipe. This study demonstrates how assuming same resistance for soil against both upward and downward relative movements of pipeline, as suggested in JGA guideline, eventuates in imprecise FEM models.

  19. Feeding Against Gravity with Spot Feeders in High Silicon Ductile Iron

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Tiedje, Niels Skat

    2014-01-01

    A test pattern, with three different moduli castings was developed to investigate methods to optimise feeding of high silicon ductile cast irons. Different feeder types, modulus, and locations were investigated using both an insulating and an exothermal sleeve material. Porosities were analysed...... by the feeders made with the insulating sleeve material was not sufficient to significantly improve feeding...... and classified using X-ray imaging and ultrasound analysis. The effect of the different feeder configurations were classified in reference to defect location, sleeve material, and feeder type, modulus, and location. The analysis showed that exothermal feeder sleeves with the right configurations can feed up...

  20. Temperature measurement during solidification of thin wall ductile cast iron. Part 1: Theory and experiment

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Temperature measurement using thermocouples (TC’s) influence solidification of the casting, especially in thin wall castings. The problems regarding acquisition of detailed cooling curves from thin walled castings is discussed. Experiments were conducted where custom made TC’s were used to acquire...... cooing curves in thin wall ductile iron castings. The experiments show how TC’s of different design interact with the melt and how TC design and surface quality affect the results of the data acquisition. It is discussed which precautions should be taken to ensure reliable acquisition of cooling curves...

  1. EVALUATION OF MACHINABILITY OF DUCTILE IRONS ALLOYED WITH Ni AND Cu IN TERMS OF CUTTING FORCES AND SURFACE QUALITY

    Directory of Open Access Journals (Sweden)

    Yücel AŞKUN

    2003-02-01

    Full Text Available Due to the enhanced strength, ductility and thoughness of Ductile Iron (DI when compared to the other types cast iron, its machinability is relatively poor. When a steel part is replaced with ductile iron, however, better machinability is considered to be the most important gain. This study presents the results of machining tests of ductile irons alloyed with Ni and Cu at various contents to determine the effect of their microstructure and mechanical properties on cutting forces and surface roughness. Six different specimen groups of ductile iron alloyed with various amounts of nickel and copper were subjected to machining tests and their machinabilities were investigated based on cutting forces and surface roughness criteria. The results were evaluated according to microstructure and mechanical properties of specimens determined before. In terms of both criterion, the best result obtained was specimen added 0.7 % Ni and 0.7 % Cu. When the specimens were evaluated according to their mechanical properties, the specimens alloyed 1 % Ni and 0.65 % Cu seemed promising.

  2. Influence of mean stress on fatigue strength of ferritic-pearlite ductile cast iron with small defects

    Science.gov (United States)

    Deguchi, T.; Kim, H. J.; Ikeda, T.; Yanase, K.

    2017-05-01

    Because of their excellent mechanical properties, low cost and good workability, the application of ductile cast iron has been increased in various industries such as the automotive, construction and rail industries. For safety designing of the ductile cast iron component, it is necessary to understand the effect of stress ratio, R, on fatigue limit of ductile cast iron in the presence of small defects. Correspondingly in this study, rotating bending fatigue tests at R = -1 and tension-compression fatigue tests at R = -1 and 0.1 were performed by using a ferritic-pearlitic ductile cast iron. To study the effects of small defects, we introduced a small drilled hole at surface of a specimen. The diameter and depth of a drilled hole were 50, 200 and 500 μm, respectively. The non-propagating cracks emanating from graphite particles and holes edge were observed at fatigue limit, irrespective of the value of stress ratio. From the microscopic observation of crack propagation behavior, it can be concluded that the fatigue limit is determined by the threshold condition for propagation of a small crack. It was found that the effect of stress ratio on the fatigue limit of ductile cast iron with small defects can be successfully predicted based on \\sqrt {area} parameter model. Furthermore, a use of the tensile strength, σ B, instead of the Vickers hardness, HV, is effective for fatigue limit prediction.

  3. COMPUTER MODELING OF STRAINS ON PHASE BOUNDARIES IN DUCTILE CAST IRON AT HOT EXTRUSION

    Directory of Open Access Journals (Sweden)

    A. I. Pokrovsky

    2017-01-01

    Full Text Available The computer modeling of the strain distribution in the structure of ductile iron with ferrite-pearlite matrix and inclusions of spherical graphite dependence on increasing degree of deformation during direct hot extrusion was researched. Using a software system of finite-element analysis ANSYS the numerical values of the strains at the phase boundaries: ferrite-perlite, graphiteferrite and also inside the graphite inclusions were defined. The analysis of the strain distribution in the investigated structures was performed and local zones of increased strains were discovered. The results of modeling are compared with metallographic analysis and fracture patterns. The obtained results could be used in the prediction of fracture zones in the cast iron products. 

  4. Influence of the surface roughness on the fatigue properties in ausferritic ductile irons (ADI

    Directory of Open Access Journals (Sweden)

    Svenningsson Roger

    2014-06-01

    Full Text Available Heat treatment of cast ductile iron (DI to ausferritic ductile iron (ADI is known to increase fatigue properties. However, the surface roughness of the cast material is also of significant importance. In this investigation, test rods with seven different surface qualities were cast from the same melt i.e. with same chemical composition. The surfaces of the test rods were varied by a number of parameters; grain size of the moulding sand, coated or non-coated mould surfaces, as-cast or machined and polished, shot peened or not. In addition, a reference material in conventional DI was cast and tested. All eight series were subjected to high-cycle fatigue bending tests. The results show that surface defects, such as micro porosity and minor inclusions drastically decrease the fatigue properties. For some ADI materials the stress amplitude limit was actually lower compared to the non-heat treated DI. The machined, polished and shot-peened material demonstrated the best fatigue properties, which is as expected.

  5. On the spheroidal graphite growth and the austenite solidification in ductile irons

    Science.gov (United States)

    Qing, Jingjing

    Evolutions of austenite and nodular/spheroidal graphite particles during solidifications of ductile irons were experimentally investigated. Spheroidal graphite particle and austenite dendrite were found nucleated independently in liquid. Austenite dendrite engulfed the spheroidal graphite particles after contact and an austenite shell formed around a spheroidal graphite particle. The graphite diameter at which the austenite shell closed around nodule was determined. Statistically determined graphite size distributions indicated multiple graphite nucleation events during solidification. Structures in a graphite nodule varied depending on the growth stages of the nodule in ductile iron. Curved graphene layers appearing as faceted growth ledges swept circumferentially around the surface of a graphite nodule at early growth stages. Mismatches between the growth fronts created gaps which divided a nodule into radially oriented conical substructures (3-D). Columnar substructure was observed in the periphery of a nodule (formed during the intermediate growth stages) on its 2-D cross section. A columnar substructure consisted of parallel peripheral grains, with their c-axes approximately parallel. Graphene layers continued building up in individual conical substructure, and a graphite nodule increased its size accordingly. Method for characterizing the crystal structures of graphite based on the selected area diffraction pattern was developed. Both hexagonal structure and rhombohedral structure were found in the spheroidal graphite particles. Possible crystallographic defects associated with hexagonal-rhombohedral structure transition were discussed. Schematic models for introducing tilt angles to the graphite lattice with basal plane tilt boundaries were constructed.

  6. Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

    International Nuclear Information System (INIS)

    Kim, K. T.; Kim, Y. S.; Chang, H. Y.; Lim, B. T.; Park, H. B.

    2016-01-01

    In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

  7. Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. T.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

    2016-08-15

    In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

  8. Dependency of tensile strength of ductile cast iron on strain rate and temperature

    Science.gov (United States)

    Ikeda, Tomohiro; Umetani, Takuo; Kai, Nobuhiro; Ogi, Keisaku; Noda, Nao-Aki; Sano, Yoshikazu

    2017-05-01

    The dependency of the tensile strength {σ }{{B}}{smooth} and the notch strength {σ }{{B}}{notch} on strain rate and temperature were investigated for conventional ferrite-pearlite type ductile cast iron (JIS-FCD500) to make clear the applicability of ductile cast iron to components for welded steel structures. High speed tensile tests were conducted on notched and smooth specimens with varying strain rate and temperature. Charpy absorbed energy was also evaluated on notched specimen with varying temperature. It is found that the tensile strength is in a good relationship with strain rate-temperature parameter R for the wide range of strain rate and temperature. With decreasing R parameter, both {σ }{{B}}{smooth} and {σ }{{B}}{notch} increase even when Charpy absorbed energy starts decreasing. It should be noted that the notch strength {σ }{{B}}{notch} is always larger than the tensile strength at room temperature {σ }{{B}, {RT}}{smooth} in the range of R parameter required for the welded structures. Therefore, the tensile strength {σ }{{B}, {RT}}{{smooth}} is confirmed to be useful for the structural design.

  9. Microstructural study and wear behavior of ductile iron surface alloyed by Inconel 617

    International Nuclear Information System (INIS)

    Arabi Jeshvaghani, R.; Jaberzadeh, M.; Zohdi, H.; Shamanian, M.

    2014-01-01

    Highlights: • The Ni-base alloy was deposited on the surface of ductile iron by TIG welding process. • Microstructure of alloyed layer consisted of carbides embedded in Ni-rich dendrite. • Hardness and wear resistance of coated sample greatly improved. • The formation of oxide layer and delamination were dominant mechanisms of wear. - Abstract: In this research, microstructure and wear behavior of Ni-based alloy is discussed in detail. Using tungsten inert gas welding process, coating of nearly 1–2 mm thickness was deposited on ductile iron. Optical and scanning electron microscopy, as well as X-ray diffraction analysis and electron probe microanalysis were used to characterize the microstructure of the surface alloyed layer. Micro-hardness and wear resistance of the alloyed layer was also studied. Results showed that the microstructure of the alloyed layer consisted of M 23 C 6 carbides embedded in Ni-rich solid solution dendrites. The partial melted zone (PMZ) had eutectic ledeburit plus martensite microstructure, while the heat affected zone (HAZ) had only a martensite structure. It was also noticed that hardness and wear resistance of the alloyed layer was considerably higher than that of the substrate. Improvement of wear resistance is attributed to the solution strengthening effect of alloying elements and also the presence of hard carbides such as M 23 C 6 . Based on worn surface analysis, the dominant wear mechanisms of alloyed layer were found to be oxidation and delamination

  10. 3D Quantitative Analysis of Graphite Morphology in Ductile Cast Iron by X-ray Microtomography

    Science.gov (United States)

    Yin, Yajun; Tu, Zhixin; Zhou, Jianxin; Zhang, Dongqiao; Wang, Min; Guo, Zhao; Liu, Changchang; Chen, Xiang

    2017-08-01

    In this article, X-ray microtomography and color metallographic techniques have been used to perform three-dimensional quantitative characterization of graphite nodule morphology in a step-shaped ductile cast iron casting. Statistical analyses of the graphite nodule count, diameter, sphericity, and spatial distribution have been processed for three samples in detail. The results reveal that graphite nodules in ductile cast iron can be categorized into two categories. The first types are nodules located in eutectic cells (NIECs), and the other one refers to nodules located between the eutectic cells (NBECs). The NIECs possess a larger average diameter but smaller sphericity compared with the NBECs, and the sphericity decreases along with the increasing of diameter. The increasing casting thickness results in an increasing count and percentage of NBECs. In addition, most nodules are NIECs in thin walls instead of NBECs in thick walls. Nonuniform spatial distributions of graphite nodules caused by the existence of NBECs have been found to become more obvious along with the increase of cast thickness.

  11. Statistical study to determine the effect of carbon, silicon, nickel and other alloying elements on the mechanical properties of as-cast ferritic ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Lacaze, J.; Sertucha, J.; Larranaga, P.; Suarez, R.

    2016-10-01

    There is a great interest in fully ferritic ductile irons due to their structural homogeneity, remarkable ductility and good response when machining. On the other hand the wide variety of raw materials available in foundry plants becomes a problem when controlling the chemical composition of the manufactured alloys. The present work shows a statistical study about the effect of different C, Si, Ni contents and other minor elements on structural and mechanical properties of a group of ferritic ductile iron alloys. A set of equations are finally presented to predict room temperature mechanical properties of ferritic ductile irons by means of their chemical composition and pearlite content. (Author)

  12. Weldability of spheroidal graphite ductile cast iron using Ni / Ni-Fe electrodes

    Directory of Open Access Journals (Sweden)

    Pascual, M.

    2009-10-01

    Full Text Available Weldability of spheroidal graphite ductile cast iron was established using a cheap Ni-Fe and a high purity Ni electrode. A preheating treatment at 350 °C and an annealing treatment at 850 °C were carried out to improve mechanical properties of welded pieces. The pure Ni electrode showed graphite diffusion in the bead with a uniform distribution of phases, improving weldability and decreasing fragility. Preheating and annealing treatments increased ductility and improved weldability.

    Se establece la soldabilidad de funciones dúctiles de grafito según las características mecánicas alcanzadas, utilizando un electrodo puro de Ni mientras se compara con uno más económico de Ni-Fe. Diferentes tratamientos t��rmicos son propuestos y analizados. El electrodo de Ni puro mostró difusión de grafito desde el material original al cordón de soldadura, dando como resultado una fase homogénea que mejoró la soldabilidad y redujo la fragilidad. Un pre tratamiento a 350 °C y un recocido a 850 °C incrementaron la ductilidad y mejoró la soldabilidad.

  13. Effect of Feeder Configuration on the Microstructure of Ductile Cast Iron

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Tiedje, Niels Skat

    2014-01-01

    iron castings. The goal is to enable metallurgists and foundry engineers to more directly target mushy zone development to prolong the possibility to feed through this section. Keeping smaller section open for an extended period will make it possible to use fewer or smaller feeders, with reduced energy......Feeding and microstructure of a test casting rigged with different feeder combinations was studied. Castings were examined and classified by soundness and microstructure. Subsequently the casting macro- and microstructure was analyzed to study how differences in solidification and segregation...... influence the soundness of different sections of the castings. Moreover, the microstructural changes due to variations in thermal gradients are classified, and the variations in the mushy zone described. The paper discusses how solidification and segregation influence porosity and microstructure of ductile...

  14. Experimental validation of error in temperature measurements in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    An experimental analysis has been performed to validate the measurement error of cooling curves measured in thin walled ductile cast iron. Specially designed thermocouples with Ø0.2 mm thermocouple wire in Ø1.6 mm ceramic tube was used for the experiments. Temperatures were measured in plates...... with thicknesses between 2 and 4.3 mm. The thermocouples were accurately placed at the same distance from the surface of the casting for different plate thicknesses. It is shown that when measuring the temperature in plates with thickness between 2 and 4.3 mm the measured temperature will be parallel shifted...... to a level about 20C lower than the actual temperature in the casting. Factors affecting the measurement error (oxide layer on the thermocouple wire, penetration into the ceramic tube and variation in placement of thermocouple) are discussed. Finally, it is shown how useful cooling curve may be obtained...

  15. Nitride precipitation during high temperature corrosion of ductile cast irons in synthetic exhaust gases

    Science.gov (United States)

    Tholence, F.; Norell, M.

    2005-02-01

    Internal nitrides form in two ductile cast irons (SiMo and Ni-Resist) intended for exhaust systems in vehicles. Samples oxidised at 650 1050 °C for 50 h in modified synthetic exhaust gases were analysed by using AES and FEG-SEM. No nitrides formed in absence of NOx. In dry petrol gas coarse nitrides (resistance of the alloy. In diesel and in normal petrol gases μ-sized MgSiN2 form in SiMo in cell boundaries where Mg segregates. This also occurs in Ni-Resist in both dry and normal petrol whereas no nitrides were observed in Ni-Resist exposed to diesel gases.

  16. Damaging micromechanisms characterization in a ferritic-pearlitic ductile cast iron

    Directory of Open Access Journals (Sweden)

    Vittorio Di Cocco

    2014-10-01

    Full Text Available The analysis of the damaging micromechanisms in Ductile Cast Irons is often focused on ferritic matrix. Up to ten years ago, for this grades of DCIs, the main damaging micromechanism was identified with the graphite elements – ferritic matrix debonding. More recent experimental results showed the presence of an internal gradient of mechanical properties in the graphite elements and the importance of other damaging micromechanisms, with a negligible importance of the graphite elements – ferritic matrix debonding mechanism. In this work, damaging micromechanisms development in a ferritic – pearlitic DCI have been investigated by means of tensile tests performed on mini-tensile specimens and observing the specimens lateral surfaces by means of a scanning electro microscope (SEM during the tests (“in-situ” tests. Experimental results have been compared with the damaging micromechanisms observed in fully ferritic and fully pearlitic DCIs.

  17. Graphite nodule count and size distribution in thin-walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Graphite nodule count and size distribution have been analysed in thin walled ductile cast iron. The 2D nodule counts have been converted into 3D nodule count by using Finite Difference Method (FDM). Particles having a diameter smaller than 5 µm should be neglected in the nodule count...... as these are inclusions and micro porosities that do not influence the solidification morphology. If there are many small graphite nodules as in thin walled castings only 3D nodule count calculated by FDM will give reliable results. 2D nodule count and 3D nodule count calculated by simple equations will give too low...... results. The 3D size distribution showed presence of primary graphite nodules in hypereutectic castings. In thin plates the nodule count is similar in eutectic and hypereutectic plates. In thicker plates the hypereutectic casting has the highest nodule count....

  18. Development of ductile cast iron for spent fuel cask applications using fracture mechanics principles

    International Nuclear Information System (INIS)

    Ray, K.K.; Tiwari, S.; Hemlata Kumari; Mamta Kumari; Kumar, Hemant; Albert, S.K.; Bhaduri, A.K.

    2016-01-01

    The structure-property relations of ductile cast irons (DCIs) with varying Cu content and ~1 wt.% Ni has been investigated with an emphasis on examining their fracture toughness property towards the development of suitable materials for large volume containers for transport of spent fuel. The detailed microstructural characteristics, hardness, tensile and fracture toughness properties of three DCIs were assessed in as-cast and annealed conditions. Fracture toughness values were determined using both ball indentation (K BI ) and J-integral (KJ Ic ) test. The obtained results assist to infer that: (i) the amount of pearlite and nodule count increases with increased amount of Cu, (ii) the hardness and strength values increases whereas fracture toughness values marginally decreases with increased Cu content, and (iii) the magnitudes of K BI estimated using a proposed analysis are in good agreement with KJ Ic values for the as-cast materials. (author)

  19. Comparing the Structure and Mechanical Properties of Welds on Ductile Cast Iron (700 MPa under Different Heat Treatment Conditions

    Directory of Open Access Journals (Sweden)

    Ronny M. Gouveia

    2018-01-01

    Full Text Available The weldability of ductile iron, as widely known, is relatively poor, essentially due to its typical carbon equivalent value. The present study was developed surrounding the heat treatability of welded joints made with a high strength ductile cast iron detaining an ultimate tensile strength of 700 MPa, and aims to determine which heat treatment procedures promote the best results, in terms of microstructure and mechanical properties. These types of alloys are suitable for the automotive industry, as they allow engineers to reduce the thickness of parts while maintaining mechanical strength, decreasing the global weight of vehicles and providing a path for more sustainable development. The results allow us to conclude that heat treatment methodology has a large impact on the mechanical properties of welded joints created from the study material. However, the thermal cycles suffered during welding promote the formation of ledeburite areas near the weld joint. This situation could possibly be dealt through the implementation of post-welding heat treatments (PWHT with specific parameters. In contrast to a ductile cast iron tested in a previous work, the bull-eye ductile cast iron with 700 MPa ultimate tensile strength presented better results during the post-welding heat treatment than during preheating.

  20. Modeling of damage in ductile cast iron – The effect of including plasticity in the graphite noduless

    DEFF Research Database (Denmark)

    Andriollo, Tito; Thorborg, Jesper; Tiedje, Niels Skat

    2015-01-01

    In the present paper a micro-mechanical model for investigating the stress-strain relation of ductile cast iron subjected to simple loading conditions is presented. The model is based on a unit cell containing a single spherical graphite nodule embedded in a uniform ferritic matrix, under the ass...

  1. Using Cored Wires Injection 2PE-9 Method in the Production of Ferritic Si-Mo Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    Guzik E.

    2012-12-01

    Full Text Available The results of studies on the use of modern two cored wires injection method for production of ferritic nodular cast iron (ductile iron with use of unique implementation of drum ladle as a treatment / transport and casting ladle instead vertical treatment ladle was described. The injection of length of Ø 9mm wires, cored: in FeSi + Mg nodulariser mixture and inoculant master alloy is a treatment method which can be used to produce iron melted in coreless induction furnace. This paper describes the results and analysis of using this method for optimal production of ductile iron under specific industrial conditions. It means, that length of nodulariser wire plus treatment and pouring temperatures were optimized. In this case, was taken ductile iron with material designation: EN-GJS-SiMo40-6 Grade according EN 16124:2010 E. Microstructure of great number of trials was controlled on internally used sample which has been correlated with standard sample before. The paper presents typical ferritic metallic matrix and nodular graphite. Additionally, mechanical properties were checked in some experiments. Mean values of magnesium recovery and cost of this new method from optimized process parameters were calculated as well.

  2. Using Cored Wires Injection 2PE-9 Method in the Production of Ferritic Si-Mo Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    E. Guzik

    2012-12-01

    Full Text Available The results of studies on the use of modern two cored wires injection method for production of ferritic nodular cast iron (ductile iron with use of unique implementation of drum ladle as a treatment / transport and casting ladle instead vertical treatment ladle was described. The injection of length of Ø 9mm wires, cored: in FeSi + Mg nodulariser mixture and inoculant master alloy is a treatment method which can be used to produce iron melted in coreless induction furnace. This paper describes the results and analysis of using this method for optimal production of ductile iron under specific industrial conditions. It means, that length of nodulariser wire plus treatment and pouring temperatures were optimized. In this case, was taken ductile iron with material designation: EN-GJS-SiMo40-6 Grade according EN 16124:2010 E. Microstructure of great number of trials was controlled on internally used sample which has been correlated with standardsample before. The paper presents typical ferritic metallic matrix and nodular graphite. Additionally, mechanical properties were checked in some experiments. Mean values of magnesium recovery and cost of this new method from optimized process parameters werecalculated as well.

  3. Solution strengthened ferritic ductile iron ISO 1083/JS/500-10 provides superior consistent properties in hydraulic rotators

    Directory of Open Access Journals (Sweden)

    Dr. Richard Larker

    2009-11-01

    Full Text Available Consistent mechanical and machining properties are essential in many applications where ductile irons offer the most cost-effective way to produce structural parts. In the production of hydraulic rotators, dimensional tolerances are typically 20 μm to obtain designated performance. For castings where intermediate strength and ductility is required, it is common knowledge that conventional ferritic-pearlitic ductile irons such as ISO 1083/500-7 show large hardness variations. These are mainly caused by the notoriously varying pearlite content, both at different locations within a part and between parts in the same or different batches. Cooling rate variations due to different wall thickness and position in the molding box, as well as varying amounts of pearlite-stabilizing elements, all contribute to detrimental hardness variations. The obvious remedy is to avoid pearlite formation, and instead obtain the necessary mechanical properties by solution strengthening of the ferritic matrix by increasing silicon content to 3.7wt% –3.8wt%. The Swedish development in this fi eld 1998 resulted in a national standardization as SS 140725, followed in 2004 by ISO 1083/JS/500-10. Indexator AB decided 2005 to specify JS/500-10 for all new ductile iron parts and to convert all existing parts. Improvements include reduction by 75% in hardness variations and increase by 30% in cutting tool life, combined with consistently better mechanical properties.

  4. Fatigue behaviour of cast iron with globular graphite

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, P.; Pusch, G.; Krodel, L. [Institut fuer Werkstofftechnik, TU Bergakademie Freiberg, Gustav-Zeuner-Strasse 5, 09599 Freiberg (Germany)

    2004-07-01

    Cast iron with bainitic matrix and globular graphite, so called austempered ductile iron (ADI), allows the substitution of heat-treatable steels. The use of ADI in safety-relevant components requires knowledge of the fracture and fatigue behaviour. Cyclic stress strain behaviour and fatigue life at total strain control and random loading have been investigated at ADI (EN-GJS-1000-5) and pearlitic cast iron (EN-GJS-600-3). In addition fracture mechanic tests at cyclic loading at various stress ratios were carried out. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  5. Studies of Gas Atmosphere Near the Metalmould Interface During Casting and Solidification of Ductile Iron

    Directory of Open Access Journals (Sweden)

    Mocek J.

    2012-12-01

    Full Text Available In sand moulds, at a distance of 3 mm from the metal- mould interface, the sensors of temperature, and of oxygen and hydrogen content were installed. Temperature and the evolution of partial gas pressure have been analysed in moulds bonded with bentonite with or without the addition of seacoal, water glass or furan resin. Moulds were poured with ductile iron. For comparison, also tests with the grey iron have been executed. It was found that the gas atmosphere near the interface depends mainly on the content of a carbonaceous substance in the mould. In the green sand moulds with 5% of seacoal or bonded with furan resin, after the mould filling, a sudden increase in the hydrogen content and the drop of oxygen is observed. This gas evolution results from the oxidation of carbon and reduction of water vapour in the mould material, and also from the reduction of water vapour and alloy reoxidation. In carbon-free sand, the evolution in the gas composition is slower because water vapour is reduced only at the interface. Changes of oxygen and hydrogen content in the controlled zone are determined by the transport phenomena.

  6. Review of current research and application of ductile cast iron quality monitoring technologies in Chinese foundry industry

    Directory of Open Access Journals (Sweden)

    Da-yong Li

    2015-07-01

    Full Text Available There is a long history of studying and making use of ductile cast iron in China. Over the years, the foundrymen in China have carried out a lot of valuable research and development work for measuring parameters and controlling the quality in ductile cast iron production. Many methods, such as rapid metallographic phase, thermal analysis, eutectic expansion ratio, surface tension measurement, melt electrical resistivity, oxygen and sulfur activity measurement, ultrasonic measurement and sound frequency measurement, have been used and have played important roles in Chinese casting production in the past. These methods can be generally classified as liquid testing and solid testing according to the sample state. Based on the analysis of the present situation of these methods applied in the Chinese metal casting industry, the authors consider that there are two difficult technical problems to be currently solved in monitoring ductile iron quality. One is to seek an effective method for quickly evaluating the nodularizing result through on-the-spot sample analysis before the liquid iron is poured into the mould. The other is to find a nondestructive method for accurately identifying casting quality before castings are delivered.

  7. New Mechanism on Synergistic Effect of Nitrite and Triethanolamine Addition on the Corrosion of Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    K. T. Kim

    2016-01-01

    Full Text Available In general, we compared the different inhibition mechanisms of organic inhibitor with that of anodic inhibitor. When triethanolamine or nitrite was added separately to tap water for inhibiting the corrosion of ductile cast iron, large amounts of inhibitor were needed. This is because the corrosion inhibitors had to overcome the galvanic corrosion that occurs between graphite and matrix. In this work, we investigated the corrosion of ductile cast iron in tap water with/without inhibitors. The corrosion rate was measured using chemical immersion test and electrochemical methods, including anodic polarization test. The inhibited surface was analyzed using EPMA and XPS. Test solutions were analyzed by performing FT-IR measurement. When triethanolamine and nitrite coexisted in tap water, synergistic effect built up, and the inhibition effect was ca. 30 times more effective than witnessed with single addition. This work focused on the synergistic effect brought about by nitrite and triethanolamine and its novel mechanism was also proposed.

  8. Relationship between cooling rate and microsegregation in bottom-chilled directionally solidified ductile irons

    Directory of Open Access Journals (Sweden)

    Chang W.S.

    2013-01-01

    Full Text Available This study explores the relationship between cooling rate and microsegregation of directionally solidified ductile iron. The unidirectional heat transfer system used in this research is made up of a copper mold kept chilled by circulating water and embedded in the bottom of Furan sand mold. Thermocouples are connected to the computer measuring system to record the cooling curves of the castings at a distance of 0, 30, 60 and 90 mm from the chilled copper mold surface. Alloys including Mn, Cr, Cu, Ni and Ti were added to the specimens. Electron microprobe analysis (EPMA was employed to examine distribution of elements between the dendrite arms and nodular graphite. Results show that unidirectional heat transfer affects directly the solidification mode and microstructure of the casting. The cooling curves reveal that local solidification time increases with increasing distance from the chilled copper mold surface. Different solidification rates with corresponding microstructure and element segregation were observed in the same unidirectionally solidified casting. Local solidification time was closely related to element segregation. The effective segregation coefficient (Keff calculated using the Scheil equation was found to vary, according to the stage of solidification. The actual segregation characteristics of complex alloys generally follow the Scheil equation.

