High Power Picosecond Laser Surface Micro-texturing of H13 Tool Steel and Pattern Replication onto ABS Plastics via Injection Moulding

Science.gov (United States)

Otanocha, Omonigho B.; Li, Lin; Zhong, Shan; Liu, Zhu

2016-03-01

H13 tool steels are often used as dies and moulds for injection moulding of plastic components. Certain injection moulded components require micro-patterns on their surfaces in order to modify the physical properties of the components or for better mould release to reduce mould contamination. With these applications it is necessary to study micro-patterning to moulds and to ensure effective pattern transfer and replication onto the plastic component during moulding. In this paper, we report an investigation into high average powered (100 W) picosecond laser interactions with H13 tool steel during surface micro-patterning (texturing) and the subsequent pattern replication on ABS plastic material through injection moulding. Design of experiments and statistical modelling were used to understand the influences of laser pulse repetition rate, laser fluence, scanning velocity, and number of scans on the depth of cut, kerf width and heat affected zones (HAZ) size. The characteristics of the surface patterns are analysed. The process parameter interactions and significance of process parameters on the processing quality and efficiency are characterised. An optimum operating window is recommended. The transferred geometry is compared with the patterns generated on the dies. A discussion is made to explain the characteristics of laser texturing and pattern replication on plastics.

Milled Die Steel Surface Roughness Correlation with Steel Sheet Friction

DEFF Research Database (Denmark)

Berglund, J.; Brown, C.A.; Rosén, B.-G.

2010-01-01

This work investigates correlations between the surface topography ofmilled steel dies and friction with steel sheet. Several die surfaces were prepared by milling. Friction was measured in bending under tension testing. Linear regression coefficients (R2) between the friction and texture...

Evaluation of the mechanical properties of Niobium modified cast AISI H 13 hot work tool steel

International Nuclear Information System (INIS)

Noorian, A.; Kheirandish, Sh.; Saghafian, H.

2010-01-01

In this research, the effects of partially replacing of vanadium and molybdenum with niobium on the mechanical properties of AISIH 13 hot-work tool steel have been studied. Cast samples made of the modified new steel were homogenized and austenitized at different conditions, followed by tempering at the specified temperature ranges. Hardness, red hardness, three point bending test and Charpy impact test were carried out to evaluate the mechanical properties together with characterizing the microstructure of the modified steel using scanning electron microscope. The results show that niobium addition modifies the cast structure of Nb-alloyed steel, and increases its maximum hardness. It was found that bending strength; bending strain, impact strength, and red hardness of the modified cast steel are also higher than those of the cast H13 steel, and lower than those of the wrought H13 steel.

Effects of Rare Earth on the Microstructure and Impact Toughness of H13 Steel

OpenAIRE

Gao, Jinzhu; Fu, Paixian; Liu, Hongwei; Li, Dianzhong

2015-01-01

Studies of H13 steel suggest that under appropriate conditions, additions of rare-earth metals (REM) can significantly enhance mechanical properties, such as impact toughness. This improvement is apparently due to the formation of finer and more dispersive RE inclusions and grain refinement after REM additions. In this present work, the microstructure evolution and mechanical properties of H13 steel with rare earth additions (0, 0.015, 0.025 and 0.1 wt.%) were investigated. The grain size, ...

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Nitrogen-Alloyed High-Mn Austenitic Hot Work Die Steel

Directory of Open Access Journals (Sweden)

Yi Zhang

2017-03-01

Full Text Available In view of the requirements for mechanical properties and service life above 650 °C, a high-Mn austenitic hot work die steel, instead of traditional martensitic hot work die steel such as H13, was developed in the present study. The effect of heat treatment on the microstructure and mechanical properties of the newly developed work die steel was studied. The results show that the microstructure of the high-Mn as-cast electroslag remelting (ESR ingot is composed of γ-Fe, V(C,N, and Mo2C. V(C,N is an irregular multilateral strip or slice shape with severe angles. Most eutectic Mo2C carbides are lamellar fish-skeleton-like, except for a few that are rod-shaped. With increasing solid solution time and temperature, the increased hardness caused by solid solution strengthening exceeds the effect of decreased hardness caused by grain size growth, but this trend is reversed later. As a result, the hardness of specimens after various solid solution heat treatments increases first and then decreases. The optimal combination of hardness and austenitic grain size can be obtained by soaking for 2 h at 1170 °C. The maximum Rockwell hardness (HRC is 47.24 HRC, and the corresponding austenite average grain size is 58.4 μm. When the solid solution time is 3 h at 1230 °C, bimodality presented in the histogram of the austenite grain size as a result of further progress in secondary recrystallization. Compared with the single-stage aging, the maximum impact energy of the specimen after two-stage aging heat treatment was reached at 16.2 J and increased by 29.6%, while the hardness decreased by 1–2 HRC. After two-stage aging heat treatment, the hardness of steel reached the requirements of superior grade H13, and the maximum impact energy was 19.6% higher than that of superior grade H13, as specified in NADCA#207-2003.

Determination of type, magnitude and direction of residual stresses generated in the welding of AISI H-13 steel with the hole drilling method

International Nuclear Information System (INIS)

Mejia; I; Maldonado, C; Bedolla, A; Velez, M; Medina, A; Bejar, L

2006-01-01

AISI H-13 steel is considered to be a highly ultra resistant steel because its resistance to stress surpasses 1380 MPa. This steel is widely used in tools that heavily used, especially under high temperatures, such as: awls, molds for pressing, extrusion dies, extrusion tools from heat impact, tools for producing screws, bolts, rivets and taps, molds for centrifugal smelting, tools for presses with shaped pieces, knives for hot cutting, among others. The weldability of AISI H-13 steel is generally poor, but it is possible if the proper precautions are taken. Cracking is perhaps the factor that most limits the weldability of AISI H-13 steel. The tendency to crack during welding for this type of steel occurs in the base metal and the zone close to the supporting material (cold cracking). The interlayer covering technique is used in the repair, welding and recovery of pieces of high alloy steels in order to avoid cracking and to lower the residual stresses generated by obstructed contraction and martensitic transformation. This work defined the type, magnitude and direction of residual stresses at different distances starting from the center of the welded union on the 25.4 mm thick AISI H-13 steel sheet. The welding was carried out in a test piece with Y-Groove geometry following JIS Z 3158 standard, using the SMAW process and an AISI 312 stainless steel interlayer between the base metal and the supporting metal. The hole-drilling method was used to measure the type, magnitude and direction of residual stresses using extensometric gauge rosette CEA-06-062UM-120 and CEA-06-062RE-120 following the guidelines established by ASTM E 837 standard. Based on the relaxed deformations that were measured, the type, magnitude and direction of residual stresses were determined with the H-DRILL residual stress program for biaxial condition. The results indicate that under these welding conditions the residual strains at different distances from the welded union are from stress and

Hardness of H13 Tool Steel After Non-isothermal Tempering

Science.gov (United States)

Nelson, E.; Kohli, A.; Poirier, D. R.

2018-04-01

A direct method to calculate the tempering response of a tool steel (H13) that exhibits secondary hardening is presented. Based on the traditional method of presenting tempering response in terms of isothermal tempering, we show that the tempering response for a steel undergoing a non-isothermal tempering schedule can be predicted. Experiments comprised (1) isothermal tempering, (2) non-isothermal tempering pertaining to a relatively slow heating to process-temperature and (3) fast-heating cycles that are relevant to tempering by induction heating. After establishing the tempering response of the steel under simple isothermal conditions, the tempering response can be applied to non-isothermal tempering by using a numerical method to calculate the tempering parameter. Calculated results are verified by the experiments.

The Influence of Temperature on the Frictional Behavior of Duplex-Coated Die Steel Rubbing Against Forging Brass

Science.gov (United States)

Ebrahimzadeh, I.; Ashrafizadeh, F.

2015-01-01

Improvement of die life under hot forging of brass alloys is considered vital from both economical and technical points of view. One of the best methods for improving die life is duplex coatings. In this research, the influence of temperature on the tribological behavior of duplex-coated die steel rubbing against forging brass was investigated. The wear tests were performed on a pin-on-disk machine from room temperature to 700 °C; the pins were made in H13 hot work tool steel treated by plasma nitriding and by PVD coatings of TiN-TiAlN-CrAlN. The disks were machined from a two-phase brass alloy too. The results revealed that the friction coefficient of this tribosystem went through a maximum at 550 °C and decreased largely at 700 °C. Furthermore, the formation of Cr2O3 caused the reduction of friction coefficient at 700 °C. PVD coatings proved their wear resistance up to 550 °C, well above the working temperature of the brass forging dies.

Atomic diffusion in laser surface modified AISI H13 steel

Science.gov (United States)

Aqida, S. N.; Brabazon, D.; Naher, S.

2013-07-01

This paper presents a laser surface modification process of AISI H13 steel using 0.09 and 0.4 mm of laser spot sizes with an aim to increase surface hardness and investigate elements diffusion in laser modified surface. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, pulse repetition frequency (PRF), and overlap percentage. The hardness properties were tested at 981 mN force. Metallographic study and energy dispersive X-ray spectroscopy (EDXS) were performed to observe presence of elements and their distribution in the sample surface. Maximum hardness achieved in the modified surface was 1017 HV0.1. Change of elements composition in the modified layer region was detected in the laser modified samples. Diffusion possibly occurred for C, Cr, Cu, Ni, and S elements. The potential found for increase in surface hardness represents an important method to sustain tooling life. The EDXS findings signify understanding of processing parameters effect on the modified surface composition.

Influence of the ion nitriding temperature in the wear resistance of AISI H13 tool steel

International Nuclear Information System (INIS)

Heck, Stenio Cristaldo; Fernandes, Frederico Augusto Pires; Pereira, Ricardo Gomes; Casteletti, Luiz Carlos; Totten, George Edward

2010-01-01

The AISI H13 tool steel for hot work is the most used in its category. This steel was developed for injection molds and extrusion of hot metals as well as for conformation in hot presses and hammers. Plasma nitriding can improve significantly the surface properties of these steels, but the treatments conditions, such as temperature, must be optimized. In this work the influence of nitriding treatment temperature on the wear behavior of this steel is investigated. Samples of AISI H13 steel were quenched and tempered and then ion nitrided in the temperatures of 450, 550 and 650 deg C, at 4mbar pressure, during 5 hours. Samples of the treated material were characterized by optical microscopy, Vickers microhardness, x-ray analysis and wear tests. Plasma nitriding formed hard diffusion zones in all the treated samples. White layers were formed in samples treated at 550 deg C and 650 deg C. The treatment temperature of 450 deg C produced the highest hardness. Treatment temperature showed great influence in the diffusion layer thickness. X-ray analysis indicated the formation of the Fe_3N, Fe_4N and CrN phases for all temperatures, but with different concentrations. Nitriding increased significantly the AISI H13 wear resistance. (author)

Effect of the Ultrasonic Nanocrystalline Surface Modification (UNSM on Bulk and 3D-Printed AISI H13 Tool Steels

Directory of Open Access Journals (Sweden)

In-Sik Cho

2017-11-01

Full Text Available A comparative study of the microstructure, hardness, and tribological properties of two different AISI H13 tool steels—classified as the bulk with no heat treatment steel or the 3D-printed steel—was undertaken. Both samples were subjected to ultrasonic nanocrystalline surface modification (UNSM to further enhance their mechanical properties and improve their tribological behavior. The objective of this study was to compare the mechanical properties and tribological behavior of these tool steels since steel can exhibit a wide variety of mechanical properties depending on different manufacturing processes. The surface hardness of the samples was measured using a micro-Vickers hardness tester. The hardness of the 3D-printed AISI H13 tool steel was found to be much higher than that of the bulk one. The surface morphology of the samples was characterized by electron backscattered diffraction (EBSD in order to analyze the grain size and number of fractions with respect to the misorientation angle. The results revealed that the grain size of the 3D-printed AISI H13 tool steel was less than 0.5 μm, whereas that of the bulk tool steel was greater than 4 μm. The number of fractions of the bulk tool steel was about 0.5 μm at a low misorientation angle, and it decreased gradually with increasing misorientation angle. The low-angle grain boundary (LAGB and high-angle grain boundary (HAGB of the bulk sample were about 21% and 79%, respectively, and those of the 3D-printed sample were about 8% and 92%, respectively. Moreover, the friction and wear behavior of the UNSM-treated AISI H13 tool steel specimen was better than those of the untreated one. This study demonstrated the capability of 3D-printed AISI H13 tool steel to exhibit excellent mechanical and tribological properties for industrial applications.

Modeling the Spray Forming of H13 Steel Tooling

Science.gov (United States)

Lin, Yaojun; McHugh, Kevin M.; Zhou, Yizhang; Lavernia, Enrique J.

2007-07-01

On the basis of a numerical model, the temperature and liquid fraction of spray-formed H13 tool steel are calculated as a function of time. Results show that a preheated substrate at the appropriate temperature can lead to very low porosity by increasing the liquid fraction in the deposited steel. The calculated cooling rate can lead to a microstructure consisting of martensite, lower bainite, retained austenite, and proeutectoid carbides in as-spray-formed material. In the temperature range between the solidus and liquidus temperatures, the calculated temperature of the spray-formed material increases with increasing substrate preheat temperature, resulting in a very low porosity by increasing the liquid fraction of the deposited steel. In the temperature region where austenite decomposition occurs, the substrate preheat temperature has a negligible influence on the cooling rate of the spray-formed material. On the basis of the calculated results, it is possible to generate sufficient liquid fraction during spray forming by using a high growth rate of the deposit without preheating the substrate, and the growth rate of the deposit has almost no influence on the cooling rate in the temperature region of austenite decomposition.

Laser surface modification of Yttria Stabilized Zirconia (YSZ) thermal barrier coating on AISI H13 tool steel substrate

Science.gov (United States)

Reza, M. S.; Aqida, S. N.; Ismail, I.

2018-03-01

This paper presents laser surface modification of plasma sprayed yttria stabilized zirconia (YSZ) coating to seal porosity defect. Laser surface modification on plasma sprayed YSZ was conducted using 300W JK300HPS Nd: YAG laser at different operating parameters. Parameters varied were laser power and pulse frequency with constant residence time. The coating thickness was measured using IM7000 inverted optical microscope and surface roughness was analysed using two-dimensional Mitutoyo Surface Roughness Tester. Surface roughness of laser surface modification of YSZ H-13 tool steel decreased significantly with increasing laser power and decreasing pulse frequency. The re-melted YSZ coating showed higher hardness properties compared to as-sprayed coating surface. These findings were significant to enhance thermal barrier coating surface integrity for dies in semi-solid processing.

Evaluation of carbon diffusion in heat treatment of H13 tool steel under different atmospheric conditions

Directory of Open Access Journals (Sweden)

Maziar Ramezani

2015-04-01

Full Text Available Although the cost of the heat treatment process is only a minor portion of the total production cost, it is arguably the most important and crucial stage on the determination of material quality. In the study of the carbon diffusion in H13 steel during austenitization, a series of heat treatment experiments had been conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied, i.e., heat treatment without atmospheric control, heat treatment with stainless steel foil wrapping, pack carburization heat treatment and vacuum heat treatment. The results showed that stainless steel foil wrapping could restrict decarburization process, resulting in a constant hardness profile as vacuum heat treatment does. However, the tempering characteristic between these two heat treatment methods is different. Results from the gas nitrided samples showed that the thickness and the hardness of the nitrided layer is independent of the carbon content in H13 steel.

Method of treating tool steel die materials

International Nuclear Information System (INIS)

Cook, C.S.; Damon, S.

1981-01-01

In a method of hardening pilger dies to provide a hard case containing residual compressive stresses and tough body, the tool steel die is heated to the austenitizing temperature range, followed by selectively removing heat from the die at a predetermined faster rate in the direction of the desired case than the rate of heat removal from the balance of the die, and thereafter tempering the die. The invention provides a fully hardened and tempered case on the working surface of the die and a tough body in the balance of the die, usually of lower hardness. (author)

Microstructure and Mechanical Properties of Laser Clad and Post-cladding Tempered AISI H13 Tool Steel

Science.gov (United States)

Telasang, Gururaj; Dutta Majumdar, Jyotsna; Wasekar, Nitin; Padmanabham, G.; Manna, Indranil

2015-05-01

This study reports a detailed investigation of the microstructure and mechanical properties (wear resistance and tensile strength) of hardened and tempered AISI H13 tool steel substrate following laser cladding with AISI H13 tool steel powder in as-clad and after post-cladding conventional bulk isothermal tempering [at 823 K (550 °C) for 2 hours] heat treatment. Laser cladding was carried out on AISI H13 tool steel substrate using a 6 kW continuous wave diode laser coupled with fiber delivering an energy density of 133 J/mm2 and equipped with a co-axial powder feeding nozzle capable of feeding powder at the rate of 13.3 × 10-3 g/mm2. Laser clad zone comprises martensite, retained austenite, and carbides, and measures an average hardness of 600 to 650 VHN. Subsequent isothermal tempering converted the microstructure into one with tempered martensite and uniform dispersion of carbides with a hardness of 550 to 650 VHN. Interestingly, laser cladding introduced residual compressive stress of 670 ± 15 MPa, which reduces to 580 ± 20 MPa following isothermal tempering. Micro-tensile testing with specimens machined from the clad zone across or transverse to cladding direction showed high strength but failure in brittle mode. On the other hand, similar testing with samples sectioned from the clad zone parallel or longitudinal to the direction of laser cladding prior to and after post-cladding tempering recorded lower strength but ductile failure with 4.7 and 8 pct elongation, respectively. Wear resistance of the laser surface clad and post-cladding tempered samples (evaluated by fretting wear testing) registered superior performance as compared to that of conventional hardened and tempered AISI H13 tool steel.

Effects of advanced laser processing on the microstructure and residual stresses of H13 tool steel

NARCIS (Netherlands)

Trojan, Karel; Ocelík, Václav; Ganev, Nikolaj; Němeček, Stanislav; Čapek, Jiří

2017-01-01

The aim of this paper is to describe the effects of laser processing on the microstructure and residual stresses of laser cladded H13 tool steel on the classical construct steel S355 substrate. This research paper concludes that in this case of laser cladding, phase transformation and not shrinkage

Thermal Fatigue of Die-Casting Dies: An Overview

Directory of Open Access Journals (Sweden)

Abdulhadi Hassan A.

2016-01-01

Full Text Available Coupled studies by experimental and numerical simulations are necessary for an increased understanding of the material behaviour as related to the interaction between the thermal and mechanical conditions. This paper focus on the mechanisms of thermal fatigue in the failure of dies and cores used in the die casting of aluminum alloys. The thermal fatigue resistance is expressed by two crack parameters which are the average maximum crack and the average cracked area. Samples of various types of H13 steel were compared with a standard H13 steel by testing under identical thermal fatigue cycles. To determine the thermal constraint developed in the sample during the test, a finite difference technique was used to obtain the temperature distribution, based on temperature measurements at the boundaries. The resulting stresses and strains were computed, and the strain calculated at the edge or weakest point of the sample was used to correlate the number of cycles to crack initiation. As the strain at the edge increased, the number of cycles to failure decreased. The influence of various factors on thermal fatigue behavior was studied including austenitizing temperature, surface condition, stress relieving, casting, vacuum melting, and resulfurization. The thermal fatigue resistance improved as the austenitizing temperature increased from 1750 to 2050ºF.

Effect of laser absorption on picosecond laser ablation of Cr12MoV mold steel, 9Cr18 stainless steel and H13A cemented carbide

Science.gov (United States)

Wu, Baoye; Liu, Peng; Wang, Xizhao; Zhang, Fei; Deng, Leimin; Duan, Jun; Zeng, Xiaoyan

2018-05-01

Due to excellent properties, Cr12MoV mold steel, 9Cr18 stainless steel and H13A cemented carbide are widely used in industry. In this paper, the effect of absorption of laser light on ablation efficiency and roughness have been studied using a picosecond pulse Nd:YVO4 laser. The experimental results reveal that laser wavelength, original surface roughness and chemical composition play an important role in controlling ablation efficiency and roughness. Firstly, higher ablation efficiency with lower surface roughness is achieved on the ablation of 9Cr18 at 532, comparing with 1064 nm. Secondly, the ablation efficiency increases while the Ra of the ablated region decreases with the decrease of original surface roughness on ablation of Cr12MoV mold steel at 532 nm. Thirdly, the ablation efficiency of H13A cemented carbide is much higher than 9Cr18 stainless steel and Cr12MoV mold steel at 1064 nm. Scanning electron microscopy images reveals the formation of pores on the surface of 9Cr18 stainless steel and Cr12MoV mold steel at 532 nm while no pores are formed at 1064 nm. As to H13A cemented carbide, worm-like structure is formed at 1064 nm. The synergetic effects of the heat accumulation, plasma shielding and ablation threshold on laser ablation efficiency and machining quality were analyzed and discussed systematically in this paper.

Economical surface treatment of die casting dies to prevent soldering in high pressure casting

International Nuclear Information System (INIS)

Fraser, D.T.; Jahedi, M.Z.

2001-01-01

This paper describes the use of a gas oxidation treatment of H13 tool steel to develop a compact iron oxide layer at the surface of core pins to prevent soldering in high pressure die casting. The performance of oxide layers in the protection of die steel against soldering during high pressure die casting was tested in a specially designed die using removable core pins and Al-11 Si-3 Cu casting alloy. The gas oxidation treatment can be applied at low temperatures and to large areas of the die surface. In addition this process is very cost effective compared to other coating processes such as physical vapour deposition (PVD), or thermo-reactive diffusion (TRD) coatings. This work demonstrated that surface treatment producing pure magnetite (Fe 3 O 4 ) layers are more protective than oxide layers containing a combination of Fe 3 O 4 (magnetite) and Fe 3 O 3 (haematite). The magnetite layer acts as a barrier between the die steel/casting alloy interface and prevents the formation of inter-metallic phases. Optical microscopy and scanning electron microscope were used to determine the thickness of the oxide layer, while X-ray diffraction was performed to determine the oxide phase structure

Toolpath strategy for cutter life improvement in plunge milling of AISI H13 tool steel

Science.gov (United States)

Adesta, E. Y. T.; Avicenna; hilmy, I.; Daud, M. R. H. C.

2018-01-01

Machinability of AISI H13 tool steel is a prominent issue since the material has the characteristics of high hardenability, excellent wear resistance, and hot toughness. A method of improving cutter life of AISI H13 tool steel plunge milling by alternating the toolpath and cutting conditions is proposed. Taguchi orthogonal array with L9 (3^4) resolution will be employed with one categorical factor of toolpath strategy (TS) and three numeric factors of cutting speed (Vc), radial depth of cut (ae ), and chip load (fz ). It is expected that there are significant differences for each application of toolpath strategy and each cutting condition factor toward the cutting force and tool wear mechanism of the machining process, and medial axis transform toolpath could provide a better tool life improvement by a reduction of cutting force during machining.

Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

Science.gov (United States)

Aqida, S. N.; Brabazon, D.; Naher, S.

2011-01-01

This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

Parametric Investigation of Diode and CO2 Laser in Direct Metal Deposition of H13 Tool Steel on Copper Substrate

OpenAIRE

M. Khalid Imran; Syed Masood; Milan Brandt; Sudip Bhattacharya; Jyotirmoy Mazumder

2011-01-01

In the present investigation, H13 tool steel has been deposited on copper alloy substrate using both CO2 and diode laser. A detailed parametric analysis has been carried out in order to find out optimum processing zone for coating defect free H13 tool steel on copper alloy substrate. Followed by parametric optimization, the microstructure and microhardness of the deposited clads have been evaluated. SEM micrographs revealed dendritic microstructure in both clads. However,...

Influence of Powder Bed Preheating on Microstructure and Mechanical Properties of H13 Tool Steel SLM Parts

Science.gov (United States)

Mertens, R.; Vrancken, B.; Holmstock, N.; Kinds, Y.; Kruth, J.-P.; Van Humbeeck, J.

Powder bed preheating is a promising development in selective laser melting (SLM), mainly applied to avoid large thermal stresses in the material. This study analyses the effect of in-process preheating on microstructure, mechanical properties and residual stresses during SLM of H13 tool steel. Sample parts are produced without any preheating and are compared to the corresponding parts made with preheating at 100°, 200°, 300°, and 400°C. Interestingly, internal stresses at the top surface of the parts evolve from compressive (-324MPa) without preheating to tensile stresses (371MPa) with preheating at 400°C. Nevertheless, application of powder bed preheating results in a more homogeneous microstructure with better mechanical properties compared to H13 SLM parts produced without preheating. The fine bainitic microstructure leads to hardness values of 650-700Hv and ultimate tensile strength of 1965MPa, which are comparable to or even better than those of conventionally made and heat treated H13 tool steel.

Medium carbon vanadium steels for closed die forging

International Nuclear Information System (INIS)

Jeszensky, Gabor; Plaut, Ronald Lesley

1993-01-01

This work analyses the medium carbon micro alloyed vanadium potential for closed die forged production. The steels reach the mechanical resistance requests during cooling after forging, eliminating the subsequent thermal treatment. Those steels also present good fatigue resistance and machinability. The industrial scale experiments are also reported

Preliminary heat treatment of 4KhM2Fch die steel

International Nuclear Information System (INIS)

Leonidov, V.M.; Berezkin, Y.A.; Nikitenko, E.V.

1986-01-01

To improve the machinability and preparation of the structure for hardening, die steels are given a preliminary treatment which provides a reduction in hardness as a result of separation in the structure of the carbide and ferrite phases, coagulation of the carbides, and acquisition by them of a granular form and also the obtaining of fine grains and a uniform distribution of the structural constituents. The microstructure was evaluated after etching in 4% nital on an MIM-8M microscope. The 4KhM2Fch steel was given a preliminary heat treatment of normalize and anneal. It was concluded that for 4KhM2Fch steel a preliminary heat treatment of normalizing from 950 0 C with a hold of 1.5-2 h, annealing at 750-760 0 C with a hold of 2-3 h, cooling to the isothermal temperature of 670-680 0 C with a hold of 3-4 h, and further air cooling is recommended. The structure after such a heat is granular pearlite with a rating 1-2 and a hardness of 220-250 HB

Effects of advanced laser processing on the microstructure and residual stresses of H13 tool steel

OpenAIRE

Trojan, Karel; Ocelík, Václav; Ganev, Nikolaj; Němeček, Stanislav; Čapek, Jiří

2017-01-01

The aim of this paper is to describe the effects of laser processing on the microstructure and residual stresses of laser cladded H13 tool steel on the classical construct steel S355 substrate. This research paper concludes that in this case of laser cladding, phase transformation and not shrinkage is likely to be a dominant effect on the formation of compressive residual stresses along the clad. Furthermore, martensitic structure and unequal concentration of alloying elements was observed on...

Effect of cryogenic treatment on microstructure, mechanical and wear behaviors of AISI H13 hot work tool steel

Science.gov (United States)

Koneshlou, Mahdi; Meshinchi Asl, Kaveh; Khomamizadeh, Farzad

2011-01-01

This paper focuses on the effects of low temperature (subzero) treatments on microstructure and mechanical properties of H13 hot work tool steel. Cryogenic treatment at -72 °C and deep cryogenic treatment at -196 °C were applied and it was found that by applying the subzero treatments, the retained austenite was transformed to martensite. As the temperature was decreased more retained austenite was transformed to martensite and it also led to smaller and more uniform martensite laths distributed in the microstructure. The deep cryogenic treatment also resulted in precipitation of more uniform and very fine carbide particles. The microstructural modification resulted in a significant improvement on the mechanical properties of the H13 tool steel.