  9. Synergistic Effect of Molybdate and Monoethanolamine on Corrosion Inhibition of Ductile Cast Iron in Tap Water

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. T.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

    2017-02-15

    A synergistic effect was observed in the combination of nitrite and ethanolamines. Ethanolamine is one of the representative organic corrosion inhibitors and can be categorized as adsorption type. However, nitrosamines can form when amines mix with sodium nitrite. Since nitrosamine is a carcinogen, the co-addition of nitrite and ethanolamine will be not practical, and thus, a non-toxic combination of inhibitors shall be needed. In order to maximize the effect of monoethanolamine, we focused on the addition of molybdate. Molybdate has been used to alternate the addition of chromate, but it showed insufficient oxidizing power relative to corrosion inhibitors. This work evaluated the synergistic effect of the co-addition of molybdate and monoethanolamine, and its corrosion mechanism was elucidated. A high concentration of molybdate or monoethanolamine was needed to inhibit the corrosion of ductile cast iron in tap water, but in the case of the co-addition of molybdate and monoethanolamine, a synergistic effect was observed. This synergistic effect could be attributed to the molybdate that partly oxidizes the metallic surface and the monoethanolamine that is simultaneously adsorbed on the graphite surface. This adsorbed layer then acts as the barrier layer that mitigates galvanic corrosion between the graphite and the matrix.

  10. A visual approach to efficient analysis and quantification of ductile iron and reinforced sprayed concrete.

    Science.gov (United States)

    Fritz, Laura; Hadwiger, Markus; Geier, Georg; Pittino, Gerhard; Gröller, M Eduard

    2009-01-01

    This paper describes advanced volume visualization and quantification for applications in non-destructive testing (NDT), which results in novel and highly effective interactive workflows for NDT practitioners. We employ a visual approach to explore and quantify the features of interest, based on transfer functions in the parameter spaces of specific application scenarios. Examples are the orientations of fibres or the roundness of particles. The applicability and effectiveness of our approach is illustrated using two specific scenarios of high practical relevance. First, we discuss the analysis of Steel Fibre Reinforced Sprayed Concrete (SFRSpC). We investigate the orientations of the enclosed steel fibres and their distribution, depending on the concrete's application direction. This is a crucial step in assessing the material's behavior under mechanical stress, which is still in its infancy and therefore a hot topic in the building industry. The second application scenario is the designation of the microstructure of ductile cast irons with respect to the contained graphite. This corresponds to the requirements of the ISO standard 945-1, which deals with 2D metallographic samples. We illustrate how the necessary analysis steps can be carried out much more efficiently using our system for 3D volumes. Overall, we show that a visual approach with custom transfer functions in specific application domains offers significant benefits and has the potential of greatly improving and optimizing the workflows of domain scientists and engineers.

  11. Failure Mechanisms and Damage Model of Ductile Cast Iron Under Low-Cycle Fatigue Conditions

    Science.gov (United States)

    Wu, Xijia; Quan, Guangchun; MacNeil, Ryan; Zhang, Zhong; Sloss, Clayton

    2014-10-01

    Strain-controlled low-cycle fatigue (LCF) tests were conducted on ductile cast iron (DCI) at strain rates of 0.02, 0.002, and 0.0002/s in the temperature range from room temperature to 1073 K (800 °C). A constitutive-damage model was developed within the integrated creep-fatigue theory (ICFT) framework on the premise of strain decomposition into rate-independent plasticity and time-dependent creep. Four major damage mechanisms: (i) plasticity-induced fatigue, (ii) intergranular embrittlement (IE), (iii) creep, and (iv) oxidation were considered in a nonlinear creep-fatigue interaction model which represents the overall damage accumulation process consisting of oxidation-assisted fatigue crack nucleation and propagation in coalescence with internally distributed damage ( e.g., IE and creep), leading to final fracture. The model was found to agree with the experimental observations of the complex DCI-LCF phenomena, for which the linear damage summation rule would fail.

  12. Microstructure and wear behaviors of WC–12%Co coating deposited on ductile iron by electric contact surface strengthening

    International Nuclear Information System (INIS)

    Qi, Xiaoben; Zhu, Shigen; Ding, Hao; Zhu, Zhengkun; Han, Zhibing

    2013-01-01

    WC–12%Co powders deposited on ductile iron by electric contact strengthening were studied. This technology was based on the application of the contact resistance heating between the electrode and work piece to form a wear resistant layer on ductile iron. The microstructure, microhardness distribution, phase transformation and wear behaviors of the coating were investigated using optical microscope, scanning electron microscope, Vickers hardness (HV 0.5 ), X-ray diffraction, rolling contact wear tests. The results showed that the WC–12%Co coating by electric contact strengthening was metallurgically bonded to the ductile iron. Additionally, the effect of experimental parameters on microhardness and wear resistance of coatings were studied using orthogonal experiment. The results showed that compared with (A) electric current and (B) rotating speed, (C) contact force displays the most significant effect on microhardness and wear resistance of coatings. The coatings produced at A = 19 kA, B = 0.3 r/min and C = 700 N possessed highest microhardness of 1073 HV 0.5 and wear resistance.

  13. A micro-mechanical analysis of thermo-elastic properties and local residual stresses in ductile iron based on a new anisotropic model for the graphite nodules

    DEFF Research Database (Denmark)

    Andriollo, Tito; Thorborg, Jesper; Tiedje, Niels Skat

    2016-01-01

    analysis to verify its consistency with the room-temperature elastic properties of ductile iron measured at the macro scale. Subsequently, it is used to investigate the formation of local residual stresses around the graphite particles by simulating the manufacturing process of a typical ferritic ductile......In this paper, the thermo-elastic behavior of the graphite nodules contained in ductile iron is derived on the basis of recent transmission electron microscopy investigations of their real internal structure. The proposed model is initially validated by performing a finite element homogenization...

  14. Thermomechanical processing and mechanical properties of hypereutectoid steels and cast irons

    Energy Technology Data Exchange (ETDEWEB)

    Lesuer, D.R.; Syn, C.K.; Sherby, O.D. (eds.)

    1998-01-01

    Recent advances in metallurgy of hypereutectoid steels and cast irons show that unique properties, such ultrahigh hardness and strength, and superplasticity, are achievable. This book focuses on the mechanical properties of hypereutectoid steels and cast irons as influenced by thermomechanical processing and microstructure. Some topics covered are: (1) Hot workability of hypereutectoid tool steels; (2) Thermomechanical processing of austempered ductile iron: An overview; (3) Mechanical behavior of ultrahigh strength, ultrahigh carbon steel wire and rod; and (4) Tensile elongation behavior of fine-grained Fe-C alloys at elevated temperatures.

  15. Influence of Austempering Heat Treatment on Microstructure and Mechanical Properties of Medium Carbon High Silicon Steel

    Science.gov (United States)

    Palaksha, P. A.; Ravishankar, K. S.

    2017-08-01

    In the present investigation, the influence of austempering heat treatment on the microstructure and mechanical properties of medium carbon high silicon steel was evaluated. The test specimens were machined from the as-received steel and were first austenitised at 900 °C for 45 minutes, followed by austempering heat treatment in salt bath at various temperatures 300 °C, 350 °C and 400 °C for a fixed duration of two hours, after that those specimens were air-cooled to room temperature. The characterization studies were carried out using optical microscope, scanning electron microscope (SEM) and x-ray diffractometer (XRD) and then correlated to the hardness and tensile properties. Results indicate that, the specimens austempered at lower temperature i.e. at 300 °C, which offered high hardness, tensile strength and lower ductility (1857 MPa and 13.3 %) due to the presence of acicular bainite i.e. lower bainite and also some martensite in the microstructure. At 350 °C, reduction in the tensile strength and hardness was observed, but comparatively higher ductility, which was favored by the presence of bainite laths i.e. upper bainitic structure along with higher retained austenite content. Finally at 400 °C, reduction in both ductility and tensile strength was observed, which is due to the precipitation of carbides between the banite laths, however good strain hardening response was observed at austempering temperatures of 350 °C and 400 °C.

  16. A study on the corrosion and erosion behavior of electroless nickel and TiAlN/ZrN duplex coatings on ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chung-Kwei [School of Dental Technology, Taipei Medical University, Taipei 110, Taiwan (China); Hsu, Cheng-Hsun, E-mail: chhsu@ttu.edu.tw [Department of Materials Engineering, Tatung University, Taipei 104, Taiwan (China); College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Cheng, Yin-Hwa [Department of Materials Engineering, Tatung University, Taipei 104, Taiwan (China); Ou, Keng-Liang [College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Department of Mechanical Engineering, National Central University, Taoyuan 320, Taiwan (China); Lee, Sheng-Long [Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China)

    2015-01-01

    Highlights: • Electroless nickel was used as an interlayer for TiAlZrN-coated ductile iron. • The duplex coatings evidently improved corrosion resistance of ductile iron. • The duplex coated ductile iron showed a good erosion resistance. - Abstract: This study utilized electroless nickel (EN) and cathodic arc evaporation (CAE) technologies to deposit protective coatings onto ductile iron. Polarization corrosion tests were performed in 3.5 wt.% sodium chloride, and also erosion tests were carried out by using Al{sub 2}O{sub 3} particles (∼177 μm in size and Mohr 7 scale) of about 5 g. Surface morphologies of the corroded and eroded specimens were observed separately. To further understand the coating effects on both the corrosive and erosive behavior of ductile iron, coating structure, morphology, and adhesion were analyzed using X-ray diffractormeter, scanning electron microscopy, and Rockwell-C indenter, respectively. The results showed that the EN exhibited an amorphous structure while the CAE-TiAlN/ZrN coating was a multilayered nanocrystalline. When the TiAlN/ZrN coated specimen with EN interlayer could effectively increase the adhesion strength between the CAE coating and substrate. Consequently, the combination of TiAlN/ZrN and EN delivered a better performance than did the monolithic EN or TiAlN/ZrN for both corrosion and erosion protection.

  17. A study on the corrosion and erosion behavior of electroless nickel and TiAlN/ZrN duplex coatings on ductile iron

    International Nuclear Information System (INIS)

    Lin, Chung-Kwei; Hsu, Cheng-Hsun; Cheng, Yin-Hwa; Ou, Keng-Liang; Lee, Sheng-Long

    2015-01-01

    Highlights: • Electroless nickel was used as an interlayer for TiAlZrN-coated ductile iron. • The duplex coatings evidently improved corrosion resistance of ductile iron. • The duplex coated ductile iron showed a good erosion resistance. - Abstract: This study utilized electroless nickel (EN) and cathodic arc evaporation (CAE) technologies to deposit protective coatings onto ductile iron. Polarization corrosion tests were performed in 3.5 wt.% sodium chloride, and also erosion tests were carried out by using Al 2 O 3 particles (∼177 μm in size and Mohr 7 scale) of about 5 g. Surface morphologies of the corroded and eroded specimens were observed separately. To further understand the coating effects on both the corrosive and erosive behavior of ductile iron, coating structure, morphology, and adhesion were analyzed using X-ray diffractormeter, scanning electron microscopy, and Rockwell-C indenter, respectively. The results showed that the EN exhibited an amorphous structure while the CAE-TiAlN/ZrN coating was a multilayered nanocrystalline. When the TiAlN/ZrN coated specimen with EN interlayer could effectively increase the adhesion strength between the CAE coating and substrate. Consequently, the combination of TiAlN/ZrN and EN delivered a better performance than did the monolithic EN or TiAlN/ZrN for both corrosion and erosion protection

  18. A program to qualify ductile cast iron for use as a containment material for type B transport cask

    International Nuclear Information System (INIS)

    Golliher, K.G.; Sorenson, K.B.; Witt, C.R.

    1990-01-01

    This paper reports on the Department of Energy (DOE) investigations for the use of ductile cast iron (DCI) as a candidate material for radioactive material transportation cask construction. The investigation will include materials testing and full-scale cask testing. The major effort will focus on materials qualification and cask evaluation of the 9 meter and puncture drop test events. Interaction by contract with the private industry, the American Society for Testing and Materials (ASTM) Committee A4.04, and the Electric Power Research Institute (EPRI) will be actively pursued to establish material specification acceptance criteria for ductile iron use as a cask material in the United States of America (USA). All test results will be documented in the safety analysis report for packaging for submission to the U.S. Nuclear Regulatory Commission (NRC). The goal of this program is a certificate of compliance for DCI from the NRC to transport high-level radioactive materials. The acceptance of DCI within the USA cask design community will offer an alternative to present-day materials for cask construction, and its entry has the potential of providing significant cost-savings

  19. Three-dimensional local residual stress and orientation gradients near graphite nodules in ductile cast iron [3D local residual stress and orientation gradients near graphite nodules in ductile cast iron

    International Nuclear Information System (INIS)

    Zhang, Y. B.; Andriollo, T.; Faester, S.; Liu, W.; Hattel, J.; Barabash, R. I.

    2016-01-01

    A synchrotron technique, differential aperture X-ray microscopy (DAXM), has been applied to characterize the microstructure and analyze the local mesoscale residual elastic strain fields around graphite nodules embedded in ferrite matrix grains in ductile cast iron. Compressive residual elastic strains are measured with a maximum strain of ~6.5–8 × 10 –4 near the graphite nodules extending into the matrix about 20 μm, where the elastic strain is near zero. The experimental data are compared with a strain gradient calculated by a finite element model, and good accord has been found but with a significant overprediction of the maximum strain. This is discussed in terms of stress relaxation during cooling or during storage by plastic deformation of the nodule, the matrix or both. Furthermore, relaxation by plastic deformation of the ferrite is demonstrated by the formation of low energy dislocation cell structure also quantified by the DAXM technique.

  20. Surface alloying of high-vanadium high-speed steel on ductile iron using plasma transferred arc technique: Microstructure and wear properties

    NARCIS (Netherlands)

    Cao, H.T.; Dong, X.P.; Pan, Z.; Wu, X.W.; Huang, Q.W.; Pei, Y.T.

    2016-01-01

    A high-vanadium high speed steel (HVHSS) alloying layer was synthesized from pre-placed powders (V-Cr-Ti-Mo) on ductile iron (DI) substrate using plasma transferred arc (PTA) technique. The PTA-alloyed layer, characterized by microhardness, optical microscopy, XRD, EDS enabled SEM, TEM and

  1. Hard-yet-tough high-vanadium high-speed steel composite coating in-situ alloyed on ductile iron by atmospheric plasma arc

    NARCIS (Netherlands)

    Cao, Huatang; Dong, Xuanpu; Pei, Yutao T.

    2018-01-01

    A graded high-vanadium alloy composite coating was synthesized from premixed powders (V, Cr, Ti, Mo, Nb) on ductile iron (DI) substrate via atmospheric plasma arc surface alloying process. The resulted cross-section microstructure is divided into three distinct zones: upper alloyed zone (AZ) rich

  2. The influence of the graphite mechanical properties on the constitutive response of a ferritic ductile cast iron – A micromechanical FE analysis

    DEFF Research Database (Denmark)

    Andriollo, Tito; Thorborg, Jesper; Hattel, Jesper Henri

    2015-01-01

    is considered and elasto-plastic behavior of both constituents is assumed; damage evolution in the ductile matrix is taken into account via Lemaitre’s isotropic model. Full 3D and 2D plane-stress finite element analyses are performed to simulate the loading conditions experienced by nodules located in the bulk...... as well as on the material surface. The effects of residual stresses arising during the manufacturing process are also accounted for. It is shown that the constitutive response of the equivalent composite medium can match ductile cast iron only if the graphite Young’s modulus value lies within a certain...

  3. Testing of heating and cooling process of ADI cast iron with use of ATND method

    Directory of Open Access Journals (Sweden)

    A. Białobrzeski

    2008-10-01

    Full Text Available ADI (Austempered Ductile Iron cast iron, owing to its unique combination of high tensile strength and abrasion resistance with very goodplasticity, founds implementation in many branches of industry as a substitute of alloy cast steel and carburized or heat treated steels. Inspite of its solid position among producers and recipients of castings, there are still undertaken studies aimed at perfection of its propertiesand recognition of mechanisms enabling obtaining such properties.The paper presents implementation of thermal-voltage-derivative (ATND method to registration of heating and cooling course of ADIcast iron with EN-GJS-1200-2 grade. ADI cast iron with EN-GJS-1200-2 grade underwent the study. Heat treatment of the cast iron wasperformed in Foundry Institute with use of LT ADI-350/1000 processing line. Results obtained from the testing illustrate in graphic formregistered heating and cooling curves of investigated cast irons obtained with use of the ATND method.

  4. Nondestructive inspection of ductile cast iron by measurement of minor magnetic hysteresis loops

    Czech Academy of Sciences Publication Activity Database

    Vértesy, G.; Uchimoto, T.; Takagi, T.; Tomáš, Ivan

    2010-01-01

    Roč. 659, č. 9 (2010), 355-360 ISSN 0255-5476 R&D Projects: GA ČR GA101/09/1323; GA AV ČR 1QS100100508 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic NDE * magnetic adaptive testing * cast iron * magnetic hysteresis Subject RIV: BM - Solid Matter Physics ; Magnetism

  5. Modelling the solidification of ductile cast iron parts with varying wall thicknesses

    DEFF Research Database (Denmark)

    Bjerre, Mathias Karsten; Tiedje, Niels Skat; Thorborg, Jesper

    2015-01-01

    In the present paper modelling the solidification of cast iron parts is considered. Common for previous efforts in this field is that they have mainly considered thin walled to medium thickness castings. Hence, a numerical model combining the solidification model presented by Lesoultet al. [1] wi...

  6. Microstructure and mechanical properties of a new type of austempered boron alloyed high silicon cast steel

    Directory of Open Access Journals (Sweden)

    Chen Xiang

    2013-05-01

    Full Text Available In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 篊 to 400 篊. The impact toughness is 4-11 J昪m-2 at room temperature and the impact fracture fractogragh indicates that the fracture is caused by the brittle fracture of the borides.

  7. 3D atomistic simulation of fatigue behavior of a ductile crack in bcc iron

    Czech Academy of Sciences Publication Activity Database

    Uhnáková, Alena; Machová, Anna; Hora, Petr

    2011-01-01

    Roč. 33, č. 9 (2011), s. 1182-1188 ISSN 0142-1123 R&D Projects: GA ČR(CZ) GAP108/10/0698 Institutional research plan: CEZ:AV0Z20760514 Keywords : 3D molecular dynamics * fatigue * bcc iron * mode I Subject RIV: JG - Metallurgy Impact factor: 1.546, year: 2011 http://www.sciencedirect.com/science/article/pii/S0142112311000600

  8. Standard test method for determining nodularity and nodule count in ductile iron using image analysis

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method is used to determine the percent nodularity and the nodule count per unit area (that is, number of nodules per mm2) using a light microscopical image of graphite in nodular cast iron. Images generated by other devices, such as a scanning electron microscope, are not specifically addressed, but can be utilized if the system is calibrated in both x and y directions. 1.2 Measurement of secondary or temper carbon in other types of cast iron, for example, malleable cast iron or in graphitic tool steels, is not specifically included in this standard because of the different graphite shapes and sizes inherent to such grades 1.3 This standard deals only with the recommended test method and nothing in it should be construed as defining or establishing limits of acceptability or fitness for purpose of the material tested. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address al...

  9. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    DEFF Research Database (Denmark)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard

    2018-01-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component...... of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper....... First, a ma terial equivalent to the ductile cast iron matrix is manufactured and subjected to dilato- metric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between...

  10. Influence of moulding conditions and mould characteristics on the contraction defects appearance in ductile iron castings

    International Nuclear Information System (INIS)

    Sertucha, J.; Suarez, R.; Legazpi, J.; Gacetabeitia, P.

    2007-01-01

    Shrinkage defects appearance in cast iron has traditionally been related to the solidification processes of the metal and the feedings ability among the different sections of castings. Recent studies have demonstrated that sand moulds properties and their thermal behaviour after pouring step have an important influence on these defects formation too. The influence of the moulding process parameters and the mould characteristics on the contraction defects is analysed in this work using test casting designed specifically for this purpose. Additionally the most important parameters are determined in order to control the manufacturing process and minimise the shrinkage appearance in the castings. (Author) 14 refs

  11. Sclero-topometry Metrology in Valorisation of Waste Oil for Micro-machining of Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    Eymard S.

    2013-12-01

    Full Text Available During the time, the specific characteristics and the efficient lifetime of oil progressively decrease, due to complex pollution, ultimately making the oil unsuitable for the initial applications. The strategy to regenerate and to valorise waste oils is investigated using improved combinations of sclerometric and topometric tests on ductile nodular cast iron. Tribo-abrasive tests are performed in critical conditions, with base oil, waste oil and regenerated oil, of similar viscosities in order to discriminate their interfacial performances. The forms of the scratch traces indicate wear resistance and tendency to elasto-plastic deformation. The mechanisms of deformation and frictional behaviours were evaluated using optical and Scanning Electron Microscopy and measured for various tribological conditions with tactile and optical profilometry. The Energy Dispersive X ray Spectroscopy completes the chemical superficial distribution of pertinent elements. The surface topography metrology is used to characterize the scratch profiles and to determine the volume of the displaced and removed material, as well as maximum pit height. The originality of this paper is that it is a unique approach specifically devoted to transformer oil concerning tribological conditions.

  12. Mechanical and Tribological Properties of HVOF-Sprayed (Cr3C2-NiCr+Ni) Composite Coating on Ductile Cast Iron

    Science.gov (United States)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-08-01

    The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions.

  13. Structure and Corrosion Behavior of Arc-Sprayed Zn-Al Coatings on Ductile Iron Substrate

    Science.gov (United States)

    Bonabi, Salar Fatoureh; Ashrafizadeh, Fakhreddin; Sanati, Alireza; Nahvi, Saied Mehran

    2018-02-01

    In this research, four coatings including pure zinc, pure aluminum, a double-layered coating of zinc and aluminum, and a coating produced by simultaneous deposition of zinc and aluminum were deposited on a cast iron substrate using electric arc-spraying technique. The coatings were characterized by XRD, SEM and EDS map and spot analyses. Adhesion strength of the coatings was evaluated by three-point bending tests, where double-layered coating indicated the lowest bending angle among the specimens, with detection of cracks at the coating-substrate interface. Coatings produced by simultaneous deposition of zinc and aluminum possessed a relatively uniform distribution of both metals. In order to evaluate the corrosion behavior of the coatings, cyclic polarization and salt spray tests were conducted. Accordingly, pure aluminum coating showed susceptibility to pitting corrosion and other coatings underwent uniform corrosion. For double-layered coating, SEM micrographs revealed zinc corrosion products as flaky particles in the pores formed by pitting on the surface, an indication of penetration of corrosion products from the lower layer (zinc) to the top layer (aluminum). All coatings experienced higher negative corrosion potentials than the iron substrate, indicative of their sacrificial behavior.

  14. Decommissioning and dismantling of nuclear facilities: Establishing methods for testing the safe design of ductile cast iron casks with higher content of metallic recycling material (EBER)

    International Nuclear Information System (INIS)

    Zenker, U.; Voelzke, H.; Droste, B.

    2001-01-01

    The safe design of ductile cast iron (DCI) casks with higher content of metallic recycling material is investigated. Based upon the requirements of transport and storage containers for radioactive waste appropriate test scenarios are defined. A representative accident scenario (5 m drop of a cubic DCI container with given material properties onto a hard repository ground simulating concrete target) is analysed numerically by means of the finite element method using three-dimensional models. Dynamic flow curves of ductile cast iron with different scrap metal additions which are necessary for precise elastic-plastic calculations are given. The accuracy and numerical stability of the resulting dynamic stresses and strains are investigated. A comparison between calculation results and measurements from drop tests with DCI containers shows, that known mechanical effects like bending vibrations of the container walls are reflected by the finite element models. The detailed stress analysis and knowledge of the material properties are prerequisites for the safety assessment concept developed for DCI casks with higher content of metallic recycling material. Equations for semi-elliptical surface cracks in the walls of a cubically shaped container which are used in the safety assessment concept are verified under dynamic conditions. This allows the specification of the maximum permissible size of crack-like flaws depending on the material quality. Mainly the fracture mechanical properties of ductile cast iron with higher content of metallic recycling material determine the suitability of such materials for transport and storage containers. (orig.) [de

  15. Study of Distortion on the Example of the Rings from Ductile Iron and Cast Steel

    Directory of Open Access Journals (Sweden)

    Łukasik K.

    2017-12-01

    Full Text Available The paper attempts to analyze distortions of cast iron and cast steel rings, after heat treatment cycles. The factors influencing distortion are: chemical composition of material, sample geometry, manufacturing process, hardenability, temperature and heat treatment method. Standard distortion tests are performed on C-ring samples. We selected a ring-model, which approximate the actual part, so that findings apply to gear rings. Because distortion depends on so many variables, this study followed strictly defined procedures. The research was started by specifying the appropriate geometry of the samples. Then, the heat treatment was conducted and samples were measured again. The obtained results allow to determine the value of the resulting distortion and their admissibility. The research will be used to evaluate the possibility of using the material to produce parts of equipment operated under extreme load conditions.

  16. Production of Selected Key Ductile Iron Castings Used in Large-Scale Windmills

    Science.gov (United States)

    Pan, Yung-Ning; Lin, Hsuan-Te; Lin, Chi-Chia; Chang, Re-Mo

    Both the optimal alloy design and microstructures that conform to the mechanical properties requirements of selected key components used in large-scale windmills have been established in this study. The target specifications in this study are EN-GJS-350-22U-LT, EN-GJS-350-22U-LT and EN-GJS-700-2U. In order to meet the impact requirement of spec. EN-GJS-350-22U-LT, the Si content should be kept below 1.97%, and also the maximum pearlite content shouldn't exceed 7.8%. On the other hand, Si content below 2.15% and pearlite content below 12.5% were registered for specification EN-GJS-400-18U-LT. On the other hand, the optimal alloy designs that can comply with specification EN-GJS-700-2U include 0.25%Mn+0.6%Cu+0.05%Sn, 0.25%Mn+0.8%Cu+0.01%Sn and 0.45%Mn+0.6%Cu+0.01%Sn. Furthermore, based upon the experimental results, multiple regression analyses have been performed to correlate the mechanical properties with chemical compositions and microstructures. The derived regression equations can be used to attain the optimal alloy design for castings with target specifications. Furthermore, by employing these regression equations, the mechanical properties can be predicted based upon the chemical compositions and microstructures of cast irons.

  17. Statistical study to determine the effect of carbon, silicon, nickel and other alloying elements on the mechanical properties of as-cast ferritic ductile irons

    Directory of Open Access Journals (Sweden)

    Lacaze, Jacques

    2016-06-01

    Full Text Available There is a great interest in fully ferritic ductile irons due to their structural homogeneity, remarkable ductility and good response when machining. On the other hand the wide variety of raw materials available in foundry plants becomes a problem when controlling the chemical composition of the manufactured alloys. The present work shows a statistical study about the effect of different C, Si, Ni contents and other minor elements on structural and mechanical properties of a group of ferritic ductile iron alloys. A set of equations are finally presented to predict room temperature mechanical properties of ferritic ductile irons by means of their chemical composition and pearlite content.Las fundiciones con grafito esferoidal de matriz totalmente ferrítica tienen gran interés debido a su homogeneidad estructural, alargamiento destacable y su buena respuesta frente a las operaciones de mecanizado. Por otro lado, la extensa variedad de materias primas disponibles en las plantas de fundición supone un problema a la hora de controlar de forma efectiva la composición química de las aleaciones preparadas. En este trabajo se ha realizado un estudio estadístico sobre la influencia de los diferentes contenidos de carbono, silicio, níquel y de otros elementos minoritarios sobre las características estructurales y las propiedades mecánicas de un grupo de fundiciones con grafito esferoidal y matriz ferrítica. Finalmente, se han obtenido un número de ecuaciones que permiten predecir las propiedades mecánicas a temperatura ambiente de estas fundiciones en función de su composición química y su contenido de perlita en la matriz metálica.

  18. Continuous austempering fluidized bed furnace. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, M.N. [Lamar Univ., Beaumont, TX (United States). Dept. of Mechanical Engineering

    1997-09-23

    The intended objective of this project was to show the benefits of using a fluidized bed furnace for austenitizing and austempering of steel castings in a continuous manner. The division of responsibilities was as follows: (1) design of the fluidized bed furnace--Kemp Development Corporation; (2) fabrication of the fluidized bed furnace--Quality Electric Steel, Inc.; (3) procedure for austempering of steel castings, analysis of the results after austempering--Texas A and M University (Texas Engineering Experiment Station). The Department of Energy provided funding to Texas A and M University and Kemp Development Corporation. The responsibility of Quality Electric Steel was to fabricate the fluidized bed, make test castings and perform austempering of the steel castings in the fluidized bed, at their own expense. The project goals had to be reviewed several times due to financial constraints and technical difficulties encountered during the course of the project. The modifications made and the associated events are listed in chronological order.

  19. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    Science.gov (United States)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard; Thorborg, Jesper; Tiedje, Niels; Hattel, Jesper

    2018-02-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper. First, a material equivalent to the ductile cast iron matrix is manufactured and subjected to dilatometric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the viscoplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain. Moreover, the model shows that the large elastic strain perturbations recorded with XRD close to the graphite-matrix interface are not artifacts due to e.g. sharp gradients in chemical composition, but correspond to residual stress concentrations induced by the conical sectors forming the internal structure of the graphite particles. In contrast to common belief, these results thus suggest that ductile cast iron parts cannot be considered, in general, as stress-free at the microstructural scale.

  20. Casting and stress-strain simulations of a cast ductile iron component using microstructure based mechanical behavior

    International Nuclear Information System (INIS)

    Olofsson, Jakob; Svensson, Ingvar L

    2012-01-01

    The industrial demand for increased component performance with concurrent reductions in component weight, development times and verifications using physical prototypes drives the need to use the full potential of casting and Finite Element Method (FEM) simulations to correctly predict the mechanical behavior of cast components in service. The mechanical behavior of the component is determined by the casting process, and factors as component geometry and casting process parameters are known to affect solidification and microstructure formation throughout the component and cause local variations in mechanical behavior as well as residual stresses. Though residual stresses are known to be an important factor in the mechanical behavior of the component, the importance of local mechanical behavior is not well established and the material is typically considered homogeneous throughout the component. This paper deals with the influence of solidification and solid state transformation on microstructure formation and the effect of local microstructure variations on the mechanical behavior of the cast component in service. The current work aims to investigate the coupling between simulation of solidification, microstructure and local variations in mechanical behavior and stress-strain simulation. This is done by performing several simulations of a ductile iron component using a recently developed simulation strategy, a closed chain of simulations for cast components, able to predict and describe the local variations in not only elastic but also plastic behavior throughout the component by using microstructural parameters determined by simulations of microstructural evolution in the component during the casting process. In addition the residual stresses are considered. The results show that the FEM simulation results are significantly affected by including microstructure based mechanical behavior. When the applied load is low and the component is subjected to stress levels

  1. A fracture mechanics safety concept to assess the impact behavior of ductile cast iron containers for shipping and storage of radioactive materials

    International Nuclear Information System (INIS)

    Voelzke, H.; Roedel, R.; Droste, B.

    1994-01-01

    Within the scope of the German licensing procedures for shipping and storage containers for radioactive materials made of ductile cast iron, BAM performs approval design tests including material tests to ensure the main safety goals of shielding, leaktightness and subcriticality under ''Type B accident conditions''. So far the safety assessment concept of BAM is based essentially on the experimental proof of container strength by prototype testing under most damaging test conditions in connection with complete approval design tests, and has been developed especially for cylindrical casks like CASTOR- and TN-design. In connection with the development of new container constructions such as ''cubic cast containers'', and the fast developments in the area of numerical calculation methods, there is a need for a more flexible safety concept especially considering fracture mechanics aspects.This paper presents the state of work at BAM for such an extended safety concept for ductile cast iron containers, based on a detailed brittle fracture safe design proof. The requirements on stress analysis (experimental or numerical), material properties, material qualification, quality assurance provisions and fracture mechanics safety assessment, including well defined and justified factors of safety, are described. ((orig.))

  2. The Structure and Bond Strength of Composite Carbide Coatings (WC-Co + Ni) Deposited on Ductile Cast Iron by Thermal Spraying

    Science.gov (United States)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-02-01

    An investigation was conducted to determine the role of Ni particles in the WC-Co coating produced with the supersonic method on microstructure, mechanical, and wear properties in a system of type: WC-Co coating/ductile cast iron. The microstructure of the thermal-sprayed WC-Co + Ni coating was characterized by scanning electron and transmission electron microscopes as well as the analysis of chemical and phase composition in microareas (EDS, XRD). The microstructure of the WC-Co + Ni coating consisted of large, partially molten Ni particles and very fine grains of WC embedded in cobalt matrix, coming to the size of nanocrystalline. Moreover, the results were discussed in reference to examination of bending strength considering cracking and delamination in the system of (WC-Co + Ni)/ductile cast iron as well as hardness and wear resistance of the coating. It was found that the addition of Ni particles was significantly increase resistance to cracking and wear behavior in the studied system.

  3. An Analysis of the Weldability of Ductile Cast Iron Using Inconel 625 for the Root Weld and Electrodes Coated in 97.6% Nickel for the Filler Welds

    Directory of Open Access Journals (Sweden)

    Francisco-Javier Cárcel-Carrasco

    2016-11-01

    Full Text Available This article examines the weldability of ductile cast iron when the root weld is applied with a tungsten inert gas (TIG welding process employing an Inconel 625 source rod, and when the filler welds are applied with electrodes coated with 97.6% Ni. The welds were performed on ductile cast iron specimen test plates sized 300 mm × 90 mm × 10 mm with edges tapered at angles of 60°. The plates were subjected to two heat treatments. This article analyzes the influence on weldability of the various types of electrodes and the effect of preheat treatments. Finally, a microstructure analysis is made of the material next to the weld in the metal-weld interface and in the weld itself. The microstructure produced is correlated with the strength of the welds. We treat an alloy with 97.6% Ni, which prevents the formation of carbides. With a heat treatment at 900 °C and 97.6% Ni, there is a dissolution of all carbides, forming nodules in ferritic matrix graphite.

  4. Mechanical milling of a nano structured ductile iron powder under dry, wet and cryogenic atmospheres; Proceso de molturacion mecanica en medio seco, humedo y criogenico de polvo de hierro ductil nanoestructurado

    Energy Technology Data Exchange (ETDEWEB)

    Cinca, N.; Hurtado, E.; Cano, I. G.; Guilemany, J. M.

    2011-07-01

    The main objective of this study, is to obtain an effective particle and grain size reduction of a nano structured iron powder by mechanical milling under different milling media. One of the main challenges in this study is to work with this material of great ductility.The variables of the study to be optimized have been the following: speed of rotation, powder to ball ratio (PBR) and the percentage of control agent to induce an effective powder fracturing in front of cold welding. The powder has been characterized by a Laser Diffraction Particle Size Analyser, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and, X-ray diffraction.Through the comparative study, it is found that operating under dry milling conditions: there is a more effective particle size reduction of 43 % and grain size reduction of 62 %. In wet conditions has been reduced the amount of oxide, as well as to obtain a more homogenous distribution of the resulting powder. The results under cryogenic media is presented as promising. (Author) 15 refs.

  5. Optimization of Master Alloy Amount and Gating System Design for Ductile Cast Iron Obtain in Lost Foam Process

    Directory of Open Access Journals (Sweden)

    Just P.

    2013-09-01

    Full Text Available The paper presents the optimization of master alloy amount for the high nodular graphite yield (80-90% in cast iron obtain in lost foam process. The influence of the gating system configuration and the shape of the reaction chamber, the degree of spheroidisation cast iron was examined. Research has shown that the, optimal of master alloy amount of 1.5% by mass on casting iron. The degree of spheroidisation is also influenced by the gating system configuration. The best spheroidisation effect was obtained for liquid cast iron was fed into the reaction chamber from the bottom and discharged from the top.

  6. Structure and mechanical properties of ductile iron GJS-500-7; Estructura y propiedades mecánicas del hierro dúctil GJS-500-7

    Energy Technology Data Exchange (ETDEWEB)

    Kuryloa, P.; Tertela, E.

    2017-09-01

    The paper presents the results of research on mechanical properties (hardness distribution along the cross section towards the cast’s core) and on the structures of ductile iron GJS-500-7. The study defines the range and form of the surface layer of cast iron. It has been shown that the surface layer of the working surface of the cast may be shaped within its transition zone. [Spanish] El artículo presenta los resultados de la investigación sobre propiedades mecánicas (distribución de la dureza a lo largo de la sección transversal del núcleo de la fundición) y de las estructuras de hierro dúctil GJS-500-7. El estudio define el rango y la forma de la capa superficial de hierro fundido. Se ha mostrado que la capa superficial de la superficie del molde trabajado puede estar conformada dentro de su zona de transición.

  7. 3D atomistic simulation of fatigue behavior of a ductile crack in bcc iron loaded in mode II

    Czech Academy of Sciences Publication Activity Database

    Uhnáková, Alena; Pokluda, J.; Machová, Anna; Hora, Petr

    2012-01-01

    Roč. 61, AUG 2012 (2012), s. 12-19 ISSN 0927-0256 R&D Projects: GA ČR(CZ) GAP108/10/0698 Institutional research plan: CEZ:AV0Z20760514 Keywords : fatigue * mode II * bcc iron * molecular dynamic simulations Subject RIV: JG - Metallurgy Impact factor: 1.878, year: 2012 http://www.sciencedirect.com/science/article/pii/S0927025612001929

  8. A Predictive Framework for Thermomechanical Fatigue Life of High Silicon Molybdenum Ductile Cast Iron Based on Considerations of Strain Energy Dissipation

    Science.gov (United States)

    Avery, Katherine R.

    Isothermal low cycle fatigue (LCF) and anisothermal thermomechanical fatigue (TMF) tests were conducted on a high silicon molybdenum (HiSiMo) cast iron for temperatures up to 1073K. LCF and out-of-phase (OP) TMF lives were significantly reduced when the temperature was near 673K due to an embrittlement phenomenon which decreases the ductility of HiSiMo at this temperature. In this case, intergranular fracture was predominant, and magnesium was observed at the fracture surface. When the thermal cycle did not include 673K, the failure mode was predominantly transgranular, and magnesium was not present on the fracture surface. The in-phase (IP) TMF lives were unaffected when the thermal cycle included 673K, and the predominant failure mode was found to be transgranular fracture, regardless of the temperature. No magnesium was present on the IP TMF fracture surfaces. Thus, the embrittlement phenomenon was found to contribute to fatigue damage only when the temperature was near 673K and a tensile stress was present. To account for the temperature- and stress-dependence of the embrittlement phenomenon on the TMF life of HiSiMo cast iron, an original model based on the cyclic inelastic energy dissipation is proposed which accounts for temperature-dependent differences in the rate of fatigue damage accumulation in tension and compression. The proposed model has few empirical parameters. Despite the simplicity of the model, the predicted fatigue life shows good agreement with more than 130 uniaxial low cycle and thermomechanical fatigue tests, cyclic creep tests, and tests conducted at slow strain rates and with hold times. The proposed model was implemented in a multiaxial formulation and applied to the fatigue life prediction of an exhaust manifold subjected to severe thermal cycles. The simulation results show good agreement with the failure locations and number of cycles to failure observed in a component-level experiment.

  9. Effect of CeO{sub 2} addition on thermal shock resistance of WC–12%Co coating deposited on ductile iron by electric contact surface strengthening

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiaoben [College of Mechanical Engineering, Donghua University, Shanghai 201620 (China); College of Mechanical Engineering, Shanghai Dianji University, Shanghai 200240 (China); Zhu, Shigen, E-mail: sgzhu@dhu.edu.cn [College of Mechanical Engineering, Donghua University, Shanghai 201620 (China); Engineering Research Center of Advanced Textile Machinery, Ministry of Education, Shanghai 201620 (China)

    2015-09-15

    Highlights: • WC–Co powders with CeO{sub 2} were deposited by electric contact strengthening (ECS). • ECS is based on electric resistive heating between the electrode and work piece. • WC–Co coating with CeO{sub 2} by ECS was metallurgically bonded to the substrate. • The addition of CeO{sub 2} could refine the coating microstructure and increase the microhardness. • By the proper addition of cerium oxide, the thermal shock performance was enhanced. - Abstract: The WC–12%Co powders with different contents of CeO{sub 2} (0.1–2 wt.%) were deposited on ductile iron by electric contact surface strengthening. The coatings with and without CeO{sub 2} were examined and tested for microstructural characteristic, phase structure, microhardness and thermal shock resistance. The comparison concluded that the proper addition of CeO{sub 2} could refine the microstructure of coatings and increase the microhardness of the coatings. By the small amount addition of cerium oxide (0.5 wt.%), the solid solution strengthening effect and grain boundaries strengthening effect would delay the time of crack formation and propagation in the coatings and enhance the thermal shock performance.

  10. Chunky graphite formation in small section ductile iron castings; Formacion de grafito chunky en piezas de pequeno espesor fabricadas utilizando fundicion de hierro con grafito esferoidal

    Energy Technology Data Exchange (ETDEWEB)

    Asenjo, I.; Larranaga, P.; Sertucha, J.

    2011-07-01

    Chunky graphite is a degenerated graphite form which can be found in the thermal centre of ductile iron heavy section castings. Previous studies made on cubic blocks (300 and 180 mm in side) manufactured using alloys with fully ferritic matrix structures show that low cooling rates, excessive post-inoculation and high silicon and/or cerium contents in the melts are the most important factors that promote this kind of defect. The enhancement of these critical factors led to obtain chunky graphite in sections lower than 50 mm. Different experimental conditions have been used in order to establish the main parameters that affect this graphite malformation. The use of cutting-edge techniques in the analysis of chemical compositions has revealed that no significant differences can be found when comparing chunky areas and well-formed spheroidal graphite areas. On the other hand, it has not been possible to establish any correlation between the oxygen contents and the scale of the defect. However, it is noteworthy that the oxygen content is related to the use of magnesium or cerium as nodulized agent. (Author) 23 refs.

  11. Ultrasonic testing of pre-turned contours for large components made of ductile iron; Ultraschallpruefung an Vordrehkonturen fuer grosse Bauteile aus Gusseisen mit Kugelgraphit

    Energy Technology Data Exchange (ETDEWEB)

    Schmitte, Till; Chichkov, Nikolai; Nemitz, Oliver; Orth, Thomas [Salzgitter Mannesmann Forschung GmbH, Duisburg (Germany); Hocks, Heinrich Jr.; Rusche, Sascha; Opalla, Dirk; Frank, Joerg [GNS Gesellschaft fuer Nuklear-Service mbH, Essen (Germany)

    2015-07-01

    In the ultrasonic testing of large, thick-walled components made of ductile iron partial acoustic paths of several meters are needed. Considered here are cylindrical components such as the body of CASTOR containers with diameters 2-3 m, a height of up to 6 m and a wall thickness of 500 mm. So far, an automated technique for this is not available, therefore such components are checked in a complex and lengthy process by manual ultrasonic testing. The development and design of the testing by means of simulations and the realization as a mobile testing device are topics of this paper. Measurements on a reference body with test reflectors in different depths are presented and discussed. [German] Bei der Ultraschall-Pruefung von grossen, dickwandigen Bauteilen aus Gusseisen mit Kugelgraphit werden teilweise Schallwege von mehreren Metern noetig. Betrachtet werden hier zylinderfoermige Bauteile, wie die Koerper von CASTOR-Behaeltern, mit Durchmessern zwischen 2 und 3 m, einer Hoehe von bis zu 6 m und Wanddicken von ca. 500 mm. Bisher ist eine automatisierte Technik hierfuer nicht verfuegbar, daher werden derartige Bauteile in einem aufwaendigen und langwierigen Prozess mittels manueller Schallung geprueft. Zur Erhoehung der Nachweissicherheit und zur Steigerung der Effizienz im Pruefablauf sollen nun senkrecht zur Achse des zylinderfoermigen Bauteils liegende unzulaessige Anzeigen im gesamten Mantelvolumen durch eine teilautomatisierte Pruefung ausgeschlossen werden. Die Entwicklung und Auslegung der Prueftechnik mittels Simulationen und die Realisierung als mobile Pruefvorrichtung sind Themen dieses Beitrags. Messungen an einem Referenzkoerper mit Testreflektoren in verschiedenen Tiefen werden vorgestellt und diskutiert.

  12. Microstructure and Sliding Wear Behaviour of In-Situ TiC-Reinforced Composite Surface Layers Fabricated on Ductile Cast Iron by Laser Alloying.

    Science.gov (United States)

    Janicki, Damian

    2018-01-05

    TiC-reinforced composite surface layers (TRLs) on a ductile cast iron EN-GJS-700-2 grade (DCI) substrate were synthesized using a diode laser surface alloying with a direct injection of titanium powder into the molten pool. The experimental results were compared with thermodynamic calculations. The TRLs having a uniform distribution of the TiC particles and their fraction up to 15.4 vol % were achieved. With increasing titanium concentration in the molten pool, fractions of TiC and retained austenite increase and the shape of TiC particles changes from cubic to dendritic form. At the same time, the cementite fraction decreases, lowering the overall hardness of the TRL. A good agreement between experimental and calculated results was achieved. Comparative dry sliding wear tests between the as-received DCI, the TRLs and also laser surface melted layers (SMLs) have been performed following the ASTM G 99 standard test method under contact pressures of 2.12 and 4.25 MPa. For both the as-received DCI and the SMLs, the wear rates increased with increasing contact pressure. The TRLs exhibited a significantly higher wear resistance than the others, which was found to be load independent.

  13. Influencia del manganeso en la producción de hierros nodulares ferríticos // Influence of manganese content on the production of ferritic ductile iron

    Directory of Open Access Journals (Sweden)

    T. Rodríguez Moliner

    1999-07-01

    Full Text Available El estudio del efecto del manganeso en los hierros nodulares es de suma importancia. Todos los autores concuerdan que para laproducción de hierros ferríticos es de suma importancia que el contenido de manganeso debe ser lo mas bajo posible. Sinembargo no existe un consenso de cuan bajo debían ser estos niveles, ya que depende conjuntamente de otros factores.Este trabajo se propuso determinar limites de concentración de manganeso para barras de 25mm de ancho y con una buenaestructura del grafito, obteniendo en cada caso hierros ferríticos directamente de fundición.Dichos limites fueron encontrados en 0.15% para producir el hierro nodular 40-18 y en 0.6% para el 42-12. Contrariamente aestudios anteriores, no se encontró ningún efecto del mismo en el conteo de los nódulos. Se determinó que el manganeso tiendea disminuir el rango de temperaturas entre la reacción estable y la inestable de descomposición de la austenita, a pesar de hacerdecrecer ambas temperaturasPalabras claves: Hierros nodulares, manganeso, ferri ta.______________________________________________________________________________AbstractThe study of the manganese effects on ductile irons is very important. Several authors agree that for the obtainment of ferriticiron grades its content should be kept as low as possible. However there is not a complete agreement on the exact levels themanganese content should be, when the intention is to use as-cast procedures.The aim of this paper was to determine the manganese limits for the obtainment of ferritic grades as-cast on 25 mm bars with agood graphite structure. Such limits were found to be 0.15% for the 40-18 grade and 0.6% for the 42-12 iron grade.On the contrary of previous studies no effect of manganese on nodule count was found. Manganese was found to decrease thetemperature range between the stable and the metastable austenite decomposition reaction, besides it decreases bothtemperatures.Key words: Duct i le iron

  14. A New Direct-Pour In-Mold (DPI) Technology for Producing Ductile and Compacted Graphite Iron Castings.

    Energy Technology Data Exchange (ETDEWEB)

    Jason Hitchings; Jay R. Hitchings

    2007-07-20

    A new "Direct Pour In-Mold" (DPI) Magnesium treatment technology has been developed that can produce both Nodular and Compacted Graphite iron. The DPI technology converts the standard horizontal runner system into a vertical one, by placing a Magnesium Ferrosilicon treatment alloy and molten metal filter into a specially designed container. The DPI container is easily placed into either vertically or horizontally parted molds, and then a base metal can be poured directly into it. The metal is treated and filtered as it passes through, and then proceeds directly into a runner or casting cavity. Various sizes of containers provide all of the necessary components required to deliver a range of weights of treated and filtered metal at accurate and consistent flow rates. The DPI containers provide energy savings over competing techniques, increased mold yields, very high Magnesium recovery, zero Magnesium fume, and no post inoculation is required. By treating the metal just prior to it entering a casting cavity many other benefits and advantages are also realized.

  15. Effects of phosphate addition on biofilm bacterial communities and water quality in annular reactors equipped with stainless steel and ductile cast iron pipes.

    Science.gov (United States)

    Jang, Hyun-Jung; Choi, Young-June; Ro, Hee-Myong; Ka, Jong-Ok

    2012-02-01

    The impact of orthophosphate addition on biofilm formation and water quality was studied in corrosion-resistant stainless steel (STS) pipe and corrosion-susceptible ductile cast iron (DCI) pipe using cultivation and culture-independent approaches. Sample coupons of DCI pipe and STS pipe were installed in annular reactors, which were operated for 9 months under hydraulic conditions similar to a domestic plumbing system. Addition of 5 mg/L of phosphate to the plumbing systems, under low residual chlorine conditions, promoted a more significant growth of biofilm and led to a greater rate reduction of disinfection by-products in DCI pipe than in STS pipe. While the level of THMs (trihalomethanes) increased under conditions of low biofilm concentration, the levels of HAAs (halo acetic acids) and CH (chloral hydrate) decreased in all cases in proportion to the amount of biofilm. It was also observed that chloroform, the main species of THM, was not readily decomposed biologically and decomposition was not proportional to the biofilm concentration; however, it was easily biodegraded after the addition of phosphate. Analysis of the 16S rDNA sequences of 102 biofilm isolates revealed that Proteobacteria (50%) was the most frequently detected phylum, followed by Firmicutes (10%) and Actinobacteria (2%), with 37% of the bacteria unclassified. Bradyrhizobium was the dominant genus on corroded DCI pipe, while Sphingomonas was predominant on non-corroded STS pipe. Methylobacterium and Afipia were detected only in the reactor without added phosphate. PCR-DGGE analysis showed that the diversity of species in biofilm tended to increase when phosphate was added regardless of the pipe material, indicating that phosphate addition upset the biological stability in the plumbing systems.

  16. Corrosion behaviour of ductile cast irons partially modified with silicon in 0.03 M NaCl; Comportamiento frente a la corrosion de fundiciones con grafito laminar y esferoidal parcialmente modificadas con silicio en NaCl 0,03 M

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, M. A.; Niklas, A.; Conde, A.; Mendez, S.; Sertucha, J.; Damborenea, J. J. de

    2014-07-01

    NaCl. The increasing demand of ductile cast irons with extensive technological applications leads to enlarge the corrosion resistance of this group of metallic materials. In this sense, the use of different chemical compositions on such cast irons becomes one of the most interesting aspects among the different ways to improve their behaviour against corrosion due to the extra opportunity for increasing the mechanical properties. Additionally such improvements have to be made without any increase of processing costs to keep the interesting competitiveness of developed cast irons. In the present work the preliminary results obtained from corrosion tests made on a group of cast irons with different chemical compositions are presented. Among ductile cast irons, silicon content has been varied in order to investigate the effect of this element on corrosion resistance of the alloys. The obtained results show a slight improvement of this property for the alloys with high silicon content with respect to the conventional ones though such effect was found in the first time period of the corrosion tests. Interestingly this improvement was found for alloys that exhibit better tensile properties than the conventional ductile irons. Thus an important way for developing new ductile cast irons with improved corrosion properties by alloying has been opened. (Author)

  17. Microstructure and Mechanical Properties of Austempered Medium-Carbon Spring Steel

    Science.gov (United States)

    Kim, Seong Hoon; Kim, Kwan-Ho; Bae, Chul-Min; Lee, Jae Sang; Suh, Dong-Woo

    2018-03-01

    Changes in microstructure and mechanical properties of medium-carbon spring steel during austempering were investigated. After austempering for 1 h at 290 °C or 330 °C, the bainite transformation stabilized austenite, and microstructure consisting of bainitic ferrite and austenite could be obtained after final cooling; the retained austenite fraction was smaller in the alloy austempered at 290 °C because carbon redistribution between bainitic ferrite and austenite slowed as the temperature decreased, and thereby gave persistent driving force for the bainite transformation. The products of tensile strength and reduction of area in the austempered alloy were much larger in the austempered steel than in quenched and tempered alloy, mainly because of significant increase in reduction of area in austempered alloy.

  18. Quality and Cost Assessment of Treatment with SiMg and NiCuMg Master Alloys vs Cored Wire in Production of Ductile Iron

    Directory of Open Access Journals (Sweden)

    E. Guzik

    2007-07-01

    Full Text Available The results of studies on the use of magnesium alloy in modern cored wire injection method for production of nodular and vermicular graphite cast irons were described. The injection of Mg cored wire length is a treatment method which can be used to process high sulphur cupola iron held in ladles or iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 47-70% for the production of vermicular and nodular graphite cast irons at Ścinawka Foundry, and for the production of nodular graphite iron at the following foundries: GZUT, KRAKODLEW, Centrozap - DEFKA, EE Zawiercie, WSK–Rzeszów, FWM PRZYSUCHA, HSW Stalowa Wola and PIOMA. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The results of numerous trials have shown that the magnesium cored wire process can produce high quality nodular and vermicular graphite irons under the specific industrial conditions of the above mentioned foundries. It has also been proved that in the manufacture of nodular graphite iron, the cost of the nodulariser in the form of elastic cored wire is lower than the cost of the FeSiMg or NiCuMg master alloys.

  19. Development of a Cast Iron Fatigue Properties Database for use with Modern Design Methods

    Energy Technology Data Exchange (ETDEWEB)

    DeLa' O, James, D.; Gundlach, Richard, B.; Tartaglia, John, M.

    2003-09-18

    A reliable and comprehensive database of design properties for cast iron is key to full and efficient utilization of this versatile family of high production-volume engineering materials. A database of strain-life fatigue properties and supporting data for a wide range of structural cast irons representing industry standard quality was developed in this program. The database primarily covers ASTM/SAE standard structural grades of ADI, CGI, ductile iron and gray iron as well as an austempered gray iron. Twenty-two carefully chosen materials provided by commercial foundries were tested and fifteen additional datasets were contributed by private industry. The test materials are principally distinguished on the basis of grade designation; most grades were tested in a 25 mm section size and in a single material condition common for the particular grade. Selected grades were tested in multiple sections-sizes and/or material conditions to delineate the properties associated with a range of materials for the given grade. The cyclic properties are presented in terms of the conventional strain-life formalism (e.g., SAE J1099). Additionally, cyclic properties for gray iron and CGI are presented in terms of the Downing Model, which was specifically developed to treat the unique stress-strain response associated with gray iron (and to a lesser extent with CGI). The test materials were fully characterized in terms of alloy composition, microstructure and monotonic properties. The CDROM database presents the data in various levels of detail including property summaries for each material, detailed data analyses for each specimen and raw monotonic and cyclic stress-strain data. The CDROM database has been published by the American Foundry Society (AFS) as an AFS Research Publication entitled ''Development of a Cast Iron Fatigue Properties Database for Use in Modern Design Methods'' (ISDN 0-87433-267-2).

  20. Ductility of Nanostructured Bainite

    Directory of Open Access Journals (Sweden)

    Lucia Morales-Rivas

    2016-12-01

    Full Text Available Nanostructured bainite is a novel ultra-high-strength steel-concept under intensive current research, in which the optimization of its mechanical properties can only come from a clear understanding of the parameters that control its ductility. This work reviews first the nature of this composite-like material as a product of heat treatment conditions. Subsequently, the premises of ductility behavior are presented, taking as a reference related microstructures: conventional bainitic steels, and TRIP-aided steels. The ductility of nanostructured bainite is then discussed in terms of work-hardening and fracture mechanisms, leading to an analysis of the three-fold correlation between ductility, mechanically-induced martensitic transformation, and mechanical partitioning between the phases. Results suggest that a highly stable/hard retained austenite, with mechanical properties close to the matrix of bainitic ferrite, is advantageous in order to enhance ductility.

  1. Microstructure and wear behavior of austempered high carbon high silicon steel

    Directory of Open Access Journals (Sweden)

    Acharya Palaksha

    2018-01-01

    Full Text Available In the present investigation, the influence of austempering temperature and time on the microstructure and dry sliding wear behavior of high silicon steel was studied. The test specimens were initially austenitised at 900°C for 30 minutes, thereafter austempered at various temperatures 280°C, 360°C and 400°C, for varying duration from 30 to 120 minutes. These samples after austempering heat treatment were subsequently air cooled to room temperature, to generate typical ausferritic microstructures and then correlated with the wear property. The test outcomes demonstrate the slight increase in specific wear rate with increase in both austempering temperature and time. Specific wear rate was found to be minimum at an austempering temperature of 280°C, that exhibits lower bainite microstructure with high hardness, on the other hand specific wear rate was found to be slightly high at increased austempering temperatures at 360°C and 400°C, due to the upper bainite structure that offered lower hardness to the matrix. The sample austempered at 280°C for 30 minutes offered superior wear resistance when compared to other austempering conditions, mainly due to the presence of fine acicular bainitic ferrite along with stabilized retained austenite and also some martensite in the microstructure.

  2. OBSERVATION OF FATIGUE CRACK PATHS IN NODULAR CAST IRON AND ADI MICROSTRUCTURES

    Directory of Open Access Journals (Sweden)

    Lukáš Bubenko

    2009-07-01

    Full Text Available When speaking about quality of construction materials, fatigue crack propagation resistance is one of the most important considered properties. That is essentially influenced by character of matrix. Here presented contribution deals with the fatigue crack propagation mode through the matrix of as-cast nodular cast iron (NCI and austempered ductile iron (ADI, whereas influence of microstructure has been considered and discussed. Experimental materials used in presented contribution were pearlitc-ferritic NCI and heat treated ADI 800. Pearlitic-ferritic NCI was used as the base for ADI production. Experiments were performed on mini round compact tension (RCT specimens using an Amsler vibrophore. Fatigue crack paths in both materials were investigated and compared. Light microscopy was used to analyze the microstructure, crack initiation and propagation within broken specimens. In both tested materials fatigue cracks always initiated at graphite-matrix interface, while graphite nodules remained generally unbroken, eventually only surface of nodules was damaged. Though, comparing two materials with different microstructures, the diversity of fatigue crack propagation modes at high deltaK and low deltaK was observed.