激光熔覆TiC-H13涂层的微结构及耐腐蚀性能的研究%Study on Microstructure and Electrochemical Corrosion Resistance of Laser Cladding TiC-H13 Steel Composite Coating

Institute of Scientific and Technical Information of China (English)

杨倩; 黄宛真; 孔凡志

2016-01-01

TiC-H 13 cladding layer was produced by laser cladding on H 13 steel substrate.The effects of TiC on microstructure and electrochemical corrosion behavior of TiC-H13 layer were studied by SEM,EDS,TEM and anodic polarization curve.The results show that good metallurgical bonding is formed between the TiC-H 13 cladding layer and H 13 steel substrate.The new phase of TiC is formed in the laser cladding layer.Compared with H13 steel,the TiC-H13 cladding layer demonstrates much higher corrosion potential and the lower corrosion current,which exhibites significantly higher corrosion resistant.%以H13钢为基体,通过激光熔覆TiC-H13混合粉末获得熔覆层,考察TiC的加入对TiC-H13熔覆层的微观结构以及耐腐蚀性能的影响.采用SEM、EDS和TEM对熔覆层内的微观组成和物相进行表征,利用电化学阳极极化曲线研究熔覆层的耐腐蚀性能.结果表明:TiC-H13粉末和H13钢基体可以形成良好的熔覆层,熔覆层与基体紧密结合,熔覆层中形成新物相TiC.与H13钢相比,TiC-H 13熔覆层的腐蚀电位明显升高,腐蚀电流明显降低,耐腐蚀性能得到显著提高.

Effects of Rare Earth on the Microstructure and Impact Toughness of H13 Steel

Directory of Open Access Journals (Sweden)

Jinzhu Gao

2015-03-01

Full Text Available Studies of H13 steel suggest that under appropriate conditions, additions of rare-earth metals (REM can significantly enhance mechanical properties, such as impact toughness. This improvement is apparently due to the formation of finer and more dispersive RE inclusions and grain refinement after REM additions. In this present work, the microstructure evolution and mechanical properties of H13 steel with rare earth additions (0, 0.015, 0.025 and 0.1 wt.% were investigated. The grain size, inclusions and fracture morphology were systematically studied by means of optical microscopy (OM, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The results indicate that REM addition of 0.015 wt.% can result in good improvement of performance compared to the REM additions of 0.025 wt.% and 0.1 wt.%. It is found that the impact toughness is significantly enhanced with the addition of 0.015% REM, which can be improved 90% from 10 J to 19 J. Such an addition of REM can result in a huge volume fraction of finer and more dispersive inclusions which are extremely good to toughness.

The thermal fatigue resistance of vermicular cast iron coupling with H13 steel units by cast-in process

International Nuclear Information System (INIS)

Wang, Chengtao; Zhou, Hong; Lin, Peng Yu; Sun, Na; Guo, Qingchun; Zhang, Peng; Yu, Jiaxiang; Liu, Yan; Wang, Mingxing; Ren, Luquan

2010-01-01

This paper focuses on improving the thermal fatigue resistance on the surface of vermicular cast iron coupling with inserted H13 steel blocks that had different cross sections, by cast-in processing. The microstructure of bionic units was examined by scanning electron microscope. Micro-hardness and thermal fatigue resistance of bionic samples with varied cross sections and spacings were investigated, respectively. Results show that a marked metallurgical bonding zone was produced at interface between the inserted H13 steel block and the parent material - a unique feature of the bionic structure in the vermicular cast iron samples. The micro-hardness of the bionic samples has been significantly improved. Thermal resistance of the samples with the circular cross section was the highest and the bionics sample with spacing of 2 mm spacing had a much longer thermal fatigue life, thus resulting in the improvement for the thermal fatigue life of the bionic samples, due to the efficient preclusion for the generation and propagation of crack at the interface of H13 block and the matrix.

An investigation of improved strength and toughness of ausformed H13 steel

International Nuclear Information System (INIS)

Cha, Yong Chul; Yoon, Han Sang

1986-01-01

The effect of ausforming for AISI H13 steel was studied. Plastic deformation of metastable austenite increased the hardness and strength of the subsequently formed martensite. The increases in yield and tensile strength were proportional to the degree of austenite deformation without sacrifice of toughness, and large deformation (60%) resulted in significant increase in impact value. Furthermore, temper resistance up to 500 deg C, that is, consequent improvement in elevated-temperature strength property was demonstrated. These results can be interpreted as being attributed to the formation of cellular substructures which were fixed by alloy carbides. (Author)

Two dimensional finite element thermal model of laser surface glazing for H13 tool steel

Science.gov (United States)

Kabir, I. R.; Yin, D.; Naher, S.

2016-10-01

A two dimensional (2D) transient thermal model with line-heat-source was developed by Finite Element Method (FEM) for laser surface glazing of H13 tool steel using commercial software-ANSYS 15. The geometry of the model was taken as a transverse circular cross-section of cylindrical specimen. Two different power levels (300W, 200W) were used with 0.2mm width of laser beam and 0.15ms exposure time. Temperature distribution, heating and cooling rates, and the dimensions of modified surface were analysed. The maximum temperatures achieved were 2532K (2259°C) and 1592K (1319°C) for laser power 300W and 200W respectively. The maximum cooling rates were 4.2×107 K/s for 300W and 2×107 K/s for 200W. Depths of modified zone increased with increasing laser power. From this analysis, it can be predicted that for 0.2mm beam width and 0.15ms time exposer melting temperature of H13 tool steel is achieved within 200-300W power range of laser beam in laser surface glazing.

Surface modification of AISI H13 tool steel by laser cladding with NiTi powder

Science.gov (United States)

Norhafzan, B.; Aqida, S. N.; Chikarakara, E.; Brabazon, D.

2016-04-01

This paper presents laser cladding of NiTi powder on AISI H13 tool steel surface for surface properties enhancement. The cladding process was conducted using Rofin DC-015 diffusion-cooled CO2 laser system with wavelength of 10.6 µm. NiTi powder was pre-placed on H13 tool steel surface. The laser beam was focused with a spot size of 90 µm on the sample surface. Laser parameters were set to 1515 and 1138 W peak power, 18 and 24 % duty cycle and 2300-3500 Hz laser pulse repetition frequency. Hardness properties of the modified layer were characterized by Wilson Hardness tester. Metallographic study and chemical composition were conducted using field emission scanning electron microscope and energy-dispersive X-ray spectrometer (EDXS) analysis. Results showed that hardness of NiTi clad layer increased three times that of the substrate material. The EDXS analysis detected NiTi phase presence in the modified layer up to 9.8 wt%. The metallographic study shows high metallurgical bonding between substrate and modified layer. These findings are significant to both increased hardness and erosion resistance of high-wear-resistant components and elongating their lifetime.

A Method Based on Semi-Solid Forming for Eliminating Coarse Dendrites and Shrinkage Porosity of H13 Tool Steel

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Yifeng Guo

2018-04-01

Full Text Available A method called forging solidifying metal (FSM, which is applied for eliminating coarse dendrites and shrinkage porosity defects of ferrous alloys was proposed based on semi-solid forming technology (SSF. To verify its feasibility, the effects of liquid fraction (FL on the microstructure of the deformed H13 steel were investigated experimentally. The coarse dendrites structure still existed and cracks appeared when the 0.1/s 50% FSM method was carried out at ~20% FL. What is significantly different from that is, the elimination of the coarse dendrites structure and shrinkage porosity defects became more significant, when this method was conducted at the end of solidification (FL < 10%. The microstructure of H13 steel was significantly refined and also became dense in such condition.

Kinetics of steel heavy ingot formation in dies of semicontinuous-casting machines

International Nuclear Information System (INIS)

Tsukerman, V.Ya.; Marchenko, I.K.

1986-01-01

Formation kinetics of round section ingot of up to 0.67 m in diameter was analyzed in dies of semicontinuous-casting machines on casting of the most usable assortment steels: medium-carbon low-alloyed and chromium-nickel stainless steels. It is established that solidification coefficient decreases in direct proportion to ingot diameter. Value of different-thickness ingot skin at die outlet is in direct proportion to a casted steel overheating temperature, ingot diameter and inversely proportional to the number and diameter of holes in a ladder nozzle and square root of ingot drawing rate

An investigation of phase transformation and crystallinity in laser surface modified H13 steel

Science.gov (United States)

Aqida, S. N.; Brabazon, D.; Naher, S.

2013-03-01

This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with Cu K α ( λ=1.5405 Å) radiation. The diffraction patterns were recorded in the 2 θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The laser-modified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the laser-modified surface.

Microstructure and corrosion behaviour of pulsed plasma-nitrided AISI H13 tool steel

International Nuclear Information System (INIS)

Basso, Rodrigo L.O.; Pastore, Heloise O.; Schmidt, Vanessa; Baumvol, Israel J.R.; Abarca, Silvia A.C.; Souza, Fernando S. de; Spinelli, Almir; Figueroa, Carlos A.; Giacomelli, Cristiano

2010-01-01

The effect of pulsed plasma nitriding temperature and time on the pitting corrosion behaviour of AISI H13 tool steel in 0.9% NaCl solutions was investigated by cyclic polarization. The pitting potential (E pit ) was found to be dependent on the composition, microstructure and morphology of the surface layers, whose properties were determined by X-ray diffraction and scanning electron microscopy techniques. The best corrosion protection was observed for samples nitrided at 480 o C and 520 o C. Under such experimental conditions the E pit -values shifted up to 1.25 V in the positive direction.

Conversion electron Moessbauer spectroscopy of plasma immersion ion implanted H13 tool steel

International Nuclear Information System (INIS)

Terwagne, G.; Hutchings, R.

1994-01-01

Conversion electron Moessbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI 3 ) at 350 C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ε-Fe 2 N through ε-Fe 3 N to γ'-Fe 4 N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone. (orig.)

Research on Oxidation Wear Behavior of a New Hot Forging Die Steel

Science.gov (United States)

Shi, Yuanji; Wu, Xiaochun

2018-01-01

Dry sliding tests for the hot forging die steel DM were performed in air under the test temperature at 400-700 °C and the time of 0.5-4 h by a UMT-3 high-temperature wear tester. The wear behavior and characteristics were studied systematically to explore the general characters in severe oxidation conditions. The results showed that a mild-to-severe oxidation wear transition occurred with an increase in the test temperature and duration. The reason was clarified as the unstable M6C carbides coarsening should be responsible for the severe delamination of tribo-oxide layer. More importantly, an intense oxidation wear with lower wear rates was found when the experimental temperature reaches 700 °C or after 4 h of test time at 600 °C, which was closely related to the degradation behavior during wear test. Furthermore, a new schematic diagram of oxidation wear of DM steel was proposed.

Improvement of Tribological Performance of AISI H13 Steel by Means of a Self-Lubricated Oxide-Containing Tribo-layer

Science.gov (United States)

Cui, Xianghong; Jin, Yunxue; Chen, Wei; Zhang, Qiuyang; Wang, Shuqi

2018-03-01

A self-lubricated oxide-containing tribo-layer was induced to form by continuously adding particles of MoS2, Fe2O3 or their mixtures onto sliding interfaces of AISI H13 and 52100 steels. The artificial tribo-layer was always noticed to form continuously and cover the worn surface (termed as cover-type), whereas the original tribo-layer spontaneously formed with no additive was usually discontinuous and inserted into the substrate (termed as insert-type). Clearly, the cover-type and insert-type tribo-layers exactly corresponded to low and high wear rates, respectively. For the mixed additives of Fe2O3 + MoS2, the protective tribo-layers presented a load-carrying capability and lubricative function, which are attributed to the existence of Fe2O3 and MoS2. Hence, the wear rates and friction coefficients of H13 steel were markedly reduced.

H2S cracking resistance of type 420 stainless steel tubulars

International Nuclear Information System (INIS)

Klein, L.J.

1984-01-01

Type 420 stainless steel (13Cr) production tubing is being used successfully in deep sour gas wells in the Tuscaloosa Trend. Despite their reputation for poor H 2 S cracking resistance in laboratory tests, 12-13% Cr steels continue to perform well in sour environments. NACE Tensile Test and Shell bent beam test results indicate Type 420 is more resistant to H 2 S cracking than Type 410, but is not as resistant as carbon steel, at to 586-690 MPa (85-100 ksi) yield strength level. In addition to evaluating Type 420 stainless steel in the standard NACE Tensile and Shell bent beam tests, the effects on cracking tendency of chloride concentration, pH, and H 2 S gas concentration in the NACE Test solution were also examined. Type 420 appears to be more resistant to H 2 S cracking than is indicated by standard laboratory tests, at least in low H 2 S level sour environments

Die krisis van ongeloof in Numeri 13-14

African Journals Online (AJOL)

Die ver- haal gebruik die aanloklikheid van die land as 'n submotief om 'n groter drama uit te beeld: die konflik tussen Israel en sy God. ISSN 0259 9422 ... In aansluiting by Eksodus 34 laat die liefde en trou van die Here aan Horn die ...... langs die weg van die tema van veertig jaar dat 'de hoofdstukken 13-14 een sleutel-.

Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel

Science.gov (United States)

Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas

2015-11-01

In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 °C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

Conversion electron Mössbauer spectroscopy of plasma immersion ion implanted H13 tool steel

Science.gov (United States)

Terwagne, G.; Collins, G. A.; Hutchings, R.

1994-12-01

Conversion electron Mössbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI3) at 350 °C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ɛ-Fe2N through ɛ-Fe3N to γ'-Fe4N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone.

Modelling of Tool Wear and Residual Stress during Machining of AISI H13 Tool Steel

Science.gov (United States)

Outeiro, José C.; Umbrello, Domenico; Pina, José C.; Rizzuti, Stefania

2007-05-01

Residual stresses can enhance or impair the ability of a component to withstand loading conditions in service (fatigue, creep, stress corrosion cracking, etc.), depending on their nature: compressive or tensile, respectively. This poses enormous problems in structural assembly as this affects the structural integrity of the whole part. In addition, tool wear issues are of critical importance in manufacturing since these affect component quality, tool life and machining cost. Therefore, prediction and control of both tool wear and the residual stresses in machining are absolutely necessary. In this work, a two-dimensional Finite Element model using an implicit Lagrangian formulation with an automatic remeshing was applied to simulate the orthogonal cutting process of AISI H13 tool steel. To validate such model the predicted and experimentally measured chip geometry, cutting forces, temperatures, tool wear and residual stresses on the machined affected layers were compared. The proposed FE model allowed us to investigate the influence of tool geometry, cutting regime parameters and tool wear on residual stress distribution in the machined surface and subsurface of AISI H13 tool steel. The obtained results permit to conclude that in order to reduce the magnitude of surface residual stresses, the cutting speed should be increased, the uncut chip thickness (or feed) should be reduced and machining with honed tools having large cutting edge radii produce better results than chamfered tools. Moreover, increasing tool wear increases the magnitude of surface residual stresses.

Evaluation of carbon diffusion in heat treatment of H13 tool steel under different atmospheric conditions

OpenAIRE

Ramezani, Maziar; Pasang, Timotius; Chen, Zhan; Neitzert, Thomas; Au, Dominique

2015-01-01

Although the cost of the heat treatment process is only a minor portion of the total production cost, it is arguably the most important and crucial stage on the determination of material quality. In the study of the carbon diffusion in H13 steel during austenitization, a series of heat treatment experiments had been conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied, i.e., heat treatment without atmospheric contro...

Study the effect of elevated dies temperature on aluminium and steel round deep drawing

International Nuclear Information System (INIS)

Lean, Yeong Wei; Azuddin, M.

2016-01-01

Round deep drawing operation can only be realized by expensive multi-step production processes. To reduce the cost of processes while expecting an acceptable result, round deep drawing can be done at elevated temperature. There are 3 common problems which are fracture, wrinkling and earing of deep drawing a round cup. The main objective is to investigate the effect of dies temperature on aluminium and steel round deep drawing; with a sub-objective of eliminate fracture and reducing wrinkling effect. Experimental method is conducted with 3 different techniques on heating the die. The techniques are heating both upper and lower dies, heating only the upper dies, and heating only the lower dies. 4 different temperatures has been chosen throughout the experiment. The experimental result then will be compared with finite element analysis software. There is a positive result from steel material on heating both upper and lower dies, where the simulation result shows comparable as experimental result. Heating both upper and lower dies will be the best among 3 types of heating techniques. (paper)

Wear and Adhesive Failure of Al2O3 Powder Coating Sprayed onto AISI H13 Tool Steel Substrate

Science.gov (United States)

Amanov, Auezhan; Pyun, Young-Sik

2016-07-01

In this study, an alumina (Al2O3) ceramic powder was sprayed onto an AISI H13 hot-work tool steel substrate that was subjected to sanding and ultrasonic nanocrystalline surface modification (UNSM) treatment processes. The significance of the UNSM technique on the adhesive failure of the Al2O3 coating and on the hardness of the substrate was investigated. The adhesive failure of the coating sprayed onto sanded and UNSM-treated substrates was investigated by a micro-scratch tester at an incremental load. It was found, based on the obtained results, that the coating sprayed onto the UNSM-treated substrate exhibited a better resistance to adhesive failure in comparison with that of the coating sprayed onto the sanded substrate. Dry friction and wear property of the coatings sprayed onto the sanded and UNSM-treated substrates were assessed by means of a ball-on-disk tribometer against an AISI 52100 steel ball. It was demonstrated that the UNSM technique controllably improved the adhesive failure of the Al2O3 coating, where the critical load was improved by about 31%. Thus, it is expected that the application of the UNSM technique to an AISI H13 tool steel substrate prior to coating may delay the adhesive failure and improve the sticking between the coating and the substrate thanks to the modified and hardened surface.

Cavitation resistance of 45 and 2H13 steels laser enriched with silicon carbides and hafnium

International Nuclear Information System (INIS)

Skodo, M.; Giren, B.; Cenian, A.

1999-01-01

Cavitation resistance of 45 and H13 steels with surface layers enriched with Hf and SiC compounds was investigated. All contamination elements were spread over the samples surfaces and subsequently alloyed with core material by CO 2 laser beam. Cavitation tests carried out at the rotating disk facility revealed multiple - 5 to 10 times - increase of erosion resistance of the processed materials during the incubation period of the destruction. This effect was found not to be decisively linked to obtained microhardness changes. (author)

Electrochemical Corrosion Behavior of Carbon Steel and Hot Dip Galvanized Steel in Simulated Concrete Solution with Different pH Values

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Wanchen XIE

2017-08-01

Full Text Available Hot dip galvanizing technology is now widely used as a method of protection for steel rebars. The corrosion behaviors of Q235 carbon steel and hot galvanized steel in a Ca(OH2 solution with a pH from 10 to 13 was investigated by electrode potential and polarization curves testing. The results indicated that carbon steel and hot galvanized steel were all passivated in a strong alkaline solution. The electrode potential of hot dip galvanized steel was lower than that of carbon steel; thus, hot dip galvanized steel can provide very good anodic protection for carbon steel. However, when the pH value reached 12.5, a polarity reversal occurred under the condition of a certain potential. Hot dip galvanized coating became a cathode, and the corrosion of carbon steel accelerated. The electrochemical behaviors and passivation abilities of hot dip galvanized steel and carbon steel were affected by pH. The higher the pH value was, the more easily they were passivated.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16675

Structural properties of H13 tool steel parts produced with use of selective laser melting technology

International Nuclear Information System (INIS)

Šafka, J; Ackermann, M; Voleský, L

2016-01-01

This paper deals with establishing of building parameters for 1.2344 (H13) tool steel processed using Selective Laser Melting (SLM) technology with layer thickness of 50 µm. In the first part of the work, testing matrix of models in the form of a cube with chamfered edge were built under various building parameters such as laser scanning speed and laser power. Resulting models were subjected to set of tests including measurement of surface roughness, inspection of inner structure with aid of Light Optical Microscopy and Scanning Electron Microscopy and evaluation of micro-hardness. These tests helped us to evaluate an influence of changes in building strategy to the properties of the resulting model. In the second part of the work, mechanical properties of the H13 steel were examined. For this purpose, the set of samples in the form of “dog bone” were printed under three different alignments towards the building plate and tested on universal testing machine. Mechanical testing of the samples should then reveal if the different orientation and thus different layering of the material somehow influence its mechanical properties. For this type of material, the producer provides the parameters for layer thickness of 30 µm only. Thus, our 50 µm building strategy brings shortening of the building time which is valuable especially for large models. Results of mechanical tests show slight variation in mechanical properties for various alignment of the sample. (paper)

Structural properties of H13 tool steel parts produced with use of selective laser melting technology

Science.gov (United States)

Šafka, J.; Ackermann, M.; Voleský, L.

2016-04-01

This paper deals with establishing of building parameters for 1.2344 (H13) tool steel processed using Selective Laser Melting (SLM) technology with layer thickness of 50 µm. In the first part of the work, testing matrix of models in the form of a cube with chamfered edge were built under various building parameters such as laser scanning speed and laser power. Resulting models were subjected to set of tests including measurement of surface roughness, inspection of inner structure with aid of Light Optical Microscopy and Scanning Electron Microscopy and evaluation of micro-hardness. These tests helped us to evaluate an influence of changes in building strategy to the properties of the resulting model. In the second part of the work, mechanical properties of the H13 steel were examined. For this purpose, the set of samples in the form of “dog bone” were printed under three different alignments towards the building plate and tested on universal testing machine. Mechanical testing of the samples should then reveal if the different orientation and thus different layering of the material somehow influence its mechanical properties. For this type of material, the producer provides the parameters for layer thickness of 30 µm only. Thus, our 50 µm building strategy brings shortening of the building time which is valuable especially for large models. Results of mechanical tests show slight variation in mechanical properties for various alignment of the sample.

Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

Science.gov (United States)

Umbrello, Domenico; Rizzuti, Stefania; Outeiro, José C.; Shivpuri, Rajiv

2007-04-01

In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

International Nuclear Information System (INIS)

Umbrello, Domenico; Rizzuti, Stefania; Outeiro, Jose C.; Shivpuri, Rajiv

2007-01-01

In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change

Die teologiese skool in die P.U.K vir C.H.O.: met die betekenis van die teologiese skool vir die Christelike wetenskap

Directory of Open Access Journals (Sweden)

F. Postma

1944-03-01

Full Text Available Die Teologiese Skool van die Gereformeerde Kerk gedink op 29 November 1944 sy vyf-en-sewentigjarige bestaan.Die Raad en Senaat van die P.U.K. vir C.H.O. wil ook langs hierdie weg die Teologiese Skool van harte gelukwens en die versekering gee dat daar by die outoriteite van die P.U.K. ’n diepgevoelde dankbaarheid heers dat hierdie inrigting sovele jare deur onse God en Vader gedra en gespaar is.

Effect of coatings obtanied by sputtering of chromium catode on the corrosion resistance of AISI H13 steel

International Nuclear Information System (INIS)

Sandoval, A; Peña, D; Piratoba, U

2013-01-01

Corrosion resistance of coatings obtained by sputtering a chromium target were evaluated. The films were deposited on substrates of disk-shaped AISI H13 steel. By means of potentiodynamic polarization curves were able to determine the current density vs. potential for the coated and uncoated substrate and the difference in the corrosion potential Ecorr. All samples with coating showed an increase in Ecorr respect to substrate. The electrochemical tests were conducted in an electrolytic solution of 3% NaCl

Materials Processing Research and Development

Science.gov (United States)

2001-11-01

interface between a Ti-6Al-4V workpiece and H13 tool steel die for various combinations of lubricants and workpiece-die temperatures. The ring test was...attaching a type-K thermocouple to the sample. The samples at 400 °C were heated using band heaters attached to H13 tool steel dies, with the...Ring Tests The ring tests were performed on a 200 kip servo-hydraulic press between H13 tool steel dies heated to the prescribed die temperatures of

Effect of Energy Input on the Characteristic of AISI H13 and D2 Tool Steels Deposited by a Directed Energy Deposition Process

Science.gov (United States)

Park, Jun Seok; Park, Joo Hyun; Lee, Min-Gyu; Sung, Ji Hyun; Cha, Kyoung Je; Kim, Da Hye

2016-05-01

Among the many additive manufacturing technologies, the directed energy deposition (DED) process has attracted significant attention because of the application of metal products. Metal deposited by the DED process has different properties than wrought metal because of the rapid solidification rate, the high thermal gradient between the deposited metal and substrate, etc. Additionally, many operating parameters, such as laser power, beam diameter, traverse speed, and powder mass flow rate, must be considered since the characteristics of the deposited metal are affected by the operating parameters. In the present study, the effect of energy input on the characteristics of H13 and D2 steels deposited by a direct metal tooling process based on the DED process was investigated. In particular, we report that the hardness of the deposited H13 and D2 steels decreased with increasing energy input, which we discuss by considering microstructural observations and thermodynamics.

Production of High Quality Die Steels from Large ESR Slab Ingots

Science.gov (United States)

Geng, Xin; Jiang, Zhou-hua; Li, Hua-bing; Liu, Fu-bin; Li, Xing

With the rapid development of manufacture industry in China, die steels are in great need of large slab ingot of high quality and large tonnage, such as P20, WSM718R and so on. Solidification structure and size of large slab ingots produced with conventional methods are not satisfied. However, large slab ingots manufactured by ESR process have a good solidification structure and enough section size. In the present research, the new slab ESR process was used to produce the die steels large slab ingots with the maximum size of 980×2000×3200mm. The compact and sound ingot can be manufactured by the slab ESR process. The ultra-heavy plates with the maximum thickness of 410 mm can be obtained after rolling the 49 tons ingots. Due to reducing the cogging and forging process, the ESR for large slab ingots process can increase greatly the yield and production efficiency, and evidently cut off product costs.

Electrochemical and wear behavior of niobium-vanadium carbide coatings produced on AISI H13 tool steel through thermo-reactive deposition/diffusion

International Nuclear Information System (INIS)

Castillejo Nieto, Fabio Enrique; Olaya Flores, Jhon Jairo; Alfonso Orjuela, Jose Edgar

2016-01-01

We deposited of niobium-vanadium carbide coatings on tool steel AISI H13 using the thermo-reactive substrates deposition/diffusion (TRD) technique. The carbides were obtained using salt baths composed of molten borax, ferroniobium, vanadium and aluminum, by heating this mixture at 1020°C for 4 hours. The coatings were characterized morphologically via electron microscopy scanning (SEM), the chemical surface composition was determined through X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX); the crystal structure was analyzed using x-ray diffraction (XRD), the mechanical properties of the coatings were evaluated using nano-indentation, The tribological properties of the coatings obtained were determined using a Pin-on-disk tribometer and the electrochemical behavior was studied through potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the hardness of the coated steel increased four times with respect to uncoated steel, and the electrochemical test established that the corrosion current is lower by one order of magnitude for coated steel

Interface bonding of NiCrAlY coating on laser modified H13 tool steel surface

Science.gov (United States)

Reza, M. S.; Aqida, S. N.; Ismail, I.

2016-06-01

Bonding strength of thermal spray coatings depends on the interfacial adhesion between bond coat and substrate material. In this paper, NiCrAlY (Ni-164/211 Ni22 %Cr10 %Al1.0 %Y) coatings were developed on laser modified H13 tool steel surface using atmospheric plasma spray (APS). Different laser peak power, P p, and duty cycle, DC, were investigated in order to improve the mechanical properties of H13 tool steel surface. The APS spraying parameters setting for coatings were set constant. The coating microstructure near the interface was analyzed using IM7000 inverted optical microscope. Interface bonding of NiCrAlY was investigated by interfacial indentation test (IIT) method using MMT-X7 Matsuzawa Hardness Tester Machine with Vickers indenter. Diffusion of atoms along NiCrAlY coating, laser modified and substrate layers was investigated by energy-dispersive X-ray spectroscopy (EDXS) using Hitachi Tabletop Microscope TM3030 Plus. Based on IIT method results, average interfacial toughness, K avg, for reference sample was 2.15 MPa m1/2 compared to sample L1 range of K avg from 6.02 to 6.96 MPa m1/2 and sample L2 range of K avg from 2.47 to 3.46 MPa m1/2. Hence, according to K avg, sample L1 has the highest interface bonding and is being laser modified at lower laser peak power, P p, and higher duty cycle, DC, prior to coating. The EDXS analysis indicated the presence of Fe in the NiCrAlY coating layer and increased Ni and Cr composition in the laser modified layer. Atomic diffusion occurred in both coating and laser modified layers involved in Fe, Ni and Cr elements. These findings introduce enhancement of coating system by substrate surface modification to allow atomic diffusion.