  3. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  4. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  5. Effect of Nanoadditives on the Wear Behavior of Spheroidal Graphite Cast Irons

    Directory of Open Access Journals (Sweden)

    J. Kaleicheva

    2017-09-01

    Full Text Available The tribological characteristics of spheroidal graphite cast irons with and without nanosized additives are investigated. The tests are performed as in cast iron condition as well after austempering. The spheroidal graphite irons are undergone to austempering in the bainite field, including heating at 900 °С for an hour, after that isothermal retention at 280 °С, 2 h and at 380 °C, 2 h. The lower bainitic and upper bainitic structures are formed during the process. Nanosized additives of titanium carbonitride and titanium nitride TiCN+TiN influence on the graphite phase characteristics and on the microstructure of the cast and austempered spheroidal graphite irons. The changes in the micro structure the irons with nanoadditives lead to an abrasive wear resistance increase. The formation of the strain induced martensite from the retained austenite in the friction contact area during wear is determined in the austempered irons. This is the reason for the wear resistance increase of the irons. The experimental testing of the wear is carried out by cinematic scheme tapper-discunder friction on the fixed abrasive. The microstructure of the patterns is observed by optical and quantitative metallography, X-Ray analysis, SEM and EDX analysis. The hardness testing is performed by Brinnel and Vickers methods.

  6. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  7. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present...... and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...

  8. Influence of treatments using different magnesium ferroalloys on the melt quality and the solidification processes of ductile irons; Influencia de los tratamientos realizados con diferentes ferroaleaciones de magnesio en la evolucion de la calidad metalurgica y los procesos de solidificacion de las funciones esferoidales

    Energy Technology Data Exchange (ETDEWEB)

    Loizaga, A.; Sertucha, J.; Suarez, R.

    2008-07-01

    In this work the metallurgical consequences of treatments applied on ductile irons using ferroalloys with different magnesium contents are analysed. The solidification processes have an important influence on the mechanical properties and the functionality of the iron castings along their service period. Consequently, the comparison of the characterstics of the cooling curves recorded from the melt and the active oxygen and sulphur contents have been used for quantifying the effects of treatments performed utilizing different types of commercial FeSiMg. The addition of magnesium into the melt strongly removes sulphur and oxygen contents and important degradations of the metallurgical quality are finally obtained as a consequence of them. On the other hand, the composition of the resulting slags and the evolution of the melt characteristics as a function of the remaining time into the pouring device is investigated. The magnesium content in ferroalloys becomes a critical parameters in the evolution of the melt quality of treated irons. (Author) 18 refs.

  9. strength and ductility of forged 1200 aluminum alloy reinforced

    African Journals Online (AJOL)

    eobe

    Keywords: Aluminum alloy; annealing; ductility; strength; iron particle. 1. INTRODUCTION. INTRODUCTION. Structural components made from aluminum alloys are vital to the aerospace, automobile and building industries because of their light weight, high strength, good formability and high corrosion resistance. However ...

  10. Carbidic Bainitic and Ausferritic Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    Gumienny G.

    2013-12-01

    Full Text Available W arty kule przedstawiono nowe rodzaje żeliwa sferoidalnego z węglikami o różnej mikrostrukturze osnowy metalowej. Żeliwo to otrzymano stosując sferoidyzację metodą Inmold. zapewniającą dużą liczbę kulek grafitu i rozdrobnienie składników osnowy metalowej. Różną mikrostrukturę osnowy metalowej żeliwa otrzymywano bez stosowania obróbki cieplnej (w stanie surowym poprzez odpowiednią kombinację ilościową dodatków stopowych. Wykazano, że dodatek molibdenu, chromu, niklu i miedzi w żeliwie sferoidalnym pozwala uzyskać osnowę metalową złożoną z bainitu górnego, jego mieszaniny z dolnym lub ausferrytu w odlewach o grubości ściany 3^-25 mm. Proces krystalizacji żeliwa przedstawiono i opisano za pomocą krzywych analizy termicznej i derywacyjnej (ATD. Pokazano efekty cieplne od przemiany austenitu w stanie stałym

  11. Fracture toughness improvement of austempered high silicon steel by titanium, vanadium and rare earth elements modification

    International Nuclear Information System (INIS)

    Chen Xiang; Li Yanxiang

    2007-01-01

    The microstructure of austempered high silicon (AHS) steel before and after treating with a modifier containing titanium, vanadium and rare earth elements (so-called Ti-V-RE modifier) and austempered at different temperatures has been investigated. The plane strain fracture toughness of the steel in room temperature and ambient atmosphere has been examined. The microstructure was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and optical metallography and correlated to the fracture toughness of the steel. The results show that the primary austenite grains are refined, the dendritic austempered structure is eliminated, and the volume of blocky shaped retained austenite is reduced by the addition of Ti-V-RE modifier. Modification with Ti-V-RE modifier can prompt the bainitic ferrite transformation and reduce the volume fraction of retained austenite. High fracture toughness is obtained for AHS steel with the addition of Ti-V-RE modifier when austempered between 350 and 385 deg. C with a retained austenite of 30-35% and the carbon content in the austenite is about 1.9-2%. The fracture toughness of AHS steel by the modification treatment can increase 10-40% than that of unmodified, an optimum value of 85 MPa m 1/2 was obtained when austempered at 385 deg. C

  12. Fracture toughness improvement of austempered high silicon steel by titanium, vanadium and rare earth elements modification

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xiang [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Li Yanxiang [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)]. E-mail: yanxiang@tsinghua.edu.cn

    2007-01-25

    The microstructure of austempered high silicon (AHS) steel before and after treating with a modifier containing titanium, vanadium and rare earth elements (so-called Ti-V-RE modifier) and austempered at different temperatures has been investigated. The plane strain fracture toughness of the steel in room temperature and ambient atmosphere has been examined. The microstructure was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and optical metallography and correlated to the fracture toughness of the steel. The results show that the primary austenite grains are refined, the dendritic austempered structure is eliminated, and the volume of blocky shaped retained austenite is reduced by the addition of Ti-V-RE modifier. Modification with Ti-V-RE modifier can prompt the bainitic ferrite transformation and reduce the volume fraction of retained austenite. High fracture toughness is obtained for AHS steel with the addition of Ti-V-RE modifier when austempered between 350 and 385 deg. C with a retained austenite of 30-35% and the carbon content in the austenite is about 1.9-2%. The fracture toughness of AHS steel by the modification treatment can increase 10-40% than that of unmodified, an optimum value of 85 MPa m{sup 1/2} was obtained when austempered at 385 deg. C.

  13. Ductile failure modeling

    DEFF Research Database (Denmark)

    Benzerga, Ahmed Amine; Leblond, Jean Baptiste; Needleman, Alan

    2016-01-01

    Ductile fracture of structural metals occurs mainly by the nucleation, growth and coalescence of voids. Here an overview of continuum models for this type of failure is given. The most widely used current framework is described and its limitations discussed. Much work has focused on extending void...... growth models to account for non-spherical initial void shapes and for shape changes during growth. This includes cases of very low stress triaxiality, where the voids can close up to micro-cracks during the failure process. The void growth models have also been extended to consider the effect of plastic...... anisotropy, or the influence of nonlocal effects that bring a material size scale into the models. Often the voids are not present in the material from the beginning, and realistic nucleation models are important. The final failure process by coalescence of neighboring voids is an issue that has been given...

  14. 46 CFR 56.60-10 - Cast iron and malleable iron.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Cast iron and malleable iron. 56.60-10 Section 56.60-10... APPURTENANCES Materials § 56.60-10 Cast iron and malleable iron. (a) The low ductility of cast iron and malleable iron should be recognized and the use of these metals where shock loading may occur should be...

  15. Iron

    Science.gov (United States)

    ... Share: Search the ODS website Submit Search NIH Office of Dietary Supplements Consumer Datos en español Health ... eating a variety of foods, including the following: Lean meat, seafood, and poultry. Iron-fortified breakfast cereals ...

  16. Development competence of an iron/steel foundry in the field of tension between material selection and production technology for engine components; Entwicklungskompetenz einer Eisen-/Stahlgiesserei im Spannungsfeld von Werkstoffauswahl und Fertigungstechnologie fuer Motorenbauteile

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R. [Eisenwerk Bruehl GmbH, Bruehl (Germany)

    2007-07-01

    If we had to summarize all aspects of the combustion engine subject, engine development is - from the viewpoint of an iron and steel foundry specialist - mainly controlled by environmental protection (CO{sub 2}) and saving energy (raw material shortage). We will always consider today's development targets, which are based on fuel reduction and power increase. To focus on development today means to focus on emission sources, on exhaust treatment and on a medium term change to alternative driving systems. Implementing these targets will always be in the focus and solutions will have to be found in the automotive industry on a continuous basis. Some of the initial phases are directly linked to the foundry and their production technology and casting material. Being foundry specialists we have to adjust our efforts for new strategies to these requirements. ERW group together with Eisenwerk Bruehl GmbH and Eisenwerk Hasenclever are going to show their methodology with the help of three examples for developing material- / production technology in CGI with vermicular-type graphite, ADI - austempered ductile iron and cast steel. (orig.)

  17. Vermicular graphite cast iron current state of the art

    OpenAIRE

    Murthy, VSR; Seshan, S; Seshan, K

    1985-01-01

    Vermicular graphite cast iron is a new addition to the family of cast irons. Various methods for producing vermicular graphite cast iron are briefly discussed in this paper. The mechanical and physical properties of cast irons with vermicular graphite have been found to be intermediate between those of gray and ductile irons. Other properties such as casting characteristics, scaling resistance, damping capacity and machinability have been compared with those of gray and ductile irons. Probabl...

  18. Structural durability criteria for commercial vehicle components from the self strengthening cast ausferrite nodular iron EN-GJS-800-8 (ADI) in comparison to the ferritic EN-GJS-400-15

    Energy Technology Data Exchange (ETDEWEB)

    Zinke, R.; Heinrietz, A.; Heim, R.; Hanselka, H. [Fraunhofer Institut fuer Betriebsfestigkeit LBF, Darmstadt (Germany); Streicher, M. [MAN Nutzfahrzeuge AG, Munich (Germany); Sonsino, C.M.

    2008-10-15

    The structural durability of safety components in the chassis comprises not only the fatigue behaviour under cyclic variable amplitude service loading, but also its interaction with prestrains caused by special events and the rupture behaviour under impact loading due to misuse. From this background, the structural durability behaviour of Panhard rods made from ferritic cast nodular iron EN-GJS-400-15 was compared with the behaviour of rods made from the austempered EN-GJS-800-8. The components investigated, Panhard rods and cast plugs, made from the austempered material revealed a higher impact resistance than the components made from the ferritic cast nodular iron. Due to their ausferrite microstructure, Panhard rods made from EN-GJS-800-8 display a significantly superior fatigue strength behaviour, especially under spectrum loading, and offer a potential for lightweight design. Prestrains do not affect the fatigue behaviour under variable amplitude loading and the plastic deformation of the component under impact loading can be increased by appropriate design reducing the stiffness in the shaft area and achieving a weight reduction by 15 %. (Abstract Copyright [2008], Wiley Periodicals, Inc.) [German] Die Betriebsfestigkeit von Fahrwerksbauteilen wird nicht nur von der Schwingfestigkeit unter zyklischen Betriebsbelastungen und Missbrauchsbelastungen bestimmt, sondern auch durch die Interaktion mit Sonderbelastungen und Missbrauchsbelastungen. Vor diesem Hintergrund wird anhand eines Panhard-Stabes, ein stabilisierendes Element im Fahrwerk von Nutzfahrzeugen, gezeigt, wie zunaechst durch eine Werkstoffsubstitution, naemlich des konventionellen Eisengraphitgusses EN-GJS-400-15 (GGG 40), durch die ADI (Ausferrite Ductile Iron)-Variante EN-GJS-800-8 mit der entsprechenden Waermebehandlung eine deutlich hoehere Schwingfestigkeit erzielt wird. Zu bemerken ist, dass der ADI-Guss gefuegebedingt gegenueber dem konventionellen ferritischen Werkstoff unter variablen

  19. Soldering with ductile active solders

    Czech Academy of Sciences Publication Activity Database

    Dupák, Jan; Ustohal, V.

    2001-01-01

    Roč. 16, č. 6 (2001), s. 855 - 861 ISSN 1042-6914 Institutional research plan: CEZ:AV0Z2065902 Keywords : active solders * ductile solders * cryogenics devices Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.288, year: 2001

  20. Improving the low temperature ductility of NiAl

    Science.gov (United States)

    Guha, Sumit; Munroe, Paul R.; Baker, Ian

    1989-01-01

    As part of a study aimed at developing a ductile NiAl-based alloy, ingots of Ni-Fe-Al alloys were cast and hot extruded to rods. The purpose of the iron additions was two-fold viz; to produce a change in the slip vector from 001 to 111 line and, in one alloy, to add a L1(2)-structured ductile second phase. Extruded Ni-20Al-30Fe was two-phase, containing a pro-eutectic B2 phase in a fine lamellar structure of B2+L1(2) phases. Room temperature tensile testing of both single extruded and double extruded alloys resulted in 8-percent and 22-percent plastic elongation and yield stresses of 850 and 760 MPa, respectively. Fracture in both cases occurred by ductile tearing of the eutectic and transgranular cleavage of the proeutectic phase at 1350 MPa. The ductility in double extruded condition is higher than that reported earlier in rapidly solidified wires by Inoue et al. (1984). By comparison, extruded single-phase B2-structured Ni-30Al-20Fe exhibited a fracture strength of 780 MPa, no plasticity, and a mixture of intergranular fracture and transgranular cleavage. This is contrast to earlier work by Inoue et al. where a yield stress of 400 MPa, 5 percent plastic strain, and a mixture of dimple and intergranular fracture was reported.

  1. In-situ SEM observation on fracture behavior of austempered silicon alloyed steel

    OpenAIRE

    Chen, Xiang; Vuorinen, Esa; Grahn, Johnny

    2009-01-01

    Crack initiation, propagation and microfracture processes of austempered high silicon cast steel have been investigated by using an in-situ tensile stage installed inside a scanning electron microscope chamber. It is revealed that micro cracks always nucleate at the yielding near imperfections and the boundary of matrix-inclusions due to the stress concentration. There are four types of crack propagations in the matrix: crack propagates along the boundary of two clusters of bainitic ferrite; ...

  2. Effect of Austempering and Martempering on the Properties of AISI 52100 Steel

    OpenAIRE

    Krishna, P. Vamsi; Srikant, R. R.; Iqbal, Mustafa; Sriram, N.

    2013-01-01

    The mechanical properties of steel decide its applicability for a particular condition. Heat treatment processes are commonly used to enhance the required properties of steel. The present work aims at experimentally investigating the effect of austempering and martempering on AISI 52100 steel. Different tests like microstructure analysis, hardness test, impact test, and wear test are carried out after heat treatment process. It was found that annealed steel was least hard and more wear prone,...

  3. Microstructures and Mechanical Properties of Austempering SUS440 Steel Thin Plates

    Directory of Open Access Journals (Sweden)

    Cheng-Yi Chen

    2016-02-01

    Full Text Available SUS440 is a high-carbon stainless steel, and its martensite matrix has high heat resistance, high corrosion resistance, and high pressure resistance. It has been widely used in mechanical parts and critical materials. However, the SUS440 martempered matrix has reliability problems in thin plate applications and thus research uses different austempering heat treatments (tempering temperature: 200 °C–400 °C to obtain a matrix containing bainite, retained austenite, martensite, and the M7C3 phase to investigate the relationships between the resulting microstructure and tensile mechanical properties. Experimental data showed that the austempering conditions of the specimen affected the volume fraction of phases and distribution of carbides. After austenitizing heat treatment (1080 °C for 30 min, the austempering of the SUS440 thin plates was carried out at a salt-bath temperature 300 °C for 120 min and water quenching was then used to obtain the bainite matrix with fine carbides, with the resulting material having a higher tensile fracture strength and average hardness (HRA 76 makes it suitable for use as a high-strength thin plate for industrial applications.

  4. Micromechanics modelling of ductile fracture

    CERN Document Server

    Chen, Zengtao

    2013-01-01

    This book summarizes research advances in micromechanics modelling of ductile fractures made in the past two decades. The ultimate goal of this book is to reach manufacturing frontline designers and materials engineers by providing a user-oriented, theoretical background of micromechanics modeling. Accordingly, the book is organized in a unique way and presents a vigorous damage percolation model developed by the authors over the last ten years. This model overcomes almost all difficulties of the existing models and can be used to completely accommodate ductile damage development within a single, measured microstructure frame. Related void damage criteria including nucleation, growth and coalescence are then discussed in detail: how they are improved, when and where they are used in the model, and how the model performs in comparison with the existing models. Sample forming simulations are provided to illustrate the model’s performance.

  5. The role of graphite morphology and matrix structure on low ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The effect of thermal cycling on Young's modulus is shown in figures 4a and b and 5a and b. There is hardly any change in the value of Young's modulus with the number of thermal. Figure 5. Variation of modulus of elasticity with number of thermal cycles (Buni 1994). ADI – austempered ductile iron; DI – spheroidal ductile ...

  6. The role of graphite morphology and matrix structure on low ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Thermal cycling resistance; graphite morphology; grey cast iron; austempered ductile iron; compacted/vermicular graphite iron; matrix decompo- sition. 1. Introduction. When a material is subjected to a temperature gradient, it tends to expand differentially. During this process, thermal stresses are induced. The source of ...

  7. Ductile failure X-prize.

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Wellman, Gerald William; Emery, John M.; Ostien, Jakob T.; Foster, John T.; Cordova, Theresa Elena; Crenshaw, Thomas B.; Mota, Alejandro; Bishop, Joseph E.; Silling, Stewart Andrew; Littlewood, David John; Foulk, James W., III; Dowding, Kevin J.; Dion, Kristin; Boyce, Brad Lee; Robbins, Joshua H.; Spencer, Benjamin Whiting

    2011-09-01

    Fracture or tearing of ductile metals is a pervasive engineering concern, yet accurate prediction of the critical conditions of fracture remains elusive. Sandia National Laboratories has been developing and implementing several new modeling methodologies to address problems in fracture, including both new physical models and new numerical schemes. The present study provides a double-blind quantitative assessment of several computational capabilities including tearing parameters embedded in a conventional finite element code, localization elements, extended finite elements (XFEM), and peridynamics. For this assessment, each of four teams reported blind predictions for three challenge problems spanning crack initiation and crack propagation. After predictions had been reported, the predictions were compared to experimentally observed behavior. The metal alloys for these three problems were aluminum alloy 2024-T3 and precipitation hardened stainless steel PH13-8Mo H950. The predictive accuracies of the various methods are demonstrated, and the potential sources of error are discussed.

  8. Transformation plasticity in ductile solids

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.B.

    1993-02-01

    Research has addressed the role of martensitic transformation plasticity in the enhancement of toughness in high-strength austenitic steels, and the enhancement of formability in multiphase low-alloy sheet steels. In the austenitic steels, optimal processing conditions have been established to achieve a significant increase in strength level, in order to investigate the interaction of strain-induced transformation with the microvoid nucleation and shear localization mechanisms operating at ultrahigh strength levels. The stress-state dependence of transformation and fracture mechanisms has been investigated in model alloys, comparing behavior in uniaxial tension and blunt-notch tension specimens. A numerical constitutive model for transformation plasticity has been reformulated to allow a more thorough analysis of transformation/fracture interactions. Processing of a new low alloy steel composition has been optimized to stabilize retained austenite by isothermal bainitic transformation after intercritical annealing. Preliminary results show a good correlation of uniform ductility with the austenite amount and stability.

  9. Computer simulation of ductile fracture

    International Nuclear Information System (INIS)

    Wilkins, M.L.; Streit, R.D.

    1979-01-01

    Finite difference computer simulation programs are capable of very accurate solutions to problems in plasticity with large deformations and rotation. This opens the possibility of developing models of ductile fracture by correlating experiments with equivalent computer simulations. Selected experiments were done to emphasize different aspects of the model. A difficult problem is the establishment of a fracture-size effect. This paper is a study of the strain field around notched tensile specimens of aluminum 6061-T651. A series of geometrically scaled specimens are tested to fracture. The scaled experiments are conducted for different notch radius-to-diameter ratios. The strains at fracture are determined from computer simulations. An estimate is made of the fracture-size effect

  10. Hot ductility behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

    Lopez-Chipres, E.; Mejia, I.; Maldonado, C.; Bedolla-Jacuinde, A.; Cabrera, J.M.

    2007-01-01

    The current study analyses the influence of boron contents (between 29 and 105 ppm) on the hot ductility of boron microalloyed steels. For this purpose, hot tensile tests were carried out at different temperatures (700, 800, 900 and 1000 deg. C) at a constant true strain rate of 0.001 s -1 . In general, results revealed an improvement of the hot ductility of steels at increasing boron content. At 700, 900 and 1000 deg. C the ductility is higher than at 800 deg. C, where boron microalloyed steels exhibit a region of ductility loss (trough region). Likewise, dynamic recrystallization only occurred at 900 and 1000 deg. C. The fracture surfaces of the tested steels at temperatures giving the high temperature ductility regime show that the fracture mode is a result of ductile failure, whereas it is ductile-brittle failure in the trough region. Results are discussed in terms of dynamic recrystallization and boron segregation towards austenite grain boundaries, which may retard the formation of pro-eutectoid ferrite and increase grain boundary cohesion

  11. Ductility of Ultra High Purity Copper

    OpenAIRE

    Fujiwara, S.; Abiko, K.

    1995-01-01

    The ductility of ultra-high purity copper at elevated temperatures was investigated : purity 99.9999% (6N) and 99.999999% (8N). Tensile tests were conducted at temperatures ranging from 293K to 1073K at strain rates of 4.2x10-5 s-1 in a high vacuum. The results are discussed in comparison with those for 99.9% (3N) copper. Ductility at intermediate temperatures was improved by an increase in purity. The temperature at which ductility dropped decreased with increases in purity. Even at the ultr...

  12. EXPERIMENTAL INVESTIGATION OF EFFECTS OF CHEMICAL VARIABLES ON IRON CASTING

    OpenAIRE

    Pradeep Kumar*, Dr Lokendra Pal Singh and Romiyo Mclin Jojowar

    2017-01-01

    Cast iron is an alloy of iron containing more than 2% carbon as an alloying element. It has almost no ductility and must be formed by casting. Ductile iron structure is developed from the melt of cast iron. The presence of silicon in higher amount promotes the graphitization, inhibiting carbon to form carbides with carbide forming elements present. The carbon forms into spheres when Ce & Mg are added to the melt of iron with very low sulphur content. Due to this special microstructure contain...

  13. Author Details - African Journals Online

    African Journals Online (AJOL)

    Surendranathan, A. O.. Vol 8, No 3 (2016) - Articles Corrosion behavior of austempered ductile iron (ADI) in iron ore slurry. Abstract PDF. ISSN: 2141-2839. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of ...

  14. Isothermal treatment of SAE92XX type high silicon steels

    International Nuclear Information System (INIS)

    Paez, J.L.; Fuentes, F.; Battegliese, A.

    1996-01-01

    SAE 9260 type steels have silicon and carbon contents similar to thoseof the ductile iron matrix, and present a bainitic transformation with the same characteristics as ADI (Austempered Ductile Iron). The hypothesis is that excellent mechanical properties can be obtained by means of austempering (in times so short as to be accessible from the industrial point of view), the same as in ADI and even better because it is a rolling material instead of a cast materials. It will be compared with the mechanical properties obtained by quenching and tempering at different temperatures. (Author) 8 refs

  15. In-situ SEM observation on fracture behavior of austempered silicon alloyed steel

    Directory of Open Access Journals (Sweden)

    Chen Xiang

    2009-08-01

    Full Text Available Crack initiation, propagation and microfracture processes of austempered high silicon cast steel have been investigated by using an in-situ tensile stage installed inside a scanning electron microscope chamber. It is revealed that micro cracks always nucleate at the yielding near imperfections and the boundary of matrix-inclusions due to the stress concentration. There are four types of crack propagations in the matrix: crack propagates along the boundary of two clusters of bainitic ferrite; crack propagates along the boundary of ferrite朼ustenite in bainitic ferrite laths; crack propagates into bainitic ferrite laths; crack nucleates and propagates in the high carbon brittle plate shape martensite which is transformed from some blocky retained austenite due to plastic deformation. Based on the observation and analysis of microfracture processes, a schematic diagram of the crack nucleation and propagation process of high silicon cast steel is proposed

  16. Undercooling and nodule count in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thick¬nesses from 2 to 8 mm involving both temperature measurements during solidification and micro¬structural examination afterwards. The nodule count was the same for the eutectic and hypereutectic...... castings in the thin plates ( 4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature prior to the eutectic recalescence (Tmin) was 15 to 20C lower for the eutectic than the hypereutectic castings. This is due to nucleation...... of graphite nodules which begins at a lover temperature in the eutectic than in the hypereutectic castings The recalescence (Trec) was however also larger for the eutectic casting and in the thin plates the maximum temperature after recalescence (Tmax) was the same in the eutectic and hypereutectic plates...

  17. Undercooling and nodule count in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thicknesses from 2 to 8 mm involving both temperature measurements during solidification and microstructural examination afterwards. The nodule count was the same for the eutectic and hypereutectic castings...... in the thin plates (≤4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature before the eutectic recalescence (Tmin) was 15 to 20ºC lower for the eutectic than for the hypereutectic castings. This is due to nucleation of graphite...... nodules which begins at a lower temperature in the eutectic than in the hypereutectic castings. The recalescence ∆Trec was however also larger for the eutectic casting and in the thin plates the maximum temperature after recalescence (Tmax) was the same in the eutectic and hypereutectic plates...

  18. Ductilization of Cr via oxide dispersions

    International Nuclear Information System (INIS)

    Brady, M.P.; Wright, I.G.; Anderson, I.M.; Sikka, V.K.; Ohriner, E.K.; Walls, C.; Westmoreland, G.; Weaver, M.L.

    2001-01-01

    Work by Scruggs et al. in the 1960's demonstrated that up to 20 % tensile ductility could be achieved at room-temperature in sintered and extruded powder metallurgical Cr alloyed with MgO. During sintering, much of the MgO converts to a MgCr 2 O 4 spinel, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. Recent efforts at Oak Ridge National Laboratory (ORNL) have succeeded in duplicating this original effect. Preliminary results suggest that the ductilization mechanism may be more complicated than the simple nitrogen gettering mechanism proposed by Scruggs, as some ductility was observed at room-temperature in Cr-MgO alloys containing nitride precipitates. Results of microstructural characterization and room-temperature mechanical property studies are presented for Cr-6MgO-(0-2.2) Ti wt.% as a function of hot-pressing and extrusion. Possible mechanisms by which the MgO additions may improve the room-temperature ductility of Cr are discussed. (author)

  19. Colour Metallography of Cast Iron - Chapter 2: Grey Iron (Ⅲ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2009-11-01

    Full Text Available The book, Colour Metallography of Cast Iron , uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos. This book consists of five sections: Chapter 1 Introduction, Chapter 2 Grey Iron, Chapter 3 Ductile Iron, Chapter 4 Vermicular Cast Iron, and Chapter 5 White Cast Iron. CHINA FOUNDRY publishs this book in several parts serially,starting from the first issue of 2009.

  20. Tensile properties of ADI material in water and gaseous environments

    Energy Technology Data Exchange (ETDEWEB)

    Rajnovic, Dragan, E-mail: draganr@uns.ac.rs [Faculty of Technical Sciences, University of Novi Sad, Trg D. Obradovića 6, 21000 Novi Sad (Serbia); Balos, Sebastian; Sidjanin, Leposava [Faculty of Technical Sciences, University of Novi Sad, Trg D. Obradovića 6, 21000 Novi Sad (Serbia); Eric Cekic, Olivera [Innovation Centre, Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade (Serbia); Grbovic Novakovic, Jasmina [Vinca Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia)

    2015-03-15

    Austempered ductile iron (ADI) is an advanced type of heat treated ductile iron, having comparable mechanical properties as forged steels. However, it was found that in contact with water the mechanical properties of austempered ductile irons decrease, especially their ductility. Despite considerable scientific attention, the cause of this phenomenon remains unclear. Some authors suggested that hydrogen or small atom chemisorption causes the weakening of the surface atomic bonds. To get additional reliable data of that phenomenon, in this paper, two different types of austempered ductile irons were tensile tested in various environments, such as: argon, helium, hydrogen gas and water. It was found that only the hydrogen gas and water gave a statistically significant decrease in mechanical properties, i.e. cause embrittlement. Furthermore, the fracture surface analysis revealed that the morphology of the embrittled zone near the specimen surface shares similarities to the fatigue micro-containing striation-like lines, which indicates that the morphology of the brittle zone may be caused by cyclic local-chemisorption, micro-embrittlement and local-fracture. - Highlights: • In contact with water and other liquids the ADI suddenly exhibits embrittlement. • The embrittlement is more pronounced in water than in the gaseous hydrogen. • The hydrogen chemisorption into ADI surface causes the formation of a brittle zone. • The ADI austempered at lower temperatures (300 °C) is more resistant to embrittlement.