Microstructural evolution and some mechanical properties of nanosized yttrium oxide dispersion strengthened 13Cr steel

International Nuclear Information System (INIS)

Nguyen, Van Tich; Doan, Dinh Phuong; Tran, Tran BaoTrung; Luong, Van Duong; Nguyen, Van An; Phan, Anh Tu

2010-01-01

Oxide dispersion strengthened (ODS) steels, manufactured by a mechanical alloying method, during the past few years, appear to be promising candidates for structural applications in nuclear power plants. The purpose of this work is to elaborate the manufacturing processes of ODS 13Cr steel with the addition of 1.0 wt% yttrium oxide through the powder metallurgy route using the high energy ball mill. Microstructural analysis by scanning electron microscopy (SEM), x-ray diffraction (XRD) and hardness testing have been used to optimize the technological parameters of milling, hot isostatic pressing and heat-treatment processes. The steel hardness increases with decreasing particle size of 13Cr ODS steel. The best hardness was obtained from more than 70 h of milling in the two tanks planetary ball mill or 30 h of milling in the one tank planetary ball mill and hot isostatic pressing at 1150 °C . The particle size of the steel is less than 100 nm, and the density and hardness are about 7.3 g cm −3 and 490 HB, respectively

Effect of Contact Time on Interface Reaction between Aluminum Silicon (7% and 11% Alloy and Steel Dies SKD 61

Directory of Open Access Journals (Sweden)

Bambang Suharno

2010-10-01

Full Text Available Die soldering (die sticking is a defect of metal casting in which molten metal “welds” to the metallic die mold surface during casting process. Die soldering is the result of an interface reaction between the molten aluminum and the die material. Aluminum alloy with 7 and 11% silicon and SKD 61 die steel are the most common melt and die material used in aluminum die casting. This research is done to study the morphology and the characteristics of the formed AlxFeySiz intermetallic layer during interface reaction at dipping test. The samples of as-anneal SKD 61 tool steel was dipped into the molten of Al-7%Si held at temperature 680oC and into molten Al-11%Si held at temperature 710oC with the different contact time of 10 minutes; 30 minutes; and 50 minutes. The research results showed that the interface reaction can form a compact intermetallic layer with AlxFey phase and a broken intermetallic layer with AlxFeySiz phase on the surface of SKD 61 tool steel. The increasing of the contact time by the immersion of material SKD 61 tool steel in both of molten Al-7%Si and Al-11%Si will increase the thickness of the AlxFeySiz intermetallic layer until an optimum point and then decreasing. The micro hardness of the AlxFeySiz intermetallic layer depends on the content of the iron. Increasing of the iron content in intermetallic layer will increase the micro hardness of the AlxFeySiz. This condition happened because the increasing of Fe content will cause forming of intermetallic AlxFeySiz phase becomes quicker.

'n Ondersoek na die eenheid en teologiese boodskap van Jesaja 13 ...

African Journals Online (AJOL)

patroon inpas nie. Volgens Wildberger is die eenheid van Jesaja 13-23 af te lei uit die inhoud van die uitsprake, aangesien die uitsprake almal teen verskillende vreemde volke gemaak word (Wildberger 1978:479). Die uitsondering is egter Jesa ja 22:1-14 wat nie teen 'n ander volk gemaak word nie, maar teen Jerusalem ...

Effect of biomimetic non-smooth unit morphology on thermal fatigue behavior of H13 hot-work tool steel

Science.gov (United States)

Meng, Chao; Zhou, Hong; Cong, Dalong; Wang, Chuanwei; Zhang, Peng; Zhang, Zhihui; Ren, Luquan

2012-06-01

The thermal fatigue behavior of hot-work tool steel processed by a biomimetic coupled laser remelting process gets a remarkable improvement compared to untreated sample. The 'dowel pin effect', the 'dam effect' and the 'fence effect' of non-smooth units are the main reason of the conspicuous improvement of the thermal fatigue behavior. In order to get a further enhancement of the 'dowel pin effect', the 'dam effect' and the 'fence effect', this study investigated the effect of different unit morphologies (including 'prolate', 'U' and 'V' morphology) and the same unit morphology in different sizes on the thermal fatigue behavior of H13 hot-work tool steel. The results showed that the 'U' morphology unit had the optimum thermal fatigue behavior, then the 'V' morphology which was better than the 'prolate' morphology unit; when the unit morphology was identical, the thermal fatigue behavior of the sample with large unit sizes was better than that of the small sizes.

Direct Metal Deposition of H13 Tool Steel on Copper Alloy Substrate: Parametric Investigation

Science.gov (United States)

Imran, M. Khalid; Masood, S. H.; Brandt, Milan

2015-12-01

Over the past decade, researchers have demonstrated interest in tribology and prototyping by the laser aided material deposition process. Laser aided direct metal deposition (DMD) enables the formation of a uniform clad by melting the powder to form desired component from metal powder materials. In this research H13 tool steel has been used to clad on a copper alloy substrate using DMD. The effects of laser parameters on the quality of DMD deposited clad have been investigated and acceptable processing parameters have been determined largely through trial-and-error approaches. The relationships between DMD process parameters and the product characteristics such as porosity, micro-cracks and microhardness have been analysed using scanning electron microscope (SEM), image analysis software (ImageJ) and microhardness tester. It has been found that DMD parameters such as laser power, powder mass flow rate, feed rate and focus size have an important role in clad quality and crack formation.

Optimization and Simulation of SLM Process for High Density H13 Tool Steel Parts

Science.gov (United States)

Laakso, Petri; Riipinen, Tuomas; Laukkanen, Anssi; Andersson, Tom; Jokinen, Antero; Revuelta, Alejandro; Ruusuvuori, Kimmo

This paper demonstrates the successful printing and optimization of processing parameters of high-strength H13 tool steel by Selective Laser Melting (SLM). D-Optimal Design of Experiments (DOE) approach is used for parameter optimization of laser power, scanning speed and hatch width. With 50 test samples (1×1×1cm) we establish parameter windows for these three parameters in relation to part density. The calculated numerical model is found to be in good agreement with the density data obtained from the samples using image analysis. A thermomechanical finite element simulation model is constructed of the SLM process and validated by comparing the calculated densities retrieved from the model with the experimentally determined densities. With the simulation tool one can explore the effect of different parameters on density before making any printed samples. Establishing a parameter window provides the user with freedom for parameter selection such as choosing parameters that result in fastest print speed.

Die casting copper motor rotors: mold materials and processing for cost-effective manufacturing

Energy Technology Data Exchange (ETDEWEB)

Peters, D.T.; Cowie, J.G.; Brush, E.F. Jr.

2000-07-01

This project seeks to demonstrate mold materials for copper pressure die-casting that are cost-effective and practical for production use in die-casting copper motor rotors. The incorporation of die-cast copper for conductor bars and end rings of the induction motor in place of aluminum would result in attractive improvements in motor energy efficiency through reductions in motor losses ranging from 15% to 20%. Die-cast motor rotors are produced in aluminum today because rotor fabrication by pressure die-casting is an established practice. Lack of a durable and cost-effective mold material has been the technical barrier preventing manufacture of the die-cast copper rotor. This project tested H-13 steel die inserts that establish the baseline. Nickel-, tungsten-, and molybdenum-based high temperature alloys were extensively tested. Results indicate that substantially extended die life is possible using high temperature die materials, pre-heated and operated at elevated temperatures. Pre-heating and high operating temperatures were shown to be critical in extending the die life by decreasing the cyclic stresses associated with thermal expansion. Extended die life provides the opportunity for economically viable copper motor rotor die-casting. (orig.)

Influence of the nitriding and TiAlN/TiN coating thickness in the mechanical properties of a duplex treated H13 steel

International Nuclear Information System (INIS)

Torres, Ricardo D.; Soares, Paulo; Suzuki, Luciane Y.; Lepienski, Carlos M.

2010-01-01

AISI H13 die steel substrates were low pressure gas nitrided in three different nitriding cases. In the nitriding case A, the surface hardness was around 12 GPa and the nitriding thickness was around 40 μm. In the nitriding case B, the hardness was the same as in case A, but the nitriding thickness was around 70 μm. Finally, in the nitriding case C, the nitriding thickness was the same as in case B, but hardness profile showed a different behavior. In case C, the surface hardness was the same as case A and B. But the hardness increases as one move away from the surface showing the highest hardness at 15 "m from the sample surface. The XRD results showed that the nitriding cases microstructure is composed mainly by the diffusion layer with small amount of Cr_2N precipitates. These nitrided samples were subsequently coated with TiAlN using cathodic arc evaporation in two thicknesses of 3 and 7 μm. These samples were characterized with respect to phase chemistry, adhesion, hardness, elastic modulus and scratch tests. The phase chemistry determined through XRD revealed that coating was mostly Ti_0_._7Al_0_._3N with some peaks of TiN which comes from the adhesion layer that was deposited prior to the deposition of TiAlN. The instrumented hardness performed in the coated samples showed that the coating system hardness changes with the nitriding cases when the coating thickness is 3 μm. On the other hand, the nitriding characteristics do not influence the coating hardness with thickness of 7 μm. In addition, the 7 μm thick coating is harder than the 3 μm thick coating. In the last part of this work, TiAlN was deposited in the AISI H13 substrate without nitriding; it was found that the hardness in this condition is higher than the nitrided/coated samples. The worn area, probed by the scratch test, was smaller for the TiAlN deposited over AISI H13 without the nitriding layer. (author)

A study on die wear model of warm and hot forgings

Science.gov (United States)

Kang, J. H.; Park, I. W.; Jae, J. S.; Kang, S. S.

1998-05-01

Factors influencing service lives of tools in warm and hot forging processes are wear, mechanical fatigue, plastic deformation and thermal fatigue, etc. Wear is the predominant factor for tool failure among these. To predict tool life by wear, Archard's model where hardness is considered as constant or function of temperature is generally applied. Usually hardness of die is a function of not only temperature but operating time of die. To consider softening of die by repeated operation it is necessary to express hardness of die by a function of temperature and time. In this study wear coefficients were measured for various temperatures and heat treatment for H13 tool steel. Also by experiment of reheating of die, die softening curves were obtained. From experimental results, relationships between tempering parameters and hardness were established to investigate effects of hardness decrease by the effect of temperatures and time. Finally modified Archard's wear model in which hardness is considered to be a function of main tempering curve was proposed. And finite element analyses were conducted by adopting suggested wear model. By comparisons of simulations and real profiles of worn die, proposed wear model was verified.

Effect of Heat Treatment on the Structure and Properties of Die Steel 70Kh3G2FTR

Science.gov (United States)

Krylova, S. E.; Kletsova, O. A.; Gryzunov, V. I.; Fot, A. P.; Tavtilov, I. Sh.

2018-01-01

The effect of heat treatment parameters on the properties and structural and phase composition of a promising die steel 70Kh3G2FTR for hot deformation is studied. The temperature-and-stress state of a hammer die under a heat treatment is simulated.

Temperature and composition profile during double-track laser cladding of H13 tool steel

Science.gov (United States)

He, X.; Yu, G.; Mazumder, J.

2010-01-01

Multi-track laser cladding is now applied commercially in a range of industries such as automotive, mining and aerospace due to its diversified potential for material processing. The knowledge of temperature, velocity and composition distribution history is essential for a better understanding of the process and subsequent microstructure evolution and properties. Numerical simulation not only helps to understand the complex physical phenomena and underlying principles involved in this process, but it can also be used in the process prediction and system control. The double-track coaxial laser cladding with H13 tool steel powder injection is simulated using a comprehensive three-dimensional model, based on the mass, momentum, energy conservation and solute transport equation. Some important physical phenomena, such as heat transfer, phase changes, mass addition and fluid flow, are taken into account in the calculation. The physical properties for a mixture of solid and liquid phase are defined by treating it as a continuum media. The velocity of the laser beam during the transition between two tracks is considered. The evolution of temperature and composition of different monitoring locations is simulated.

Aircraft Steels

Science.gov (United States)

2009-02-19

component usage. PH 13-8Mo is a precipitation-hardenable martensitic stainless steel combining excellent corrosion resistance with strength. Custom 465 is...a martensitic , age-hardenable stainless steel capable of about 1,724 MPa (250 ksi) UTS when peak-aged (H900 condition). Especially, this steel can...NOTES 14. ABSTRACT Five high strength steels (4340, 300M, AerMet 100, Ferrium S53, and Hy-Tuf) and four stainless steels (High Nitrogen, 13

The relationship of cutting force with hole quality in drilling process of AISI H13 steel

Directory of Open Access Journals (Sweden)

Tekaüt İsmail

2017-01-01

Full Text Available The harmony of the drilling machine-cutting tool-work piece is very important for producing the machine part with the ideal dimensions. For this purpose in this study, the effect of cutting forces on hole quality (surface roughness, diameter deviation and circular deviation was investigated by 14 mm diameter uncoated and (AlCrN monolayer coated carbide drills for drilling AISI H13 hot work tool steel on vertical machining center. Four different cutting speeds (60, 75, 90 and 108 m / min and three different feed rates (0.15, 0.20 and 0.25 mm / rev were used in the experiments. Cutting forces have been found to be effective in improving hole quality. Better hole quality has obtained with coated drills than uncoated drills in experiments. It has been observed that coated drills have the effect of improving the hole quality due to the operation with less cutting force and better chip evacuation.

Effect of triangular texture on the tribological performance of die steel with TiN coatings under lubricated sliding condition

Science.gov (United States)

Chen, Ping; Xiang, Xin; Shao, Tianmin; La, Yingqian; Li, Junling

2016-12-01

The friction and wear of stamping die surface can affect the service life of stamping die and the quality of stamping products. Surface texturing and surface coating have been widely used to improve the tribological performance of mechanical components. This study experimentally investigated the effect of triangular surface texture on the friction and wear properties of the die steel substrate with TiN coatings under oil lubrication. TiN coatings were deposited on a die steel (50Cr) substrate through a multi-arc ion deposition system, and then triangular surface texturing was fabricated by a laser surface texturing. The friction and wear test was conducted by a UMT-3 pin-on-disk tribometer under different sliding speeds and different applied loads, respectively. The adhesion test was performed to evaluate the effectiveness of triangular texturing on the interfacial bonding strength between the TiN coating and the die steel substrate. Results show that the combination method of surface texturing process and surface coating process has excellent tribological properties (the lowest frictional coefficient and wear volume), compared with the single texturing process or the single coating process. The tribological performance is improved resulting from the high hardness and low elastic modulus of TiN coatings, and the generation of hydrodynamic pressure, function of micro-trap for wear debris and micro-reservoirs for lubricating oil of the triangular surface texture. In addition, the coating bonding strength of the texturing sample is 3.63 MPa, higher than that of the single coating sample (3.48 MPa), but the mechanisms remain to be further researched.

Interlocking multi-material components made of structured steel sheets and high-pressure die cast aluminium

Science.gov (United States)

Senge, S.; Brachmann, J.; Hirt, G.; Bührig-Polaczek, A.

2017-10-01

Lightweight design is a major driving force of innovation, especially in the automotive industry. Using hybrid components made of two or more different materials is one approach to reduce the vehicles weight and decrease fuel consumption. As a possible way to increase the stiffness of multi-material components, this paper presents a process chain to produce such components made of steel sheets and high-pressure die cast aluminium. Prior to the casting sequence the steel sheets are structured in a modified rolling process which enables continuous interlocking with the aluminium. Two structures manufactured by this rolling process are tested. The first one is a channel like structure and the second one is a channel like structure with undercuts. These undercuts enable the formation of small anchors when the molten aluminium fills them. The correlation between thickness reduction during rolling and the shape of the resulting structure was evaluated for both structures. It can be stated that channels with a depth of up to 0.5 mm and a width of 1 mm could be created. Undercuts with different size depending on the thickness reduction could be realised. Subsequent aluminium high-pressure die casting experiments were performed to determine if the surface structure can be filled gap-free with molten aluminium during the casting sequence and if a gap-free connection can be achieved after contraction of the aluminium. The casting experiments showed that both structures could be filled during the high-pressure die casting. The channel like structure results in a gap between steel and aluminium after contraction of the cast metal whereas the structure with undercuts leads to a good interlocking resulting in a gap-free connection.

Analysis of the Forces in Micromilling of Hardened AISI H13 Steel with Different Grain Sizes Using the Taguchi Methodology

Directory of Open Access Journals (Sweden)

Carlos Henrique Lauro

2014-05-01

Full Text Available The micromachining process has been applied to the free form and micromolds markets. This has occurred due to the growth in demand for microcomponents. However, micromachining of hardened steels is a challenge due to the reduction in tool life and the increase of the surface roughness when compared with the macromachining process. This paper focused on the analysis of micromilling forces on hardened AISI H13 steel with different grain sizes. Experimental tests were carried out on workpieces with different austenitic grain sizes and a hardness of 46 HRC. Micro-end-mill cutters with a diameter of 0.5 mm and (TiAlN coatings were applied in the milling of workpieces of 11 × 11 mm. The input parameters were two radial depths of cut, two cutting speeds, and two feed rates. The influence of the input parameters on the response cutting force was analyzed using the Taguchi method. Finally, considering the large grain size, the cutting forces in the x-, y-, and z-axes direction were small.

Medium carbon vanadium steels for closed die forging; Acos de medio carbono microligados ao vanadio para forjaria em matriz fechada

Energy Technology Data Exchange (ETDEWEB)

Jeszensky, Gabor; Plaut, Ronald Lesley

1994-12-31

This work analyses the medium carbon micro alloyed vanadium potential for closed die forged production. The steels reach the mechanical resistance requests during cooling after forging, eliminating the subsequent thermal treatment. Those steels also present good fatigue resistance and machinability. The industrial scale experiments are also reported 16 refs., 21 figs.

Finite element modelling of chain-die forming for ultra-high strength steel

Science.gov (United States)

Majji, Raju; Xiang, Yang; Ding, Scott; Yang, Chunhui

2017-10-01

There has been a high demand for weight reduction in automotive vehicles while maintaining passenger safety. A potential steel material to achieve this is Ultra High Strength Steel (UHSS). As a high strength material, it is difficult to be formed with desired profiles using traditional sheet metal forming processes such as Cold Roll Forming. To overcome this problem, a potentially alternative solution is Chain-die Forming (CDF), recently developed. The basic principal of the CDF is to fully combine roll forming and bending processes. The main advantage of this process is the elongated deformation length that significantly increases effective roll radius. This study focuses on identifying issues with the CDF by using CAD modelling, Motion Analysis and Finite Element Analysis (FEA) to devise solutions and construct a more reliable process in an optimal design sense. Some attempts on finite element modelling and simulation of the CDF were conducted using relatively simple models in literature and the research was still not sufficient enough for optimal design of a typical CDF for UHSS. Therefore two numerical models of Chain-die Forming process are developed in this study, including a) one having a set of rolls similar to roll forming but with a large radius, i.e., 20 meters; and b) the other one with dies and punch segments similar to a typical CDF machine. As a case study, to form a 60° channel with single pass was conducted using these two devised models for a comparison. The obtained numerical results clearly show the CDF could generate less residual stress, low strain and small springback of a single pass for the 60° UHSS channel. The design analysis procedure proposed in this study could greatly help the mechanical designers to devise a cost-effective and reliable CDF process for forming UHSS.

Tensile properties of the modified 13Cr martensitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Mabruri, Efendi, E-mail: effe004@lipi.go.id; Anwar, Moch Syaiful, E-mail: moch.syaiful.anwar@lipi.go.id; Prifiharni, Siska, E-mail: siska.prifiharni@lipi.go.id; Romijarso, Toni B.; Adjiantoro, Bintang [Research Center for Metallurgy and Materials, Indonesian Institute of Sciences (LIPI) Kawasan Puspiptek Gd. 470 Serpong, Tangerang Selatan 15314 (Indonesia)

2016-04-19

This paper reports the influence of Mo and Ni on the tensile properties of the modified 13Cr martensitic stainless steels in tempered condition. Four steels with different content of Mo and Ni were prepared by induction melting followed by hot forging, quenching and tempering. The experimental results showed that the addition of about 1% and 3% Mo has a beneficial effect to increase both the tensile strength and the elongation of the steels. On the contrary, the addition of about 3% Ni into the martensitic stainless steel results in decreasing of both the tensile strength and the elongation. Among the alloys investigated the 13Cr3Mo type steel exhibited largest tensile strength of 1348 MPa and largest elongation of 12%. The observation on the tensile fractured surfaces by using scanning electron microscope supported these findings.

Tensile properties of the modified 13Cr martensitic stainless steels

International Nuclear Information System (INIS)

Mabruri, Efendi; Anwar, Moch Syaiful; Prifiharni, Siska; Romijarso, Toni B.; Adjiantoro, Bintang

2016-01-01

This paper reports the influence of Mo and Ni on the tensile properties of the modified 13Cr martensitic stainless steels in tempered condition. Four steels with different content of Mo and Ni were prepared by induction melting followed by hot forging, quenching and tempering. The experimental results showed that the addition of about 1% and 3% Mo has a beneficial effect to increase both the tensile strength and the elongation of the steels. On the contrary, the addition of about 3% Ni into the martensitic stainless steel results in decreasing of both the tensile strength and the elongation. Among the alloys investigated the 13Cr3Mo type steel exhibited largest tensile strength of 1348 MPa and largest elongation of 12%. The observation on the tensile fractured surfaces by using scanning electron microscope supported these findings.

Experimental studies on improving the performance of electrochemical machining of high carbon, high chromium die steel using jet patterns

Directory of Open Access Journals (Sweden)

V. Sathiyamoorthy

2014-03-01

Full Text Available Electrochemical machining (ECM is a non-traditional process used mainly to cut hard or difficult-to-cut metals, where the application of a more traditional process is not convenient. Stiff market competition and ever-growing demand for better, durable and reliable products has brought about a material revolution, which has greatly expanded the families of difficult-to-machine materials namely highcarbon,high-chromium die steel; stainless steel and superalloys. This investigation attempts to analyze the effect of electrolyte distribution on material removal rate (MRR and surface roughness (SR on electrochemical machining of high-carbon, high-chromium die steel using NaCl aqueous solution. Three electrolyte jet patterns namely straight jet in circular, inclined jet in circular and straight jet in spiral were used for this experimentation. The results reveal that electrolyte distribution significantly improves the performance of ECM and the straight jet in spiral pattern performs satisfactorily in obtaining better MRR and surface roughness.

Die Reformdiskussion in der senegalesischen Sprachplanungs- politik

African Journals Online (AJOL)

Die Reformdiskussion in der senegalesischen Sprachplanungspolitik 13 hatten afrikanische Bildungspolitiker und Kulturtheoretiker (Senghor, Nkrumah, Kenyatta, etc.) sehr früh die Rolle der Sprache und Bildung in einem zukünftigen souveränen afrikanischen Staat anerkannt. Die damals geführten staatsrechtlichen ...

Investigation of plume dynamics during picosecond laser ablation of H13 steel using high-speed digital holography

Science.gov (United States)

Pangovski, Krste; Otanocha, Omonigho B.; Zhong, Shan; Sparkes, Martin; Liu, Zhu; O'Neill, William; Li, Lin

2017-02-01

Ablation of H13 tool steel using pulse packets with repetition rates of 400 and 1000 kHz and pulse energies of 75 and 44 μ {J}, respectively, is investigated. A drop in ablation efficiency (defined here as the depth per pulse or μ {m}{/}μ {J}) is shown to occur when using pulse energies of E_{{pulse}} > 44 μ {J}, accompanied by a marked difference in crater morphology. A pulsed digital holographic system is applied to image the resulting plumes, showing a persistent plume in both cases. Holographic data are used to calculate the plume absorption and subsequently the fraction of pulse energy arriving at the surface after traversing the plume for different pulse arrival times. A significant proportion of the pulse energy is shown to be absorbed in the plume for E_{{pulse}} > 44 μ {J} for pulse arrival times corresponding to {>}1 MHz pulse repetition rate, shifting the interaction to a vapour-dominated ablation regime, an energetically costlier ablation mechanism.

ézráh, in die Afrikaanse Bybelvertaling meestal weerg

African Journals Online (AJOL)

Test

sich erst ausbilden, als Israel in Palástina als Herr auf eignem Grund und. Boden sass5). Hierdie anachronisme blyk ewe-eens uit vs. 17 waar daar staan—want op daardie selfde dag het ek julle leërs uit Egipteland uitgelei. Die perfectum hósë' ti word deur die LXX weggewerk wat met die futurum exaxö weergegee word.

Reparation of damaged forging dies

Directory of Open Access Journals (Sweden)

Vukić Lazić

2015-03-01

Full Text Available The forging dies are in exploitation exposed to elevated temperatures and variable impact loads, both compressive and shear. Steels for manufacturing of these tools must endure those loads while maintaining mechanical properties and being resistant to wear and thermal fatigue. For those reasons, the alloyed steels are used for making the forging dies, though they have less weldability, because alloying increases proneness to hardening. Any reparatory hard facing (HF of the damaged dies would require the specially adjusted technology to the particular piece. In this paper reparatory hard facing of dies used for forging pieces in the automobile industry is considered. Prior to reparatory hard facing of the real tools, numerous experimental hard facings on models were performed. All the model hard facings were done on the same steels which were used for production of the real forging dies. To define the optimal hard facing technology one needs to derive the optimal combination of the adequate heat treatment(s, to select the proper filler metals and the welding procedure. The established optimal HF technology was applied to real forging dies whose service life was further monitored in conditions of exploitation

Multi-field coupling finite element analysis for determining the influence of temperature field on die service life during precision-forming process of steel synchronizer ring

International Nuclear Information System (INIS)

Zhao, Jun; Luo, Shan-Ming; Li, Feng-Qiang; Xu, Chen-Bing

2017-01-01

Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.

Multi-field coupling finite element analysis for determining the influence of temperature field on die service life during precision-forming process of steel synchronizer ring

Energy Technology Data Exchange (ETDEWEB)

Zhao, Jun; Luo, Shan-Ming; Li, Feng-Qiang; Xu, Chen-Bing [Xiamen University of Technology, Xiamen (China)

2017-07-15

Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.

Aging between 300 and 450 deg C of wrought martensitic 13-17 wt-%Cr stainless steels

International Nuclear Information System (INIS)

Yrieix, B.; Guttmann, M.

1993-06-01

Martensitic stainless steels containing 13-17 wt-% Cr, some also containing nickel and some having precipitation hardening additions, have been aged between 300 and 450 deg C for times up to 30 000 h. For all the steels examined, the aging response takes the form of an increase of strength and hardness, correlated with embrittlement. The rate and intensity of aging increase with increasing chromium and molybdenum concentrations. In addition, two steels exhibit some temper embrittlement on long term aging at 400 deg C; such embrittlement of these materials is not expected in service at temperatures up to 300 deg C. A general method of prediction of the mechanical properties of these steels as a function of aging conditions is proposed. (authors). 11 refs., 17 figs., 7 tabs

Properties of 13HMF steel welded joints after long-lasting service

International Nuclear Information System (INIS)

Zeman, M.