  1. Fatigue behavior of ADI: Some specific features

    Energy Technology Data Exchange (ETDEWEB)

    Svejcar, J.; Vechet, S.; Pokluda, J. [Technical Univ. of Brno (Czech Republic). Faculty of Mechanical Engineering

    1997-12-31

    The paper summarizes the results of fatigue tests on austempered ductile iron. Attention is mainly focused on the effect of graphite on crack propagation and on some irregularities exhibited by ADI and other ductile irons, e.g., some specific features of fatigue fracture (especially the occurrence of fatigue striations on intergranular facets), decrease of fatigue limit with increasing UTS, and anomalous dependence of loading cycle amplitude on mean cycle stress.

  2. Calculation Method of Lateral Strengths and Ductility Factors of Constructions with Shear Walls of Different Ductility

    Science.gov (United States)

    Yamaguchi, Nobuyoshi; Nakao, Masato; Murakami, Masahide; Miyazawa, Kenji

    2008-07-01

    For seismic design, ductility-related force modification factors are named R factor in Uniform Building Code of U.S, q factor in Euro Code 8 and Ds (inverse of R) factor in Japanese Building Code. These ductility-related force modification factors for each type of shear elements are appeared in those codes. Some constructions use various types of shear walls that have different ductility, especially for their retrofit or re-strengthening. In these cases, engineers puzzle the decision of force modification factors of the constructions. Solving this problem, new method to calculate lateral strengths of stories for simple shear wall systems is proposed and named `Stiffness—Potential Energy Addition Method' in this paper. This method uses two design lateral strengths for each type of shear walls in damage limit state and safety limit state. Two lateral strengths of stories in both limit states are calculated from these two design lateral strengths for each type of shear walls in both limit states. Calculated strengths have the same quality as values obtained by strength addition method using many steps of load-deformation data of shear walls. The new method to calculate ductility factors is also proposed in this paper. This method is based on the new method to calculate lateral strengths of stories. This method can solve the problem to obtain ductility factors of stories with shear walls of different ductility.

  3. Tratamiento isotérmico de los aceros aleados al silicio Tipo SAE 92XX

    Directory of Open Access Journals (Sweden)

    Páez, J. L.

    1996-02-01

    Full Text Available SAE 9260 type steels have silicon and carbon contents similar to those of the ductile iron matrix, and present a bainitic transformation with the same characteristics as ADI (Austempered Ductile Iron. The hypothesis is that excellent mechanical properties can be obtained by means of austempering (in times so short as to be accessible from the industrial point of view, the same as in ADI and even better because it is a rolling material instead of a cast material. It will be compared with the mechanical properties obtained by quenching and tempering at different temperatures.

    La composición química de los aceros SAE 92XX es similar a la de la matriz metálica de una fundición esferoidal, por lo que se pensó en someter a un acero de ese tipo a tratamientos de austempering similares a los que se aplican para lograr una ADI (Austempered Ductile Iron, y verificar si se alcanzaban valores aceptables de plasticidad con elevados valores de resistencia a la tracción para el mismo acero, tal y como sucede con aquellas fundiciones, y comparar dichos resultados con los obtenidos en el mismo acero con tratamientos convencionales de temple y revenido. Se alcanzaron valores que demostraron que, por austempering, se logran excelentes valores de plasticidad, muy superiores a los alcanzados por temple y revenido para durezas del mismo orden.

  4. Analyses of cavitation instabilities in ductile metals

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2007-01-01

    , and also tests for a thin ductile metal layer bonding two ceramic blocks have indicated rapid void growth. Analyses for these material configurations are discussed here. When the void radius is very small, a nonlocal plasticity model is needed to account for observed size-effects, and recent analyses......Cavitation instabilities have been predicted for a single void in a ductile metal stressed under high triaxiality conditions. In experiments for a ceramic reinforced by metal particles a single dominant void has been observed on the fracture surface of some of the metal particles bridging a crack...... for the influence of such size-effects on cavitation instabilities are presented. When a metal contains a distribution of micro voids, and the void spacing compared to void size is not extremely large, the surrounding voids may affect the occurrence of a cavitation instability at one of the voids. This has been...

  5. A review of macroscopic ductile failure criteria.

    Energy Technology Data Exchange (ETDEWEB)

    Corona, Edmundo; Reedlunn, Benjamin

    2013-09-01

    The objective of this work was to describe several of the ductile failure criteria com- monly used to solve practical problems. The following failure models were considered: equivalent plastic strain, equivalent plastic strain in tension, maximum shear, Mohr- Coulomb, Wellman's tearing parameter, Johnson-Cook and BCJ MEM. The document presents the main characteristics of each failure model as well as sample failure predic- tions for simple proportional loading stress histories in three dimensions and in plane stress. Plasticity calculations prior to failure were conducted with a simple, linear hardening, J2 plasticity model. The resulting failure envelopes were plotted in prin- cipal stress space and plastic strain space, where the dependence on stress triaxiality and Lode angle are clearly visible. This information may help analysts select a ductile fracture model for a practical problem and help interpret analysis results.

  6. Author Details

    African Journals Online (AJOL)

    Afonja, AA. Vol 14, No 2 (2005) - Articles The effects of isothermal transformation on the fatigue strength of austempered ductile iron. Abstract. ISSN: 1019-1593. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

  7. Fatigue Lifetime of ADI from Ultimate Tensile Strength to Permanent Fatigue Limit

    Czech Academy of Sciences Publication Activity Database

    Zapletal, J.; Věchet, S.; Kohout, J.; Obrtlík, Karel

    -, č. 1 (2008), s. 40-43 ISSN 0556-171X. [MSMF /5./. Brno, 27.06.2007-29.06.2007] R&D Projects: GA ČR GA106/03/1265 Institutional research plan: CEZ:AV0Z20410507 Keywords : austempered ductile iron * fatigue behaviour * S N curve Subject RIV: JL - Materials Fatigue, Friction Mechanics

  8. The comparison of cyclic deformation curve determination for ADI

    Czech Academy of Sciences Publication Activity Database

    Zapletal, J.; Obrtlík, Karel; Věchet, S.

    308 2005, - (2005), s. 305-309 ISSN 1429-6055. [Miedzynarodowe sympozjum /20./. Ustroň-Jaszowiec, 07.12.2005-09.12.2005] R&D Projects: GA ČR(CZ) GA106/03/1265 Institutional research plan: CEZ:AV0Z20410507 Keywords : cyclic stress-strain curve * austempered ductile iron Subject RIV: JG - Metallurgy

  9. S¯adhan¯a Vol. 29, 2004 Subject Index

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Effects of processing on nutritional composi- tion and quality evaluation of candied celeriac. 1. Attitude control. Precision pointing of imaging spacecraft using gyro-based attitude reference with horizon sensor updates. 189. Austempered ductile iron. The role of graphite morphology and matrix structure on low frequency ...

  10. Effect of Austempering Time on the Microstructure and Carbon Partitioning of Ultrahigh Strength Steel 56NiCrMoV7

    Directory of Open Access Journals (Sweden)

    Quanshun Luo

    2017-07-01

    Full Text Available Ultrahigh strength steel 56NiCrMoV7 was austempered at 270 °C for different durations in order to investigate the microstructure evolution, carbon partitioning behaviour and hardness property. Detailed microstructure has been characterised using optical microscopy and field emission gun scanning electron microscopy. A newly developed X-ray diffraction method has been employed to dissolve the bainitic/martensitic ferrite phase as two sub-phases of different tetragonal ratios, which provides quantitative analyses of the carbon partitioning between the resultant ferrites and the retained austenite. The results show that, a short-term austempering treatment was in the incubation period of the bainite transformation, which resulted in maximum hardness being equivalent to the oil-quenching treatment. The associated microstructure comprises fine carbide-free martensitic and bainitic ferrites of supersaturated carbon contents as well as carbon-rich retained austenite. In particular, the short-term austempering treatment helped prevent the formation of lengthy martensitic laths as those being found in the microstructure of oil-quenched sample. When the austempering time was increased from 20 to 80 min, progressive decrease of the hardness was associated with the evolution of the microstructure, including progressive coarsening of bainitic ferrite, carbide precipitating inside high-carbon bainitic ferrite and its subsequent decarbonisation.

  11. Ductile alloys for sealing modular component interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Marra, John J.; Wessell, Brian J.; James, Allister W.; Marsh, Jan H.; Gear, Paul J.

    2017-08-08

    A vane assembly (10) having: an airfoil (12) and a shroud (14) held together without metallurgical bonding there between; a channel (22) disposed circumferentially about the airfoil (12), between the airfoil (12) and the shroud (14); and a seal (20) disposed in the channel (22), wherein during operation of a turbine engine having the vane assembly (10) the seal (20) has a sufficient ductility such that a force generated on the seal (20) resulting from relative movement of the airfoil (12) and the shroud (14) is sufficient to plastically deform the seal (20).

  12. System Reliability of Timber Structures with Ductile Behaviour

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Čizmar, Dean

    2011-01-01

    . An evaluation method of the ductile behaviour is introduced. For different ductile behaviours, the system reliability is estimated based on Monte Carlo simulation. A correlation between the strength of the structural elements is introduced. The results indicate that the reliability of a structural timber system......The present paper considers the evaluation of timber structures with the focus on robustness due to connection ductility. The robustness analysis is based on the structural reliability framework applied to a simplified mechanical system. The structural timber system is depicted as a parallel system...... can be significantly increased due to the ductile behavior....

  13. Reconstituted Keratin Biomaterial with Enhanced Ductility

    Directory of Open Access Journals (Sweden)

    Halleh Atri

    2015-11-01

    Full Text Available Nowadays the waste from protein fibres represents an important renewable source for a new generation of biomaterials and promising competitors for carbohydrate based biomaterials. Regenerated keratin biomaterials are biodegradable in vivo and in vitro, biocompatible, and support cell attachment and proliferation; however, their major drawback has been their weak mechanical properties such as ductility. The following study was conducted in an attempt to improve the ductility of reconstituted keratin films obtained from Australian merino wool fibres. Keratin was extracted from wool fibres according to an established protocol proposed by Yamauchi, and then dialyzed and desalted by multiple diafiltration wash cycles. The resulting keratin film was transparent, biodegradable, and, opposite to its predecessors, mechanically durable, possessing a Young modulus about 12.5 MPa with 35% extensibility. The polypeptide chains were found to rearrange themselves in the β-sheet state in this keratin film, which was shown to be semi-crystalline. This film, unlike its predecessors, did not support human cell proliferation. These properties of the diafiltered keratin film have led us to think that diafiltration resulted in producing a totally new keratin film, which is envisaged to find applications in various areas.

  14. Graphite nodules in fatigue-tested cast iron characterized in 2D and 3D

    DEFF Research Database (Denmark)

    Mukherjee, Krishnendu; Fæster, Søren; Hansen, Niels

    2017-01-01

    Thick-walled ductile iron casts have been studied by applying (i) cooling rate calculations by FVM, (ii) microstructural characterization by 2D SEM and 3D X-ray tomography techniques and (iii) fatigue testing of samples drawn from components cast in sand molds and metal molds. An analysis has shown...... correlations between cooling rate, structure and fatigue strengths demonstrating the benefit of 3D structural characterization to identify possible causes of premature fatigue failure of ductile cast iron....

  15. Final report of `research on advanced uses of cast materials`; Chusho kigyo taisaku gijutsu tokubetsu kenkyu `chuzo zairyo no kodo riyo gijutsu ni kansuru kenkyu` shuryo hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    Tada, S.; Takahashi, T.; Abe, T. [Tohoku National Industrial Research Institute, Sendai (Japan)

    1997-03-31

    For the advanced utilization of casting iron, temperature differential austempering and partial austempering with the gradient mechanical properties of ADI (austempered ductile iron) by local electric method were experimentally investigated. For the former, gradient mechanical properties are obtained by giving temperature difference to the material in the process of austempering of casting iron, to add the strength and toughness. For the latter, mechanical properties are controlled by repeating partial austempering with changing the isothermal transformation condition by means of local electric method, to obtain the strength characteristics with appropriate balance. As a result of the former experiment, function gradient materials could be obtained with continuously changing internal mechanical properties. The fabricated material provided different properties depending on the direction of load. Radial crushing strength constant of the ring material depended on the treatment temperature of inside surface of the specimen. Fatigue and yield strengths can be simultaneously improved. As a result of the latter experiment, it was found that the mechanical properties can be improved at arbitrary part by the partial austempering. 13 refs., 25 figs., 4 tabs.

  16. Iron Chelation

    Science.gov (United States)

    Skip to main content Menu Donate Treatments Therapies Iron Chelation Iron chelation therapy is the main treatment ... have iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you ...

  17. Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Gheorghe Hutiu

    2018-02-01

    Full Text Available Some forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents or for parts working under harsh conditions (e.g., pipes or turbines would benefit from a method/technique that distinguishes ductile from brittle fractures of metals—as material defects are one of the potential causes of incidents. Nowadays, the gold standard in material studies is represented by scanning electron microscopy (SEM. However, SEM instruments are large, expensive, time-consuming, and lab-based; hence, in situ measurements are impossible. To tackle these issues, we propose as an alternative, lower-cost, sufficiently high-resolution technique, Optical Coherence Tomography (OCT to perform fracture analysis by obtaining the topography of metallic surfaces. Several metals have been considered in this study: low soft carbon steels, lamellar graphite cast iron, an antifriction alloy, high-quality rolled steel, stainless steel, and ductile cast iron. An in-house developed Swept Source (SS OCT system, Master-Slave (MS enhanced is used, and height profiles of the samples’ surfaces were generated. Two configurations were used: one where the dimension of the voxel was 1000 μm3 and a second one of 160 μm3—with a 10 μm and a 4 μm transversal resolution, respectively. These height profiles allowed for concluding that the carbon steel samples were subject to ductile fracture, while the cast iron and antifriction alloy samples were subjected to brittle fracture. The validation of OCT images has been made with SEM images obtained with a 4 nm resolution. Although the OCT images are of a much lower resolution than the SEM ones, we demonstrate that they are sufficiently good to obtain clear images of the grains of the metallic materials and thus to distinguish between ductile and brittle fractures—especially with the higher resolution MS/SS-OCT system. The investigation is finally extended to the most useful case of

  18. Influence of ageing, inclusions and voids on ductile fracture ...

    Indian Academy of Sciences (India)

    Unknown

    inclusions present. The initiation of voids at small particles in the ductile fracture process appears to have little effect on fracture toughness. The strain hardening capacity has a marked effect on void size, and is an indicator of fracture toughness in the commercial Al alloy. Keywords. Ageing; inclusions; voids; ductile fracture; ...

  19. Hydrogen induced ductility losses in austenitic stainless steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, J.A.; West, A.J.

    1978-06-01

    The effect of hydrogen on the tensile behavior of austenitic stainless steel welds was studied in two AISI 300 series alloys and two nitrogen strengthened alloys. The microstructure of these welds typically contained several percent ferrite in an austenite matrix. Hydrogen was found to reduce the ductility of all welds; however, the severity of ductility loss decreased with increasing stacking fault energy, as observed in previous studies on wrought material. In the lowest stacking fault energy welds, 304L and 308L, hydrogen changed the fracture mode from simple rupture to a mixed mode of ductile and brittle fracture associated with the austenite ferrite interface. Higher stacking fault energy welds, 309S and 22-13-5, showed smaller losses in ductility. In these materials hydrogen assisted the ductile rupture process by aiding void growth and coalescence, without changing the fracture mode. Varying the amount of ferrite from approximately one to 10 percent had no significant effect on performance in hydrogen.

  20. Prediction of Ductile Fracture Surface Roughness Scaling

    DEFF Research Database (Denmark)

    Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth

    2012-01-01

    . Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting...... three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low...... strength, which result in large voids near the crack tip at an early stage, and small second phase particles, which require large strains before cavities nucleate. The larger inclusions are represented discretely and various three dimensional distributions of the larger particles are considered...

  1. Hot Ductility Behavior of a Peritectic Steel during Continuous Casting

    Directory of Open Access Journals (Sweden)

    Mustafa Merih Arıkan

    2015-06-01

    Full Text Available Hot ductility properties of a peritectic steel for welded gas cylinders during continuous casting were studied by performing hot tensile tests at certain temperatures ranging from 1200 to 700 °C for some cooling rates by using Gleeble-3500 thermo-mechanical test and simulation machine in this study. The effects of cooling rate and strain rate on hot ductility were investigated and continuous casting process map (time-temperature-ductility were plotted for this material. Reduction of area (RA decreases and cracking susceptibility increases during cooling from solidification between certain temperatures depending on the cooling rate. Although the temperatures which fracture behavior change upon cooling during continuous casting may vary for different materials, it was found that the type of fracture was ductile at 1100 and 1050 °C; semi-ductile at 1000 °C, and brittle at 800 °C for the steel P245NB. There is a ductility trough between 1000 and 725 °C. The ductility trough gets slightly narrower as the cooling rate decreases.

  2. 76 FR 31936 - Non-Malleable Cast Iron Pipe Fittings From the People's Republic of China: Final Results of...

    Science.gov (United States)

    2011-06-02

    ... Secretary, Import Administration regarding the Final Scope Ruling on Black Cast Iron Cast, Green Ductile...-Market Economy Treatment The Department considers the PRC to be a non-market economy (``NME'') country.\\3...

  3. Oil quenched malleable iron, the strength of an old material in a “green cast” development and a new future

    Directory of Open Access Journals (Sweden)

    Cornelis J. van Ettinger

    2010-11-01

    Full Text Available Malleable iron lost the interest and the development stopped in the turbulent seventies of tremendous developments of new technologies. The personal computer, emission spectrometer, thermal analysis, cold-box core system and automatic vertical moulding were introduced into the foundry industry. Experience shows that these new technologies do not always match up with malleable iron. Solidification and mould filling simulation programs are not always capable to handle a low carbon equivalent iron like malleable iron. Recent developments show however by using these new technologies and combined with practical experience, it is possible to increase the casting yield of malleable iron to the same level as ductile iron. The mechanical properties, especially the yield strength of malleable iron according to the standard are equivalent to those of ductile iron, however the yield strength of oil quenched malleable iron is significantly higher than that of ductile iron. An extensive investigation is made between ductile iron, air quenched and oil quenched malleable irons based on the properties of more than 350 test bars produced under the same conditions. The results are compared with the existing international standards and discussed. Other properties like fatigue strength and response to surface treatments as induction hardening are also discussed. The costs of malleable iron are reviewed and compared with other ferro alloys. These recent developments in increasing the casting yield, the understanding of the strength, makes malleable iron competitive with ductile iron and cheaper than the first grade of ausferritic ductile iron, or steel qualities. It is possible to design lighter and save weight which is essential in the automotive industry. An example of “green cast” development for typical applications, used in automotive transmissions and engines are shown.

  4. High-temperature ductility of electro-deposited nickel

    Science.gov (United States)

    Dini, J. W.; Johnson, H. R.

    1977-01-01

    Work done during the past several months on high temperature ductility of electrodeposited nickel is summarized. Data are presented which show that earlier measurements made at NASA-Langley erred on the low side, that strain rate has a marked influence on high temperature ductility, and that codeposition of a small amount of manganese helps to improve high temperature ductility. Influences of a number of other factors on nickel properties were also investigated. They included plating solution temperature, current density, agitation, and elimination of the wetting agent from the plating solution. Repair of a large nozzle section by nickel plating is described.

  5. Identification Damage Model for Thermomechanical Degradation of Ductile Heterogeneous Materials

    Science.gov (United States)

    Amri, A. El; Yakhloufi, M. H. El; Khamlichi, A.

    2017-05-01

    The failure of ductile materials subject to high thermal and mechanical loading rates is notably affected by material inertia. The mechanisms of fatigue-crack propagation are examined with particular emphasis on the similarities and differences between cyclic crack growth in ductile materials, such as metals, and corresponding behavior in brittle materials, such as intermetallic and ceramics. Numerical simulations of crack propagation in a cylindrical specimen demonstrate that the proposed method provides an effective means to simulate ductile fracture in large scale cylindrical structures with engineering accuracy. The influence of damage on the intensity of the destruction of materials is studied as well.

  6. Microalloying Boron Carbide with Silicon to Achieve Dramatically Improved Ductility.

    Science.gov (United States)

    An, Qi; Goddard, William A

    2014-12-04

    Boron carbide (B4C) is a hard material whose value for extended engineering applications such as body armor; is limited by its brittleness under impact. To improve the ductility while retaining hardness, we used density functional theory to examine modifying B4C ductility through microalloying. We found that replacing the CBC chain in B4C with Si-Si, denoted as (B11Cp)-Si2, dramatically improves the ductility, allowing a continuous shear to a large strain of 0.802 (about twice of B4C failure strain) without brittle failure. Moreover, (B11C)-Si2 retains low density and high hardness. This ductility improvement arises because the Si-Si linkages enable the icosahedra accommodate additional shear by rotating instead of breaking bonds.

  7. Robustness Evaluation of Timber Structures with Ductile Behaviour

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Cizmar, D.

    2009-01-01

    as a parallel system. A measure of ductile behaviour is introduced. For different values of this measure the system reliability is estimated based on Monte Carlo simulation where correlation between the strength of structural elements and load models for permanent and live load are introduced. The results......The present paper considers robustness evaluation of timber structures where the ductile behavior of joints of timber material is taken into account. The robustness analysis is based on the structural reliability framework used on a simplified mechanical system modelling a structural timber system...... indicate the reliability of a structural timber ystem can be increased apprximately 20 % awarding the ductile behaviour. At last the paper discusses possible structural timber systems which have potential for providing ductility and redundancy....

  8. Influence of phosphorus on the creep ductility of copper

    International Nuclear Information System (INIS)

    Sandström, Rolf; Wu, Rui

    2013-01-01

    Around 1990 it was discovered that pure copper could have extra low creep ductility in the temperature interval 180–250 °C. The material was intended for use in canisters for nuclear waste disposal. Although extra low creep ductility was not observed much below 180 °C and the temperature in the canister will never exceed 100 °C, it was feared that the creep ductility could reach low values at lower temperatures after long term exposure. If 50 ppm phosphorus was added to the copper the low creep ductility disappeared. A creep cavitation model is presented that can quantitatively describe the cavitation behaviour in uniaxial and multiaxial creep tests as well as the observed creep ductility for copper with and without phosphorus. A so-called double ledge model has been introduced that demonstrates why the nucleation rate of creep cavities is often proportional to the creep rate. The phosphorus agglomerates at the grain boundaries and limits their local deformation and thereby reduces the formation and growth of cavities. This explains why extra low creep ductility does not occur in phosphorus alloyed copper

  9. Intrinsic ductility and environmental embrittlement of binary Ni3Al

    International Nuclear Information System (INIS)

    George, E.P.; Liu, C.T.; Pope, D.P.

    1993-01-01

    Polycrystalline, B-free Ni 3 Al (23.4 at.% Al), produced by cold working and recrystallizing a single crystal, exhibits room temperature tensile ductilities of 3-5% in air and 13-16% in oxygen. These ductilities are considerably higher than anything previously reported, and demonstrate that the 'intrinsic' ductility of Ni 3 Al is much higher than previously thought. They also show that the moisture present in ordinary ambient air can severely embrittle Ni 3 Al (ductility decreasing from a high of 16% in oxygen to a low of 3% in air). Fracture is predominantly intergranular in both air and oxygen. This indicates that, while moisture can further embrittle the GBs in Ni 3 Al, they persist as weak links even in the absence of environmental embrittlement. However, they are not 'intrinsically brittle' as once thought, since they can withstand relatively large plastic deformations prior to fracture. Because B essentially eliminates environmental embrittlement in Ni 3 Al - and environmental embrittlement is a major cause of poor ductility in B-free Ni 3 Al - it is concluded that a significant portion of the so-called B effect must be related to suppression of moisture-induced environmental embrittlement. However, since B-doped Ni 3 Al fractures transgranularly, whereas B-free Ni 3 Al fractures predominantly intergranularly, B must have the added effect that it strengthens the GBs. A comparison with the earlier work on Zr-doped Ni 3 Al shows that Zr improves the ductility of Ni 3 Al, both in air and (and even more dramatically) in oxygen. While the exact mechanism of this ductility improvement is not clear at present, Zr appears to have more of an effect on (enhancing) GB strength than on (suppressing) environmental embrittlement

  10. Energetic approach for ductile tearing; Approche energetique de la dechirure ductile

    Energy Technology Data Exchange (ETDEWEB)

    Marie, St

    1999-07-01

    This study focuses on ductile crack initiation and propagation. It aims to propose an approach for the engineer allowing the prediction of the evolution of cracks in large scale components, from parameters determined on laboratory specimens. A crack initiation criterion, defining a J{sub i} tenacity related to crack tip blunting proposed in the literature is validated in the study. This criterion is shown to be transferable from laboratory specimens to structures. The literature review shows that an approach based on the dissipated energy in the fracture process during propagation offers an economical and simple solution to simulate large crack growth. A numerical method is proposed to estimate this fracture energy. The existence of an energy parameter G{sub fr} is shown, by simulating the propagation by the simultaneous release of several elements and by the use of the Rice integral with an original integration path. This parameter represents the needed energy for a unit crack extension and appears to be intrinsic to the material. A global energy statement allows to relate this parameter to a variation of the plastic part of J integral. It offers a second numerical method to simulate the propagation just from stationary numerical calculations, as well as the elaboration of a simplified method. This approach, using two parameters J{sub i} and G{sub fr}, intrinsic to the material and experimentally measurable on specimens, is validated on many tests such as crack pipes subjected to four points bending and cracked rings in compression. For example, this approach allows to model up to 90 mm ductile tearing in a pipe with a circumferential through-wall crack in ferritic steel, or to anticipate the evolution of a semi-elliptical crack in an aged austenitic ferritic steel plate subjected to bending. (author)

  11. Numerical modeling of ductile tearing effects on cleavage fracture toughness

    International Nuclear Information System (INIS)

    Dodds, R.H. Jr.; Tang, M.; Anderson, T.L.

    1994-05-01

    Experimental studies demonstrate a significant effect of specimen size, a/W ratio and prior ductile tearing on cleavage fracture toughness values (J c ) measured in the ductile-to-brittle transition region of ferritic materials. In the lower-transition region, cleavage fracture often occurs under conditions of large-scale yielding but without prior ductile crack extension. The increased toughness develops when plastic zones formed at the crack tip interact with nearby specimen surfaces which relaxes crack-tip constraint (stress triaxiality). In the mid-to-upper transition region, small amounts of ductile crack extension (often c -values. Previous work by the authors described a micromechanics fracture model to correct measured J c -values for the mechanistic effects of large-scale yielding. This new work extends the model to also include the influence of ductile crack extension prior to cleavage. The paper explores development of the new model, provides necessary graphs and procedures for its application and demonstrates the effects of the model on fracture data sets for two pressure vessel steels (A533B and A515)

  12. A Study on Ductility of Prestressed Concrete Pier Based on Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    H. Wang

    2016-12-01

    Full Text Available The ductility of prestressed concrete pier is studied based on response surface methodology. Referring to the pervious prestressed concrete pier, based on Box-Behnken design, the ductility of 25 prestressed concrete piers is calculated by numerical method. The relationship between longitudinal reinforcement ratio, shear reinforcement ratio, prestressed tendon quantity, concrete compressive strength and ductility factor is gotten. The influence of the longitudinal reinforcement ratio, the shear reinforcement ratio, the prestressed tendon quantity and concrete compressive strength to curvature ductility is discussed. Then the ductility regression equation is deduced. The result showed that the influence of the prestressed tendon quantity to the ductility of prestressed concrete pier is significant. With the increasing of the prestressed tendon quantity, the curvature ductility curved reduces. With the increasing of shear reinforcement ratio and compressive strength of concrete, the curvature ductility increases linearly. And the influence of the longitudinal reinforcement ratio to ductility of the prestressed concrete pier is insignificant.

  13. Ductility of reinforced concrete columns confined with stapled strips

    International Nuclear Information System (INIS)

    Tahir, M.F.; Khan, Q.U.Z.; Shabbir, F.; Sharif, M.B.; Ijaz, N.

    2015-01-01

    Response of three 150x150x450mm short reinforced concrete (RC) columns confined with different types of confining steel was investigated. Standard stirrups, strips and stapled strips, each having same cross-sectional area, were employed as confining steel around four comer column bars. Experimental work was aimed at probing into the affect of stapled strip confinement on post elastic behavior and ductility level under cyclic axial load. Ductility ratios, strength enhancement factor and core concrete strengths were compared to study the affect of confinement. Results indicate that strength enhancement in RC columns due to strip and stapled strip confinement was not remarkable as compared to stirrup confined column. It was found that as compared to stirrup confined column, stapled strip confinement enhanced the ductility of RC column by 183% and observed axial capacity of stapled strip confined columns was 41 % higher than the strip confined columns. (author)

  14. Brittle and ductile friction and the physics of tectonic tremor

    Science.gov (United States)

    Daub, Eric G.; Shelly, David R.; Guyer, Robert A.; Johnson, P.A.

    2011-01-01

    Observations of nonvolcanic tremor provide a unique window into the mechanisms of deformation and failure in the lower crust. At increasing depths, rock deformation gradually transitions from brittle, where earthquakes occur, to ductile, with tremor occurring in the transitional region. The physics of deformation in the transition region remain poorly constrained, limiting our basic understanding of tremor and its relation to earthquakes. We combine field and laboratory observations with a physical friction model comprised of brittle and ductile components, and use the model to provide constraints on the friction and stress state in the lower crust. A phase diagram is constructed that characterizes under what conditions all faulting behaviors occur, including earthquakes, tremor, silent transient slip, and steady sliding. Our results show that tremor occurs over a range of ductile and brittle frictional strengths, and advances our understanding of the physical conditions at which tremor and earthquakes take place.

  15. Additively manufactured hierarchical stainless steels with high strength and ductility

    Science.gov (United States)

    Wang, Y. Morris; Voisin, Thomas; McKeown, Joseph T.; Ye, Jianchao; Calta, Nicholas P.; Li, Zan; Zeng, Zhi; Zhang, Yin; Chen, Wen; Roehling, Tien Tran; Ott, Ryan T.; Santala, Melissa K.; Depond, Philip J.; Matthews, Manyalibo J.; Hamza, Alex V.; Zhu, Ting

    2018-01-01

    Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.

  16. Toughened microstructures for ductile phase reinforced molybdenum disilicide

    International Nuclear Information System (INIS)

    Pickard, S.M.; Ghosh, A.K.

    1995-01-01

    Various morphologies of ductile Nb refractory metal reinforcement are incorporated into a MoSi 2 matrix using powder metallurgy, including single-ply laminates, continuous metal ribbons and sections of 2-dimensional wire mesh. Hot forging techniques are used to redistribute the reinforcement and change the dimensions and the aspect ratio of the reinforcing metal ligaments. Work-of-rupture measurements are conducted on bend test specimens and precracked tensile specimens of the composite so that the toughness contribution from the various ductile metal morphologies can be assessed according to its effectiveness. Accompanying microstructural examination of crack bridging interaction with the reinforcement is conducted

  17. Physical factors controlling the ductility of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y. [Central South University, China; Liu, Chain T [ORNL; Zhang, Z. [University of Tennessee, Knoxville (UTK); Keppens, V. [University of Tennessee, Knoxville (UTK)

    2008-01-01

    In order to identify key physical factor controlling the deformation and fracture behavior of bulk metallic glasses (BMGs), we compiled and analyzed the elastic moduli and compressive ductility for BMGs. In addition, new modulus data were generated in the critical ranges in order to facilitate the analysis. We have found that the intrinsic ductility of BMGs can be correlated with the bulk-to-shear modulus ratio B/G according to Pugh's [Philos. Mag. 45, 823 (1954) ] rule. In some individual BMG systems, for example, Fe based, the relationship seems to be very clear. The physical meaning of this correlation is discussed in terms of atomic bonding and connectivity.

  18. Inoculation Effects of Cast Iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2012-12-01

    Full Text Available The paper presents a solidification sequence of graphite eutectic cells of A and D types, as well as globular and cementite eutectics. The morphology of eutectic cells in cast iron, the equations for their growth and the distances between the graphite precipitations in A and D eutectic types were analyzed. It is observed a critical eutectic growth rate at which one type of eutectic transformed into another. A mathematical formula was derived that combined the maximum degree of undercooling, the cooling rate of cast iron, eutectic cell count and the eutectic growth rate. One type of eutectic structure turned smoothly into the other at a particular transition rate, transformation temperature and transformational eutectic cell count. Inoculation of cast iron increased the number of eutectic cells with flake graphite and the graphite nodule count in ductile iron, while reducing the undercooling. An increase in intensity of inoculation caused a smooth transition from a cementite eutectic structure to a mixture of cementite and D type eutectic structure, then to a mixture of D and A types of eutectics up to the presence of only the A type of eutectic structure. Moreover, the mechanism of inoculation of cast iron was studied.

  19. Analysis of carbon partitioning during ausferritic reaction in ADI

    Directory of Open Access Journals (Sweden)

    Z. Ławrynowicz

    2008-10-01

    Full Text Available The investigation was carried out to examine the influence of temperature and times of austempering process on the maximum extend towhich the ausferritic reaction can proceed and the carbon content in retained austenite. Specimens prepared from ductile cast iron wereaustenitised at 950oC for 60 minutes and austempered at four temperatures: 250, 300, 350 and 400oC. The samples were austempered atthese temperatures for 15, 30, 60, 120 and 240 minutes and finally quenched to ambient temperature. Volume fractions of retainedaustenite and carbon concentration in the residual austenite have been observed by using X-ray diffraction. Additionally, carbonconcentration in the residual austenite was calculated using volume fraction data of austenite and a model developed by Bhadeshia basedon the McLellan and Dunn quasi-chemical thermodynamic model. It was found that the obtained extend of ausferritic transformation isonly possible when the microstructure consists of not only ausferrite but additionally precipitated carbides.

  20. Energy Saving Melting and Revert Reduction Technology: Aging of Graphitic Cast Irons and Machinability

    Energy Technology Data Exchange (ETDEWEB)

    Richards, Von L. [Advanced Technology Inst., Virginia Beach, VA (United States)

    2012-09-19

    The objective of this task was to determine whether ductile iron and compacted graphite iron exhibit age strengthening to a statistically significant extent. Further, this effort identified the mechanism by which gray iron age strengthens and the mechanism by which age-strengthening improves the machinability of gray cast iron. These results were then used to determine whether age strengthening improves the machinability of ductile iron and compacted graphite iron alloys in order to develop a predictive model of alloy factor effects on age strengthening. The results of this work will lead to reduced section sizes, and corresponding weight and energy savings. Improved machinability will reduce scrap and enhance casting marketability. Technical Conclusions: Age strengthening was demonstrated to occur in gray iron ductile iron and compacted graphite iron. Machinability was demonstrated to be improved by age strengthening when free ferrite was present in the microstructure, but not in a fully pearlitic microstructure. Age strengthening only occurs when there is residual nitrogen in solid solution in the Ferrite, whether the ferrite is free ferrite or the ferrite lamellae within pearlite. Age strengthening can be accelerated by Mn at about 0.5% in excess of the Mn/S balance Estimated energy savings over ten years is 13.05 trillion BTU, based primarily on yield improvement and size reduction of castings for equivalent service. Also it is estimated that the heavy truck end use of lighter castings for equivalent service requirement will result in a diesel fuel energy savings of 131 trillion BTU over ten years.

  1. Low temperature enhanced ductility of friction stir processed 5083 ...

    Indian Academy of Sciences (India)

    Administrator

    forming loads. The occurrence of a relatively high value of strain rate sensitivity, m of 0⋅45 for a grain size of. 0⋅95 μm, suggests the operation of superplastic deformation under these present experimental conditions. Keywords. AA5083; friction stir processing; ductility; superplasticity. 1. Introduction. Friction stir processing ...

  2. Low temperature enhanced ductility of friction stir processed 5083 ...

    Indian Academy of Sciences (India)

    ... rates, and demonstrated that a decrease in grain size resulted in significantly enhanced ductility and lower forming loads. The occurrence of a relatively high value of strain rate sensitivity, of 0.45 for a grain size of 0.95 m, suggests the operation of superplastic deformation under these present experimental conditions.

  3. Ductile mode grinding of reaction-bonded silicon carbide mirrors.

    Science.gov (United States)

    Dong, Zhichao; Cheng, Haobo

    2017-09-10

    The demand for reaction-bonded silicon carbide (RB-SiC) mirrors has escalated recently with the rapid development of space optical remote sensors used in astronomy or Earth observation. However, RB-SiC is difficult to machine due to its high hardness. This study intends to perform ductile mode grinding to RB-SiC, which produces superior surface integrity and fewer subsurface damages, thus minimizing the workload of subsequent lapping and polishing. For this purpose, a modified theoretical model for grain depth of cut of grinding wheels is presented, which correlates various processing parameters and the material characteristics (i.e., elastic module) of a wheel's bonding matrix and workpiece. Ductile mode grinding can be achieved as the grain depth of cut of wheels decreases to be less than the critical cut depth of workpieces. The theoretical model gives a roadmap to optimize the grinding parameters for ductile mode grinding of RB-SiC and other ultra-hard brittle materials. Its feasibility was validated by experiments. With the optimized grinding parameters for RB-SiC, the ductile mode grinding produced highly specular surfaces (with roughness of ∼2.2-2.8  nm Ra), which means the material removal mechanism of RB-SiC is dominated by plastic deformation rather than brittle fracture. Contrast experiments were also conducted on fused silica, using the same grinding parameters; this produced only very rough surfaces, which further validated the feasibility of the proposed model.

  4. High-pressure structural stability of the ductile intermetallic ...

    Indian Academy of Sciences (India)

    Administrator

    Murnaghan equation of state fit to the pressure, volume data yielded a bulk modulus of 67∙6 GPa with the pressure derivative of bulk modulus fixed at 4. Keywords. Intermetallics; X-ray ... ners of the unit cell cube occupied by the 'M' element and cube centre occupied by the 'R' element. Although some ductility has been ...

  5. Construction-friendly ductile shear joints for precast concrete panels

    DEFF Research Database (Denmark)

    Sørensen, Jesper Harrild; Hoang, Linh Cao; Fischer, Gregor

    2015-01-01

    for the mounting of a vertical locking bar. Where limited space is available bending and subsequent straightening of the U-bars are required to assemble the adjacent panels, a procedure which imposes substantial ductility requirements on the reinforcement as well as some manual workload. This paper introduces...

  6. Strength and Ductility of Forged 1200 Aluminum Alloy Reinforced ...

    African Journals Online (AJOL)

    With 50% reduction and fine-sized steel particles (512μm) in aluminum alloy, tensile strength dropped to 160MPa without significant decrease in ductility (1.7). Microstructure of cast samples show the presence of fine Fe particles at grain boundaries after annealing with most of the particles in solid solution. Al3Fe and AlFeSi ...

  7. Displacement-length scaling of brittle faults in ductile shear.

    Science.gov (United States)

    Grasemann, Bernhard; Exner, Ulrike; Tschegg, Cornelius

    2011-11-01

    Within a low-grade ductile shear zone, we investigated exceptionally well exposed brittle faults, which accumulated antithetic slip and rotated into the shearing direction. The foliation planes of the mylonitic host rock intersect the faults approximately at their centre and exhibit ductile reverse drag. Three types of brittle faults can be distinguished: (i) Faults developing on pre-existing K-feldspar/mica veins that are oblique to the shear direction. These faults have triclinic flanking structures. (ii) Wing cracks opening as mode I fractures at the tips of the triclinic flanking structures, perpendicular to the shear direction. These cracks are reactivated as faults with antithetic shear, extend from the parent K-feldspar/mica veins and form a complex linked flanking structure system. (iii) Joints forming perpendicular to the shearing direction are deformed to form monoclinic flanking structures. Triclinic and monoclinic flanking structures record elliptical displacement-distance profiles with steep displacement gradients at the fault tips by ductile flow in the host rocks, resulting in reverse drag of the foliation planes. These structures record one of the greatest maximum displacement/length ratios reported from natural fault structures. These exceptionally high ratios can be explained by localized antithetic displacement along brittle slip surfaces, which did not propagate during their rotation during surrounding ductile flow.

  8. Displacement–length scaling of brittle faults in ductile shear

    Science.gov (United States)

    Grasemann, Bernhard; Exner, Ulrike; Tschegg, Cornelius

    2011-01-01

    Within a low-grade ductile shear zone, we investigated exceptionally well exposed brittle faults, which accumulated antithetic slip and rotated into the shearing direction. The foliation planes of the mylonitic host rock intersect the faults approximately at their centre and exhibit ductile reverse drag. Three types of brittle faults can be distinguished: (i) Faults developing on pre-existing K-feldspar/mica veins that are oblique to the shear direction. These faults have triclinic flanking structures. (ii) Wing cracks opening as mode I fractures at the tips of the triclinic flanking structures, perpendicular to the shear direction. These cracks are reactivated as faults with antithetic shear, extend from the parent K-feldspar/mica veins and form a complex linked flanking structure system. (iii) Joints forming perpendicular to the shearing direction are deformed to form monoclinic flanking structures. Triclinic and monoclinic flanking structures record elliptical displacement–distance profiles with steep displacement gradients at the fault tips by ductile flow in the host rocks, resulting in reverse drag of the foliation planes. These structures record one of the greatest maximum displacement/length ratios reported from natural fault structures. These exceptionally high ratios can be explained by localized antithetic displacement along brittle slip surfaces, which did not propagate during their rotation during surrounding ductile flow. PMID:26806996

  9. Carbon Concentration of Austenite

    Directory of Open Access Journals (Sweden)

    Z. Ławrynowicz

    2007-07-01

    Full Text Available The investigation was carried out to examine the influence of temperature and times of austempering process on the maximum extend towhich the bainite reaction can proceed and the carbon content in retained austenite. It should be noted that a small percentage change in theaustenite carbon content can have a significant effect on the subsequent austempering reaction changing the volume fraction of the phasespresent and hence, the resulting mechanical properties. Specimens were prepared from an unalloyed ductile cast iron, austenitised at 950oCfor 60 minutes and austempered by the conventional single-step austempering process at four temperatures between BS and MS, eg., 250,300, 350 and 400oC. The samples were austempered at these temperatures for 15, 30, 60, 120 and 240 minutes and finally quenched toambient temperature. Volume fractions of retained austenite and carbon concentration in the residual austenite have been observed byusing X-ray diffraction. Additionally, carbon concentration in the residual austenite was calculated using volume fraction data of austeniteand a model developed by Bhadeshia based on the McLellan and Dunn quasi-chemical thermodynamic model. The comparison ofexperimental data with the T0, T0' and Ae3' phase boundaries suggests the likely mechanism of bainite reaction in cast iron is displacive rather than diffusional. The carbon concentration in retained austenite demonstrates that at the end of bainite reaction the microstructure must consist of not only ausferrite but additionally precipitated carbides.

  10. Development and use of ADI materials at DB AG; Entwicklung und Einsatz von ADI-Werkstoffen bei der DB AG

    Energy Technology Data Exchange (ETDEWEB)

    Maedler, K. [Deutsche Bahn AG, Brandenburg-Kirchmoeser (Germany). Forschungs- und Technologie-Zentrum

    1999-07-01

    ADI (austempered ductile iron) has many interesting properties and can replace steel in many applications in railwy engineering provided that the life cycle cost and noise emissions can be minimized on the one hand and that material producers are able on the other hand to produce ADI materials of constant quality. [German] Der Werkstoff ADI (austempered ductile iron) bietet ein breites Spektrum guenstiger Eigenschaften, die sich fuer zahlreiche, bisher aus Stahl hergestellte Bauteile im schienengebundenen Verkehr anbieten. Gelingt es, diese Eigenschaften gezielt zur Verminderung der Lebenszykluskosten ueber die Verringerung der Kosten fuer Herstellung, Wartung, Instandhaltung und Energieverbrauch einzusetzen und nicht zuletzt die Schallabstrahlung zu minimieren, dann ist dieser Werkstoff eine Alternative zu bislang bei der Bahn eingesetzten Materialien. Voraussetzung fuer eine Werkstoffsubstitution ist neben dem Nachweis der technischen und wirtschaftlichen Ueberlegenheit beim Einsatz dieses Materials eine hohe Prozesssicherheit beim Hersteller, um auch grosse Serien in gleichbleibend hoher Qualitaet zu erzeugen. (orig.)

  11. The recommendation system knowledge representation and reasoning procedures under uncertainty for metal casting

    Directory of Open Access Journals (Sweden)

    S. Kluska-Nawarecka

    2015-01-01

    Full Text Available The paper presents an information system dedicated to requirements recommendation and knowledge sharing. It presents methodology of constructing domain knowledge base and application procedure on the example of production technology of Austempered Ductile Iron (ADI. For knowledge representation and reasoning Logic of Plausible Reasoning (LPR is used. Both equally applicable LPR for formalization the knowledge of foundry technology, as well as the described system solution have the unique character.

  12. Analysis Strategy for Fracture Assessment of Defects in Ductile Materials

    International Nuclear Information System (INIS)

    Dillstroem, Peter; Andersson, Magnus; Sattari-Far, Iradj; Weilin Zang

    2009-06-01

    The main purpose of this work is to investigate the significance of the residual stresses for defects (cracks) in ductile materials with nuclear applications, when the applied primary (mechanical) loads are high. The treatment of weld-induced stresses as expressed in the SACC/ProSACC handbook and other fracture assessment procedures such as the ASME XI code and the R6-method is believed to be conservative for ductile materials. This is because of the general approach not to account for the improved fracture resistance caused by ductile tearing. Furthermore, there is experimental evidence that the contribution of residual stresses to fracture diminishes as the degree of yielding increases to a high level. However, neglecting weld-induced stresses in general, though, is doubtful for loads that are mostly secondary (e.g. thermal shocks) and for materials which are not ductile enough to be limit load controlled. Both thin-walled and thick-walled pipes containing surface cracks are studied here. This is done by calculating the relative contribution from the weld residual stresses to CTOD and the J-integral. Both circumferential and axial cracks are analysed. Three different crack geometries are studied here by using the finite element method (FEM). (i) 2D axisymmetric modelling of a V-joint weld in a thin-walled pipe. (ii) 2D axisymmetric modelling of a V-joint weld in a thick-walled pipe. (iii) 3D modelling of a X-joint weld in a thick-walled pipe. t. Each crack configuration is analysed for two load cases; (1) Only primary (mechanical) loading is applied to the model, (2) Both secondary stresses and primary loading are applied to the model. Also presented in this report are some published experimental investigations conducted on cracked components of ductile materials subjected to both primary and secondary stresses. Based on the outcome of this study, an analysis strategy for fracture assessment of defects in ductile materials of nuclear components is proposed. A new

  13. Native iron

    DEFF Research Database (Denmark)

    Brooks, Charles Kent

    2015-01-01

    , a situation unique in the Solar System. In such a world, iron metal is unstable and, as we all know, oxidizes to the ferric iron compounds we call 'rust'. If we require iron metal it must be produced at high temperatures by reacting iron ore, usually a mixture of ferrous (Fe2+) and ferric (Fe3+) oxides (Fe2O3......, hematite, or FeO.Fe2O3, magnetite), with carbon in the form of coke. This is carried out in a blast furnace. Although the Earth's core consists of metallic iron, which may also be present in parts of the mantle, this is inaccessible to us, so we must make our own. In West Greenland, however, some almost...... unique examples of iron metal, otherwise called 'native iron' or 'telluric iron', occur naturally....

  14. Simulations of ductile flow in brittle material processing

    Energy Technology Data Exchange (ETDEWEB)

    Luh, M.H.; Strenkowski, J.S.

    1988-12-01

    Research is continuing on the effects of thermal properties of the cutting tool and workpiece on the overall temperature distribution. Using an Eulerian finite element model, diamond and steel tools cutting aluminum have been simulated at various, speeds, and depths of cut. The relative magnitude of the thermal conductivity of the tool and the workpiece is believed to be a primary factor in the resulting temperature distribution in the workpiece. This effect is demonstrated in the change of maximum surface temperatures for diamond on aluminum vs. steel on aluminum. As a preliminary step toward the study of ductile flow in brittle materials, the relative thermal conductivities of diamond on polycarbonate is simulated. In this case, the maximum temperature shifts from the rake face of the tool to the surface of the machined workpiece, thus promoting ductile flow in the workpiece surface.

  15. Ductile fracture estimation of reactor pressure vessel under thermal shock

    International Nuclear Information System (INIS)

    Takahashi, Jun; Sakai, Shinsuke; Okamura, Hiroyuki

    1990-01-01

    This paper presents a new scheme for the estimation of unstable ductile fracture of a reactor pressure vessel under thermal shock conditions. First, it is shown that the bending moment applied to the cracked section can be evaluated by considering the plastic deformation of the cracked section and the thermal deformation of the shell. As the contribution of the local thermal stress to the J-value is negligible, the J-value under thermal shock can be easily evaluated by using fully plastic solutions for the cracked part. Next, the phenomena of ductile fracture under thermal shock are expressed on the load-versus-displacement diagram which enables us to grasp the transient phenomena visually. In addition, several parametrical surveys are performed on the above diagram concerning the variation of (1) thermal shock conditions, (2) initial crack length, and (3) J-resistance curve (i.e. embrittlement by neutron irradiation). (author)

  16. A variational void coalescence model for ductile metals

    KAUST Repository

    Siddiq, Amir

    2011-08-17

    We present a variational void coalescence model that includes all the essential ingredients of failure in ductile porous metals. The model is an extension of the variational void growth model by Weinberg et al. (Comput Mech 37:142-152, 2006). The extended model contains all the deformation phases in ductile porous materials, i.e. elastic deformation, plastic deformation including deviatoric and volumetric (void growth) plasticity followed by damage initiation and evolution due to void coalescence. Parametric studies have been performed to assess the model\\'s dependence on the different input parameters. The model is then validated against uniaxial loading experiments for different materials. We finally show the model\\'s ability to predict the damage mechanisms and fracture surface profile of a notched round bar under tension as observed in experiments. © Springer-Verlag 2011.

  17. Ductile-brittle transition in transverse isotropic fibrous networks

    Science.gov (United States)

    Luo, Guoquan; Shi, Liping; Li, Mingwei; Zhong, Yesheng; He, Xiaodong; Wang, Jiazhi

    2018-01-01

    Anisotropic fibrous networks, especially transverse isotropic fibrous networks, are widely used to model the microstructures of biological tissues, polymer gels, fibrous thermal insulations, and other fibrous materials. In this letter, we build a three-dimensional transverse isotropic fibrous network model and study its mechanical properties along the through-thickness direction. We propose a measurement of anisotropy for transverse isotropic fibrous networks and then study the influence of anisotropy on the networks' mechanical properties, including its elastic modulus, maximum elongation, and stress-strain curve, by means of finite-element simulation. We also study theoretically the influence of anisotropy on maximum elongation. We find that as the anisotropy of the networks becomes stronger, the elastic modulus decreases and the maximum elongation increases, indicating a transition in mechanical properties from brittle to ductile. We identify this transition as the "ductile-brittle transition." This transition can help guide the design and regulate the mechanical properties of a transverse isotropic fibrous network.

  18. Modification of evaluation response spectrum by ductility of equipment anchorage

    International Nuclear Information System (INIS)

    Choi, I. G.; Jun, Y. S.; Su, J. M.

    2003-01-01

    The failure mode of welded anchorage is assumed as brittle in the seismic capacity evaluation of nuclear power plant equipments. But the welded anchorage has some ductile capacity. This limited displacement capacity can cause the reduction of the effective frequency of high frequency equipments and the increase of the inelastic energy absorption capacity due to the nonlinear behavior. In this study, the uniform hazard spectrum for Korean nuclear power plant site was modified using the response spectrum reduction factor developed by EPRI. The spectral acceleration for various damping ratio was determined by the theoretical method based on the random vibration theory. In conclusion, the high frequency components of evaluation response spectra were greatly reduced due to the consideration of welded anchorage ductility. This reduced response spectra can be used for the development of in-structure response spectra used in the seismic capacity evaluation of high frequency equipments

  19. Study on ductile fracture evaluation for austenitic stainless steel

    International Nuclear Information System (INIS)

    Miura, Naoki; Shimakawa, Takashi; Kashima, Koichi; Michiba, Kouji; Hiramatsu, Hideki.

    1994-01-01

    In the development of Fast Breeder Reactors (FBRs), structural integrity must be assured for components subjected to high temperatures up to 550degC, even though possible defects are presumed. Nonlinear fracture mechanics is one of the most effective approaches to evaluate ductile fracture behavior of cracked components. In this study, ductile fracture tests were conducted at room temperature and 550degC for austenitic stainless steel SUS304 and 316FR, which were candidates for FBR structural material. The applicability of fracture parameters was investigated from tests using small CT specimens, small CCT specimens, and wide CCT specimens. Fracture tests under the condition of combined tension and bending loads were also performed to investigate the effect of additional bending stress due to the temperature gradient through thickness. It was ascertained that fracture load could be predicted based on the net section collapse criterion and was not so affected by an additional bending stress. (author)

  20. Limits to ductility set by plastic flow localization

    International Nuclear Information System (INIS)

    Needleman, A.; Rice, J.R.

    1977-11-01

    The theory of strain localization is reviewed with reference both to local necking in sheet metal forming processes and to more general three dimensional shear band localizations that sometimes mark the onset of ductile rupture. Both bifurcation behavior and the growth of initial imperfections are considered. In addition to analyses based on classical Mises-like constitutive laws, approaches to localization based on constitutive models that may more accurately model processes of slip and progressive rupturing on the microscale in structural alloys are discussed. Among these non-classical constitutive features are the destabilizing roles of yield surface vertices and of non-normality effects, arising, for example, from slight pressure sensitivity of yield. Analyses based on a constitutive model of a progressively cavitating dilational plastic material which is intended to model the process of ductile void growth in metals are also discussed. A variety of numerical results are presented. In the context of the three dimensional theory of localization, it is shown that a simple vertex model predicts ratios of ductility in plane strain tension to ductility in axisymmetric tension qualitatively consistent with experiment, and the destabilizing influence of a hydrostatic stress dependent void nucleation criterion is illustrated. In the sheet necking context, and focussing on positive biaxial stretching, it is shown that forming limit curves based on a simple vertex model and those based on a simple void growth model are qualitatively in accord, although attributing instability to very different physical mechanisms. These forming limit curves are compared with those obtained from the Mises material model and employing various material and geometric imperfections

  1. Modeling combined tension-shear failure of ductile materials

    International Nuclear Information System (INIS)

    Partom, Y

    2014-01-01

    Failure of ductile materials is usually expressed in terms of effective plastic strain. Ductile materials can fail by two different failure modes, shear failure and tensile failure. Under dynamic loading shear failure has to do with shear localization and formation of adiabatic shear bands. In these bands plastic strain rate is very high, dissipative heating is extensive, and shear strength is lost. Shear localization starts at a certain value of effective plastic strain, when thermal softening overcomes strain hardening. Shear failure is therefore represented in terms of effective plastic strain. On the other hand, tensile failure comes about by void growth under tension. For voids in a tension field there is a threshold state of the remote field for which voids grow spontaneously (cavitation), and the material there fails. Cavitation depends on the remote field stress components and on the flow stress. In this way failure in tension is related to shear strength and to failure in shear. Here we first evaluate the cavitation threshold for different remote field situations, using 2D numerical simulations with a hydro code. We then use the results to compute examples of rate dependent tension-shear failure of a ductile material.

  2. Development of stiffer and ductile glulam portal frame

    Science.gov (United States)

    Komatsu, Kohei

    2017-11-01

    Portal frame structures, which are constituted of straight glulam beams and columns connected semi-rigidly by steel insert gusset plate with a lot of drift pins, were the first successful glulam structures widely used in Japan. In addition to this connection system, the author invented also a new type of jointing devise for glulam structures named as "Lagscrewbolt" which had a full threaded portion at inner part to grip wooden member as well as another thread part at the end of shank to connect with other member. The initial type of "Lagscrewbolt" was successfully applied to a various types of glulam buildings which could be rapidly built-up on construction site. Its strength performance, however, was rather brittle therefore the improvement of the ductility was a crucial research subject. In order to give a sufficient ductility on the "Lagscrewbolted joint system", so-called "Slotted Bolted Connection" concept was adopted for making use of large energy dissipation characteristics due to high-tension bolted steel connection with slotted bolt holes. Static & dynamic performance of glulam portal frame specimens was evaluated by static cyclic loading test as well as shaking table test. Current latest form of the jointing system can show very high ductility as well as stable hysteretic cyclic loops by inserting brass-shim between steel-to-steel friction interfaces

  3. Hot ductility and fracture mechanisms of a structural steel

    International Nuclear Information System (INIS)

    Calvo, J.; Cabrera, J. M.; Prado, J. M.

    2006-01-01

    The hot ductility of a structural steel produced from scrap recycling has been studied to determine the origin of the transverse cracks in the corners that appeared in some billets. Samples extracted both from a billet with transverse cracks and from a billet with no external damage were tested. To evaluate the influence of residual elements and inclusions, the steel was compared to another one impurity free. Reduction in area of the samples tensile tested to the fracture was taken as a measure of the hot ductility. The tests were carried out at temperatures ranging from 1000 degree centigree to 650 degree centigree and at a strain rate of 1.10-3 s-1. The fracture surfaces of the tested samples were observed by scanning electron microscopy in order to determine the embrittling mechanisms that could be acting. The steel with residuals and impurities exhibited lower ductility values for a wider temperature range than the clean steel. The embrittling mechanisms also changed as compared to the impurity free steel. (Author)

  4. Outcome of impact disruption of iron meteorites at room temperature

    Science.gov (United States)

    Katsura, T.; Nakamura, A.; Takabe, A.; Okamoto, T.; Sangen, K.; Hasegawa, S.; Liu, X.; Mashimo, T.