2002-01-01

Results are presented of research conducted on the 13HMF steel in the as-received condition after long-lasting service over 100000 hours. Simulation tests have been performed by means of modern research methods. The influence of thermal cycles on the microstructure (continuous cooling TTT diagrams), plastic properties (notch toughness and hardness) of simulated heat affected zones and reheat cracking resistance has been evaluated by using the thermal and strain cycle simulator. Susceptibility to thermal fatigue has been determined, the creep strength estimated and welding heat input was given, as well as the post weld heat treatment conditions of the 13HMF steel after service. properties of the welded joints made of 13HMF steel after long-lasting service are given. (author)

Primärer Hyperaldosteronismus - die häufigste monokausale Ursache der "essenziellen Hypertonie"

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Tomaschitz A

2009-01-01

Full Text Available Der primäre Hyperaldosteronismus (PHA ist durch eine vom Renin-Angiotensin-System entkoppelte, inadäquat gesteigerte Aldosteronproduktion charakterisiert, die durch Kochsalzbelastung nicht ausreichend supprimierbar ist. Die Prävalenz des PHA wird in hypertensiven Patienten auf 5–13 %, sowie bei therapierefraktären hypertensiven Patienten auf 23 % geschätzt. Damit ist der PHA die häufigste Ursache einer sekundären Hypertonie. Zusätzlich ist eine erhöhte Aldosteronkonzentration unabhängig vom Blutdruck mit einem gesteigerten Risiko für die Entstehung einer kardiovaskulären Erkrankung, den plötzlichen Herztod, die linksventrikuläre Hypertrophie, eines Schlaganfalls, einer intrazerebralen Blutung, einer Niereninsuffizienz, einer Atherosklerose, eines gesteigerten Gefäßremodellings und des metabolischen Syndroms assoziiert. Die Ursache eines PHA ist in mehr als 95 % eine bilaterale Nebennierenrindenhyperplasie (idiopathischer Hyperaldosteronismus [IHA] oder ein Aldosteron-produzierendes Adenom (APA der Nebenniere. Der diagnostische Ablauf des PHA gliedert sich in drei Teile: (1 Screening, (2 Bestätigungstest und (3 Subtypenevaluierung (CT-Untersuchung und Nebennierenvenensampling. Die Aldosteron-Renin-Ratio- (ARR- Bestimmung ist der derzeit empfohlene Screeningtest bei Verdacht auf einen PHA. Durch unterschiedliche Vortestbedingungen und Medikamente können jedoch falsch positive und falsch negative Untersuchungsergebnisse resultieren. Entsprechend einer Kosten-Nutzen-Analyse wird derzeit nur in bestimmten Gruppen hypertensiver Patienten ein PHA-Screening empfohlen. Aufgrund der zahlreichen organschädigenden Aldosteron- induzierten Effekte wäre jedoch ein Screening aller hypertensiven Patienten zu überlegen. Nach einer unilateralen laparoskopischen Adrenalektomie (bei APA oder einer seltenen unilateralen Hyperplasie kann bei 30–60 % der Patienten eine Verbesserung der Blutdrucksituation erzielt werden. Bei Patienten mit einem

Spark Plasma Co-Sintering of Mechanically Milled Tool Steel and High Speed Steel Powders.

Science.gov (United States)

Pellizzari, Massimo; Fedrizzi, Anna; Zadra, Mario

2016-06-16

Hot work tool steel (AISI H13) and high speed steel (AISI M3:2) powders were successfully co-sintered to produce hybrid tool steels that have properties and microstructures that can be modulated for specific applications. To promote co-sintering, which is made difficult by the various densification kinetics of the two steels, the particle sizes and structures were refined by mechanical milling (MM). Near full density samples (>99.5%) showing very fine and homogeneous microstructure were obtained using spark plasma sintering (SPS). The density of the blends (20, 40, 60, 80 wt % H13) was in agreement with the linear rule of mixtures. Their hardness showed a positive deviation, which could be ascribed to the strengthening effect of the secondary particles altering the stress distribution during indentation. A toughening of the M3:2-rich blends could be explained in view of the crack deviation and crack arrest exerted by the H13 particles.

Spark Plasma Co-Sintering of Mechanically Milled Tool Steel and High Speed Steel Powders

Directory of Open Access Journals (Sweden)

Massimo Pellizzari

2016-06-01

Full Text Available Hot work tool steel (AISI H13 and high speed steel (AISI M3:2 powders were successfully co-sintered to produce hybrid tool steels that have properties and microstructures that can be modulated for specific applications. To promote co-sintering, which is made difficult by the various densification kinetics of the two steels, the particle sizes and structures were refined by mechanical milling (MM. Near full density samples (>99.5% showing very fine and homogeneous microstructure were obtained using spark plasma sintering (SPS. The density of the blends (20, 40, 60, 80 wt % H13 was in agreement with the linear rule of mixtures. Their hardness showed a positive deviation, which could be ascribed to the strengthening effect of the secondary particles altering the stress distribution during indentation. A toughening of the M3:2-rich blends could be explained in view of the crack deviation and crack arrest exerted by the H13 particles.

Effects of mechanical strain amplitude on the isothermal fatigue behavior of H13

Science.gov (United States)

Zeng, Yan; Zuo, Peng-peng; Wu, Xiao-chun; Xia, Shu-wen

2017-09-01

Isothermal fatigue (IF) tests were performed on H13 tool steel subjected to three different mechanical strain amplitudes at a constant temperature to determine the effects of mechanical strain amplitude on the microstructure of the steel samples. The samples' extent of damage after IF tests was compared by observation of their cracks and calculation of their damage parameters. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to observe the microstructure of the samples. Cracks were observed to initiate at the surface because the strains and stresses there were the largest during thermal cycling. Mechanical strain accelerated the damage and softening of the steel. A larger mechanical strain caused greater deformation of the steel, which made the precipitated carbides easier to gather and grow along the deformation direction, possibly resulting in softening of the material or the initiation of cracks.

An experimental analysis of process parameters to manufacture micro-channels in AISI H13 tempered steel by laser micro-milling

Science.gov (United States)

Teixidor, D.; Ferrer, I.; Ciurana, J.

2012-04-01

This paper reports the characterization of laser machining (milling) process to manufacture micro-channels in order to understand the incidence of process parameters on the final features. Selection of process operational parameters is highly critical for successful laser micromachining. A set of designed experiments is carried out in a pulsed Nd:YAG laser system using AISI H13 hardened tool steel as work material. Several micro-channels have been manufactured as micro-mold cavities varying parameters such as scanning speed (SS), pulse intensity (PI) and pulse frequency (PF). Results are obtained by evaluating the dimensions and the surface finish of the micro-channel. The dimensions and shape of the micro-channels produced with laser-micro-milling process exhibit variations. In general the use of low scanning speeds increases the quality of the feature in both surface finishing and dimensional.

Microstructure and phase transformations in laser clad CrxSy/Ni coating on H13 steel

Science.gov (United States)

Lei, Yiwen; Sun, Ronglu; Tang, Ying; Niu, Wei

2015-03-01

Laser cladding was carried out onto H13 steel with preplaced NiCrBSi+Ni/MoS2 powders using CO2 laser under the optimized experimental parameters of laser power 2 kW, scanning velocity 6 mm/s and laser beam diameter 3 mm. An X-ray diffractometer and scanning electron microscope with energy dispersive spectroscopy were applied to analyze the microstructure and phase compositions of the coating. Thermodynamic calculation was performed with Thermo-Calc software on the basis of a commercially available Ni-based Alloys' database. The experimental results show that MoS2 decomposed and S reacted with Cr to form nonstoichiometric CrxSy during the laser cladding process. The coating consists of spherical CrxSy particles, primary γ-Ni dendrite, interdendritic eutectic (γ-Ni+NiMo) and precipitated NiMo. The precipitated NiMo was fine and uniformly distributed in primary γ-Ni dendrite. The calculated results and experimental data indicate that the solidification process in the coating during laser cladding process was liquid→liquid+CrxSy→ liquid+CrxSy+γ-Ni→liquid+CrxSy+γ-Ni+ eutectic (γ-Ni+NiMo). A solid state phase transformation (fine and uniformly distributed NiMo precipitated from γ-Ni) occurred after the solidification process. The calculations agree well with the experimental data and it is helpful to understand the phase transformation and microstructure evolution in the coating.

The Characteristics and Generating Mechanism of Large Precipitates in Ti-Containing H13 Tool Steel

Science.gov (United States)

Xie, You; Cheng, Guoguang; Chen, Lie; Zhang, Yandong; Yan, Qingzhong

2017-02-01

The characteristics of large precipitates in H13 tool steel with 0.015wt% Ti were studied. The result shows that three types of phases larger than 1 μm exist in the as-cast ingot, that is, (Ti, V) (C, N) type phase, (V, Mo, Cr)C type phase and sulfide. (Ti, V) (C, N) type phase could be further classified as the homogeneous Ti-rich one and the Ti-V-rich one in which Ti/V ratio gradually changes. (V, Mo, Cr)C type phase contains the V-rich one and the Mo-Cr-rich one. The compositional characteristics in all of them have little relation with the cutting position or cooling rate. The precipitating process could be well described through calculation by Thermo-Calc software. During solidification, the primary phase (Ti, V)(C, N) first starts to precipitate in the form of Ti-rich carbonitride. With the development of solidification, the ratio of Ti decreases and that of V increases. Then the primary phase Ti-V-rich (Ti, V)(C, N) and V-rich (V, Mo, Cr)C appears successively. Mo-Cr-rich (V, Mo, Cr)C phase does not precipitate until the solidification process reaches to the end. Sulfide precipitates before (V, Mo, Cr)C type phase and it could act as the nucleus of (V, Mo, Cr)C.

Anti-Corrosion Performance of 1,3-BENZOTHIAZOLE on 410 Martensitic Stainless Steel in H2SO4

Science.gov (United States)

Loto, Roland Tolulope

The corrosion inhibition effect of synthesized 1,3-benzothiazole at very low concentrations on 410 martensitic stainless steel in 3MH2SO4 solution was studied through potentiodynamic polarization and weight loss measurements. The observation showed that the organic compound performed effectively with average inhibition efficiencies of 94% and 98% at the concentrations studied from both electrochemical methods due to the inhibition action of protonated inhibitor molecules in the acid solution. The amine and aromatics functional groups of the molecules active in the corrosion inhibition reaction were exposed from Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopic analysis. Thermodynamic calculations showed cationic adsorption to be chemisorption adsorption, obeying the Langmuir adsorption isotherm. Images from optical microscopy showed an improved morphology in comparison to images from corroded stainless steel. Severe surface deterioration and macro-pits were observed in the uninhibited samples.

Structure, mechanical and corrosion properties of powdered stainless steel Kh13

International Nuclear Information System (INIS)

Radomysel'skij, I.D.; Napara-Volgina, S.G.; Orlova, L.N.; Apininskaya, L.M.

1982-01-01

Structure, mechanical and corrosion properties are studied for compact powdered stainless steel, Grade Kh13, produced from prealloyed powder and a mixture of chromium and iron powders by hot vacuum pressing (HVP) following four schemes: HVP of unsintered billets; HVP of presintered billets; HVP of unsintered billets followed by diffusion annealing; HVP of sintered billets followed by diffusion annealing. Analysis of the structure, mechanical and corrosion properties of Kh13 steel produced according to the four schemes confirmed that production of this steel by the HVP method without presintering of porous billets and diffusion annealing of compact stampings is possible only when prealloyed powder of particular composition is used as a starting material

Micro-Bulges Investigation on Laser Modified Tool Steel Surface

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Fauzun Fazliana

2017-01-01

Full Text Available This paper presents micro-bulges investigation on laser modified tool steel. The aim of this study is to understand the effect of laser irradiance and interaction time on surface morphology configuration. An Nd:YAG laser system with TEM00 pulse processing mode was used to modify the samples. Metallographic study shows samples were analyzed for focal position effect on melted pool size, angle of peaks geometry and laser modified layer depth. Surface morphology were analyzed for surface roughness. Laser modified layer shows depth ranged between 42.22 and 420.12 μm. Angle of peak bulge was found to be increase with increasing peak power. The maximum roughness, Ra, achieved in modified H13 was 21.10 μm. These findings are significant to enhance surface properties of laser modified steel and cast iron for dies and high wear resistance applications.

Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

International Nuclear Information System (INIS)

Ai, Zhiyong; Jiang, Jinyang; Sun, Wei; Song, Dan; Ma, Han; Zhang, Jianchun; Wang, Danqian

2016-01-01

Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

Energy Technology Data Exchange (ETDEWEB)

Ai, Zhiyong, E-mail: 230139452@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Jiang, Jinyang, E-mail: jiangjinyang16@163.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Sun, Wei, E-mail: sunwei@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Song, Dan, E-mail: songdancharls@hhu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); College of Mechanics and Materials, Hohai University, Nanjing 210098, Jiangsu (China); Ma, Han, E-mail: mahan-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Zhang, Jianchun, E-mail: Zhangjc-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Wang, Danqian, E-mail: wonderbaba@126.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China)

2016-12-15

Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

Passivation Characteristics of Alloy Corrosion-Resistant Steel Cr10Mo1 in Simulating Concrete Pore Solutions: Combination Effects of pH and Chloride.

Science.gov (United States)

Ai, Zhiyong; Sun, Wei; Jiang, Jinyang; Song, Dan; Ma, Han; Zhang, Jianchun; Wang, Danqian

2016-09-01

The electrochemical behaviour for passivation of new alloy corrosion-resistant steel Cr10Mo1 immersed in alkaline solutions with different pH values (13.3, 12.0, 10.5, and 9.0) and chloride contents (0.2 M and 1.0 M), was investigated by various electrochemical techniques: linear polarization resistance, electrochemical impedance spectroscopy and capacitance measurements. The chemical composition and structure of passive films were determined by XPS. The morphological features and surface composition of the immersed steel were evaluated by SEM together with EDS chemical analysis. The results evidence that pH plays an important role in the passivation of the corrosion-resistant steel and the effect is highly dependent upon the chloride contents. In solutions with low chloride (0.2 M), the corrosion-resistant steel has notably enhanced passivity with pH falling from 13.3 to 9.0, but does conversely when in presence of high chloride (1.0 M). The passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer enriched in Fe oxides and hydroxides, and an inner layer, rich in Cr species. The film composition varies with pH values and chloride contents. As the pH drops, more Cr oxides are enriched in the film while Fe oxides gradually decompose. Increasing chloride promotes Cr oxides and Fe oxides to transform into their hydroxides with little protection, and this is more significant at lower pH (10.5 and 9.0). These changes annotate passivation characteristics of the corrosion-resistant steel in the solutions of different electrolyte.

Optimizing Heat Treatment Process of Fe-13Cr-3Mo-3Ni Martensitic Stainless of Steel

Science.gov (United States)

Anwar, M. S.; Prifiharni, S.; Mabruri, E.

2017-05-01

The Fe-13Cr-3Mo-3Ni stainless steels are modified into martensitic stainless steels for steam turbine blades application. The working temperature of steam turbine was around 600 - 700 °C. The improvement properties of turbine blade material is necessary to maintain steam turbine work. The previous research revealed that it has corrosion resistance of Fe-13Cr-3Mo-3Ni which is better than 13Cr stainless steels in the chloride environment. In this work, the effect of heat treatment on microstructure and hardness of Fe-13Cr-3Mo-3Ni stainless steels has been studied. The steel was prepared by induction melting followed by hot forging. The steels were austenitized at 1000, 1050, and 1100 °C for 1 hour and were tempered at 600, 650, and 700 °C for 1 hour. The steels were then subjected to metallographic observation and hardness test of Rockwell C. The optimal heat treatment of Fe-13Cr-3Mo-3Ni was carried out austenitized in 1050 °C and tempered in 600 - 700 °C.

Tribological behaviour of line hardening of steel U13A with Nd: TAG laser

International Nuclear Information System (INIS)

Sagaro, R.; Ceballos, J. S.; Mascarell, J.; Blanco, A.

1999-01-01

To diminish wear in tribological systems is frequently to harden locally the load carrying areas, which are subjected to wear. A Nd: YAG laser was for the improvement of hardness and wear resistance of steel U13A. The friction and wear characteristics of steel U13A in sliding contact against steel 65MN4 under unlubricated conditions were evaluated for conventional treatments and after laser irradiation. In addition the transformations occurring during laser treatments and the influence of laser parameters for quenching on tribological characteristics are presented. The experimental work indicates that wear resistance of steel U13A (AISI W 112) is several times higher then that for conventional heat treatments

Surface Nb-ALLOYING on 0.4C-13Cr Stainless Steel: Microstructure and Tribological Behavior

Science.gov (United States)

Yu, Shengwang; You, Kai; Liu, Xiaozhen; Zhang, Yihui; Wang, Zhenxia; Liu, Xiaoping

2016-02-01

0.4C-13Cr stainless steel was alloyed with niobium using double glow plasma surface alloying and tribological properties of Nb-alloyed steel such as hardness, friction and wear were measured. Effects of the alloying temperature on microstructure and the tribological behavior of the alloyed steel were investigated compared with untreated steel. Formation mechanisms of Nb-alloyed layers and increased wear resistance were also studied. The result shows that after surface Nb-alloying treatment, the 0.4C-13Cr steel exhibits a diffusion adhesion at the alloyed layer/substrate interface and improved tribological property. The friction coefficient of Nb-alloyed steel is decreased by about 0.3-0.45 and the wear rate after Nb-alloying is only 2-5% of untreated steel.

Effect of tempering temperature on microstructure and sliding wear property of laser quenched 4Cr13 steel

NARCIS (Netherlands)

Ouyang, J.H.; Pei, Y.T.; Li, X.D.; Lei, T.C.

1994-01-01

4Cr13 martensite stainless steel was quenched by a CO2 laser and tempered for 2 h at different temperatures in the range 200 °C to 550 °C. The microstructure of treated layer was observed by SEM, XRD and TEM. Tempering leads to the decomposition of a large number of retained austenites in laser

The effects of annealing temperature and cooling rate on carbide precipitation behavior in H13 hot-work tool steel

International Nuclear Information System (INIS)

Kang, Minwoo; Park, Gyujin; Jung, Jae-Gil; Kim, Byung-Hoon; Lee, Young-Kook

2015-01-01

Highlights: • Unexpected Mo carbides formed during slow cooling from low annealing temperatures. • Mo carbides formed during the migration of Mo for a transition of Cr-rich carbide. • Mo carbides were precipitated at the boundaries of M 7 C 3 carbides and ferrite grains. • Annealing conditions for the precipitation of Mo carbides were discussed. - Abstract: The precipitation behavior of H13 hot-work tool steel was investigated as a function of both annealing temperature and cooling rate through thermodynamic calculations and microstructural analyses using transmission and scanning electron microscope and a dilatometer. The V-rich MC carbide and Cr-rich M 7 C 3 and M 23 C 6 carbides were observed in all annealed specimens regardless of annealing and cooling conditions, as expected from an equilibrium phase diagram of the steel used. However, Mo-rich M 2 C and M 6 C carbides were unexpectedly precipitated at a temperature between 675 °C and 700 °C during slow cooling at a rate of below 0.01 °C/s from the annealing temperatures of 830 °C and below. The solubility of Mo in both M 7 C 3 and ferrite reduces with decreasing temperature during cooling. Mo atoms diffuse out of both M 7 C 3 and ferrite, and accumulate locally at the interface between M 7 C 3 and ferrite. Mo carbides were form at the interface of M 7 C 3 carbides during the transition of Cr-rich M 7 C 3 to stable M 23 C 6

Use of niobium to substitute vanadium in the steel for hot work AISI H3

International Nuclear Information System (INIS)

Branco, J.R.T.; Jesus, B.G. de

1984-01-01

Experimental results on austenitic grain size, quenching hardness and response to tempering measured on a H13 tool steel modified by niobium additions are described. It is shown that the replacement of 25 and 50% percent of the total vanadium by 0,05% of niobium does not change the response to quenching and tempering. (Author) [pt

Post-irradiation characterization of PH13-8Mo martensitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Jong, M.; Schmalz, F.; Rensman, J.W. [Nuclear Research and consultancy Group, Westerduinweg 3, 1755 ZG Petten (Netherlands); Luzginova, N.V., E-mail: luzginova@nrg.eu [Nuclear Research and consultancy Group, Westerduinweg 3, 1755 ZG Petten (Netherlands); Wouters, O.; Hegeman, J.B.J.; Laan, J.G. van der [Nuclear Research and consultancy Group, Westerduinweg 3, 1755 ZG Petten (Netherlands)

2011-10-01

The irradiation response of PH13-8Mo stainless steel was measured up to 2.5 dpa at 200 and 300 deg. C irradiation temperatures. The PH13-8Mo, a martensitic precipitation-hardened steel, was produced by Hot Isostatic Pressing at 1030 deg. C. The fatigue tests (high cycle fatigue and fatigue crack propagation) showed a test temperature dependency but no irradiation effects. Tensile tests showed irradiation hardening (yield stress increase) of approximately 37% for 200 deg. C irradiated material tested at 60 deg. C and approximately 32% for 300 deg. C irradiated material tested at 60 deg. C. This contradicts the shift in reference temperature (T{sub 0}) measured in toughness tests (Master Curve approach), where the {Delta}T{sub 0} for 300 deg. C irradiated is approximately 170 deg. C and the {Delta}T{sub 0} for the 200 deg. C irradiated is approximately 160 deg. C. This means that the irradiation hardening of PH13-8Mo steel is not suitable to predict the shift in the reference temperature for the Master Curve approach.

Studies on Stress Corrosion Cracking of Super 304H Austenitic Stainless Steel

Science.gov (United States)

Prabha, B.; Sundaramoorthy, P.; Suresh, S.; Manimozhi, S.; Ravishankar, B.

2009-12-01

Stress corrosion cracking (SCC) is a common mode of failure encountered in boiler components especially in austenitic stainless steel tubes at high temperature and in chloride-rich water environment. Recently, a new type of austenitic stainless steels called Super304H stainless steel, containing 3% copper is being adopted for super critical boiler applications. The SCC behavior of this Super 304H stainless steel has not been widely reported in the literature. Many researchers have studied the SCC behavior of steels as per various standards. Among them, the ASTM standard G36 has been widely used for evaluation of SCC behavior of stainless steels. In this present work, the SCC behavior of austenitic Fe-Cr-Mn-Cu-N stainless steel, subjected to chloride environments at varying strain conditions as per ASTM standard G36 has been studied. The environments employed boiling solution of 45 wt.% of MgCl2 at 155 °C, for various strain conditions. The study reveals that the crack width increases with increase in strain level in Super 304H stainless steels.

Effect of Heat Treatment on Microstructure and Mechanical Properties of Laser Additively Manufactured AISI H13 Tool Steel

Science.gov (United States)

Chen, ChangJun; Yan, Kai; Qin, Lanlan; Zhang, Min; Wang, Xiaonan; Zou, Tao; Hu, Zengrong

2017-11-01

The effect of heat treatment on microstructure and mechanical properties (microhardness, wear resistance and impact toughness) of laser additively manufactured AISI H13 tool steel was systemically investigated. To understand the variation of microstructure and mechanical properties under different heat treatments, the as-deposited samples were treated at 350, 450, 550, 600 and 650 °C/2 h, respectively. Microstructure and phase transformation were investigated through optical microscopy, scanning electron microscope and transmission electron microscope. The mechanical properties were characterized by nanoindentation tests, Charpy tests and high-temperature wear tests. The microstructure of as-deposited samples consisted of martensite, ultrafine carbides and retained austenite. After the tempering treatment, the martensite was converted into tempered martensite and some fine alloy carbides which precipitated in the matrix. When treated at 550 °C, the greatest hardness and nanohardness were 600 HV0.3 and 6119.4 MPa due to many needle-like carbides precipitation. The value of hardness increased firstly and then decreased when increasing the temperature. When tempered temperatures exceeded 550 °C, the carbides became coarse, and martensitic matrix recrystallized at the temperature of 650 °C. The least impact energy was 6.0 J at a temperature of 550 °C. Samples tempered at 550 °C had larger wear volume loss than that of others. Wear resistances of all samples under atmospheric condition at 400 °C showed an oxidation mechanism.

Wear characterization of a tool steel surface modified by melting and gaseous alloying

International Nuclear Information System (INIS)

Rizvi, S.A.

1999-01-01

Hot forging dies are subjected to laborious service conditions and so there is a need to explore means of improving die life to increase productivity and quality of forgings. Surface modification in order to produce wear resistant surface is an attractive method as it precludes the need to use expensive and highly alloyed steels. In this study, a novel, inexpensive surface modification technique is used to improve the tri biological properties of an H13 tool steel. Surface melting was achieved using a tungsten heat source and gaseous alloying produced under a shield of argon, carbon dioxide, carbon dioxide-argon mixture and nitrogen gases. The change in wear behaviour was compared through micro-hardness indentation measurements and using a dry sliding pin-on-plate wear testing machine. This study shows superior wear behaviour of the modified surfaces when compared to the untreated surfaces. The increase in wear resistance is attributed to the formation of carbides when surfaces are melted under a carbon dioxide shield. However, in the case of nitrogen and argon gaseous alloying, an increase in wear resistance can be attributed to an increase in surface hardness which in turn effects surface deformation behaviour. (author)

Effect of Al Hot-Dipping on High-Temperature Corrosion of Carbon Steel in N2/0.1% H2S Gas

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Muhammad Ali Abro

2016-02-01

Full Text Available High-temperature corrosion of carbon steel in N2/0.1% H2S mixed gas at 600–800 °C for 50–100 h was studied after hot-dipping in the aluminum molten bath. Hot-dipping resulted in the formation of the Al topcoat and the Al-Fe alloy layer firmly adhered on the substrate. The Al-Fe alloy layer consisted primarily of a wide, tongue-like Al5Fe2 layer and narrow Al3Fe layer. When corroded at 800 °C for 100 h, the Al topcoat partially oxidized to the protective but non-adherent α-Al2O3 layer, and the interdiffusion converted the Al-Fe alloy layer to an (Al13Fe4, AlFe3-mixed layer. The interdiffusion also lowered the microhardness of the hot-dipped steel. The α-Al2O3 layer formed on the hot-dipped steel protected the carbon steel against corrosion. Without the Al hot-dipping, the carbon steel failed by forming a thick, fragile, and non-protective FeS scale.

Morphology and Performance of 5Cr5MoV Casting Die Steel in the Process of Surfacing

Science.gov (United States)

Song, Yulai; Kong, Xiangrui; Yang, Pengcong; Fu, Hongde; Wang, Xuezhu

2017-12-01

To investigate the microstructures and mechanical properties of the deposited metal on surface of die steel, two layer of weld-seam were prepared on the surface of 5Cr5MoV die steel by arc surfacing. The surface microstructures and microhardness were characterized by scanning electron microscopy, energy dispersive spectrometer and Vickers microhardness tester, respectively. The effect of load on the abrasion resistance and wear mechanism of the base metal and surfacing metal was studied by pin-on-disk tribometer. The results showed that martensite and retained austenite exist in weld-seam, both of them grow up in the form of dendrites and equiaxed grains and microhardness reach 774.2HV. The microstructures of the quenching zone mainly consist of martensite and retained austenite, while tempered martensite is the dominant phase in partial quenching zone. The abrasion resistance of the surfacing metal is superior to the base metal based on the results of wear test. The wear rates of surfacing metal and base metal raise with the increase of load. The wear rates of base metal raise extremely when the load reach 210N. Both of two kinds of materials have the similar wear mechanism, namely, abrasive wear at low load, oxidative wear and adhesive wear at high load.