    2014-07-01

    The iron meteorites and some M-class asteroids are generally understood to originate in the cores of differentiated planetesimals or in the local melt pools of primitive bodies. On these primitive bodies and planetesimals, a wide range of collisional events at different mass scales, temperatures, and impact velocities would have occurred. Iron materials have a brittle-ductile transition at a certain temperature, which depends on metallurgical factors such as grain size and purity, and on conditions such as strain-rate and confining pressure [1]. An evolutional scenario of iron meteorite parent bodies was proposed in which they formed in the terrestrial planet region, after which they were scattered into the main belt by collisions, Yarkovsky thermal forces, and resonances [2]. In this case, they may have experienced collisional evolution in the vicinity of the Earth before they were scattered into the main belt. The size distribution of iron bodies in the main belt may therefore have depended on the disruption threshold of iron bodies at temperature above the brittle-ductile transition. This paper presents the results of impact-disruption experiments of iron meteorite and steel specimens mm-cm in size as projectiles or targets conducted at room temperature using three light-gas guns and one powder gun. Our iron specimens were almost all smaller in size than their counterparts (as targets or projectiles, respectively). The fragment size distribution of iron material was different from that of rocks. In iron fragmentation, a higher percentage of the mass is concentrated in larger fragments, i.e., the mass fraction of fine fragments is much less than that of rocks shown in the Figure (left). This is probably due to the ductile nature of the iron materials at room temperature. Furthermore, the Figure (right) shows that the largest fragment mass fraction f is dependent not only on the energy density but also on the size of the specimens. In order to obtain a generalized

  5. Structure Distribution in Precise Cast Iron Moulded on Meltable Model

    Directory of Open Access Journals (Sweden)

    Skrbek B.

    2015-12-01

    Full Text Available Topic of this work is to compare metalurgy of cast irons poured into sand moulds and into shell molds at IEG Jihlava company and from it following differencies in structures of thin- and thick-walled castings. This work is dealing with investigation and experimental measurement on surfaces and sections suitable thin- and thick-walled investment castings at IEG Jihlava. Cast irons with flake graphite (grey cast iron and cast irons with spheroidal graphite (ductile cast iron. Both mechanical and physical properties are determined using calculations from as measured values of wall thicknesses L and Lu, Vickers hardness and remanent magnetism. Measurement results are discussed, findings are formulated and methods for castings metallurgical quality improvement are recommended finally.

  6. Numerical simulations of material mismatch and ductile crack growth

    Energy Technology Data Exchange (ETDEWEB)

    Oestby, Erling

    2002-07-01

    Both the global geometry and inhomogeneities in material properties will influence the fracture behaviour of structures in presence of cracks. In this thesis numerical simulations have been used to investigate how some aspects of both these issues affect the conditions at the crack-tip. The thesis is organised in an introduction chapter, summarising the major findings and conclusions, a review chapter, presenting the main aspects of the developments in the field of fracture mechanics, and three research papers. Paper I considers the effect of mismatch in hardening exponent on the local near-tip stress field for stationary interface cracks in bi-materials under small scale yielding conditions. It is demonstrated that the stress level in the weaker material increases compared to what is found in the homogeneous material for the same globally applied load level, with the effect being of increasing importance as the crack-tip is approached. Although a coupling between the radial and angular dependence of the stress fields exists, the evolving stress field can still be normalised with the applied J. The effect on the increase in stress level can closely be characterised by the difference in hardening exponent, {delta}n, termed the hardening mismatch, and is more or less independent of the absolute level of hardening in the two materials. Paper II and Ill deal with the effects of geometry, specimen size, hardening level and yield stress mismatch in relation to ductile crack growth. The ductile crack growth is simulated through use of the Gurson model. In Paper H the effect of specimen size on the crack growth resistance is investigated for deep cracked bend and shallow cracked tensile specimens. At small amounts of crack growth the effect of specimen size on the crack growth resistance is small, but a more significant effect is found for larger amounts of crack growth. The crack growth resistance decreases in smaller specimens loaded in tension, whereas the opposite is

  7. Comprehensive Understanding of Ductility Loss Mechanisms in Various Steels with External and Internal Hydrogen

    Science.gov (United States)

    Takakuwa, Osamu; Yamabe, Junichiro; Matsunaga, Hisao; Furuya, Yoshiyuki; Matsuoka, Saburo

    2017-11-01

    Hydrogen-induced ductility loss and related fracture morphologies are comprehensively discussed in consideration of the hydrogen distribution in a specimen with external and internal hydrogen by using 300-series austenitic stainless steels (Types 304, 316, 316L), high-strength austenitic stainless steels (HP160, XM-19), precipitation-hardened iron-based super alloy (A286), low-alloy Cr-Mo steel (JIS-SCM435), and low-carbon steel (JIS-SM490B). External hydrogen is realized by a non-charged specimen tested in high-pressure gaseous hydrogen, and internal hydrogen is realized by a hydrogen-charged specimen tested in air or inert gas. Fracture morphologies obtained by slow-strain-rate tensile tests (SSRT) of the materials with external or internal hydrogen could be comprehensively categorized into five types: hydrogen-induced successive crack growth, ordinary void formation, small-sized void formation related to the void sheet, large-sized void formation, and facet formation. The mechanisms of hydrogen embrittlement are broadly classified into hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP). In the HEDE model, hydrogen weakens interatomic bonds, whereas in the HELP model, hydrogen enhances localized slip deformations. Although various fracture morphologies are produced by external or internal hydrogen, these morphologies can be explained by the HELP model rather than by the HEDE model.

  8. Evaluation of Floor Response Spectrum considering Ductility of Structure

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junhee; Choi, In-Kil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    The FRS (floor response spectrum) is directly influenced by the behavior of structure under the seismic load. If the structure is nonlinear range, the energy dissipation will be occurred by the damage of structure and the maximum force will be reduced. In Zion method, the inelastic energy abortion factor has been used to consider the nonlinearity of structure. This factor was used for the seismic fragility of structure. For the seismic fragility of equipment, the uncertainty of this factor was used differently according to the story level. But this method is not warranted under the strong earthquake leads to the structural damage. Therefore it is needed to evaluate the FRS considering the nonlinear behavior of structure and to assessment the conservatism related to nonlinear behavior of structure in FRS. In this study, the nonlinear analysis was performed for the conservatism of FRS under the damage of structure. The conservatism of FRS by the nonlinear analysis was compared by that proposed by the Zion method. The conservatism of floor acceleration response for the equipment was evaluated by performing the nonlinear analysis. From the nonlinear analysis results, it was showed that the median and β{sub c} of FRSR was increased with the ductility of structure and the response of equipment had the resonance effect between the frequency of equipment and structure. The seismic capacity of equipment by the Zion method can be different from the real seismic capacity of equipment because the inelastic structure response factor has nothing to do with the ductility of structure. Therefore the median and COV for FRSR should be defined considering the ductility of structure and the frequency of equipment for more exactly evaluating the seismic capacity of equipment.

  9. Temperature measurement during solidification of thin wall ductile cast iron. Part 2: Numerical simulations

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Temperature measurements in castings are carried out with thermocouples (TC’s), which are inserted in the melt. The TC influence solidification of the casting, especially in thin wall castings where the heat content of the melt is small compared to the cooling power of the TC. A numerical analysis...... of factors influencing temperature measurement in thin walled castings was carried out. The calculations are based on and compared with experiments presented in part 1 of this paper. The analysis shows that the presence of the TC has only a minor influence on the microstructure of the casting. The influence...... is restricted to a volume within 2mm from the TC. Measured cooling curves will have the right shape. In a 2 mm plate the measured temperature was 17 °C below the true temperature in the melt. However, the cooling curve provides important information about nucleation and growth during solidification....

  10. Quantification of Feeding Effects of Spot Feeding Ductile Iron Castings made in Vertically Parted Moulds

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Tiedje, Niels Skat; Sällström, J.

    In vertically parted molds it is traditionally difficult to feed heavy sections that cannot be reached by traditional side/top feeders or other conventional methods. This project aims at quantifying the effects of using molded-in ram-up spot feeders as a means of feeding isolated sections in cast...

  11. Modeling the elastic behavior of ductile cast iron including anisotropy in the graphite nodules

    DEFF Research Database (Denmark)

    Andriollo, Tito; Thorborg, Jesper; Hattel, Jesper Henri

    2016-01-01

    by means of a 3D periodic unit cell model. In this respect, an explicit procedure to enforce both periodic displacement and periodic traction boundary conditions in ABAQUS is presented, and the importance of fulfilling the traction continuity conditions at the unit cell boundaries is discussed. It is shown...

  12. Texture evaluation in ductile fracture process by neutron diffraction measurement

    Science.gov (United States)

    Sunaga, H.; Takamura, M.; Ikeda, Y.; Otake, Y.; Hama, T.; Kumagai, M.; Suzuki, H.; Suzuki, S.

    2016-08-01

    A neutron diffraction measurement was performed to reveal microstructural aspects of the ductile fracture in ferritic steel. The diffraction patterns were continuously measured at the center of the reduced area while a tensile specimen was loaded under tension until the end of the fracture process. The measurement results showed that the volume fraction of (110)-oriented grains increased when the texture evolved as a result of plastic deformation. But the mechanism of texture evolution may be changed during necking, decreasing an increase rate of the volume fraction.

  13. Localized ductile deformation in the Rieserferner Pluton (Eastern Alps)

    Science.gov (United States)

    Ceccato, Alberto; Pennacchioni, Giorgio

    2017-04-01

    In the Rieserferner Pluton (Eastern Alps, 32±0.2 Ma, Romer et al., 2003) the post-magmatic cooling and exhumation stages were accompanied by a series of solid-state deformations including jointing, quartz veining, dyke emplacement, localized (cm-dm) ductile shearing and brittle-ductile faulting. The earliest stage of post-magmatic deformation includes the formation of pervasive steeply-dipping joints mainly arranged in two "conjugate" sets striking respectively E-W and NW-SE. These joints were extensively intruded by synkinematic aplite-pegmatite dykes and by quartz veins. Joints, veins and (locally) dikes were exploited as strike-slip ductile shear zones consistently with a WNW-ESE shortening. The mylonitized quartz veins are relatively coarse grained (mm-grain size) and show dominant dynamic recrystallization by grain boundary migration. A later set of joints is shallowly dipping E and is also commonly filled with quartz (and local epidote) veins. Ductile shearing of these vein-filled joints resulted in localized tonalite mylonites and quartz mylonites with a top-to-east kinematics. The quartz mylonites are fine grained (10-20 μm grain size) and resulted from dominant subgrain rotation recrystallization. The foliation of associated tonalite mylonites is marked by biotite+plagioclase+white mica+epidote±sphene±garnet. The "high-temperature" mylonites are crosscut by swarms of steeply-dipping fractures and faults striking N-S and showing a characteristic anastomosing-irregular pattern. These fractures are clustered in zones as large as 10 m and are associated with veins filled with calcite+white mica and with basic dykes (dated at 26 Ma: Steenken et al., 2000). Fluid-rock interactions along these fractures induced weakening and development of local low-temperature mylonites, where deformation mechanisms included pressure-solution and low-temperature plasticity of quartz. The orientation and kinematics of E-dipping mylonites and later low-temperature mylonites

  14. Ductility and Ultimate Capacity of Prestressed Steel Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Chengquan Wang

    2017-01-01

    Full Text Available Nonlinear numerical analysis of the structural behaviour of prestressed steel reinforced concrete (PSRC beams was carried out by using finite element analysis software ABAQUS. By comparing the load-deformation curves, the rationality and reliability of the finite element model have been confirmed; moreover, the changes of the beam stiffness and stress in the forcing process and the ultimate bearing capacity of the beam were analyzed. Based on the model, the effect of prestressed force, and H-steel to the stiffness, the ultimate bearing capacity and ductility of beam were also analyzed.

  15. Iron refractory iron deficiency anemia

    Science.gov (United States)

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

  16. Influence of molding sand on the number of grains graphite and on the rate of thin ferrite in pieces in a nodular iron ferritic matrix

    Directory of Open Access Journals (Sweden)

    B. Khatemi

    2010-07-01

    Full Text Available The nodular cast irons are characterized by high mechanical properties compared to cast iron with lamellar graphite or vermiculargraphite. The ductile iron has already been the subject of many studies especially since the literature is rich on them, and sources of information are different. The fact is that the mechanical properties of nodular cast iron (FGS depend on the number of graphitegrains, their roundness, the solidification rate and nature of the matrix [3]. Many studies of nodular cast irons showed that the morespherical particles of graphite, the higher the mechanical properties are high. In gray cast irons, the graphite spheroids have anticrackingand give the ductile iron ductility. Note in this connection that the higher the number of graphite grains, the higher theductile iron has better mechanical properties. In cast iron, the nature of the matrix is depending on several parameters including thecooling rate of molten metal, the thickness, shape and dimensions of parts. The faster cooling is slow over rate of ferrite is important[3, 4]. In this paper, we tested three types of sand casting: sand –based sodium silicate, furan resin and green sand on samplesspherical graphite cast iron of different thickness. The objective in this article is to determine the number of grains of graphite andferrite for each type of sand casting under the same experimental conditions including the cooling rate and chemical composition ofthe liquid metal.

  17. Solidification of cast iron - A study on the effect of microalloy elements on cast iron

    DEFF Research Database (Denmark)

    Moumeni, Elham

    , nodule count and fraction of solid phases) have shown a good agreement with experimental studies; following this, inoculation parameters in the model have been studied and discussed. The effect of Ti and S on the microstructure of grey iron is studied. Optical and electron microscopy are used to examine...... inoculants in four different thicknesses has been produced and studied; chemical analysis, metallographic investigation and thermal analysis of the specimens have been carried out. A numerical model for solidification of ductile iron has been implemented and the results (i.e. cooling curve, cooling rate...... (~10µm) at low (0.012 wt%) as well as at high S contents. Ti also caused increased segregation in the microstructure of the analysed irons and larger eutectic grains (cells). The inclusions have been identified in an effort to explain the nucleation of the phases of interest. The reasons for increase...

  18. Crack and fracture behaviour in tough ductile materials

    International Nuclear Information System (INIS)

    Venter, R.D.; Hoeppner, D.W.

    1985-10-01

    The report describes various approaches and developments pertaining to the understanding of crack and fracture behaviour in tough ductile materials. The fundamental elastic fracture mechanics concepts based on the concepts of energy, stress field, and displacement are introduced and their interrelationships demonstrated. The extension of these concepts to include elasto-plastic fracture mechanics considerations is reviewed in the context of the preferred options available for the development of appropriate design methodologies. The recommendations of the authors are directed towards the continued development of the J-integral concept. This energy-based concept, in its fundamental form, has a sound theoretical basis and as such offers the possibility of incorporating elasto-plastic fracture mechanics considerations in the crack and fracture behaviour of tough ductile materials. It must however be emphasized that the concise defintion of J becomes increasingly suspect as the crack length increases. J is not a material property, as is J IC , but emerges as a useful empirical parameter which is dependent upon the particular geometry and the loading imposed on the structure. It is proposed that 'lowest bound' J-resistance curves and the associated J-T curves be experimentally developed and employed in the design process. Improvements to these 'lowest bounds' can be developed through extensive analysis of the twin J-CTOA criteria and validation of this approach through near full scale tests

  19. Analysis of ductile crack growth by a simple damage model

    International Nuclear Information System (INIS)

    Zhang, Ch.; Gross, D.

    1993-01-01

    A strip damage-zone model of the Dugdale-Barenblatt-model type is presented in this paper for analyzing crack growth in ductile materials with damage evolution. In particular, a semi-infinite Mode-1 crack in plane stress or plane strain is considered. The damage is assumed to be present in form of dispersed microvoids, which are localized into a narrow strip direct ahead of a crack-tip. This configuration approximates the real situation naturally arising due to the high stress and strain concentrations in the proximity of the crack-tip. A simple damage model of the Gurson-model type is developed for uniaxial tension to describe the macroscopic properties of the strip damage-zone. Under small-scale yielding and small-scale damage conditions, a system of nonlinear integral equations for the plastic strain and the length of the damage-zone is derived. Numerical results are presented and discussed for the crack opening displacement, the stress and damage distribution within the plastic/damage zone, and the crack resistance curve. Special attention is devoted to reveal the effect of damage evolution on the ductile crack growth

  20. Ductility of aluminium alloy AA7075 at high strain rates

    Energy Technology Data Exchange (ETDEWEB)

    El-Magd, E.; Brodmann, M. [Technische Hochschule Aachen (Germany). Dept. of Mater. Sci.

    2000-09-01

    Under dynamic loading the stabilising effect of increased strain rate sensitivity of the material restrains neck formation in tension tests and leads to an increase in ductility. On the other hand the adiabatic character of the deformation process reduces the flow stress and promotes instability, localisation and adiabatic shear band initiation. Furthermore, the notch sensitivity of the material increases with increasing strain rate. Dynamic and quasi-static tension and compression tests were carried out on the age hardenable aluminium wrought alloy AA7075. There, dispers distributed precipitations are often the starting point for ductile fracture caused by impact due to the nucleation, growth and coalescence of voids and micro-cracks in case of tension. Neck formation under tensile loading and instabilities like shear bands in case of compression are discussed on the basis of the theory of imperfection under consideration of the increased strain rate sensitivity of the material and the adiabatic character of the deformation process at high strain rates. In case of tensile loading, tests with various notched geometries allowed the study of the influence of degree of multiaxiality. Through combination of experiment and simulation, the influence of strain rate on the local fracture strain could be determined for tensile and compression loading. (orig.)

  1. The effects of steel fibre reinforced concrete on system ductility

    Directory of Open Access Journals (Sweden)

    Yilmaz, U. S.

    2007-03-01

    Full Text Available Steel fibre-reinforced concrete is being used extensively today in both field applications and experimental studies on concrete strength and ductility. The state of passive confinement generated by the fibre delays cracking and enhances ductility. The present paper reports on both experimental and analytical studies. In the former, a series of 16 steel-fibre reinforced concrete prismatic specimens were subjected to axial loads and the respective axial load-unit strain diagrams were subsequently plotted to determine the effect of steel fibres on reinforced concrete column ductility. Secondly, an analytical study was run to determine the additional ductility accruing to a frame system when steel fibres are included in the concrete. Analytical models were generated for 16 two-storey, single-span reinforced concrete frames. The columns in these frames were designed to the same characteristics as the specimens used in the experimental tests. Non-linear static (pushover analyses were performed for each frame to obtain load-displacement curves and determine the effect of steel fibres on reinforced concrete column ductility.El hormigón reforzado con fibra de acero se emplea actualmente tanto en obra como en los trabajos experimentales para estudiar la resistencia mecánica y ductilidad del hormigón. El estado de confinamiento pasivo producido por la fibra retrasa la fisuración y aumenta la ductilidad. El presente trabajo es de índole tanto experimental como analítica. En primer lugar, en la parte experimental se aplica una fuerza axial a 16 probetas prismáticas (160 x 160 x 840 mm de hormigón reforzado con fibra de acero para determinar su comportamiento, obteniéndose las curvas de fuerza axial-deformación unitaria correspondientes a partir de los resultados observados. A partir de una evaluación de dichos resultados experimentales, se determina el efecto que ejercen las fibras de acero sobre la ductilidad de las probetas de hormigón armado

  2. Clean iron production and machining technology. Year 1 summary report, January 1--December 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-05

    The first phase of this project was conducted to develop a technique for evaluating the machinability of gray and ductile iron. That technique was then used to measure the machinability of a variety of irons and determine the processing factors that influenced and controlled machinability. The procedure developed to evaluate machinability involved drilling holes with a feed rate of 0.009 in/rev at various surface speeds. High speed steel drills were used so wear was observed more quickly. Microcarbides present in the irons were found to dominate the machinability. Pearlitic irons considered to have ``acceptable`` machinability (indicated either by tool life measured in the laboratory using high speed steel (HSS) drills or reports from commercial machine shops using other cutters) were found to contain from 8.9 to 10.5% by weight microscopic carbides. The tool wear rate increased when machining at higher surface speeds or machining irons containing higher weight percentage of microcarbides. All irons containing above 11.5% microcarbides consistently exhibited poor machinability. Tool wear results obtained using cubic boron nitride (CBN) cutters paralleled those obtained with HSS. Higher iron microcarbide concentrations produced faster tool wear. Experiments are now being formulated to explore methods of improving iron machinability. Future work will extend the study to ductile irons.

  3. Ductile fracture assessment using parameters from small specimens

    Energy Technology Data Exchange (ETDEWEB)

    Talja, H. [VTT Manufacturing Technology, Espoo (Finland)

    1998-12-31

    The topic of this thesis is the computational aspects in the assessment of ductile failure in metals. The first part briefly describes the micromechanics of ductile crack growth and methods for assessing it. The `classic` approach to describe material behaviour using fracture mechanics is summarised. The limitations of the one parameter approach based on the stress intensity factor K or the J- integral are described. Attempts to extend the application field of fracture mechanics parameters by introducing triaxility or constraint parameters are also presented. Different local approach methodologies are summarised. Special attention is paid to the modified Gurson model, which is based on micro-mechanical studies of void initiation, growth and coalescence. The main part of the work consists of numerical analyses with the modified Gurson model. The parameters of the model are first determined by matching tensile test results by finite element analysis, and then applied to J-R curve prediction. This methodology is applied to several reactor pressure vessel materials: A533B, 20 MnMoNi 5 5 and austenitic VVER 440 cladding. As a result, the applicability of different specimen types for the parameter determination of the modified Gurson model has been evaluated. Because a combination of experimental and numerical work is needed, it proved to be most feasible to use specimens which can be simulated with two-dimensional or axisymmetric finite element models. Further, a practical way to treat anisotropic material behaviour using the modified Gurson model by using separate parameter sets for different orientations has been proposed and verified. The correspondence between the observed scatters in tensile and fracture mechanical test results has been examined. Best agreement was obtained fitting the scatter of tensile tests by varying the values of initial parameters. Reasons for apparently higher ductility measured from sub-sized than standard size tensile specimens were

  4. Ductile Binder Phase For Use With Almgb14 And Other Hard Ceramic Materials

    Science.gov (United States)

    Cook, Bruce A.; Russell, Alan; Harringa, Joel

    2005-07-26

    This invention relates to a ductile binder phase for use with AlMgB14 and other hard materials. The ductile binder phase, a cobalt-manganese alloy, is used in appropriate quantities to tailor good hardness and reasonable fracture toughness for hard materials so they can be used suitably in industrial machining and grinding applications.

  5. Cast iron - a predictable material

    Directory of Open Access Journals (Sweden)

    Jorg C. Sturm

    2011-02-01

    Full Text Available High strength compacted graphite iron (CGI or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings. The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation. Depending on the alloy poured, different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting. Therefore, it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields. To be able to quantitatively predict these defects, solidification simulation had to be combined with density and mass transport calculations, in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges. For cast iron foundries, the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes, especially since the influence of alloying elements, melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron. This allows the prediction of local structures, phases and ultimately the local mechanical properties of cast irons, to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting. Casting quality issues related to thermally driven

  6. The ductile/brittle transition provides the critical test for materials failure theory

    Science.gov (United States)

    Christensen, Richard M.

    2018-02-01

    It is reasoned that any materials failure theory that claims generality must give full account of ductile versus brittle failure behaviour. Any such proposed theory especially must admit the capability to generate the ductile/brittle transition. A derivation of the failure surface orientations from a particular isotropic materials failure theory reveals that uniaxial tension has its ductile/brittle transition at T/C = 1/2, where T and C are the uniaxial strengths. Between this information and the corresponding ductile/brittle transition in uniaxial compression it becomes possible to derive the functional form for the fully three-dimensional ductile/brittle transition. These same general steps of verification must be fulfilled for any other candidate general failure theory.

  7. Development of Flexible Link Slabs using Ductile Fiber Reinforced Concrete

    DEFF Research Database (Denmark)

    Lárusson, Lárus Helgi

    Civil engineering structures with large dimensions, such as multi-span bridges, overpasses and viaducts, are typically equipped with mechanical expansion joints. These joints allow the individual spans of the structure to undergo unrestrained deformations due to thermal expansions and load......, it is suggested to replace the mechanical expansion joint and implement a flexible, precast ductile concrete link slab element between simply supported bridge spans. To design and analyze the suggested link slab element, each constituent of the element, i.e. the structural reinforcement and the cementitious...... and under cyclic loading. The findings from the investigations on bond-slip, tension stiffening and tension strengthening are used in Chapter 5 as inputfor the design and analysis of the loaddeformation response and the crack development of a prefabricated flexible link slab elements potentially connecting...

  8. Modelling of damage development and ductile failure in welded joints

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    This thesis focuses on numerical analysis of damage development and ductile failure in welded joints. Two types of welds are investigated here. First, a study of the localization of plastic flow and failure in aluminum sheets, welded by the relatively new Friction Stir (FS) Welding method, has been...... conducted ([P1], [P2], [P7]-[P9]). The focus in the thesis is on FS-welded 2xxx and 6xxx series of aluminum alloys, which are attractive, for example, to the aerospace industry, since the 2024 aluminum in particular, is typically classified as un-weldable by conventional fusion welding techniques. Secondly......, a study of the damage development in Resistance SpotWelded joints, when subject to the commonly used static shear-lab or cross-tension testing techniques, has been carried out ([P3]-[P6]). The focus in thesis is on the Advanced High Strength Steels, Dual-Phase 600, which is used in for example...

  9. Appreciation of Triaxiality Influence in Plastic Deformation Accompanying Ductile Rupture

    Science.gov (United States)

    Coseru, Ancuta-Ioana; Zichil, Valentin; Lupascu, Stefan

    2017-12-01

    In this paper, the authors propose a studying method for the deformation that appears before crack of ductile materials using the Lode parameter determined by the numerical calculation applied on simple models, verified in previous studies. In order to highlight the influence of the Lode parameter, the tests were performed at simple but also at compound tests. The necessity of these studies lies in the fact that the acknowledged models (the use of the integral J, the critical stress intensity factor Kc or the CPCD method) do not fully explain the phenomenon of deformation before breaking the elasto-plastic materials. The tests were imagined under the form of sets. Each set of tests was performed on smooth specimens and on specimens with a notch radius of 0.5, 2, 4 and 10 mm. Also, each set of tests was performed for pure tensile and combined tensile-torque test.

  10. Statistics of ductile fracture surfaces: the effect of material parameters

    DEFF Research Database (Denmark)

    Ponson, Laurent; Cao, Yuanyuan; Bouchaud, Elisabeth

    2013-01-01

    distributed. The three dimensional analysis permits modeling of a three dimensional material microstructure and of the resulting three dimensional stress and deformation states that develop in the fracture process region. Material parameters characterizing void nucleation are varied and the statistics......The effect of material parameters on the statistics of fracture surfaces is analyzed under small scale yielding conditions. Three dimensional calculations of ductile crack growth under mode I plane strain, small scale yielding conditions are carried out using an elastic-viscoplastic constitutive...... of the resulting fracture surfaces is investigated. All the fracture surfaces are found to be self-affine over a size range of about two orders of magnitude with a very similar roughness exponent of 0.56 ± 0.03. In contrast, the full statistics of the fracture surfaces is found to be more sensitive to the material...

  11. Effect of inclusion density on ductile fracture toughness and roughness

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Ponson, L.; Osovski, S.

    2014-01-01

    that result in void nucleation at an early stage are modeled discretely while smaller particles that require large strains to nucleate voids are homogeneously distributed. Full field solutions are obtained for eight volume fractions, ranging from 1% to 19%, of randomly distributed larger inclusions. For each...... on the inclusion volume fraction. Consideration of the full statistics of the fracture surface roughness revealed other parameters that vary with inclusion volume fraction. For smaller values of the discretely modeled inclusion volume fraction (≤7%), there is a linear correlation between several measures......Three dimensional calculations of ductile fracture under mode I plane strain, small scale yielding conditions are carried out using an elastic-viscoplastic constitutive relation for a progressively cavitating solid with two populations of void nucleating second phase particles. Larger inclusions...

  12. A multi-surface plasticity model for ductile fracture simulations

    Science.gov (United States)

    Keralavarma, Shyam M.

    2017-06-01

    The growth and coalescence of micro-voids in a material undergoing ductile fracture depends strongly on the loading path. Void growth occurs by diffuse plasticity in the material and is sensitive to the hydrostatic stress, while void coalescence occurs by the localization of plastic deformation in the inter-void ligaments under a combination of normal and shear stresses on the localization plane. In this paper, a micromechanics-based plasticity model is developed for an isotropic porous material, accounting for both diffuse and localized modes of plasticity at the micro-scale. A multi-surface approach is adopted, and two existing plasticity models that separately account for the two modes of yielding, above, are synthesized to propose an effective isotropic yield criterion and associated state evolution equations. The yield criterion is validated by comparison with quasi-exact numerical yield loci computed using a finite elements based limit analysis procedure. It is shown that the new criterion is in better agreement with the numerical loci than the Gurson model, particularly for large values of the porosity for which the loading path dependence of the yield stress is well predicted by the new model. Even at small porosities, it is shown that the new model predicts marginally lower yield stresses under low triaxiality shear dominated loadings compared to the Gurson model, in agreement with the numerical limit analysis data. Predictions for the strains to the onset of coalescence under proportional loading, obtained by numerically integrating the model, indicate that void coalescence tends to occur at relatively small plastic strain and porosity levels under shear dominated loadings. Implications on the prediction of ductility using the new model in fracture simulations are discussed.

  13. Fracture mechanisms in multilayer phosphorene assemblies: from brittle to ductile.

    Science.gov (United States)

    Liu, Ning; Hong, Jiawang; Zeng, Xiaowei; Pidaparti, Ramana; Wang, Xianqiao

    2017-05-24

    The outstanding mechanical performance of nacre has stimulated numerous studies on the design of artificial nacres. Phosphorene, a new two-dimensional (2D) material, has a crystalline in-plane structure and non-bonded interaction between adjacent flakes. Therefore, multi-layer phosphorene assemblies (MLPs), in which phosphorene flakes are piled up in a staggered manner, may exhibit outstanding mechanical performance, especially exceptional toughness. Therefore, molecular dynamics simulations are performed to study the dependence of the mechanical properties on the overlap distance between adjacent phosphorene layers and the number of phosphorene flakes per layer. The results indicate that when the flake number is equal to 1, a transition of fracture patterns is observed by increasing the overlap distance, from a ductile failure controlled by interfacial friction to a brittle failure dominated by the breakage of covalent bonds inside phosphorene flakes. Moreover, the failure pattern can be tuned by changing the number of flakes in each phosphorene layer. The results imply that the ultimate strength follows a power law with the exponent -0.5 in terms of the flake number, which is in good agreement with our analytical model. Furthermore, the flake number in each phosphorene layer is optimized as 2 when the temperature is 1 K in order to potentially achieve both high toughness and strength. Moreover, our results regarding the relations between mechanical performance and overlap distance can be explained well using a shear-lag model. However, it should be pointed out that increasing the temperature of MLPs could cause the transition of fracture patterns from ductile to brittle. Therefore, the optimal flake number depends heavily on temperature to achieve both its outstanding strength and toughness. Overall, our findings unveil the fundamental mechanism at the nanoscale for MLPs as well as provide a method to design phosphorene-based structures with targeted properties

  14. Development of ductile high-strength chromium alloys, phase 2

    Science.gov (United States)

    Filippi, A. M.

    1973-01-01

    Strength and ductility were evaluated for chromium alloys dispersion hardened with the putative TaC, TaB, CbC, and CbB compounds. TaC and TaB proved to be the most potent strengtheners, but when combined, their effect far outweighed that produced individually. Tests at 1422 K (2100 F) on an alloy containing these two compounds at the combined level of 0.5 m/o revealed a 495 MN/sq m (70 ksi) tensile strength for wrought material, and a 100 hour rupture strength of 208 MN/sq m (30 ksi) when solution annealed and aged to maximize creep resistance. These levels of high temperature strength greatly exceed that reported for any other chromium-base alloy. The ductile-to-brittle transition temperature (DBTT) of the two phase strengthened alloy occurred at approximately 588 K (600 F) when heat treated to optimize creep strength and was not improved by fabrication to produce a wrought and recovered microstructure. The lowest DBTT measured on any of the alloys investigated was 422 K (300 F). Strengthening phases actually formed in Cr-Ta-B and Cr-Cb-B compositions are probable M2CrB2 (M=Ta or Cb) compounds of tetragonal crystal structure. The likely habit relationship between these compounds and chromium is postulated. Cube habit coherency was identified for TaC precipitation in chromium by electron microscopy. In another study, the maximum solubility of carbon in chromium was indicated to lie between 3/4 and 1 a/o and that of boron to be 1/2 a/o.

  15. Neoarchean ductile deformation in the Northeastern North China Craton: The Shuangshanzi ductile shear zone in Qinglong area, eastern Heibei, China

    Science.gov (United States)

    Liu, Boran; Neubauer, Franz; Liu, Junlai; Jin, Wei; Li, Weimin; Liang, Chenyue

    2017-04-01

    Archean granitic gneiss domes and greenstone belts are well-preserved in eastern NCC, one of the oldest Archean terrains in the world. The Shuangshanzi ductile shear zone in Qinglong, eastern Hebei Province is located between an Archean granitic gneiss dome and a greenstone belt within an uplift in eastern NCC. Supracrustal rocks from the Neoarchean Shuangshanzi and Zhuzhangzi Groups were sheared, but some Archean granitic gneisses were also involved in the shearing along the eastern margin. In the southern part, the narrow NE-trending shear zone dips NW with dip angles of 40-60° and, in the northern part, the shear zone dips NWN with dip angles of 70-85°. Microstructural and EBSD fabric analyses suggest that the shear zone was developed at upper greenschist facies to lower amphibolite facies conditions with deformation temperatures of 400 to 550°C.LA-ICP-MS zircon U-Pb ages of mylonitized granitic rocks and undeformed quartz diorite cutting the shear zone suggest that the Shuangshanzi ductile shear zone was formed between 2550 Ma and 2452 Ma. Detailed kinematic studies of the shear zone show a clear sinistral shear sense with a slightly oblique-slip component in the northern part and a sinistral transtensional slip component in the southern part. It is therefore suggested that the shear zone was formed during the Anziling doming with respect to the down-slipping Neoarchean Shuangshanzi and Zhuzhangzi Groups. The difference in kinematics along the southern and the northern sections is interpreted to be caused by the doming with an uneven clockwise spiral rotation. The BIF-rich supracrustal rocks have higher density than their neighboring granitic gneisses, and therefore can easily sink to form synclines by sagduction processes. The sagduction is mainly triggered by gravitational inversion of high density supracrustal rocks with respect to relatively light granitic gneisses within the dome. As a result, the gneisses synchronously moved upward. A shear zone was

  16. Production of spheroidal graphite cast iron (S. G. Iron) for an automobile brake drum

    International Nuclear Information System (INIS)

    Butt, M.T.Z.; Aziz, S.

    2005-01-01

    The role of automobile industry for any country has a great importance. Break drum is one of the essential parts of automobile car and its local casting is required in order to achieve the target for automobile industry because it has special significance. Break drum being the important constituent of the system of an automobile requires a great degree of accuracy and reliability. S. G. Iron is preferred because of its mechanical properties i.e., higher strength modulus, impact resistance and ductility along with excellent machinability and manufacturing ease. (author)

  17. Synthesis of nanoparticles from malleable and ductile metals using powder-free, reactant-assisted mechanical attrition.

    Science.gov (United States)

    McMahon, Brandon W; Perez, Jesus Paulo L; Yu, Jiang; Boatz, Jerry A; Anderson, Scott L

    2014-11-26

    A reactant-assisted mechanochemical method was used to produce copious nanoparticles from malleable/ductile metals, demonstrated here for aluminum, iron, and copper. The milling media is intentionally degraded via a reactant-accelerated wear process, where the reactant aids particle production by binding to the metal surfaces, enhancing particle production, and reducing the tendency toward mechanochemical (cold) welding. The mechanism is explored by comparing the effects of different types of solvents and solvent mixtures on the amount and type of particles produced. Particles were functionalized with oleic acid to aid in particle size separation, enhance dispersion in hydrocarbon solvents, and protect the particles from oxidation. For aluminum and iron, the result is air-stable particles, but for copper, the suspended particles are found to dissolve when exposed to air. Characterization was performed using electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance, and X-ray photoelectron spectroscopy. Density functional theory was used to examine the nature of carboxylic acid binding to the aluminum surface, confirming the dominance of bridging bidentate binding.

  18. Fabrication and mechanical properties of Fe sub 3 Al-based iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; McKamey, C.G.; Howell, C.R.; Baldwin, R.H.

    1990-03-01

    Iron aluminides based on Fe{sub 3}Al are ordered intermetallic alloys that offer good oxidation resistance, excellent sulfidation resistance, and lower material cost than many stainless steels. These materials also conserve strategic elements such as chromium and have a lower density than stainless steels. However, limited ductility at ambient temperature and a sharp drop in strength have been major deterrents to their acceptance for structural applications. This report presents results on iron aluminides with room-temperature elongations of 15 to 20%. Ductility values were improved by a combination of thermomechanical processing and heat-treatment control. This method of ductility improvement has been demonstrated for a range of compositions. Melting, casting, and processing of 7-kg (15-lb) heats produced at the Oak Ridge National Laboratory (ORNL) and 70-kg (150-lb) commercial heats are described. Vacuum melting and other refining processes such as electroslag remelting are recommended for commercial heats. The Fe{sub 3}Al-based iron aluminides are hot workable by forging or extruding at temperatures in the range of 850 to 1100{degree}C. rolling at 800{degree}C is recommended with a final 50% reduction at 650{degree}C. Tensile and creep properties of 7- and 70-kg (15- and 150-lb) heats are presented. The presence of impurities such as manganese an silicon played an important role in reducing the ductility of commercially melted heats. 7 refs., 60 figs., 12 tabs.

  19. Corrosion performance of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe[sub 3]Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000[degrees]C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  20. Corrosion performance of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000{degrees}C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  1. Analytical investigation of bidirectional ductile diaphragms in multi-span bridges

    Science.gov (United States)

    Wei, Xiaone; Bruneau, Michel

    2018-04-01

    In the AASHTO Guide Specifications for Seismic Bridge Design Provisions, ductile diaphragms are identified as Permissible Earthquake-Resisting Elements (EREs), designed to help resist seismic loads applied in the transverse direction of bridges. When adding longitudinal ductile diaphragms, a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge's longitudinal and transverse axes. This paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces (BRBs) in straight multi-span bridge with simply supported floating spans. The flexibility of the substructures in the transverse and longitudinal direction of the bridge is considered. Design procedures for the bidirectional ductile diaphragms are first proposed. An analytical model of the example bridge with bidirectional ductile diaphragms, designed based on the proposed methodology, is then built in SAP2000. Pushover and nonlinear time history analyses are performed on the bridge model, and corresponding results are presented. The effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated, in order to better understand the impact on the bridge's dynamic performance.

  2. Ductility demands on buckling-restrained braced frames under earthquake loading

    Science.gov (United States)

    Fahnestock, Larry A.; Sause, Richard; Ricles, James M.; Lu, Le-Wu

    2003-12-01

    Accurate estimates of ductility demands on buckling-restrained braced frames (BRBFs) are crucial to performance-based design of BRBFs. An analytical study on the seismic behavior of BRBFs has been conducted at the ATLSS Center, Lehigh University to prepare for an upcoming experimental program. The analysis program DRAIN-2DX was used to model a one-bay, four-story prototype BRBF including material and geometric nonlinearities. The buckling-restrained brace (BRB) model incorporates both isotropic and kinematic hardening. Nonlinear static pushover and time-history analyses were performed on the prototype BRBF. Performance objectives for the BRBs were defined and used to evaluate the time-history analysis results. Particular emphasis was placed on global ductility demands and ductility demands on the BRBs. These demands were compared with anticipated ductility capacities. The analysis results, along with results from similar previous studies, are used to evaluate the BRBF design provisions that have been recommended for codification in the United States. The results show that BRB maximum ductility demands can be as high as 20 to 25. These demands significantly exceed those anticipated by the BRBF recommended provisions. Results from the static pushover and time-history analyses are used to demonstrate why the ductility demands exceed those anticipated by the recommended provisions. The BRB qualification testing protocol contained in the BRBF recommended provisions is shown to be inadequate because it requires only a maximum ductility demand of at most 7.5. Modifications to the testing protocol are recommended.

  3. The Effect of Hydrogen on the Mechanical Properties of Cast Irons and ADI with Various Carbon Equivalent and Graphite Morphology

    International Nuclear Information System (INIS)

    Cho, Yong Gi; Lee, Kyung Sub

    1989-01-01

    The effect of hydrogen on the mechanical properties of cast irons, flake, CV graphite cast iron ductile iron and ADI have been investigated. The effects of various carbon equivalent, graphite morphology and matrix have been analyzed to determine the predominant factor which influences on the hydrogen embrittlement. The effect of various carbon equivalent on the embrittlement was little in the similar graphite morphology. The embrittlement of ferrite matrix changed by heat treatment was less than that of pearlite matrix. In the case of ADI, the tendency of hydrogen embrittlement of lower bainite matrix was less remarkable than that of upper banite matrix. As the result of hydrogen charging, the tendency of interface decohesion between matrix-graphite was increased in flake G.C.I., and the trend from ductile fracture mode to brittle fracture mode was observed in CV G.C.I and ductile iron. Lower bainite in ADI showed the ductile fracture mode. Hydrogen solubility of lower bainite was higher than that of upper bainite

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron in your body causes iron-deficiency anemia. Lack of iron usually is due to blood loss, ... can help prevent overdosing in children. Because recent research supports concerns that iron deficiency during infancy and ...

  5. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, eggs, ... is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and iron- ...

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... absorb iron from the gastrointestinal tract (GI tract). Blood loss When you lose blood, you lose iron. ... other conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To ...

  7. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other dark ... of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other dark ...

  8. Iron-Deficiency Anemia

    Science.gov (United States)

    ... Home / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español ... bleeding Consuming less than recommended daily amounts of iron Iron-deficiency anemia can be caused by getting ...

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... drawings also can cause iron-deficiency anemia. Poor Diet The best sources of iron are meat, poultry, ... more likely to develop iron-deficiency anemia. Vegetarian diets can provide enough iron if you eat the ...

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... you are diagnosed with iron-deficiency anemia. Risk Factors You may have an increased risk for iron- ... iron-deficiency anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... The best sources of iron are meat, poultry, fish, and iron-fortified foods (foods that have iron ... you: Follow a diet that excludes meat and fish, which are the best sources of iron. However, ...

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... good nonmeat sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach ... good nonmeat sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach ...

  13. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... to moderate iron-deficiency anemia, or red blood cell transfusion for severe iron-deficiency anemia. You may ... body needs iron to make healthy red blood cells. Iron-deficiency anemia usually develops over time because ...

  14. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... from developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, ... iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and ...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... re more likely to develop iron-deficiency anemia. Vegetarian diets can provide enough iron if you eat ... which are the best sources of iron. However, vegetarian diets can provide enough iron if you eat ...

  16. Iron-Deficiency Anemia

    Science.gov (United States)

    ... re more likely to develop iron-deficiency anemia. Vegetarian diets can provide enough iron if you eat ... which are the best sources of iron. However, vegetarian diets can provide enough iron if you eat ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... can provide enough iron if you eat the right foods. For example, good nonmeat sources of iron ... can provide enough iron if you eat the right foods. For example, good nonmeat sources of iron ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-deficiency anemia may require treatment in a hospital, blood transfusions , iron injections, or intravenous iron therapy. ... Treatment may need to be done in a hospital. The goals of treating iron-deficiency anemia are ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... develop new therapies for conditions that affect the balance of iron in the body and lead to ... Disease Control and Prevention) Iron - Health Professional Fact Sheet (NIH) Iron Dietary Supplement Fact Sheet (NIH) Iron- ...

  20. Iron-Deficiency Anemia

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    Full Text Available ... pregnancy. Good sources of iron are meat, poultry, fish, and iron-fortified foods that have iron added. Vegetarian diets can provide enough iron if you choose nonmeat sources ...

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other ... sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... enough iron-rich foods, such as meat and fish, may result in you getting less than the ... pregnancy. Good sources of iron are meat, poultry, fish, and iron-fortified foods that have iron added. ...

  3. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-rich foods, especially during certain stages of life when more iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and iron- ...

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... for your body to absorb iron from the gastrointestinal tract (GI tract). Blood loss When you lose blood, ... iron deficiency. Endurance athletes lose iron through their gastrointestinal tracts. They also lose iron through the breakdown of ...

  5. Ductile shape memory alloys of the Cu-Al-Mn system

    International Nuclear Information System (INIS)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1995-01-01

    Cu-Al-Mn shape memory alloys with enhanced ductility have been developed by decreasing the degree of order in the β parent phase. Cu-Al-Mn alloys with Al contents lower than 18% exhibit good ductility with elongations of about 15% and excellent cold-workability arising from a lower degree of order in the Heusler (L21) β 1 parent phase, without any loss in their shape memory behavior. In this paper the mechanical and shape memory characteristics, such as the cold-workability, the Ms temperatures, the shape memory effect and the pseudo-elasticity of such ductile Cu-Al-Mn alloys are presented. (orig.)

  6. Hot ductility of structural steels melted with the use of direct reduction charge

    International Nuclear Information System (INIS)

    Marchenko, V.N.; Bulat, S.I.; Litvinenko, D.A.

    1982-01-01

    A possibility of the use of direct reduction charge during the open arc melting of the 40Kh2N2MA steel with the subsequent electroslag remelting was investigated. It is shown that the use of such charge free from non-ferrous metal admixtures permits to increase an alloy hot ductility in the hot-brittleness range from 900 up to 1500 deg C. An increase of the deformation rate from 0.1 up to 1 s - 1 increases 1.5-3 times a level of minimum ductility within this temperature range. It is established that antimony and bismuth impurities considerably decrease hot ductility

  7. Quantification of damage evolution for a micromechanical model of ductile fracture in spallation of tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, A.K.; Thissell, W.R.; Tonks, D.L.; Hixon, R.; Addessio, F.

    1997-05-01

    The authors present quantification of micromechanical features such as voids that comprise the ductile fracture obtained under uniaxial strain condition in a spall test of commercial purity tantalum. Two evolutionary parameters of ductile fracture void formation are quantified: (i) the void volume fraction (porosity) and its distribution with respect to the distance from the main spall fracture plane, and (ii) void diameter distribution. The results complement the discussion of the implications of void clustering and linking for micromechanical modeling of ductile fracture as presented in a paper by D. L. Tonks et al. in this volume.

  8. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  9. Brittleness and elastic limit of iron-aluminium 40 at high strain rates

    International Nuclear Information System (INIS)

    Cottu, J.P.

    1967-01-01

    Iron-aluminium 40 - a B2 ordered solid solution - was tensile tested to provide information on the brittleness of this alloy and its dependence on strain rate and temperature. For slow strain rates (0.34 per cent s -1 ) cleaved fracture prevails when temperature is kept below 400 deg. C, while a ductile rupture is observed, with an almost 100 per cent necking at higher temperatures. In this case, recrystallization occurs during the deformation. For higher strain rates - 335 per cent s -1 ), a ductility reduction - owed to intergranular fracture - precedes the brittle-ductile transition. This property may be bound to the peak on the yield stress temperature curve, which is itself connected to the ordered structure of this alloy. (author) [fr

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Research Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...

  11. Review on symmetric structures in ductile shear zones

    Science.gov (United States)

    Mukherjee, Soumyajit

    2017-07-01

    Symmetric structures in ductile shear zones range widely in shapes and geneses. Matrix rheology, its flow pattern, its competency contrast with the clast, degree of slip of the clast, shear intensity and its variation across shear zone and deformation temperature, and degree of confinement of clast in shear zones affects (independently) the degree of symmetry of objects. Kinematic vorticity number is one of the parameters that govern tail geometry across clasts. For example, symmetric and nearly straight tails develop if the clast-matrix system underwent dominantly a pure shear/compression. Prolonged deformation and concomitant recrystallization can significantly change the degree of symmetry of clasts. Angular relation between two shear zones or between a shear zone and anisotropy determines fundamentally the degree of symmetry of lozenges. Symmetry of boudinaged clasts too depends on competency contrast between the matrix and clast in some cases, and on the degrees of slip of inter-boudin surfaces and pure shear. Parasitic folds and post-tectonic veins are usually symmetric.

  12. Quantifying Damage Accumulation During Ductile Plastic Deformation Using Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Suter, Robert M. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Rollett, Anthony D. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2015-08-15

    Under this grant, we have developed and demonstrated the ability of near-field High Energy Diffraction Microscopy (nf-HEDM) to map crystal orientation fields over three dimensions in deformed polycrystalline materials. Experimental work was performed at the Advanced Photon Source (APS) at beamline 1-ID. Applications of this new capability to ductile deformation of copper and zirconium samples were demonstrated as was the comparison of the experimental observations to computational plasticity models using a fast Fourier transform based algorithm that is able to handle the large experimental data sets. No such spatially resolved, direct comparison between measured and computed microstructure evolutions had previously been possible. The impact of this work is reflected in numerous publications and presentations as well as in the investments by DOE and DOD laboratories of millions of dollars in applying the technique, developing sophisticated new hardware that allows the technique to be applied to a wide variety of materials and materials problems, and in the use of the technique by other researchers. In essence, the grant facilitated the development of a new form of three dimensional microscopy and its application to technologically critical states of polycrystalline materials that are used throughout the U.S. and world economies. On-going collaborative work is further optimizing experimental and computational facilities at the APS and is pursuing expanded facilities.

  13. Mechanisms for Ductile Rupture - FY16 ESC Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Boyce, Brad L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carroll, Jay D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Noell, Phillip [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bufford, Daniel Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hattar, Khalid Mikhiel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-01-01

    Ductile rupture in metals is generally a multi-step process of void nucleation, growth, and coalescence. Particle decohesion and particle fracture are generally invoked as the primary microstructural mechanisms for room-temperature void nucleation. However, because high-purity materials also fail by void nucleation and coalescence, other microstructural features must also act as sites for void nucleation. Early studies of void initiation in high-purity materials, which included post-mortem fracture surface characterization using scanning electron microscopy (SEM) and high-voltage electron microscopy (HVEM) and in-situ HVEM observations of fracture, established the presence of dislocation cell walls as void initiation sites in high-purity materials. Direct experimental evidence for this contention was obtained during in-situ HVEM tensile tests of Be single crystals. Voids between 0.2 and 1 μm long appeared suddenly along dislocation cell walls during tensile straining. However, subsequent attempts to replicate these results in other materials, particularly α -Fe single crystals, were unsuccessful because of the small size of the dislocation cells, and these remain the only published in-situ HVEM observations of void nucleation at dislocation cell walls in the absence of a growing macrocrack. Despite this challenge, other approaches to studying void nucleation in high-purity metals also indicate that dislocation cell walls are nucleation sites for voids.

  14. Low ductility creep failure in austenitic weld metals

    International Nuclear Information System (INIS)

    Thomas, R.G.

    Creep tests have been carried out for times of up to approx. 22,000 hrs on three austenitic weld metals of nominal composition 17Cr-8Ni-2Mo, 19Cr-12Ni-3Mo+Nb and 17Cr-10Ni-2Mo. The two former deposits were designed to produce delta-ferrite contents in the range 3-9% while the latter was designed to be fully austenitic. The common feature of all three weld metals was that they all gave very low strains at failure, typically approx. 1%. The microstructures of the failed creep specimens have been studied using optical and electron microscopy and the precipitate structures related to the occurrence of low creep strains. Creep deformation and fracture mechanisms in austenitic materials in general have been reviewed and this has been used as a basis for discussion of the observations of the present work. Finally, some of the factors that can be controlled to improve long-term creep ductility have been appraised

  15. A nonlinear CDM based damage growth law for ductile materials

    Science.gov (United States)

    Gautam, Abhinav; Priya Ajit, K.; Sarkar, Prabir Kumar

    2018-02-01

    A nonlinear ductile damage growth criterion is proposed based on continuum damage mechanics (CDM) approach. The model is derived in the framework of thermodynamically consistent CDM assuming damage to be isotropic. In this study, the damage dissipation potential is also derived to be a function of varying strain hardening exponent in addition to damage strain energy release rate density. Uniaxial tensile tests and load-unload-cyclic tensile tests for AISI 1020 steel, AISI 1030 steel and Al 2024 aluminum alloy are considered for the determination of their respective damage variable D and other parameters required for the model(s). The experimental results are very closely predicted, with a deviation of 0%-3%, by the proposed model for each of the materials. The model is also tested with predictabilities of damage growth by other models in the literature. Present model detects the state of damage quantitatively at any level of plastic strain and uses simpler material tests to find the parameters of the model. So, it should be useful in metal forming industries to assess the damage growth for the desired deformation level a priori. The superiority of the new model is clarified by the deviations in the predictability of test results by other models.

  16. Comparison of ductile-to-brittle transition curve fitting approaches

    International Nuclear Information System (INIS)

    Cao, L.W.; Wu, S.J.; Flewitt, P.E.J.

    2012-01-01

    Ductile-to-brittle transition (DBT) curve fitting approaches are compared over the transition temperature range for reactor pressure vessel steels with different kinds of data, including Charpy-V notch impact energy data and fracture toughness data. Three DBT curve fitting methods have been frequently used in the past, including the Burr S-Weibull and tanh distributions. In general there is greater scatter associated with test data obtained within the transition region. Therefore these methods give results with different accuracies, especially when fitting to small quantities of data. The comparison shows that the Burr distribution and tanh distribution can almost equally fit well distributed and large data sets extending across the test temperature range to include the upper and lower shelves. The S-Weibull distribution fit is poor for the lower shelf of the DBT curve. Overall for both large and small quantities of measured data the Burr distribution provides the best description. - Highlights: ► Burr distribution offers a better fit than that of a S-Weibull and tanh fit. ► Burr and tanh methods show similar fitting ability for a large data set. ► Burr method can fit sparse data well distributed across the test temperature. ► S-Weibull method cannot fit the lower shelf well and show poor fitting quality.

  17. Standard test methods for bend testing of material for ductility

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 These test methods cover bend testing for ductility of materials. Included in the procedures are four conditions of constraint on the bent portion of the specimen; a guided-bend test using a mandrel or plunger of defined dimensions to force the mid-length of the specimen between two supports separated by a defined space; a semi-guided bend test in which the specimen is bent, while in contact with a mandrel, through a specified angle or to a specified inside radius (r) of curvature, measured while under the bending force; a free-bend test in which the ends of the specimen are brought toward each other, but in which no transverse force is applied to the bend itself and there is no contact of the concave inside surface of the bend with other material; a bend and flatten test, in which a transverse force is applied to the bend such that the legs make contact with each other over the length of the specimen. 1.2 After bending, the convex surface of the bend is examined for evidence of a crack or surface irregu...

  18. Low alloy steel versus ADI – differences and similarities

    Directory of Open Access Journals (Sweden)

    A. Krzyńska

    2009-01-01

    Full Text Available The results of comparison between the microstructure of selected bainitic low alloy steel and austempered ductile iron ADI are presented. The aim of the comparison was to find out differences and similarities existing in these iron carbon commercial alloys. In this paper our own results on ADI structure and literature data were used. It follows from discussion presented here that both microstructure and properties of ADI are very close that which are observed in low alloy carbon steel. Moreover, we suggest that there is no so doubt to treat ADI mechanical properties as steel containing nodular inclusions of graphite.

  19. Neoarchean ductile deformation of the Northeastern North China Craton: The Shuangshanzi ductile shear zone in Qinglong, eastern Hebei, North China

    Science.gov (United States)

    Liu, Boran; Neubauer, Franz; Liu, Junlai; Jin, Wei; Li, Weimin; Liang, Chenyue

    2017-05-01

    Archean granitic gneiss domes and greenstone belts are well-preserved in eastern North China Craton (NCC), one of the oldest Archean terrains in the world. The Shuangshanzi ductile shear zone in Qinglong, eastern Hebei Province is located between an Archean granitic gneiss dome and a greenstone belt within an uplift in eastern NCC. Supracrustal rocks from the Neoarchean Shuangshanzi and Zhuzhangzi Groups, and some Archean granitic gneisses were involved in the shearing along the eastern margin. In the southern part, the narrow NE-trending shear zone dips NW with dip angles of 40-60° and, in the northern part, the shear zone dips NWN with dip angles of 70-85°. Microstructural and EBSD fabric analyses suggest that the shear zone was developed at upper greenschist facies to lower amphibolite facies conditions with deformation temperatures of 400-550 °C. LA-ICP-MS zircon U-Pb dating of mylonitized granitic rocks and undeformed quartz diorite cutting the shear zone suggest that the Shuangshanzi ductile shear zone was formed between 2550 Ma and 2452 Ma. Detailed kinematic studies of the shear zone show a clear sinistral shear sense with a slightly oblique-slip component in the northern part and a sinistral transtensional slip component in the southern part. It is therefore suggested that the shear zone was formed during the Anziling doming with respect to the down-slipping Neoarchean Shuangshanzi and Zhuzhangzi Groups. The difference in kinematics along the southern and the northern sections is interpreted to be caused by the doming with an uneven clockwise spiral rotation. The BIF-rich supracrustal rocks have higher density than their neighboring granitic gneisses, and therefore can easily sink to form synclines by sagduction processes. The sagduction is mainly triggered by gravitational inversion of high density supracrustal rocks with respect to relatively light granitic gneisses within the dome. As a result, the gneisses synchronously moved upward. A shear zone

  20. IRON DOME

    African Journals Online (AJOL)

    Automated precise guided missile defence has been around for some years, and is a modern-day mechanism used frequently since 2011 to defend against rocket attacks penetrating national airspace. Israel's automated Iron Dome. Missile Defence System has intercepted over 1 000 rockets during two recent.