Les dysthyroïdies chez l’hémodialysé chronique

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Najoua Zbiti

2010-10-01

Full Text Available INTRODUCTION: Les dysthyroïdies chez l’hémodialysé chronique sont représentées par une hypothyroïdie: dite le syndrome de basse T3, actuellement nommée "le syndrome de la maladie euthyroïdienne". L’objectif de notre travail est de déterminer le profil thyroïdien de nos HDC afin de préciser la prévalence des différents troubles thyroïdiens dans notre population et de dégager les facteurs prédictifs, aussi on a précisé l’évolution sur une période de 3 ans. METHODES: Il s’agit d’une étude rétrospective réalisée en Mars 2007 concernant 68 patients adultes en hémodialyse périodique. Nous avons analysé les paramètres anthropométriques, cliniques et biologiques. Le dosage des hormones thyroïdiennes ((triiodothyronine libre FT3, (thyroxine libre FT4 et (thyréostimuline ultra-sensible TSHus s’est effectué selon la méthode radio-immunologique. Nous avons comparé 2 groupes de patients avec et sans dysthyroïdie (définie par un taux anormal de FT3 et/ou de FT4 et/ou de TSH afin de dégager les facteurs de risque. On a réalisé une surveillance biologique des hormones thyroïdiennes pendant 3 ans afin de préciser l’incidence des différents troubles thyroïdiens dans la même population. RESULTATS: Tous les patients sont en euthyroïdie clinique. On n’a noté aucun cas de goitre. Le profil thyroïdien est caractérisé par une hypothyroïdie biologique, la prévalence était de 28%. Nous n'avons pas trouvé des cas d'hyperthyroïdie. L'étude comparative des deux groupes de malades biologiquement euthyroïdiens et hypothyroïdiens a révèle le syndrome inflammatoire (p=0.001, l’âge avancé (p=0.003, et la durée prolongée en hémodialyse (p=0.04 comme des facteurs de risque liés à l’hypothyroïdie biologique. Deux HDC ont nécessité un traitement hormonal substitutif vu le contexte du diabète dans un cas et de la grossesse dans l’autre cas. Le suivi biologique pendant trois ans n’a r

Analysis and modeling of hot extrusion die for its service life enhancement

Science.gov (United States)

Akhtar, Syed Sohail

Aluminum extrusion finds extensive application in the construction, automobile and aerospace industries. High pressures, elevated temperatures, complex and intricate section geometries lead to repeated mechanical and thermal stresses in the die and affiliated tooling. Product rework and rejects can be traced back to various defects spread over the die life cycle: die design, die manufacture and heat treatment, process parameters, inprocess die maintenance/correction and, billet type and quality. Therefore, improved and efficient service life of die and related tooling used in the extrusion press is one the most important factors in maximizing productivity and minimizing cost for ensuring the economical efficiency of an aluminum extrusion plant. How often a die has to be scrapped and replaced with a new one directly contributes to the commercial viability of producing a certain profile. The focus of the current work is on three distinct yet inter-related studies pertaining to the improvement of aluminum extrusion die. Study-A (Die Failure Analysis) is an investigation of various modes and critical failure types based on industrial data (Chapter-2 ), examination of failed dies and finite element simulation for identification of critical process parameters and design features in die fatigue-life (Chapter-3). In Study-B (Die Surface Hardening Treatment), two-stage controlled gas nitriding process for H13 steel is evaluated, both experimentally and numerically, in terms of nitrided case morphology and properties (Chapter-4) followed by experimental and numerical investigation of the effects of repeated nitriding (Chapter-5), pre-nitriding surface preparation (Chapter-6) and die profile geometry (Chapter-7) on nitriding performance in regard to die service life. In Study-C (Effect of Billet Quality on Die Life), the effect of billet quality and related influencing extrusion parameters on the die service life is investigated based on industrial data and some regression

Microstructural evolution of HFIR-irradiated low activation F82H and F82H-10B steels

International Nuclear Information System (INIS)

Wakai, E.; Shiba, K.; Sawai, T.; Hashimoto, N.; Robertson, J.P.; Klueh, R.L.

1998-01-01

Microstructures of reduced-activation F82H (8Cr-2W-0.2V-0.04Ta) and the F82H steels doped with 10 B, irradiated at 250 and 300 C to 3 and 57 dpa in the High Flux Isotope Reactor (HFIR), were examined by TEM. In the F82H irradiated at 250 C to 3 dpa, dislocation loops, small unidentified defect clusters with a high number density, and a few MC precipitates were observed in the matrix. The defect microstructure after 300 C irradiation to 57 dpa is dominated by the loops, and the number density of loops was lower than that of the F82H- 10 B steel. Cavities were observed in the F82H- 10 B steels, but the swelling value is insignificant. Small particles of M 6 C formed on the M 23 C 6 carbides that were present in both steels before the irradiation at 300 C to 57 dpa. A low number density of MC precipitate particles formed in the matrix during irradiation at 300 C to 57 dpa

Structural materialization of stainless steel molds and dies by the low temperature high density plasma nitriding

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Aizawa Tatsuhiko

2015-01-01

Full Text Available Various kinds of stainless steels have been widely utilized as a mold substrate material for injection molding and as a die for mold-stamping and direct stamping processes. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical elements at present. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness of 1400 Hv within its thickness of 40 μm without any formation of nitrides after 14.4 ks plasma nitriding at 693 K. This nitrogen solid-solution treated stainless steel had thermal resistivity even at the mold-stamping conditions up to 900 K.

The Analysis of Force Parameters in Drawing Process of High Carbon Steel Wires in Conventional and Hydrodynamic Dies

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Suliga M.

2017-12-01

Full Text Available The paper analyzes force parameters in the process of multistage drawing of steel wires in conventional and hydrodynamic dies. The drawing process of the wire rod with a diameter of 5.5 mm for wires with a diameter of 1.70 mm was performed in 12 drafts with the usage of the multistage drawbench Koch KGT with the speed range of 5-25 m/s.

Tool Wear and Formation Mechanism of White Layer When Hard Milling H13 Steel under Different Cooling/Lubrication Conditions

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Song Zhang

2014-04-01

Full Text Available The present work aims at revealing the formation mechanism of white layer and understanding the effects of tool wear and cooling/lubrication condition on white layer when hard milling H13 steel with coated cutting tools. Hard milling experiments were carried out, and tool wear and its effect on formation of white layer were investigated. Compared to dry cutting condition, CMQL (cryogenic minimum quantity lubrication technique can obviously reduce tool wear and prolong tool life owing to its good cooling and lubrication properties. The optical images of the subsurface materials indicate that the formation of white layer is related to tool wear; moreover, the thickness of white layer increases with the increase of tool wear. SEM (scanning electron microscope images and XRD (X-ray diffraction analysis confirm that the formation of white layer is mainly due to the mechanical effect rather than the thermal effect. It also proves that white layer is partly decreased or can be totally eliminated by optimizing process parameters under CMQL cutting condition. CMQL technique has the potential to be used for achieving prolonged tool life and enhanced surface integrity.

Modeling and Analysis of Deformation for Spiral Bevel Gear in Die Quenching Based on the Hardenability Variation

Science.gov (United States)

Zhang, Yingtao; Wang, Gang; Shi, Wankai; Yang, Lin; Li, Zhichao

2017-07-01

Spiral bevel gears are widely used to transmit energy between intersecting axes. The strength and fatigue life of the gears are improved by carburizing and quenching. A die quenching process is used to control the deformation of the gear. The deformation is determined by the variations in the hardenability for a certain die quenching process. The relationship between hardenability, phase transformation and deformation needs to be studied to minimize deformation during the adjustment of the die quenching process parameters. In this paper, material properties for 22CrMoH steel are determined by the results of Jominy tests, dilatometry experiments and static mechanical property tests. The material models were built based on testing results under the consideration of hardenability variation. An finite element analysis model was developed to couple the phase transformation and deformation history of the complete carburizing and die quenching process for the spiral bevel gears. The final microstructures in the gear were bainite for low hardenability steel and a mixture of bainite and ferrite for high hardenability steel. The largest buckling deformation at the gear bottom surface is 0.375 mm at the outer circle for the low hardenability gear and 0.091 mm at the inner circle for the high hardenability gear.

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Hoh; Kim, In Sub; Noh, Sung Kee

1995-01-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively. 13 figs., 1 tabs., 17 refs. (Author)

Experimental investigation and modelling of surface roughness and resultant cutting force in hard turning of AISI H13 Steel

Science.gov (United States)

Boy, M.; Yaşar, N.; Çiftçi, İ.

2016-11-01

In recent years, turning of hardened steels has replaced grinding for finishing operations. This process is compared to grinding operations; hard turning has higher material removal rates, the possibility of greater process flexibility, lower equipment costs, and shorter setup time. CBN or ceramic cutting tools are widely used hard part machining. For successful application of hard turning, selection of suitable cutting parameters for a given cutting tool is an important step. For this purpose, an experimental investigation was conducted to determine the effects of cutting tool edge geometry, feed rate and cutting speed on surface roughness and resultant cutting force in hard turning of AISI H13 steel with ceramic cutting tools. Machining experiments were conducted in a CNC lathe based on Taguchi experimental design (L16) in different levels of cutting parameters. In the experiments, a Kistler 9257 B, three cutting force components (Fc, Ff and Fr) piezoelectric dynamometer was used to measure cutting forces. Surface roughness measurements were performed by using a Mahrsurf PS1 device. For statistical analysis, analysis of variance has been performed and mathematical model have been developed for surface roughness and resultant cutting forces. The analysis of variance results showed that the cutting edge geometry, cutting speed and feed rate were the most significant factors on resultant cutting force while the cutting edge geometry and feed rate were the most significant factor for the surface roughness. The regression analysis was applied to predict the outcomes of the experiment. The predicted values and measured values were very close to each other. Afterwards a confirmation tests were performed to make a comparison between the predicted results and the measured results. According to the confirmation test results, measured values are within the 95% confidence interval.

Effect of Surface Modification on Corrosion Resistance of Uncoated and DLC Coated Stainless Steel Surface

Science.gov (United States)

Scendo, Mieczyslaw; Staszewska-Samson, Katarzyna

2017-08-01

Corrosion resistance of 4H13 stainless steel (EN-X46Cr13) surface uncoated and coated with an amorphous hydrogenated carbon (a-C:H) film [diamond-like carbon (DLC)] in acidic chloride solution was investigated. The DLC films were deposited on steel surface by a plasma deposition, direct current discharge (PDCD) method. The Fourier transform infrared (FTIR) was used to determine the chemical groups existing on DLC films. The surface of the specimens was observed by a scanning electron microscope (SEM). The tribological properties of the both materials were examined using a ball-on disk tribometer. The microhardness (HV) of diamond-like carbon film increased over five times in relation to the 4H13 stainless steel without of DLC coating. Oxidation kinetic parameters were determined by gravimetric and electrochemical methods. The high value of polarization resistance indicates that the DLC film on substrate was characterized by low electrical conductivity. The corrosion rate of 4H13 stainless steel with of DLC film decreased about eight times in relation to uncoated surface of 4H13 stainless steel.

Close toleranoe forging of chromium steel blades for powerful steam turbines

International Nuclear Information System (INIS)

Shastin, Eh.G.; Kositskij, Yu.N.; Lyubchits, G.A.

1989-01-01

Work on simulating technological process on die-forging hammer was performed in order to reduce the preparation period bringing technology of close tolerance forging of turbine blades to a commercial level. A special attention was paid to development of accurate forming of forgings of 20Kh13Sh, 12Kh13 and 15Kh11MFSh steels on screw presses with nominal effort equal to 80 and 144 MN

Corrosion fatigue investigation of a high nitrogen 12% Cr-steel and of a high strength martensitic PH 13-8 Mo steel under simulated steam turbine conditions. Final report

International Nuclear Information System (INIS)

Schmitt-Thomas, K.G.; Schweigart, H.

1992-01-01

This report summarizes the results of the corrosion fatigue investigations of two martensitic stainless steels (PH 13-8 Mo, X20 CrMoV 12 1; corrosion medium: 0,01 m NaCl or 22 wt% NaCl; pH value 3 or 7). The working programm includes electrochemical and corrosion fatigue tests. Also chemical analysis, mechanical-technological and metallographical as SEM investigations were performed. (orig.)

Wear of Shaped Surfaces of PVD Coated Dies for Clinching

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Miroslav Džupon

2017-11-01

Full Text Available A clinching method that uses a simple toolset consisting of a punch and a die, is utilized for joining lightweight materials. This paper is aimed at investigating the wear of the die cavity of a clinching tool. A clinching tool with a specially shaped cavity was used for joining thin hot-dip galvanized steel sheets. Various types of physical vapour deposition (PVD coatings such as ZrN, CrN and TiCN were deposited on the shaped surface of the die using Lateral Rotating Arc-Cathodes technology. Hot-dip galvanized steel sheets were used for testing the clinching tool. The material properties of PVD coatings that were deposited on the shaped part of the clinching die were evaluated. Finite Element Analysis was used to localize the area of the shaped part of the die and the part of surface area of the cylindrical die cavity of ϕ 5.0 mm, in which high contact pressure values were predicted. The prediction of the start of the wear cycle was verified experimentally by the clinching of 300 samples of hot-dip galvanized steel sheets. Unlike the CrN and ZrN coatings, the TiCN coating remained intact on the entire surface of the die.

Composition and B-H curve analysis of low carbon steel from Krakatau Steel company using VSM And EDX for magnet design of 13 MeV cyclotron

International Nuclear Information System (INIS)

Taufik; Emy Mulyani; Kusminarto; Slamet Santosa

2012-01-01

Cyclotron is one type of particle accelerator that accelerate particle in circular trajectory, in order to obtain high kinetic energy. One of the main components is the cyclotron magnet system that serves to form a cyclic particle trajectories and made of forged low carbon steel. In the magnet design, the selection of magnetic materials is very important in determining whether cyclotron magnet can operate properly or not and even can be optimal. That is why we need to test samples of magnetic materials from local production in this case two samples of material produced by PT Krakatau Steel (KS). Tests performed include testing of BH curve using VSM (Vibrating Sample Magnetometer) and material composition using EDX (Energy-dispersive X-ray spectroscopy). Obtained BH curve is used as material data in three-dimensional simulation using the Opera 3D with referee to magnetic model of Kirams 13. From this study it can be concluded that the position of the test object to the direction of the magnetic field induction gives different BH curve and the samples obtained from KS has a carbon content which is still high. The lower the carbon content in the iron will produce a better magnetic properties. Material samples analyzed will produce a field that is not optimal when it is used in a 13 MeV cyclotron magnet. (author)

Characterization of the interfacial heat transfer coefficient for hot stamping processes

Science.gov (United States)

Luan, Xi; Liu, Xiaochuan; Fang, Haomiao; Ji, Kang; El Fakir, Omer; Wang, LiLiang

2016-08-01

In hot stamping processes, the interfacial heat transfer coefficient (IHTC) between the forming tools and hot blank is an essential parameter which determines the quenching rate of the process and hence the resulting material microstructure. The present work focuses on the characterization of the IHTC between an aluminium alloy 7075-T6 blank and two different die materials, cast iron (G3500) and H13 die steel, at various contact pressures. It was found that the IHTC between AA7075 and cast iron had values 78.6% higher than that obtained between AA7075 and H13 die steel. Die materials and contact pressures had pronounced effects on the IHTC, suggesting that the IHTC can be used to guide the selection of stamping tool materials and the precise control of processing parameters.

An Experiment Study on Surface Roughness in High Speed Milling NAK80 Die Steel

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Su Fa

2016-01-01

Full Text Available The paper introduces that the high speed milling experiments on NAK80 die steel was carried out on the DMU 60 mono BLOCK five axis linkage high speed CNC machining center tool by the TiAlN coated tools, in order to research the effect of milling parameters on surface roughness Ra. The results showed that the Ra value increased with the decrease of milling speed vc, increased with the axial depth of milling ap, and feed per tooth fz and radial depth of milling ae. On the basis of the single factor experiment results, the mathematics model for between surface roughness and milling parameters were established by linear regression analysis.

Hydrogen degradation of the 26H2MF alloy steel in H2SO4 and hydrocarbon environments

International Nuclear Information System (INIS)

Zielinski, A.; Swieczko-Zurek, B.; Michaliak, P.

2004-01-01

The Polish 26H2M alloy steel has been subjected to different heat treatment resulting in different microstructure and fracture appearance. The slow strain rate tests have been made on smooth round specimens in diluted sulphuric acid, boiler fuel and used mineral machine oil. The 26H2MF steel has become relatively immune in neutral boiler fuel and mineral oil and been heavily suffered from hydrogen degradation in acidic environment. The results demonstrate that the 26H2MF steel is highly susceptible to hydrogen degradation but in absence of stress raisers the increased hydrogen absorption in hydrocarbons can cause only small loss of its plasticity. (author) >>>

DIE PLEK VAN SANG EN MUSIEK IN DIE PROTESTANTSE ...

African Journals Online (AJOL)

Test

Sy moet hierdie opdrag uitvoer deur mid del van die Prediking d.w.s. deur middel van die Woord-vorm, maar ook deur die bediening van die sakramente, dws. deur middel van die vorm van die Daad. Maar nou wil God nie hê dat die Kerk slegs één maal die Evangelie sal predik en die mense sal doop om hulle daarna.

Advanced cold rolled steels for automotive applications

Energy Technology Data Exchange (ETDEWEB)

Hofmann, H. [ThyssenKrupp Steel AG, Eberhardstrasse 12, 44145 Dortmund (Germany); Mattissen, D.; Schaumann, T.W. [ThyssenKrupp Steel AG, Duisburg (Germany)

2006-09-15

Advanced multiphase steels offer a great potential for bodies-in-white through their combination of formability and achievable component strength levels. They are first choice for strength and crash-relevant parts of challenging geometry. The intensive development of high-strength multiphase steels by ThyssenKrupp has led to hot dip galvanizing concepts with an outstanding forming potential. Hot rolled, hot dip galvanized complex phase steels are currently produced in addition to cold rolled DP and RA steels. New continuously annealed grades with tensile strength levels of up to 1000 MPa in combination with sufficient ductility for applications mainly in the field of structural automobile elements make use of the classic advantages of microalloying as well as the principles of DP and TRIP steels. Further improvement of properties will be reached by the new class of high manganese alloyed steels. (Abstract Copyright [2006], Wiley Periodicals, Inc.) [German] Fortschrittliche Multiphasen-Staehle eroeffnen wegen der inzwischen erreichbaren Kombination aus Umformbarkeit und Bauteilfestigkeit ein enormes Potenzial fuer Rohkarosserien. Sie stellen eine erste Wahl dar, wenn es um Festigkeit und um Crashsicherheit geht und besondere Anforderungen an die Bauteilgeometrien gestellt werden. Bei ThyssenKrupp hat die Entwicklung hochfester Multiphasen-Staehle in Verbindung mit dem Feuerverzinken zur Realisierung von Blechhalbzeugen gefuehrt, die hervorragend formbar sind. Es werden heute feuerverzinkte Komplexphasenstaehle neben den bewaehrten kaltgewalzten Dualphasen(DP) - und Retained Austenit(RA)-Staehlen produziert. Die neuen kontinuierlich gegluehten Stahlvarianten mit Festigkeiten bis zu 1000 MPa in Kombination mit der bei Strukturbauteilen im Automobilbau geforderten Duktilitaet nutzen sowohl die klassischen Vorteile des Mikrolegierens aus und dazu die Prinzipien, die man bei DP- und TRIP-Staehlen anwendet. Eine weitere Verbesserung des Eigenschaftsprofils wird mit dem

Friction stir welding of F82H steel for fusion applications

Energy Technology Data Exchange (ETDEWEB)

Noh, Sanghoon, E-mail: shnoh@kaeri.re.kr [Fusion Structural Materials Division, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of); Ando, Masami; Tanigawa, Hiroyasu [Fusion Structural Materials Division, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan); Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan)

2016-09-15

In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

Friction stir welding of F82H steel for fusion applications

International Nuclear Information System (INIS)

Noh, Sanghoon; Ando, Masami; Tanigawa, Hiroyasu; Fujii, Hidetoshi; Kimura, Akihiko

2016-01-01

In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

Spectral Analysis of CO2 Corrosion Product Scales on 13Cr Tubing Steel

International Nuclear Information System (INIS)

Guan-fa, Lin; Zhen-quan, Bai; Yao-rong, Feng; Xun-yuan, Xu

2008-01-01

CO 2 corrosion product scales formed on 13 Cr tubing steel in autoclave and in the simulated corrosion environment of oil field are investigated in the paper. The surface and cross-section profiles of the scales were observed by scanning electron microscopy (SEM), the chemical compositions of the scales were analyzed using energy dispersion analyzer of X-ray (EDAX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to confirm the corrosion mechanism of the 13 Cr steel in the simulated CO 2 corrosion environment. The results show that the corrosion scales are formed by the way of fashion corrosion, consist mainly of four elements, i.e. Fe, Cr, C and O, and with a double-layer structure, in which the surface layer is constituted of bulky and incompact crystals of FeCO 3 , and the inner layer is composed of compact fine FeCO 3 crystals and amorphous Cr(OH) 3 . Because of the characteristics of compactness and ionic permeating selectivity of the inner layer of the corrosion product scales, 13 Cr steel is more resistant in CO 2 corrosion environment

Effects of initial microstructure and helium production on radiation hardening in F82H Steels

Energy Technology Data Exchange (ETDEWEB)

Okubo, N.; Wakai, E.; Takada, F.; Jitsukawa, S. [Japan Atomic Energy Agency, Naga-gun, Ibaraki-ken (Japan); Katoh, Y. [Oak Ridge Noational Laboratory, TN (United States)

2007-07-01

Full text of publication follows: Fission neutron irradiation to steels doped with isotope boron-10 is frequently conducted to study effects of the helium production on mechanical properties. The intrinsic mechanical properties of F82H steels could have been changed due to the boron doping. Recently, we reported that co-doping with boron and nitrogen to F82H (F82H+B+N) improved the mechanical properties of F82H doped only with boron. The mechanical properties of F82H+B+N are successfully comparable with the non-doped F82H before irradiation. In order to evaluate the effects of initial microstructure and helium production on radiation hardening, F82H and F82H+B+N were irradiate d Specimens used in this study were standard F82H martensitic steels, F82H steels doped with 60 mass ppm {sup 10}B and 200 ppm N (F82H+10B+N) and F82H steels doped with 60 mass ppm {sup 11}B and 200 ppm N (F82H+11B+N). Initial microstructures were changed by tempering conditions, and the tempering temperatures were at 700, 750 and 780 deg. C. Irradiation was performed at nominally 250 deg. C to 2 dpa in JMTR. Tensile properties were measured for the specimens before and after irradiation. Change of yield stress due to the irradiation in the F82H+11B+N steels depended strongly on the initial microstructure and hardness before irradiation. The radiation hardening due to helium production in the F82H+10B+N steels was less than 60 MPa in these experiments. Size of dimple in the fracture surface of specimen with helium production was larger than that with non-helium production. (authors)

Mechanism of generation of large (Ti,Nb,V)(C,N)-type precipitates in H13 + Nb tool steel

Science.gov (United States)

Xie, You; Cheng, Guo-guang; Chen, Lie; Zhang, Yan-dong; Yan, Qing-zhong

2016-11-01

The characteristics and generation mechanism of (Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of (Ti,Nb,V)(C,N) phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich (Ti,Nb,V)(C,N) precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2-5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of (Ti,Nb,V)(C,N) is concentrated. The average composition of the single Ti-V-rich phase is (Ti0.511V0.356Nb0.133)(C x N y ), whereas that for the single Nb-rich phase is (Ti0.061V0.263Nb0.676)(C x N y ). The calculation results based on the Scheil-Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.

Study of wettability and cell viability of H implanted stainless steel

Science.gov (United States)

Shafique, Muhammad Ahsan; Ahmad, Riaz; Rehman, Ihtesham Ur

2018-03-01

In the present work, the effect of hydrogen ion implantation on surface wettability and biocompatibility of stainless steel is investigated. Hydrogen ions are implanted in the near-surface of stainless steel to facilitate hydrogen bonding at different doses with constant energy of 500 KeV, which consequently improve the surface wettability. Treated and untreated sample are characterized for surface wettability, incubation of hydroxyapatite and cell viability. Contact angle (CA) study reveals that surface wettability increases with increasing H-ion dose. Raman spectroscopy shows that precipitation of hydroxyapatite over the surface increase with increasing dose of H-ions. Cell viability study using MTT assay describes improved cell viability in treated samples as compared to the untreated sample. It is found that low dose of H-ions is more effective for cell proliferation and the cell count decreases with increasing ion dose. Our study demonstrates that H ion implantation improves the surface wettability and biocompatibility of stainless steel.

Effect of heat treatment on the characteristics of tool steel deposited by the directed energy deposition process

Science.gov (United States)

Park, Jun Seok; Lee, Min-Gyu; Cho, Yong-Jae; Sung, Ji Hyun; Jeong, Myeong-Sik; Lee, Sang-Kon; Choi, Yong-Jin; Kim, Da Hye

2016-01-01

The directed energy deposition process has been mainly applied to re-work and the restoration of damaged steel. Differences in material properties between the base and the newly deposited materials are unavoidable, which may affect the mechanical properties and durability of the part. We investigated the effect of heat treatment on the characteristics of tool steel deposited by the DED process. We prepared general tool steel materials of H13 and D2 that were deposited onto heat-treated substrates of H13 and D2, respectively, using a direct metal tooling process. The hardness and microstructure of the deposited steel before and after heat treatment were investigated. The hardness of the deposited H13 steel was higher than that of wrought H13 steel substrate, while that of the deposited D2 was lower than that of wrought D2. The evolution of the microstructures by deposition and heat treatment varied depending on the materials. In particular, the microstructure of the deposited D2 steel after heat treatment consisted of fine carbides in tempered martensite and it is expected that the deposited D2 steel will have isotropic properties and high hardness after heat treatment.

Formability of dual-phase steels in deep drawing of rectangular parts: Influence of blank thickness and die radius

Science.gov (United States)

López, Ana María Camacho; Regueras, José María Gutiérrez

2017-10-01

The new goals of automotive industry related with environment concerns, the reduction of fuel emissions and the security requirements have driven up to new designs which main objective is reducing weight. It can be achieved through new materials such as nano-structured materials, fibre-reinforced composites or steels with higher strength, among others. Into the last group, the Advance High Strength Steels (AHSS) and particularly, dual-phase steels are in a predominant situation. However, despite of their special characteristics, they present issues related to their manufacturability such as springback, splits and cracks, among others. This work is focused on the deep drawing processof rectangular shapes, a very usual forming operation that allows manufacturing several automotive parts like oil pans, cases, etc. Two of the main parameters in this process which affect directly to the characteristics of final product are blank thickness (t) and die radius (Rd). Influence of t and Rd on the formability of dual-phase steels has been analysed considering values typically used in industrial manufacturing for a wide range of dual-phase steels using finite element modelling and simulation; concretely, the influence of these parameters in the percentage of thickness reduction pt(%), a quite important value for manufactured parts by deep drawing operations, which affects to its integrity and its service behaviour. Modified Morh Coulomb criteria (MMC) has been used in order to obtain Fracture Forming Limit Diagrams (FFLD) which take into account an important failure mode in dual-phase steels: shear fracture. Finally, a relation between thickness reduction percentage and studied parameters has been established fordual-phase steels, obtaining a collection of equations based on Design of Experiments (D.O.E) technique, which can be useful in order to predict approximate results.

Plastohydrodynamic drawing and coating of stainless steel wire using a tapered bore die of no metal to metal contact

Science.gov (United States)

Hasan, S.; Basmage, O.; Stokes, J. T.; Hashmi, M. S. J.

2018-05-01

A review of wire coating studies using plasto-hydrodynamic pressure shows that most of the works were carried out by conducting experiments simultaneously with simulation analysis based upon Bernoulli's principle and Euler and Navier-Stokes (N-S) equations. These characteristics relate to the domain of Computational Fluid Dynamics (CFD) which is an interdisciplinary topic (Fluid Mechanics, Numerical Analysis of Fluid flow and Computer Science). This research investigates two aspects: (i) simulation work and (ii) experimentation. A mathematical model was developed to investigate the flow pattern of the molten polymer and pressure distribution within the wire-drawing dies, assessment of polymer coating thickness on the coated wires and speed of coating on the wires at the outlet of the drawing dies, without deploying any pressurizing pump. In addition to a physical model which was developed within ANSYS™ environment through the simulation design of ANSYS™ Workbench. The design was customized to simulate the process of wire-coating on the fine stainless-steel wires using drawing dies having different bore geometries such as: stepped parallel bore, tapered bore and combined parallel and tapered bore. The convergence of the designed CFD model and numerical and physical solution parameters for simulation were dynamically monitored for the viscous flow of the polypropylene (PP) polymer. Simulation results were validated against experimental results and used to predict the ideal bore shape to produce a thin coating on stainless wires with different diameter. Simulation studies confirmed that a specific speed should be attained by the stainless-steel wires while passing through the drawing dies. It has been observed that all the speed values within specific speed range did not produce a coating thickness having the desired coating characteristic features. Therefore, some optimization of the experimental set up through design of experiments (Stat-Ease) was applied to

Die historiese betroubaarheid van die aartsvadervertellinge. 'n Beknopte bespreking van die huidige debat na aanleiding van die jongste publikasie

Directory of Open Access Journals (Sweden)

W. Vosloo

1982-08-01

Full Text Available Die afgelope twintig jaar was daar �n toenemende belangstelling in die aartsvadervertellinge in Genesis. Benewens die talle tydskrifartikels het skrywers soos die volgende ook boeke oor die onderwerp die lig laat sien: A. Parrot (1962, W. M. Clark (1964, R. Kilian (1966, R. E. Clements (1967, N. Lohfink (1967, H. Weidemann (1968, R. Martin-Achard (1969, T. L. Thompson (1974, J. van Seters (1975, J. P. Fokkelman (1975, C. Westermann (1976, R. Rendtorff (1977, J. Bright (1977, W. McKane (1979 en A. R. Millard en D. J. Wiseman (1980.

Comparison of surface roughness and chip characteristics obtained under different modes of lubrication during hard turning of AISI H13 tool work steel.

Science.gov (United States)

Raj, Anil; Wins, K. Leo Dev; Varadarajan, A. S.

2016-09-01

Surface roughness is one of the important parameters, which not only affects the service life of a component but also serves as a good index of machinability. Near Dry Machining, methods (NDM) are considered as sustainable alternative for workshops trying to bring down their dependence on cutting fluids and the hazards associated with their indiscriminate usage. The present work presents a comparison of the surface roughness and chip characteristics during hard turning of AISI H13 tool work steel using hard metal inserts under two popular NDM techniques namely the minimal fluid application and the Minimum Quantity Lubrication technique(MQL) using an experiment designed based on Taguchi's techniques. The statistical method of analysis of variance (ANOVA) was used to determine the relative significance of input parameters consisting of cutting speed, feed and depth of cut on the attainable surface finish and the chip characteristics. It was observed that the performance during minimal fluid application was better than that during MQL application.

Metallurgical Characterization of Reduced Activation Martensitic Steel F-82H Modified

International Nuclear Information System (INIS)

Fernandez, P.; Lapena, J.; Lancha, A.M.; Gomez-Briceno, D.; Schirra, M.

1999-12-01

During 1995-1998 within of research and development programs on reduced ferritic/martensitic steels for fusion, metallurgical characterization of 8Cr-2WVTa steel, denominated F-28H modified, have been carried out. The work has focused on studying the microstructural and mechanical (tensile, creep, low cycle fatigue and charpy) characteristics of as-received state and aged material in the temperature range 300 degree centigrade to 600 degree centigrade for periods up to 5000 h. (Author) 45 refs

Evaluation of interlocking bond strength between structured 1.0338 steel sheets and high pressure die cast AlMg5Si2

Science.gov (United States)

Senge, S.; Brachmann, J.; Hirt, G.; Bührig-Polaczek, A.

2018-05-01

Multi-material components open up new possibilities for functional design. Such components combine beneficial physical properties of different materials in a single component as for instance chemical resistance, high strength or low density. The challenge is a reliable bond between both materials to enable a long term usage. This paper deals with a form closure connection to ensure a solid connection between steel strips and high pressure die cast aluminium. Two different sizes of channel structures with width ratios of 1.0 and 1.35 are produced on a steel sheet. An ensuing flat rolling pass is performed to create undercuts with a width of up to 50 µm, enabling an interlocking of the molten aluminium in the concluding casting process. For both rolling processes the resulting geometry is analysed depending on the thickness reduction. In a subsequent high pressure die casting process, aluminium is applied resulting in a complete form filling for the coarser structure. Comparing structures with and without undercuts, only structures suited with undercuts remain gap-free after solidification contraction. The finer structure could not be filled completely; nevertheless these structures result in shear strength of up to 45 MPa transversal to the channel-direction.

Characterization of an AISI H-13 steel for work in hot

International Nuclear Information System (INIS)

Godinez, J.; Robles, E.

1998-01-01

Two materials were acquired which elaborated through secondary refining processes known as electroslag refusing (ESR) and electric arc in vacuum refusing (VAR) were acquired. These materials were thermically treated, for subsequently to determine their mechanical properties in longitudinal and transversal directions with respect to rolling direction, moreover they were characterized through scanning electron microscopy and X-ray diffraction determining microstructure, carbides and non-metallic inclusions. The results of the mechanical essays allowed to evaluate the fracture toughness to this steel by the Barsom and Rolfe method. (Author)

Behaviour of carbon steel and chromium steels in CO2 environments

International Nuclear Information System (INIS)

Lefebvre, B.; Bounie, P.; Guntz, G.; Prouheze, J.C.; Renault, J.J.

1984-01-01

The behavior in aqueous CO 2 environments of steel with chromium content between 0 and 22% has been studied by autoclave tests. The influence of chromium and molybdenum contents has been investigated particularly on 13 Cr steel. Conventional electrochemical test results are related to the CO 2 autoclave test results. The influence of the environment: temperature, chloride concentration, partial pressure of CO 2 and some amount of H 2 S on the corrosion resistance are discussed

Effect of temperature and aluminium additions on the mechanical properties of the 13% chromium ferrite stainless steels

International Nuclear Information System (INIS)

Martins, S.

1975-01-01

The potential interest of the ferritic stainless steels as component materials for nuclear power reactors led to investigate how aluminium influences the mechanical properties of 13% chromium ferritic stainless steels between room temperature and about 700 0 C. Nominal 13% chromium and 0.04 to 0.08% carbon ferritic stainless steels containing 0, 0.13, 2.19 and 4.15% aluminium, respectively, were obtained by vacuum remelting of a commercial martensitic-ferritic stainless steel and suitable additions of aluminium. After successive rolling operations and recrystallizations performed in order to obtain final 0.5 mm thick sheets with similar average grain sizes the specimens of the above mentioned steels were tested in a tensile test Instron machine, with a constant strain rate (approximately equal to 1.6 x 10 -3 min -1 ), at room temperature, 140, 265, 415, 565 and 715 0 C. The results obtained show that strengthening by aluminium is strongly temperature dependent. At 265 0 C all the steels presentes serrated plastic deformation (Portevin-Le Chatelier effect), which is attributed to interactions of the interstitial and substitutional solute atoms with dislocations in the body centered cubic structure. Flow stress drops were still observed at 465 0 C, although the tests performed at 565 and 715 0 C showed work-softening of the materials and total absence of serrations. Stress relaxation tests at room temperature yielded values of the apparent activation volumes, which are scattered between about 100 and 130 b 3 (b-Burgers vector), being almost constant with stress, strain and aluminium content. Therefore, although aluminium appreciably strengthens the 13% chromium steel, the behaviour summarized suggests that the mechanism controlling plastic deformation at room temperature is the same for all the tested steels, the values of the apparent activitation volumes being probably determined by the interstitial content. Stress relaxation tests at 20, 75, 140 and 265 0 C for

Brittle Fracture Behaviors of Large Die Holders Used in Hot Die Forging

Directory of Open Access Journals (Sweden)

Weifang Zhang

2017-05-01

Full Text Available Brittle fracture of large forging equipment usually leads to catastrophic consequences. To avoid this kind of accident, the brittle fracture behaviors of a large die holder were studied by simulating the practical application. The die holder is used on the large die forging press, and it is made of 55NiCrMoV7 hot-work tool steel. Detailed investigations including mechanical properties analysis, metallographic observation, fractography, transmission electron microscope (TEM analysis and selected area electron diffraction (SAED were conducted. The results reveal that the material generated a large quantity of large size polyhedral M23C6 (M: Fe and Cr mainly and elongated M3C (M: Fe mainly carbides along the martensitic lath boundaries when the die holder was recurrently tempered and water-cooled at 250 °C during the service. The large size carbides lead to the material embrittlement and impact toughness degradation, and further resulted in the brittle fracture of the die holder. Therefore, the operation specification must be emphasized to avoid the die holder being cooled by using water, which is aimed at accelerating the cooling.

Welding procedure for 06Kh13N7D2 steel

International Nuclear Information System (INIS)

Muromtsev, B.I.; Turkov, I.I.

1990-01-01

Based on the results of investigations into the process strength, mechanical and corrosion properties of 08Kh13N7D2 steel welded joints, the optimal method of its welding and a possibility of applying it for high-strength mounting in nuclear power plants are determined

Mechanical and fatigue properties of martensitic Fe-13Cr steel in contact with lead and lead-bismuth melts

Energy Technology Data Exchange (ETDEWEB)

Yaskiv, O.I., E-mail: oleh.yaskiv@ipm.lviv.ua; Fedirko, V.M.

2014-01-15

Highlights: •We investigated the influence of Pb and Pb-Bi melts on mechanical properties of Fe-13Cr steel at high temperatures. •We revealed the temperature interval of liquid metal embrittlement of Fe-13Cr steel. •Pb-Bi has more negative impact as compared with Pb for both plasticity and fatigue. -- Abstract: The influence of stagnant liquid-metal environments (Pb and Pb-Bi) on mechanical (strength and plasticity) and fatigue properties (low cycle fatigue) of martensitic Fe-13Cr steel in temperature interval of 250–600 °S have been investigated. Heavy liquid metals facilitate decreasing in ultimate strength by 10–20% against that in vacuum. The increase of temperature enhances this effect. Fe-13Cr steel is susceptible to liquid-metal embrittlement in the temperature interval of 350–450 °S, which manifests itself more substantially in lead-bismuth eutectic. The decrease of plasticity in Pb is 11% at 450 °S and in Pb-Bi is 30% in temperature interval 350–400 °S. Liquid metal environments significantly reduce fatigue life of Fe-13Cr steel. Pb-Bi has a more negative impact. In particular, with increasing total strain amplitude (up to 1.0%), the decrease in the cycle number to fracture by more than two orders of magnitude occurs.

Corrosion mechanism of 13Cr stainless steel in completion fluid of high temperature and high concentration bromine salt

International Nuclear Information System (INIS)

Liu, Yan; Xu, Lining; Lu, Minxu; Meng, Yao; Zhu, Jinyang; Zhang, Lei

2014-01-01

Highlights: • The corrosion behavior of 13Cr steel exposed to bromine salt completion fluid containing high concentration bromine ions was investigated. • There are passive circles around pits on the 13Cr steel surface after 7 d of exposure. • Macroscopic galvanic corrosion formed between the passive halo and the pit. • The mechanism of pitting corrosion on 13Cr stainless steel exposed to heavy bromine brine was established. - Abstract: A series of corrosion tests of 13Cr stainless steel were conducted in a simulated completion fluid environment of high temperature and high concentration bromine salt. Corrosion behavior of specimens and the component of corrosion products were investigated by means of scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The results indicate that 13Cr steel suffers from severe local corrosion and there is always a passive halo around every pit. The formation mechanism of the passive halo is established. OH − ligand generates and adsorbs in a certain scale because of abundant OH − on the surface around the pits. Passive film forms around each pit, which leads to the occurrence of passivation in a certain region. Finally, the dissimilarities in properties and morphologies of regions, namely the pit and its corresponding passive halo, can result in different corrosion sensitivities and may promote the formation of macroscopic galvanic pairs

Sliding Wear Behaviour and Corosion Resistance to Ringer’s Solution of Uncoated and DLC Coated X46Cr13 Steel

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Scendo M.

2016-12-01

Full Text Available Sliding wear properties and corrosion resistance in Ringer’s solution of uncoated and diamond-like carbon (DLC coated X46Cr13 steel was tested. The Raman spectra showed that the DLC film was successfully coated by plasma assisted CVD method onto the steel surface. The wear test, carried out using a ball-on disk tribometer, revealed that the DLC coating show better resistance to sliding wear and lower friction coefficient against a 100Cr6 steel ball than five times softer X46Cr13 steel. The oxidation kinetic parameters were determined by means of both the gravimetric and electrochemical method. It was found that the DLC coating markedly decreased the rate of corrosion of the X46Cr13 steel, irrespective of the corrosion mechanism involved.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

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Jose Mario Paiva

2018-02-01

Full Text Available In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,AlN deposited by physical vapor deposition (PVD have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC and one central rotating cathode (CERC. The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

Science.gov (United States)

Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

2018-02-28

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Song, Taek Hoh; Kim, In Sub [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Noh, Sung Kee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-08-01

In connection with the safe storage of high level nuclear waste, effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H{sub 2}O{sub 2}. The experimental results show that H{sub 2}O{sub 2} increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H{sub 2}O{sub 2} concentration increased, indicating that pitting resistance was decreased by the existence of H{sub 2}O{sub 2} in the electrolyte. These effects of H{sub 2}O{sub 2} on corrosion of 304L stainless steel are considered to be similar to those of {gamma}-irradiation. To compare the effects of H{sub 2}O{sub 2} with those of O{sub 2}, cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H{sub 2}O{sub 2} on the corrosion behavior were very similar to those of O{sub 2} such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H{sub 2}O{sub 2} were restricted by the large current density of proton reduction and by the le Chatelier`s principle respectively. 13 figs., 1 tabs., 17 refs. (Author).

Corrosion processes and coalification of ferrtic-martensitic steels in H{sub 2}O-CO{sub 2} atmospheres; Korrosionsprozesse und Aufkohlung von ferritisch-martensitischen Staehlen in H{sub 2}O-CO{sub 2} Atmosphaeren

Energy Technology Data Exchange (ETDEWEB)

Huenert, Daniela

2010-09-20

The dissertation desribes the corrosion of steels with chromium concentrations of 1-12 percent in H{sub 2}O-CO{sub 2} atmospheres at variable pressure in the temperature range of 500-650 C and shows the corresponding degree of coalification. The investigations were carried out in a specially constructed corrosion unit which enables simulations of the power plant conditions temperature, pressure, gas composition, and gas flow rate. Above 575 C, the experimentally measured corrosion rates decrease, similar to those in hydrogen. Below 575 C, higher corrosion rates are observed in H{sub 2}O-CO{sub 2} atmospheres than in hydrogen, which is assumed to be the result of chromium fixation by the carbon formed in the corrosion process and of the existence of wuestite below this temperature. Below 600 C, temperature and pressure act independently of each other. Investigations between 600 and 625 C showed that pressure and temperature are not independent parameters with regard to oxide layer growth. The combined effect of these parameters results in higher corrosion rates and coalification depths. The dissertation describes this higher corrosion rate and coalification depth by an enhanced transport model. (orig.) [German] In der vorliegenden Arbeit wurde das Korrosionsverhalten an Stahlqualitaeten mit Chromgehalten zwischen 1 und 12 % in H{sub 2}O-CO-2-Atmosphaeren bei unterschiedlichem Druck im Temperaturbereich von 500 bis 650 C dargestellt und die parallel erfolgende Aufkohlung gezeigt. Fuer die Untersuchungen wurde eine Korrosionsanlage aufgebaut, welche die Simulation der Kraftwerksbedingungen Temperatur, Druck und Gaszusammensetzung und -geschwindigkeit erlaubt. Die experimentell bestimmten Korrosionsraten sind oberhalb von 575 C vergleichbar mit denen in Wasserdampf. Unterhalb von 575 C werden hoehere Korrosionsraten in H2O-CO2- Atmosphaeren beobachtet als in Wasserdampf, was als Folge der Fixierung des Chroms durch den waehrend des Korrosionsprozesses gebildeten

Development of materials for the rapid manufacture of die cast tooling

Science.gov (United States)

Hardro, Peter Jason

The focus of this research is to develop a material composition that can be processed by rapid prototyping (RP) in order to produce tooling for the die casting process. Where these rapidly produced tools will be superior to traditional tooling production methods by offering one or more of the following advantages: reduced tooling cost, shortened tooling creation time, reduced man-hours for tool creation, increased tool life, and shortened die casting cycle time. By utilizing RP's additive build process and vast material selection, there was a prospect that die cast tooling may be produced quicker and with superior material properties. To this end, the material properties that influence die life and cycle time were determined, and a list of materials that fulfill these "optimal" properties were highlighted. Physical testing was conducted in order to grade the processability of each of the material systems and to optimize the manufacturing process for the downselected material system. Sample specimens were produced and microscopy techniques were utilized to determine a number of physical properties of the material system. Additionally, a benchmark geometry was selected and die casting dies were produced from traditional tool materials (H13 steel) and techniques (machining) and from the newly developed materials and RP techniques (selective laser sintering (SLS) and laser engineered net shaping (LENS)). Once the tools were created, a die cast alloy was selected and a preset number of parts were shot into each tool. During tool creation, the manufacturing time and cost was closely monitored and an economic model was developed to compare traditional tooling to RP tooling. This model allows one to determine, in the early design stages, when it is advantageous to implement RP tooling and when traditional tooling would be best. The results of the physical testing and economic analysis has shown that RP tooling is able to achieve a number of the research objectives, namely

Characterization of an AISI H-13 steel for work in hot; Caracterizacion del acero H-13 AISI para trabajado en caliente

Energy Technology Data Exchange (ETDEWEB)

Godinez, J.; Robles, E. [Instituto Nacional de Investigaciones Nucleares, Departamento de Sintesis y Caracterizacion de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

Two materials were acquired which elaborated through secondary refining processes known as electroslag refusing (ESR) and electric arc in vacuum refusing (VAR) were acquired. These materials were thermically treated, for subsequently to determine their mechanical properties in longitudinal and transversal directions with respect to rolling direction, moreover they were characterized through scanning electron microscopy and X-ray diffraction determining microstructure, carbides and non-metallic inclusions. The results of the mechanical essays allowed to evaluate the fracture toughness to this steel by the Barsom and Rolfe method. (Author)

Heating temperature effect on ferritic grain size of rotor steel

International Nuclear Information System (INIS)

Cheremnykh, V.G.; Derevyankin, E.V.; Sakulin, A.A.

1983-01-01

The heating temperature effect on ferritic grain size of two steels 13Kh1M1FA and 25Kh1M1FA is evaluated. It is shown that exposure time increase at heating temperatures below 1000 deg C up to 10h changes but slightly the size of the Cr-Mo-V ferritic grain of rotor steel cooled with 25 deg C/h rate. Heating up to 1000 deg C and above leads to substantial ferritic grain growth. The kinetics of ferritic grain growth is determined by the behaviour of phases controlling the austenitic grain growth, such as carbonitrides VCsub(0.14)Nsub(0.78) in 13Kh1M1FA steel and VCsub(0.18)Nsub(0.72) in 25Kh1M1FA steel. Reduction of carbon and alloying elements content in steel composition observed at the liquation over rotor length leads to a certain decrease of ferritic grain resistance to super heating

Shear Behavior of Corrugated Steel Webs in H Shape Bridge Girders

Directory of Open Access Journals (Sweden)

Qi Cao

2015-01-01

Full Text Available In bridge engineering, girders with corrugated steel webs have shown good mechanical properties. With the promotion of composite bridge with corrugated steel webs, in particular steel-concrete composite girder bridge with corrugated steel webs, it is necessary to study the shear performance and buckling of the corrugated webs. In this research, by conducting experiment incorporated with finite element analysis, the stability of H shape beam welded with corrugated webs was tested and three failure modes were observed. Structural data including load-deflection, load-strain, and shear capacity of tested beam specimens were collected and compared with FEM analytical results by ANSYS software. The effects of web thickness, corrugation, and stiffening on shear capacity of corrugated webs were further discussed.

The Study on Weldability of Boron Steel and Hot-Stamped Steel by Using Laser Heat Source (Ⅲ) - Comparison on Laser Weldability of Boron Steel and Hot -Stamped Steel-

Energy Technology Data Exchange (ETDEWEB)

Choi, So Young; Kim, Jong Do [Korea Maritime and Ocean University, Busan (Korea, Republic of); Kim, Jong Su [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2015-01-15

This study was conducted to compare the laser weldability of boron steel and hot-stamped steel. In general, boron steel is used in the hot-stamping process. Hot-stamping is a method for simultaneously forming and cooling boron steel in a press die after heating it to the austenitizing temperature. Hot-stamped steel has a strength of 1500 MPa or more. Thus, in this study, the laser weldability of boron steel and that of hot-stamped steel were investigated and compared. A continuous wave disk laser was used to produce butt and lap joints. In the butt welding, the critical cooling speed at which full penetration was obtained in the hot-stamped steel was lower than that of boron steel. In the lap welding, the joint widths were similar regardless of the welding speed when full penetration was obtained.

The Study on Weldability of Boron Steel and Hot-Stamped Steel by Using Laser Heat Source (Ⅲ) - Comparison on Laser Weldability of Boron Steel and Hot -Stamped Steel-

International Nuclear Information System (INIS)

Choi, So Young; Kim, Jong Do; Kim, Jong Su

2015-01-01

This study was conducted to compare the laser weldability of boron steel and hot-stamped steel. In general, boron steel is used in the hot-stamping process. Hot-stamping is a method for simultaneously forming and cooling boron steel in a press die after heating it to the austenitizing temperature. Hot-stamped steel has a strength of 1500 MPa or more. Thus, in this study, the laser weldability of boron steel and that of hot-stamped steel were investigated and compared. A continuous wave disk laser was used to produce butt and lap joints. In the butt welding, the critical cooling speed at which full penetration was obtained in the hot-stamped steel was lower than that of boron steel. In the lap welding, the joint widths were similar regardless of the welding speed when full penetration was obtained

Hydrogen behaviour in the aged low activation martensitic steel F82H for fusion reactor applications

International Nuclear Information System (INIS)

Benamati, G.

1997-10-01

A time dependent permeation method is used to measure the permeability, diffusivity and solubility of hydrogen in the low activation martensitic steel F82H aged for 2000 h under vacuum at 773 K. The measurements cover the temperature range from 373 to 723 K which includes the onset of hydrogen trapping effects on diffusivity and solubility. The results are interpreted using a trapping model. The number of trap sites and their average energies for hydrogen in the aged F82H steel are determined. These data are compared with those obtained for deuterium in F82H steel

Les dysthyroïdies chez l'hémodialysé chronique | Zbiti | Pan African ...

African Journals Online (AJOL)

Introduction: Les dysthyroïdies chez l'hémodialysé chronique sont représentées par une hypothyroïdie: dite le syndrome de basse T3, actuellement nommée "le syndrome de la maladie euthyroïdienne". L'objectif de notre travail est de déterminer le profil thyroïdien de nos HDC afin de préciser la prévalence des différents ...

Nanostructure and Properties of Corrosion Resistance in C+Ti Multi-Ion-Implanted Steel

Institute of Scientific and Technical Information of China (English)

张通和; 吴瑜光; 刘安东; 张旭; 王晓妍

2003-01-01

The corrosion and pitting corrosion resistance of C+ Ti dual and C+Ti+C ternary implanted H13 steel were studied by using a multi-sweep cyclic voltammetry and a scanning electron microscope. The effects of phase formation on corrosion and pitting corrosion resistance were explored. The x-ray diffraction analysis shows that the nanometer-sized precipitate phases consist of compounds of Fe2 Ti, TiC, Fe2C and Fe3 C in dual implanted layer and even in ternary implanted layer. The passivation layer consists of these nanometer phases. It has been found that the corrosion and pitting corrosion resistance of dual and ternary implanted H13 steel are improved extremely. The corrosion resistance of ternary implanted layer is better than that of dual implantations and is enhanced with the increasing ion dose. When the ion dose of Ti is 6 × 1017/cm2 in the ternary implantation sample, the anodic peak current density is 95 times less than that of the H13 steel. The pitting corrosion potential of dual and ternary implantation samples is in the range from 55mV to 160mV which is much higher than that of the H13 steel. The phases against the corrosion and pitting corrosion are nanometer silkiness phases.

Stress corrosion cracking evaluation of martensitic precipitation hardening stainless steels

Science.gov (United States)

Humphries, T. S.; Nelson, E. E.

1980-01-01

The resistance of the martensitic precipitation hardening stainless steels PH13-8Mo, 15-5PH, and 17-4PH to stress corrosion cracking was investigated. Round tensile and c-ring type specimens taken from several heats of the three alloys were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, to salt spray, and to a seacoast environment. The results indicate that 15-5PH is highly resistant to stress corrosion cracking in conditions H1000 and H1050 and is moderately resistant in condition H900. The stress corrosion cracking resistance of PH13-8Mo and 17-4PH stainless steels in conditions H1000 and H1050 was sensitive to mill heats and ranged from low to high among the several heats included in the tests. Based on a comparison with data from seacoast environmental tests, it is apparent that alternate immersion in 3.5 percent salt water is not a suitable medium for accelerated stress corrosion testing of these pH stainless steels.

An overview of high thermal conductive hot press forming die material development

Directory of Open Access Journals (Sweden)

A.R. Zulhishamuddin

2015-12-01

Full Text Available Most of the automotive industries are using high strength steel components, which are produced via hot press forming process. This process requires die material with high thermal conductivity that increases cooling rate during simultaneous quenching and forming stage. Due to the benefit of high quenching rate, thermal conductive die materials were produced by adding carbide former elements. This paper presents an overview of the modification of alloying elements in tool steel for high thermal conductivity properties by transition metal elements addition. Different types of manufacturing processes involved in producing high thermal conductive materials were discussed. Methods reported were powder metallurgy hot press, direct metal deposition, selective laser melting, direct metal laser sintering and spray forming. Elements likes manganese, nickel, molybdenum, tungsten and chromium were proven to increase thermal conductivity properties. Thermal conductivity properties resulted from carbide network presence in the steel microstructure. To develop feasible and low cost hot press forming die material, casting of Fe-based alloy with carbide former composition can be an option. Current thermal conductivity properties of hot press forming die material range between 25 and 66 W/m.K. The wide range of thermal conductivity varies the mechanical properties of the resulting components and lifetime of HPF dies.

Role of Nb in low interstitial 13Cr super martensitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Ma, X.P.; Wang, L.J. [Key Laboratory for Anisotropy and Texture of Materials, Northeastern University, Shenyang 110004 (China); Liu, C.M., E-mail: cmliu@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials, Northeastern University, Shenyang 110004 (China); Subramanian, S.V. [Department of Materials Science and Engineering, McMaster University, Hamilton, L8S-4L7 (Canada)

2011-08-25

Highlights: {yields} Nb retards the kinetics of reversed austenite formation. {yields} Nb suppresses the occurrence of Cr rich precipitates. {yields} Nano-scale precipitates contribute to the significant increase in strength. - Abstract: The effect of adding 0.1 wt% Nb to low interstitial (N 0.01 wt%, C 0.01 wt%) 13Cr super martensitic stainless steel (SMSS) on solid phase transformation and microstructures achieved by normalizing and tempering was investigated using dilatometer, electron backscattered diffraction (EBSD), transmission electron microscope (TEM), X-ray diffraction (XRD), and its consequence on mechanical properties was examined to clarify the role of Nb in low interstitial martensitic stainless steel. Nb was found to retard kinetics of reversed austenite formation during tempering and to suppress the occurrence of Cr rich precipitates. The measurement of mechanical properties shows that while the strength properties were significantly increased by nano-scale precipitates enriched in Nb in the steel with 0.10 wt% Nb, the ductility and toughness properties were restored by optimum volume fraction of retained austenite. Excellent strength and adequate toughness properties were obtained by tempering the steel with 0.10 wt% Nb and low interstitial (N 0.01 wt%, C 0.01 wt%) steel at 600 deg. C.

XPS study of the ultrathin a-C:H films deposited onto ion beam nitrided AISI 316 steel

International Nuclear Information System (INIS)

Meskinis, S.; Andrulevicius, M.; Kopustinskas, V.; Tamulevicius, S.

2005-01-01

Effects of the steel surface treatment by nitrogen ion beam and subsequent deposition of the diamond-like carbon (hydrogenated amorphous carbon (a-C:H) and nitrogen doped hydrogenated amorphous carbon (a-CN x :H)) films were investigated by means of the X-ray photoelectron spectroscopy (XPS). Experimental results show that nitrogen ion beam treatment of the AISI 316 steel surface even at room temperature results in the formation of the Cr and Fe nitrides. Replacement of the respective metal oxides by the nitrides takes place. Formation of the C-N bonds was observed for both ultrathin a-C:H and ultrathin a-CN x :H layers deposited onto the nitrided steel. Some Fe and/or Cr nitrides still were presented at the interface after the film deposition, too. Increased adhesion between the steel substrate and hydrogenated amorphous carbon layer after the ion beam nitridation was explained by three main factors. The first two is steel surface deoxidisation/passivation by nitrogen as a result of the ion beam treatment. The third one is carbon nitride formation at the nitrided steel-hydrogenated amorphous carbon (or a-CN x :H) film interface

Intergranular corrosion of 13Cr and 17Cr martensitic stainless steels in accelerated corrosive solution and high-temperature, high-purity water

International Nuclear Information System (INIS)

Ozaki, Toshinori; Ishikawa, Yuichi

1988-01-01

Intergranular corrosion behavior of 13Cr and 17Cr martensitic stainless steels was studied by electrochemical and immersing corrosion tests. Effects of the mEtallurgical and environmental conditions on the intergranular corrosion of various tempered steels were examined by the following tests and discussed. (a) Anodic polarization measurement and electrolytical etching test in 0.5 kmol/m 3 H 2 SO 4 solution at 293 K. (b) Immersion corrosion test in 0.88 kmol/m 3 HNO 3 solution at 293 K. (c) Long-time immersion test for specimens with a crevice in a high purity water at 473 K∼561 K. It was found from the anodic polarization curves in 0.5 kmol/m 3 H 2 SO 4 solution-at 293 K that the steels tempered at 773∼873 K had susceptibility to intergranular corrosion in the potential region indicating a second current maximum (around-0.1 V. vs. SCE). But the steel became passive in the more noble potential region than the second current peak potential, while in the less noble potential region general corrosion occurred independent of its microstructure. The intergranular corrosion occurred due to the localized dissolution along the pre-austenitic grain boundary and the martensitic lath boundary. It could be explained by the same dissolution model of the chromium depleted zone as proposed for the intergranular corrosion of austenitic and ferritic stainless steels. The intergranular corrosion occurred entirely at the free surface in 0.88 kmol/m 3 HNO 3 solution, while in the high temperature and high purity water only the entrance of the crevice corroded. It was also suggested that this intergranular corrosion might serve as the initiation site for stress corrosion cracking of the martensitic stainless steel. (author)

Correlation of microstructure and low cycle fatigue properties for 13.5Cr1.1W0.3Ti ODS steel

International Nuclear Information System (INIS)

He, P.; Klimenkov, M.; Möslang, A.; Lindau, R.; Seifert, H.J.

2014-01-01

Reduced activation oxide dispersion strengthened (ODS) steels are prospective structural materials for the blanket system and first wall components in Tokamak-type fusion reactors. Under the pulsed operation, these components will be predominantly subjected to cyclic thermal–mechanical loading which leads to inevitable fatigue damage. In this work, strain controlled isothermal fatigue tests were conducted for 13.5Cr1.1W0.3Ti ODS steel at 550 °C. The total strain range varied from 0.54% to 0.9%. After thermomechanical processing, 13.5CrWTi–ODS steel exhibits a remarkable lifetime extension with a factor of 10–20 for strain ranges Δε ⩽ 0.7%. 13.5Cr ODS steel shows no cyclic softening at all during the whole testing process irrespective of the strain range. TEM observations reveal ultrastable grain structure and constant dislocation densities around 10 14 m −2 , independent of the number of cycles or the applied strain amplitude. The presence of the stabilized ultrafine Y–Ti–O dispersoids enhances the microstructural stability and therefore leads to outstanding fatigue resistance for 13.5Cr1.1W0.3Ti–ODS steel

Correlation of microstructure and low cycle fatigue properties for 13.5Cr1.1W0.3Ti ODS steel

Energy Technology Data Exchange (ETDEWEB)

He, P., E-mail: pei.he@kit.edu; Klimenkov, M.; Möslang, A.; Lindau, R.; Seifert, H.J.

2014-12-15

Reduced activation oxide dispersion strengthened (ODS) steels are prospective structural materials for the blanket system and first wall components in Tokamak-type fusion reactors. Under the pulsed operation, these components will be predominantly subjected to cyclic thermal–mechanical loading which leads to inevitable fatigue damage. In this work, strain controlled isothermal fatigue tests were conducted for 13.5Cr1.1W0.3Ti ODS steel at 550 °C. The total strain range varied from 0.54% to 0.9%. After thermomechanical processing, 13.5CrWTi–ODS steel exhibits a remarkable lifetime extension with a factor of 10–20 for strain ranges Δε ⩽ 0.7%. 13.5Cr ODS steel shows no cyclic softening at all during the whole testing process irrespective of the strain range. TEM observations reveal ultrastable grain structure and constant dislocation densities around 10{sup 14} m{sup −2}, independent of the number of cycles or the applied strain amplitude. The presence of the stabilized ultrafine Y–Ti–O dispersoids enhances the microstructural stability and therefore leads to outstanding fatigue resistance for 13.5Cr1.1W0.3Ti–ODS steel.

The Results Of The Investigation Of Thermomechanical Processing Of PM Steel

International Nuclear Information System (INIS)

Szczepanik, Stefan; Wisniewski, Bartosz; Krawiarz, Jerzy

2007-01-01

Hot die forging of PM steel is used to obtain products with high densities. The combination of this process with heat treatment of forgings directly after their forming is researched in order to reduce energy consumption in the manufacture of PM steel products. This work determined the influence of the cooling ratio directly after hot forging of PM steel samples on their structure and mechanical properties. The properties of the PM preforms were examined after sintering and after sintering, quenching into water and tempering for 1 h at 250, 350 and 550 deg. C, respectively, as well as after forging at given temperatures and cooling in water and air, respectively. Forged steel after quenching was tempered at the same temperature as the sintered samples. Good mechanical properties were obtained by hot forging at 1100 deg. C. Sintered steel with 0.6 % Cgraphite is characterized by good hardenability and is susceptible to plastic forming at 1100 - 940 deg. C. During its cooling in air a bainitic-martensitic structure is obtained, whereas after cooling in water the structure is martensitic. The properties of the forged steel are strongly dependent on deformation temperature and cooling conditions. The tensile strength of the forged PM steel with 0.6 Cgraphite after forming at 1100 deg. C is much higher than that of the same heat-treated as-sintered steel. Traditional heat treatment applied to materials after deformation at 1100 deg. C slightly increases properties in comparison to the material directly quenched into water. The best strength was 1585 ± 193 MPa, bending strength 3364 ± 142 MPa and hardness 588 ± 43 HB. Application of controlled cooling of sintered PM steel directly after close-die forging diminishes the energy consumption during product manufacture

Influence of coatings on the corrosion fatigue behaviour on 13% chromium steel

Energy Technology Data Exchange (ETDEWEB)

Schmitt-Thomas, K G; Meisel, H; Sessler, W

1986-01-01

The influence of coatings on the corrosion fatigue behaviour of 13% chromium steel has been studied. There have been selected different coating systems: Barrier coating (enamel), diffusion coatings, (aluminizing, chromizing) and anodic coating, (aluminium, zinc, tin, cadmium). The corrosion fatigue limits of coated with uncoated specimens in neutral NaCl-solution are compared. Salt-concentrations were 0,01 and 22% (=0,38 M) NaCl at 80/sup 0/C and 150/sup 0/C. The tests were carried out with alternating tensions and a constant frequency of 50 Hz. Only the use of anodic coatings improved the corrosion fatigue behaviour of the chromium steel.

Creep of ex-service AISI-316H steel at very low strain rates

Energy Technology Data Exchange (ETDEWEB)

Kloc, Lubos; Sklenicka, Vaclav [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials; Spindler, Michael [British Energy Generation, Barbwood, Gloucester (United Kingdom)

2010-07-01

The creep response of ex-service Type 316H austenitic steel was investigated at temperatures from 470 to 550 C and stresses from 80 to 120 MPa. These conditions lead to very low strain rates. Both helicoid spring specimen tests and conventional uniaxial creep tests were used to measure these very low creep strains. An internal stress model was used to analyse the creep curves and the results were compared to creep curves obtained on a Type 316H in the as-received condition, which for austenitic steels is after solution heat treatment. The creep behavior of the ex-service steel was very similar to that of the as-received steel. Thus, no creep damage or significant change of microstructure was detected during the service period of 65,000 hours at {proportional_to} 520 C. It was found that the helicoid spring specimen technique provides results compatible with that of conventional creep tests, but with superior accuracy with very low creep strains. (orig.)

Analysis of the non-isothermal austenite-martensite transformation in 13% Cr-type martensitic stainless steels

International Nuclear Information System (INIS)

Garcia-De-Andris, C.; Alvarez, L.F.

1996-01-01

In martensitic stainless steels, as in other alloyed containing carbide-forming elements, the carbide dissolution and precipitation processes that take place during heat treatment can cause modifications to the chemical composition of the austenite phase of these steels. The chemical composition of this phase is a fundamental factor for the evolution of the martensitic transformation. As a result of their influence on the dissolution and precipitation processes, the parameters of the quenching heat treatment exert a strong influence on the behavior of the martensitic transformation in these steels. In the present study, the effect of the heating temperature and the cooling rate on the martensitic transformation in two 13% Cr-type martensitic stainless steels with different carbon contents were properly evaluated. (author)

Initiation and developmental stages of steel corrosion in wet H2S environments

International Nuclear Information System (INIS)

Bai, Pengpeng; Zhao, Hui; Zheng, Shuqi; Chen, Changfeng

2015-01-01

Highlights: • The initiation and development stages of steel corrosion in wet H 2 S environment were investigated. • Preferential dissolution at the grain boundaries of steel allowed corrosion products to form and accumulate. • The shapes and crystal types of corrosion products at various steel layers differed. • With increasing duration time, the S 2− peak with a binding energy of 161.2 eV gradually decreased. • A model of the formation process of corrosion product films was proposed. - Abstract: The initiation and various developmental stages of steel corrosion in H 2 S environments were investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Results revealed that grain boundaries corrode at the initiation stage and that corrosion products initially form on both sides of the grain boundary and then accumulate. Corrosion products grew at the interface between the steel and corrosion product layer at the developmental stage. XPS analyses showed the composition and valence states of the corrosion products, and a model of the formation process of corrosion product films was proposed

Slurry Erosion Studies on Surface Modified 13Cr-4Ni Steels: Effect of Angle of Impingement and Particle Size

Science.gov (United States)

Manisekaran, T.; Kamaraj, M.; Sharrif, S. M.; Joshi, S. V.

2007-10-01

Hydroturbine steels, such as 13Cr-4Ni martensitic steels, are generally subjected to heavy-erosive wear and loss of efficiency due to solid particulate entrainment in the water. Surface-modified steels have proven to give better performance in terms of erosive wear resistance. In the present study, an attempt is made to investigate the effect of angle of impingement and particle size on slurry-jet erosion behavior of pulsed plasma nitrided and laser hardened 13Cr-4Ni steels. Laser hardening process has shown good performance at all angles of impingement due to martensitic transformation of retained austenite. Plastic deformation mode of material removal was also an evident feature of all laser-hardened surface damage locations. However, pulsed-plasma nitrided steels have exhibited chip formation and micro-cutting mode of erosive wear. Erosion with 150-300 μm size was twice compared to 150 μm size slurry particulates.

Effect of coatings on long term behaviour of a commercial stainless steel for solid oxide electrolyser cell interconnect application in H2/H2O atmosphere

International Nuclear Information System (INIS)

Ardigo, M.R.; Popa, I.; Chevalier, S.; Girardon, P.; Perry, F.; Laucournet, R.; Brevet, A.; Desgranges, C.

2014-01-01

K41X (AISI 441) stainless steel evidenced a high electrical conductivity after 3000 h ageing in H 2 /H 2 O side when used as interconnect for solid oxide electrolyser cells (SOEC) working at 800 C. Perovskite (La 1-x Sr x MnO 3-δ ) and spinel (Co 3 O 4 ) oxides coatings were applied on the surface of the ferritic steel for ageing at 800 C for 3000 h. Both coatings improved the behaviour of the steel and give interesting opportunities to use the K41X steel as interconnect for hydrogen production via high temperature steam electrolysis. Co 3 O 4 reduced into Co leading to a very good Area Specific Resistance (ASR) parameter, 0.038 Ωcm 2 . Despite a good ASR (0.06 Ωcm 2 ), La 1-x Sr x MnO 3-δ was less promising because it partially decomposed into MnO and La 2 O 3 during ageing in H 2 /H 2 O atmosphere. (authors)

Modeling of Cooling Channels of Injection Mould using Functionally Graded Material

International Nuclear Information System (INIS)

Shin, Ki Hoon

2011-01-01

The cycle time in injection moulding greatly depends on the cooling time of the plastic part that is controlled by cooling channels. Cooling channels are required to facilitate the heat transfer rate from the die to the coolant without reducing the strength of the die. Employing layered manufacturing techniques (LMT), a die embedding conformal cooling channels can be fabricated directly while conventional cooling channels are usually made of straight drilled hole. Meanwhile, H13 tool steel is widely used as the die material because of its high thermal resistance and dimensional stability. However, H13 with a low thermal conductivity is not efficient for certain part geometries. In this context, the use of functionally graded materials (FGMs) between H13 and copper may circumvent a tradeoff between the strength and the heat transfer rate. This paper presents a method for modeling of conformal cooling channels made of FGMs

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

NARCIS (Netherlands)

Bojack, A.; Zhao, L.; Morris, P.F.; Sietsma, J.

2016-01-01

The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two

Ductility of high chromium stainless steels

International Nuclear Information System (INIS)

Peretyat'ko, V.N.; Kazantsev, A.A.

1997-01-01

Aimed to optimize the hot working conditions for high chromium stainless steels the experiments were carried in the temperature range of 800-1300 deg C using hot torsion tests and cylindrical specimens of ferritic and ferritic-martensitic steels 08Kh13, 12Kh13, 20Kh13, 30Kh13 and 40Kh13. Testing results showed that steel plasticity varies in a wide range depending on carbon content. Steels of lesser carbon concentration (08Kh13 and 12Kh13) exhibit a sharp increase in plasticity with a temperature rise, especially in the interval of 1200-1250 deg C. Steels 20Kh13 and 30Kh13 display insignificant plasticity increasing, whereas plastic properties of steel 40Kh13 increase noticeably in the range of 1000-1300 deg C. It is shown that optimal hot working conditions for specific steel must be selected with account of steel phase composition at high temperatures

Substrate pH and butterfly bush response to dolomitic lime or steel slag amendment

Science.gov (United States)

Steel slag is a fertilizer amendment with a high concentration of calcium oxide, and thus capable of raising substrate pH similar to dolomitic lime. Steel slag, however, contains higher concentrations of some nutrients, such as iron, manganese, and silicon, compared to dolomitic lime. The objectiv...

Outgassing characteristics of F82H ferritic steel as a low activation material for fusion reactor

International Nuclear Information System (INIS)

Odaka, Kenji; Satou, Osamu; Ootsuka, Michio; Abe, Tetsuya; Hara, Shigemitsu; Takatsu, Hideyuki; Enoeda, Mikio.

1997-01-01

Outgassing characteristics of F82H ferritic steel as a low activation material for the blanket of fusion device were investigated. A test chamber was constructed by welding F82H ferritic steel plates. The inner surface of the chamber was buffed and electropolished. The test chamber was degassed by the prebaking at temperature of 350degC for 20 h in vacuum. Then outgassing rates of the test chamber were measured by the throughput method as a function of pumping time for the cases that the test chamber was baked and not baked. The typical outgassing rate after baking at 250degC for 24 h was 3 x 10 -9 Pa·ms -1 and it seems that this value is sufficiently small to produce pressures at least as low as 10 -9 Pa in the vacuum chamber made of F82H ferritic steel. In the pump-down of the test chamber without baking after exposure to air, the outgassing rate decreases with pumping time and reached 1 x 10 -7 Pa·ms -1 at t = 10 5 s. The activation energy of hydrogen in bulk diffusion in the F82H ferritic steel was measured and found to be 7 kcal/mol. (author)

Microstructural evolution in Fe-0.13P-0.05C steel during compression at elevated temperatures

Science.gov (United States)

Mehta, Y.; K, Rajput S.; P, Chaudhari G.; V, Dabhade V.

2018-03-01

The microstructural evolution was studied in order to adjust the processing parameters for hot forming. Fe-0.13P-0.05C steel was subjected to hot compression tests using a thermo-mechanical simulator. The tests were performed at the temperatures ranging from 800°C-950°C. The strain rates chosen at all these temperatures were 0.01, 0.1 and 1 s‑1. The effects of the strain rates and hot compression temperatures on the microstructural aspects of the steel were examined using optical microscopy. The outcomes indicate that the mean grain dimension of the hot compressed Fe-0.13P-0.05C steel escalates with increases in the deformation temperature and also with decreases in strain rate. Dynamic recrystallization was observed to be the instrument of grain refinement. The minimum grain dimension of 5.6 μm was attained at 800°C and 0.1s‑1.

Effects of Mo Content on Microstructure and Mechanical Property of PH13-8Mo Martensitic Precipitation-Hardened Stainless Steel

Science.gov (United States)

Yubing, Pei; Tianjian, Wang; Zhenhuan, Gao; Hua, Fan; Gongxian, Yang

This paper introduces the effects of Mo content on microstructure and mechanical property of PH13-8Mo martensitic precipitation-hardened stainless steel which is used for LP last stage blade in steam turbine. Thermodynamic software Thermo-Calc has been used to calculate precipitation temperature and the mass fraction of precipitated phases in PH13-8Mo steel with different Mo content. The result shows that when the mass of Mo is below 0.6wt.%, chi-phase mu-phase and sigma-phase could disappear. The microstructure and mechanical property of high Mo PH13-8Mo (Mo=0.57wt.%) and low Mo PH13-8Mo (Mo=2.15wt.%)have been investigated in different heat treatments. The investigations reveal that austenitizing temperature decrease with the reduce of Mo content, so the optimum solution temperature for low Mo PH13-8Mo is lower than that for high Mo PH13-8Mo.The influence of solution temperature on grain size is weakened with the increase of Mo content, Mo rich carbides could retard coarsening of grain. An enormous amount of nano-size uniformly distributed β-NiAl particles are found in both kinds of steels using transmission electron microscopy, they are the most important strengthening phase in PH13-8Mo.

Die Biopsie von Knochen- und Weichteiltumoren

OpenAIRE

Fuchs, B

2008-01-01

Technisch stellt die Biopsie von Knochen- und Weichteiltumoren einen simplen Akt dar, intellektuell aber ist die Planung einer Biopsie höchst anspruchsvoll. Zu häufig werden heutzutage immer noch Biopsien unsachgemäss durchgeführt, so dass die Behandlung - im besten Fall - erschwert wird. Eine unsachgemäss durchgeführte Biopsie führt häufig zu negativen funktionellen Konsequenzen für den Patienten, im schlimmsten Fall kann es die Prognose direkt beeinträchtigen. Aus diesem Grund soll...

Investigation of Eh, pH and corrosion potential of steel in anoxic groundwater

Energy Technology Data Exchange (ETDEWEB)

Peat, R.; Brabon, S.; Fennell, P.A.H.; Rance, A.P.; Smart, N.R. [AEA Technology (United Kingdom)

2001-01-01

SKB intend to dispose of the spent nuclear fuel produced by Sweden's eleven nuclear reactors by encapsulating it in corrosion-resistant copper canisters containing a cast iron or carbon steel insert. After encapsulation, the fuel will be transported to a geological repository, where the containers will be deposited at a depth of 500 to 700 m in granitic rock and surrounded by a bentonite clay backfill material. If, or when the copper corrosion shield fails, the iron insert will be in contact with oxygen-free water and hydrogen-producing, anaerobic corrosion will start. SKB have carried out modelling calculations of the oxidising power (Eh) of groundwater and wished to confirm the results by carrying out experimental measurements. The objective of the work described in this report was to demonstrate the feasibility of monitoring Eh, pH and corrosion potential in a cell where anaerobic corrosion of steel in artificial groundwater was occurring. To this end, gas cells similar to those used previously for anaerobic corrosion rate measurements were used as the basis for the design of an electrochemical cell. The cell incorporated electrodes to provide an in situ measurement of the redox potential, Eh, the pH and the corrosion potential of carbon steel. The main stages of the work were: Design of the electrochemical cell; Preparation of silver-silver chloride and calomel reference electrodes; Calibration of the reference electrodes and commercial glass pH electrodes against a standard hydrogen electrode; Assembly of the test cell under anoxic conditions; Monitoring the cell before and after the addition of steel wires to the test solution. Details of the design of the test cell and the experimental procedures used are described. Two cells were set up. The first employed a silver-silver chloride reference electrode, which was failed after approximately 400 hours, and the second cell therefore used a calomel reference electrode. The results of the electrode

Static Recrystallization Behavior of Z12CN13 Martensite Stainless Steel

Science.gov (United States)

Luo, Min; Zhou, Bing; Li, Rong-bin; Xu, Chun; Guo, Yan-hui

2017-09-01

In order to increase the hot workability and provide proper hot forming parameters of forging Z12CN13 martensite stainless steel for the simulation and production, the static recrystallization behavior has been studied by double-pass hot compression tests. The effects of deformation temperature, strain rate and inter-pass time on the static recrystallization fraction by the 2% offset method are extensively studied. The results indicate that increasing the inter-pass time and the deformation temperature as well as strain rate appropriately can increase the fraction of static recrystallization. At the temperature of 1050-1150 °C, inter-pass time of 30-100 s and strain rate of 0.1-5 s-1, the static recrystallization behavior is obvious. In addition, the kinetics of static recrystallization behavior of Z12CN13 steel has been established and the activation energy of static recrystallization is 173.030 kJ/mol. The substructure and precipitates have been studied by TEM. The results reveal that the nucleation mode is bulging at grain boundary. Undissolved precipitates such as MoNi3 and Fe3C have a retarding effect on the recrystallization kinetics. The effect is weaker than the accelerating effect of deformation temperature.

Influence of Thermal Homogenization Treatment on Structure and Impact Toughness of H13 ESR Steel

Institute of Scientific and Technical Information of China (English)

MA Dang-shen; ZHOU Jian; CHEN Zai-zhi; ZHANG Zhong-kan; CHEN Qi-an; LI De-hui

2009-01-01

The as-cast microstrueture of H13 ESR ingot and the influence of high temperature diffusion treatment on the structure and impact toughness have been investigated. The results show that the dendrite arm spacing gradually becomes wide from the surface to the center of ingot, and the large primary carbide particles always exist in interdendritic segregation areas; by means of high temperature diffusion treatment of ingot prior to hot forging, the banded segregation is nearly eliminated, the annealed structure is more uniform and the isotropic properties have been improved remarkably.

Study of peculiarities of hydrogen isotopes mixture permeation through low activated steel F82H

International Nuclear Information System (INIS)

Kenzhin, Ye.A.; Tazhibayeva, I.L; Kulsartov, T.V.; Shestakov, V.P.; Chikhray, Ye.V.; Afanasev, S.E.; Zheldak, Yu.L.

2003-01-01

Full text: The problem of diffusion tritium leakage through blanket materials of future fusion device makes some constructive difficulties concerned with protection of personnel and environment and also with losses of tritium, which is planned to be used in the same device. One of the little-studied problems in the tritium leakage process in Fusion Power Plant is that in fact tritium will penetrate through materials while other hydrogen isotopes are present. These are deuterium and hydrogen which always are present in metals. Therefore, for evaluation of tritium leakage in future Fusion Power Plant under such conditions it is necessary to have experimental data about permeation of these hydrogen isotopes through the structure materials.One of proposed structure materials of fusion reactor blanket is low activated steel F82H. The experiment results on evaluation of .hydrogen, deuterium and its mixture interaction parameters with steel F82H are shown in this work. The tests were carried out within temperature range 273-973 K under inlet hydrogen pressure of 100-2000 Pa. Diffusivity, deuterium and hydrogen permeation constants for low activated steel F82H was determined from experiment results. Those experimental results were used for created phenomenology model which describes hydrogen isotope penetration through tube sample from hydrogen isotopes mixture. That model was used so determining the ratios of desorption rates (D-D, D-H, H-H) on outlet side of sample. Using of so obtained results, we can correctly evaluate, the titanium leakage from blanket of fusion machine which will be constructed using low activated steel F82H

Microstructure of steel X 20 Cr 13 in the electron microscopical picture

International Nuclear Information System (INIS)

Gesatzke, W.

1982-01-01

The tempered microstructure of the steel X 20 Cr 13 is described by an electron microscopical overall picture and additional information is gained which would not be possible with the optical microscope. The large transmission area permits one to quantitatively evaluate a microstructure component which due to its small size can only be measured with electron microscope pictures. (orig.) [de

Behavior of steels in flowing liquid PbBi eutectic alloy at 420-600 deg. C after 4000-7200 h

International Nuclear Information System (INIS)

Mueller, G.; Heinzel, A.; Konys, J.; Schumacher, G.; Weisenburger, A.; Zimmermann, F.; Engelko, V.; Rusanov, A.; Markov, V.

2004-01-01

This paper presents the results of steel exposure up to 7200 h in flowing LBE at elevated temperatures and is a follow-up paper of that with results of an exposure of up to 2000 h. The examined AISI 316 L, 1.4970 austenitic and MANET 10Cr martensitic steels are suitable as a structural material in LBE (liquid eutectic Pb 45 Bi 55 ) up to 550 deg. C, if 10 -6 wt% of oxygen is dissolved in the LBE. The martensitic steel develops a thick magnetite and spinel layer while the austenites have thin spinel surface layers at 420 deg. C and thick oxide scales like the martensitic steel at 550 deg. C. The oxide scales protect the steels from dissolution attack by LBE during the whole test period of 7200 h. Oxide scales that spall off are replaced by new protective ones. At 600 deg. C severe attack occurs already after 2000 and 4000 h of exposure. Steels with 8-15 wt% Al alloyed into the surface suffer no corrosion attack at all experimental temperatures and exposure times

Die Wirkung von Desacetylcefotaxin, einem Metaboliten von Cefotaxim, in vitro und auf die experimentelle Infektion mit Escherichia coli

OpenAIRE

Wirbelauer, J.; Hof, H.; Hacker, Jörg

2009-01-01

Die MHK-Werte von Desacetylcefotaxim gegen verschiedene, z. T. ampicillinresistente Stämme von Escherichia coH, die mit Hilfe einer Agardilutionsmethode erhoben wurden, waren höher als die von Cefotaxim und Ceftriaxon, jedoch niedriger als die von Cefoxitin. In einem Modell der systemischen Infektion der Maus mit einem plasmidtragenden, betalactamaseproduzierenden Stamm von E. coli führte die Therapie mit Desacetylcefotaxim zu einer starken Reduktion der Keime pro Leber. Im Vergleich zur Ther...

Mechanical characteristics of a tool steel layer deposited by using direct energy deposition

Science.gov (United States)

Baek, Gyeong Yun; Shin, Gwang Yong; Lee, Eun Mi; Shim, Do Sik; Lee, Ki Yong; Yoon, Hi-Seak; Kim, Myoung Ho

2017-07-01

This study focuses on the mechanical characteristics of layered tool steel deposited using direct energy deposition (DED) technology. In the DED technique, a laser beam bonds injected metal powder and a thin layer of substrate via melting. In this study, AISI D2 substrate was hardfaced with AISI H13 and M2 metal powders for mechanical testing. The mechanical and metallurgical characteristics of each specimen were investigated via microstructure observation and hardness, wear, and impact tests. The obtained characteristics were compared with those of heat-treated tool steel. The microstructures of the H13- and M2-deposited specimens show fine cellular-dendrite solidification structures due to melting and subsequent rapid cooling. Moreover, the cellular grains of the deposited M2 layer were smaller than those of the H13 structure. The hardness and wear resistance were most improved in the M2-deposited specimen, yet the H13-deposited specimen had higher fracture toughness than the M2-deposited specimen and heat-treated D2.

The analysis of ion nitriding and nitrogen ion implantation on tribological properties of steels 33H3MF and 36H3M

International Nuclear Information System (INIS)

Zandecki, R.

1993-01-01

Surface properties of two kinds of steel 33H3MF and 36H3M have been investigated. Three different methods of steel surface treatment have been used: ion nitriding, nitrogen ion implantation and mixing method being the sum of the first and second ones. The microstructure, microhardness distribution, fatigue strength, friction coefficient and other tribological properties have been measured and compared. 60 refs, 74 figs, 19 tabs

Starting of H9ANFNb(P91) steel tubing production for energetics in domestic steel-works; Uruchomienie w krajowych hutach produkcji rur ze stali H9AMFNb(P91) przeznaczonych dla energetyki

Energy Technology Data Exchange (ETDEWEB)

Wiedermann, J. [Instytut Metalurgii Zelaza, Gliwice (Poland); Bieniek, K. [Huta Jednosc, Siemianowice Slaskie (Poland); Pogoda, K. [Huta Batory, Chorzow (Poland)

1996-12-31

The results of primary investigations and attempt of ferritic steel H9AMFNb production in domestic steel-works have been reported. The prototype series of tubes for energetic boilers have been tested and their mechanical properties determined. It has been found the applicability of the material for use in energetics. 9 refs, 4 figs, 3 tabs.

Process Optimization of EDM Cutting Process on Tool Steel using Zinc Coated Electrode

Directory of Open Access Journals (Sweden)

Hanizam H.

2017-01-01

Full Text Available In WEDM machining process, surface finish quality depends on intensity and duration of spark plasma. Electrode wire diameter has significant effect on the spark intensity and yet the studies on this matter still less. Therefore, the main objectives of this studies are to compare the different diameters of zinc coated and uncoated brass electrode on H13 tool steel surface roughness. The experiments were conducted on Sodick VZ300L WEDM and work piece material of tool steel AISI H13 block. Electrode of zinc coated brass with diameters of 0.1 mm, 0.2 mm, 0.25 mm and uncoated brass 0.2 mm were used. The surface roughness of cutting was measured using the SUR-FTEST SJ-410 Mitutoyo, surface roughness tester. The results suggest that better surface roughness quality can be achieved through smaller electrode wire diameter. The zinc coated improves flushing ability and sparks intensity resulting in better surface finish of H13 tool steel. New alloys and coating materials shall be experimented to optimized the process further.

Dimensional and material characteristics of direct deposited tool steel by CO II laser

Science.gov (United States)

Choi, J.

2006-01-01

Laser aided direct metalimaterial deposition (DMD) process builds metallic parts layer-by-layer directly from the CAD representation. In general, the process uses powdered metaUmaterials fed into a melt pool, creating fully dense parts. Success of this technology in the die and tool industry depends on the parts quality to be achieved. To obtain designed geometric dimensions and material properties, delicate control of the parameters such as laser power, spot diameter, traverse speed and powder mass flow rate is critical. In this paper, the dimensional and material characteristics of directed deposited H13 tool steel by CO II laser are investigated for the DMD process with a feedback height control system. The relationships between DMD process variables and the product characteristics are analyzed using statistical techniques. The performance of the DMD process is examined with the material characteristics of hardness, porosity, microstructure, and composition.

Corrosion fatigue crack growth in clad low-alloy steels: Part 1, medium-sulfur forging steel

International Nuclear Information System (INIS)

James, L.A.; Poskie, T.J.; Auten, T.A.; Cullen, W.H.

1996-01-01

Corrosion fatigue crack propagation tests were conducted on a medium- sulfur ASTM A508-2 forging steel overlaid with weld-deposited Alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 30.3--38.3 mm, and depths of 13.1--16.8 mm. The experiments were conducted in a quasi-stagnant low-oxygen (O 2 < 10 ppb) aqueous environment at 243 degrees C, under loading conditions (ΔK, R, and cyclic frequency) conductive to environmentally-assisted cracking (EAC) in higher-sulfur steels under quasi-stagnant conditions. Earlier experiments on unclad compact tension specimens of this heat of steel did not exhibit EAC, and the present experiments on semi-elliptical surface cracks penetrating cladding also did not exhibit EAC

High-Temperature Corrosion of T92 Steel in N{sub 2}/H{sub 2}O/H{sub 2}S-Mixed Gas

Energy Technology Data Exchange (ETDEWEB)

Shi, Yuke; Kim, Min Jung; Park, Soon Yong; Abro, M. Ali; Yadav, Poonam; Lee, Dong Bok [Sungkyunkwan University, Suwon (Korea, Republic of)

2016-06-15

The ASTM T92 steel was corroded at 600 ℃ and 800 ℃ at 1 atm of N{sub 2}/3.1%H{sub 2}O/2.42%H{sub 2}S-mixed gas. The formed scales were thick and fragile. They consisted primarily of the outer FeS scale and the inner (FeS, FeCr{sub 2}S{sub 4})-mixed scale containing a small amount of the Cr{sub 2}O{sub 3} scale. This indicated that corrosion occurred mainly via sulfidation rather than oxidation due to the H{sub 2}S gas. Since FeS was present throughout the whole scale, T92 steel was non-protective, displaying high corrosion rates.

Die Freunde im und die Freude am Fernsehen

Directory of Open Access Journals (Sweden)

Amina Ovcina Cajacob

2012-09-01

Full Text Available Das Ziel der vorliegenden Arbeit besteht darin, die Wirkungen von Popstars und Popbands auf Jugendliche (13- bis 17-Jährige zu erforschen. Im Mittelpunkt der Interessen steht die Frage, welche Wirkungen aus der Rezeption von Musiksendungen (bzw. Videoclips von Musiksendern entstehen und welche Charakteristika innerhalb der aufgebauten Beziehungen zu den Stars bemerkbar sind. Andererseits wurden die Unterschiede und Parallelen zwischen parasozialen Beziehungen zu den Stars und orthosozialen Beziehungen aufgezeigt. Im Zusammenhang mit der empirischen Untersuchung bezieht sich die Autorin auf den Uses-and-Gratifications-Approach, wobei die bedürfnissbefriedigenden Wirkungen von Musikkanälen und den dazu gehörigen Popstars im Mittelpunkt stehen. Mit Hilfe des Uses-and-Gratifications-Approach wird angenommen, dass das Konsumieren der Musiksendungen und der Musikstars von den Jugendlichen gezielt zur Befriedigung bestimmter Bedürfnisse eingesetzt wird.The objective of this study is to explore the effects of pop stars on adolescents (aged between 13 and 17. The focus of interest is the question what effect music channels (i.e. video clips from music channels produce and what characteristics are noticeable from the formed relationship between adolescents and pop stars. On the other side, parallels and differences have been drawn between the para-social relationships to pop stars and ortho-social relationships. In connection with empirical study, the author also refers to Uses-and Gratification-Approach where the need satisfying effects of music channels and pop stars are in focus. With the help of Uses-and Gratification-Approach it will be assumed, that aim of watching music channels and therefore pop stars will be pointed toward the gratification of specific needs.

Preliminary tension effect on low-cycle fatigue of 40Kh13 steel in gaseous hydrogen

International Nuclear Information System (INIS)

Romaniv, A.N.

1984-01-01

Comparative bending tests of specimens deformed by tension at 65, 18 and 30% in hydrogen and vacuum were accomplished to reveal the effect of preliminary tension on low-cycle fatigue strength of 40Kh13 martensitic steel. It was found that small amounts of preliminary strains induced a considerable decrease in low-cycle durability in vacuum and hydrogen which was connected with developing defects arising at the early stages of plastic deformation. A rather high degree of preliminary tension promoted steel homogenization, hydrogen embrittlement decrease and service behaviour improvement

Passivation condition of carbon steel in bentonite/sand mixture

International Nuclear Information System (INIS)

Taniguchi, Naoki; Kawakami, Susumu

2002-03-01

It is essential to understand the corrosion type of carbon steel under the repository conditions for the lifetime assessment of carbon steel overpack used for geological isolation of high-level radioactive waste. According to the previous study, carbon steel is hard to passivate in buffer material assuming a chemical condition range of groundwater in Japan. However, concrete support will be constructed around the overpack in the case of repository in the soft rock system and groundwater having a higher pH may infiltrate to buffer material. There is a possibility that the corrosion type of carbon steel will be influenced by the rise of the pH in groundwater. In this study, anodic polarization experiments were performed to understand the passivation condition of carbon steel in buffer material saturated with water contacted with concrete. An ordinary concrete an a low-alkalinity concrete were used in the experiment. The results of the experiments showed that the carbon steel can passivate under the condition that water having pH > 13 infiltrate to the buffer material assuming present property of buffer material. If the low-alkalinity concrete is selected as the support material, passivation can not occur on carbon steel overpack. The effect of the factors of buffer material such as dry density and mixing ratio of sand on the passivation of carbon steel was also studied. The results of the study showed that the present property of buffer material is enough to prevent passivation of carbon steel. (author)

13C, 1H spin-spin coupling constants. Pt. 4

International Nuclear Information System (INIS)

Aydin, R.; Guenther, H.

1979-01-01

One-bond, geminal, and vicinal 13 C, 1 H coupling constants have been determined for adamantane using α-and β-[D]adamantane and the relation sup(n)J( 13 C, 1 H)=6,5144sup(n)J( 13 C, 2 H) for the conversion of the measured sup(n)J( 13 C, 2 H) values. It is shown that the magnitude of 3 Jsub(trans) is strongly influenced by the substitution pattern. Relative H,D isotope effects for 13 C chemical shifts are given. (orig.) [de

NDOGM EN H IST OR IES OOG PU NT BESIEN . Die Apostoliese

African Journals Online (AJOL)

Test

ou kerkleraars oer die hiernamaals heidense bestanddele bevat het, waardeur die beskouing van die Roomse Kerk oor die nederdaiing be- invloed is. Rome leer dat die hiernamaals vyf verskillende plekke bevat. Christus het na een van daardie vyf plekke afgedaal. en wel na die verblyfplek van die gelowiges wat voor sy ...

Inhibition of Escherichia coli O157:H7 on stainless steel using Pseudomonas veronii biofilms.

Science.gov (United States)

Kim, Y; Kim, H; Beuchat, L R; Ryu, J-H

2018-05-01

We produced a Pseudomonas veronii biofilm on the surface of a stainless steel that is inhibitory to Escherichia coli O157:H7. Pseudomonas veronii strain KACC 81051BP, isolated from lettuce, readily formed biofilm on the surface of stainless steel coupons (SSCs) immersed in tryptic soy broth at 25°C. Cells showed significantly (P ≤ 0·05) enhanced tolerance to desiccation stress (43% relative humidity (RH)) and retained antimicrobial activity against E. coli O157:H7. The number of E. coli O157:H7 (control; 4·1 ± 0·1 log CFU per coupon) on sterile SSCs decreased to 2·7 ± 0·2 log CFU per coupon after exposure to 43% RH at 25°C for 48 h, while the population of E. coli O157:H7 (4·1 ± 0·0 log CFU per coupon) on SSCs containing P. veronii biofilm decreased to below the theoretical detection limit (1·5 log CFU per coupon) within 24 h. The antimicrobial biofilm produced on stainless steel may have application in preventing cross-contamination by E. coli O157:H7 on other abiotic surfaces in food-contact environments. The presence of Escherichia coli O157:H7 on environmental surfaces of food manufacturing, transportation and storage facilities is a significant food safety concern because it can result in cross-contamination of food products. In this study, we developed a Pseudomonas veronii biofilm on the surface of a stainless steel that inhibits the growth of E. coli O157:H7. Since P. veronii in biofilm resists desiccation, it provides persistent antimicrobial activity. Information presented here provides novel and practical insights to developing biological strategies to inactivate E. coli O157:H7 on diverse surfaces in food processing and handling environments. © 2018 The Society for Applied Microbiology.

Extraction residue analysis on F82H-BA07 heat and other reduced activation ferritic/martensitic steels

International Nuclear Information System (INIS)

Nagasaka, Takuya; Hishinuma, Yoshimitsu; Muroga, Takeo; Li, Yanfen; Watanabe, Hideo; Tanigawa, Hiroyasu; Sakasegawa, Hideo; Ando, Masami

2011-01-01

Extraction residue analysis was conducted on reduced activation ferritic/martensitic steels, such as F82H-BA07 heat, F82H-IEA heat, JLF-1 JOYO heat and CLAM steel. M 23 C 6 type precipitates, TaC precipitates and Fe 2 W Laves phase were identified in the present analyses. M 23 C 6 precipitates were coarsened in F82H-BA07 compared with the other steels at as-normalized and tempered (NT) condition. TaC precipitate formation was enhanced in JLF-1 and CLAM compared with F82H-BA07 and F82H-IEA at as-NT condition. Laves phase were detected in F82H-IEA after aging above 550 o C, where solid solution W was significantly decreased. F82H-IEA exhibited hardening after aging at 400 and 500 o C for 100 khr, whereas softening at 600 and 650 o C. This behavior is similar to JLF-1 and CLAM, and can be understood by precipitation of TaC and Laves phase.

New trends in cold-chamber die casting machine design

Directory of Open Access Journals (Sweden)

R. Dańko

2015-07-01

Full Text Available Larger and larger proportions of aluminium castings, especially those produced by the die casting process, can be observed during recent years in the automotive industry, house-hold articles and others. In case of the automotive industry, apart from the traditional elements produced by the die pressure method such as engine blocks or crank shaft bedplates, aluminium is displacing steel from structural parts of cars (‘body in white’. The current state and development directions of the structural solutions of cold-chamber die castings are analysed in this paper. These solutions drive the prospective development of these machines and die casting technology. The focus is mainly on essential functional systems such as: hydraulic drives of closing and locking units, as well as pressing in die machines of known companies present on the European market.

Solank verlange die sweep swaai. Danie Marais. Kaapstad ...

African Journals Online (AJOL)

In “Reisiger 13” word die beeld van NASA se Voyager I-ruimtesending ingespan om die digter se poëtiese missie in hierdie bundel (ook met 'n verwysing na sy debuut) te verduidelik: Daarom lanseer ek vannag die Rei- siger 13. [...] 'n Black Magic-boksie met 'n kiekie van vrou, kroos en kat, 'n paar knipsels en 'n mix-CD ...

Die funksie van die belydenis in die struktuur van die kerk en die ...

African Journals Online (AJOL)

Ter wille van die argument wat in hierdie voordrag na vore gebring word, word vier sodanige konstituerende elemente van die kerklike struktuur onderskei, te wete die belydenis, die teologie, die verkondi- ging (meer bepaald die prediking) en die kerkorde (kerkwet volgens ons terminologie). Ons gaan nou elkeen hiervan ...

Hydrogen Diffusion and H{sub 2}S Corrosion in Steel

Energy Technology Data Exchange (ETDEWEB)

Haugstveit, Bjarte Erlend

2001-01-01

The electrochemical permeation technique introduced by Devanathan and Stachurski has been used to measure the effective diffusivity of hydrogen in steel in a H{sub 2}S-saturated aqueous environment. The linear polarization resistance (LPR) method has been used to measure the corrosion rate. The effective diffusion coefficient of hydrogen has been found to be in the range of 1*10-12 to 7*10-11, depending on the environmental conditions. The corrosion film was identified as mackinawite, and it affected the permeation process of hydrogen. The results supported the assumption that the diffusion process can be described by a three layer model and indicated that the model could be reduced to a two layer model in the cases of iron and steel. A model aimed to describe the reaction pathway of hydrogen through the surface film and into the steel is proposed. The corrosion film influenced the corrosion rate, and it was least protective against corrosion at pH 6.5. Corrosion rates were in the range of 0.2-1 mm/year. The corrosion rate was increased significantly at pH 3.5, but the effect of the surface film was stronger and overshadowed the pH effect at the higher pH values. Increased flow velocity also lead to increased corrosion rate, but this effect was less significant compared to the effect of pH and the surface film. DEG decreased the corrosion rate. The uncertainty in the diffusion measurements was mainly due to the assumption of a constant sub-surface concentration of atomic hydrogen, which was not fulfilled. A method less dependent on constant surface conditions would probably yield better estimates of the effective diffusivity. The uncertainty in the corrosion measurements was mainly due to the uncertainty in the value of the Stern-Geary constant. The qualitative assumptions based on the results in this thesis are assumed to be valid. A test section designed for this thesis was tested and was found successful in corrosion rate measurements, but proved to be

die rol van die unieverdedigingsmag in die onderdrukking van die

African Journals Online (AJOL)

agv regeringsoptrede nie.39. Siotsom. In die geskiedenis van die Unieverdedigings- mag word die gebeure random die 1914-staking oorskadu deur die Rebellie en Suid-Afrika se deelname aan die Eerste Wereldoorlog. Tog was dit 'n belangrike mylpaal in die geskiedenis van die organisasie, omdat dit sy eerste optrede ...

Development of Integrated Die Casting Process for Large Thin-Wall Magnesium Applications

Energy Technology Data Exchange (ETDEWEB)

Carter, Jon T. [General Motors LLC, Warren, MI (United States); Wang, Gerry [Meridian Lightweight Technologies, Plymouth MI (United States); Luo, Alan [General Motors LLC, Warren, MI (United States)

2017-11-29

The purpose of this project was to develop a process and product which would utilize magnesium die casting and result in energy savings when compared to the baseline steel product. The specific product chosen was a side door inner panel for a mid-size car. The scope of the project included: re-design of major structural parts of the door, design and build of the tooling required to make the parts, making of parts, assembly of doors, and testing (both physical and simulation) of doors. Additional work was done on alloy development, vacuum die casting, and overcasting, all in order to improve the performance of the doors and reduce cost. The project achieved the following objectives: 1. Demonstrated ability to design a large thin-wall magnesium die casting. 2. Demonstrated ability to manufacture a large thin-wall magnesium die casting in AM60 alloy. 3. Tested via simulations and/or physical tests the mechanical behavior and corrosion behavior of magnesium die castings and/or lightweight experimental automotive side doors which incorporate a large, thin-wall, powder coated, magnesium die casting. Under some load cases, the results revealed cracking of the casting, which can be addressed with re-design and better material models for CAE analysis. No corrosion of the magnesium panel was observed. 4. Using life cycle analysis models, compared the energy consumption and global warming potential of the lightweight door with those of a conventional steel door, both during manufacture and in service. Compared to a steel door, the lightweight door requires more energy to manufacture but less energy during operation (i.e., fuel consumption when driving vehicle). Similarly, compared to a steel door, the lightweight door has higher global warming potential (GWP) during manufacture, but lower GWP during operation. 5. Compared the conventional magnesium die casting process with the “super-vacuum” die casting process. Results achieved with cast tensile bars suggest some

Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

Energy Technology Data Exchange (ETDEWEB)

D. Schwam: J.F. Wallace: Y. Zhu: J.W. Ki

2004-10-01

The utilization of aluminum die casting as enclosures where internal equipment is rotating inside of the casting and could fracture requires a strong housing to restrain the fractured parts. A typical example would be a supercharger. In case of a failure, unless adequately contained, fractured parts could injure people operating the equipment. A number of potential reinforcement materials were investigated. The initial work was conducted in sand molds to create experimental conditions that promote prolonged contact of the reinforcing material with molten aluminum. Bonding of Aluminum bronze, Cast iron, and Ni-resist inserts with various electroplated coatings and surface treatments were analyzed. Also toughening of A354 aluminum cast alloy by steel and stainless steel wire mesh with various conditions was analyzed. A practical approach to reinforcement of die cast aluminum components is to use a reinforcing steel preform. Such performs can be fabricated from steel wire mesh or perforated metal sheet by stamping or deep drawing. A hemispherical, dome shaped casting was selected in this investigation. A deep drawing die was used to fabricate the reinforcing performs. The tendency of aluminum cast enclosures to fracture could be significantly reduced by installing a wire mesh of austenitic stainless steel or a punched austenitic stainless steel sheet within the casting. The use of reinforcements made of austenitic stainless steel wire mesh or punched austenitic stainless steel sheet provided marked improvement in reducing the fragmentation of the casting. The best strengthening was obtained with austenitic stainless steel wire and with a punched stainless steel sheet without annealing this material. Somewhat lower results were obtained with the annealed punched stainless steel sheet. When the annealed 1020 steel wire mesh was used, the results were only slightly improved because of the lower mechanical properties of this unalloyed steel. The lowest results were

Die beeld van die opvoeder — 'n groep Opvoedkunde-studente se ...

African Journals Online (AJOL)

Erna Kinsey

noemde tipe opvoeder die "folterkameronderwyser". Uit voorafgaande blyk dit eerstens dat opvoeders 'n belangrike invloed op leerders se akademiese suksesse en/of mislukkings, asook hulle persoonlike geluk kan hê, tweedens tree opvoeders om altruïs- tiese, maar ook om egosentriese redes tot die onderwysberoep toe ...

Irradiation and inhomogeneity effects on ductility and toughness of (ODS)-7 -13Cr steels

International Nuclear Information System (INIS)

Preininger, D.

2007-01-01

Full text of publication follows: The superimposed effect of irradiation defect and structural inhomogeneity formation on tensile ductility and dynamic toughness of ferritic-martensitic 7-13CrW(Mo)VTa(Nb) and oxide dispersion-strengthened (ODS)-7-13CrWVTa(Ti)- RAFM steels has been examined by work hardening and local stress/strain-induced ductile fracture models. Structural inhomogeneities which strongly promoting plastic instability and localized flow might be formed by the applied fabrication process, high dose irradiation and additionally further during deformation by enhanced local dislocation generation around fine particles or due to slip band formation with localized heating at high impact strain rates ε'. The work hardening model takes into account superimposed dislocation multiplication from stored dislocations, dispersions and also grain boundaries as well as annihilation by cross-slip. Analytical relations have been deduced from the model describing uniform ductility and ductile upper shelf energy (USE) observed from Charpy-impact testes. Especially, the influence of different irradiation defects like atomic clusters, dislocation loops and coherent chromium-rich α'- precipitates have been considered together with effects from strain rate as well as irradiation (TI) and test temperature TT. Strengthening by clusters and more pronounced by dislocation loops formed at higher TI>250 deg. C reduces uniform ductility and also distinctly stronger dynamic toughness USE. A superimposed hardening by the α'- formation in higher Cr containing 9-13Cr steels strongly reduces toughness assisted by a combined grain-boundary embrittlement with reduction of the ductile fracture stress. But that improves work hardening and uniform ductility as observed particularly due to nano-scale Y 2 O 3 - dispersions in ODS-RAFM steels. For ODS- steels additionally the strength-induced reduction of toughness is diminished by a combined microstructural-induced increase of the ductile

die geskiedenis van die saw gedenkteken te fort klapperkop militere ...

African Journals Online (AJOL)

As gevolg van enige optrede, op enige plek, te enige tyd, deur enige vyand van die RSA of deur enige terroris(te), insurgent(e) of ander persoon of persone wat die RSA en sy volkere kwaadgesind is. h. Binne twee jaar (vyfhondred-en-dertig dae) nadat hy/sy met 'n ongeskiktheids- pensioen uit diens getree het agv siekte,.

Effects of H2O and H2O2 on thermal desorption of tritium from stainless steel

International Nuclear Information System (INIS)

Quinlan, M. J.; Shmayda, W. T.; Lim, S.; Salnikov, S.; Chambers, Z.; Pollock, E.; Schroeder, W. U.

2008-01-01

Tritiated stainless steel was subjected to thermal desorption at various temperatures, different temperature profiles, and in the presence of different helium carrier gas additives. In all cases the identities of the desorbing tritiated species were characterized as either water-soluble or insoluble. The samples were found to contain 1.1 mCi±0.4 mCi. Approximately ninety-five percent of this activity was released in molecular water-soluble form. Additives of H 2 O or H 2 O 2 to dry helium carrier gas increase the desorption rate and lower the maximum temperature to which the sample must be heated, in order to remove the bulk of the tritium. The measurements validate a method of decontamination of tritiated steel and suggest a technique that can be used to further explore the mechanisms of desorption from tritiated metals. (authors)

High pressure die casting of Fe-based metallic glass

Science.gov (United States)

Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

2016-01-01

Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications. PMID:27725780

High pressure die casting of Fe-based metallic glass.

Science.gov (United States)

Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

2016-10-11

Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

High pressure die casting of Fe-based metallic glass

Science.gov (United States)

Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

2016-10-01

Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

Oxide formation and precipitation behaviors on interface of F82H steel joints during HIPing and hot pressing

International Nuclear Information System (INIS)

Kishimoto, H.; Ono, T.; Sakasegawa, H.; Tanigawa, H.; Ando, M.; Shibayama, T.; Kohno, Y.; Kohyama, A.

2013-01-01

Joining technologies for F82H steels are important issues for the development of fusion energy. The hot isostatic pressing (HIP) method is appropriate for consolidating the first wall of the blanket because of the flexibility of the shape of HIPed products. The HIP method is planned for fabricating a complex-shaped first wall component with built-in cooling channels; thus, accumulation of studies of microstructural and mechanical property changes, especially lower toughness of the HIPed joints, is essential. Present research aims to reveal the microstructural evolution of F82H joints fabricated by the HIP method compared with joints fabricated by hot pressing, focusing on the formation of oxides on the interface. F82H joints were characterized using 1/3-scale Charpy V-notch impact test, transmission electron microscope, scanning electron microscope, and electron probe analysis to survey the microstructural characteristics of the interface

On the inhibition of mild steel corrosion by 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol

International Nuclear Information System (INIS)

Musa, Ahmed Y.; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar; Takriff, Mohd Sobri; Daud, Abdul Razak; Kamarudin, Siti Kartom

2010-01-01

The corrosion inhibition of mild steel in a 2.5 M H 2 SO 4 solution by 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol (APTT) was studied at different temperatures, utilising open circuit potential, potentiodynamic and impedance measurements. The results indicate that APTT performed as an excellent mixed-type inhibitor for mild steel corrosion in a 2.5 M H 2 SO 4 solution and that the inhibition efficiencies increased with the inhibitor concentration but decreased proportionally with temperature. The kinetic and thermodynamic parameters for adsorption of APTT on the mild steel surface were calculated. A chemisorption mechanism of APTT molecules on the mild steel surface was proposed based on the thermodynamic adsorption parameters.

Small specimen test technology of fracture toughness in structural material F82H steel for fusion nuclear reactors

International Nuclear Information System (INIS)

Wakai, Eiichi; Ohtsuka, Hideo; Jitsukawa, Shiro; Matsukawa, Shingo; Ando, Masami

2006-03-01

Small specimen test technology (SSTT) has been developed to investigate mechanical properties of nuclear materials. SSTT has been driven by limited availability of effective irradiation volumes in test reactors and accelerator-based neutron and charged particle sources, and it is very useful for the reduction of waste materials produced in nuclear engineering. In this study new bend test machines have been developed to obtain fracture behaviors of F82H steel for very small bend specimens of pre-cracked t/2-1/3CVN (Charpy V-notch) with 20 mm-length and DFMB (deformation and fracture mini bend specimen) with 9 mm-length and disk compact tension of 0.18DCT type, and fracture behaviors were examined to evaluate DBTT (ductile-brittle transition temperature) at temperature from -180 to 25degC. The effect of specimen size on DBTT of F82H steel was also examined by using Charpy type specimens such as 1/2t-CVN, 1/3CVN and t/2-1/3CVN. In this paper, it also provides the information of the specimens irradiated at 250degC and 350degC to about 2 dpa in the capsule of 04M-67A and 04M-68A of JMTR experiments. (author)

Properties of powder metallurgy steel forgings

International Nuclear Information System (INIS)

Crowson, A.; Anderson, F.E.

1977-01-01

The effects of processing variables on the mechanical properties of heat-treated powder metallurgy (P/M) steel forgings were determined. Prealloyed 4600 steel powder blended with graphite to yield 4640 was compacted into preforms and hot forged in a warm, closed die. Variables studied were preform density, method of lubrication, preform sintering (time, temperature and atmosphere), forging pressure (20 and 40 tsi) and temperature (1850 0 F, 2000 0 F and 2200 0 F), and forging ratio (0.75 and 0.95). Relationships between interconnected porosity and total porosity for the various preform densities were determined. High density compacts required higher sintering temperatures due to the restricted mobility of the reducing gases in the pores. Die wall lubrication was comparable to admixed lubrication, and it simplified powder mixing and preform sintering operations. Forgings with densities from 99 to 99.8 percent of theoretical density were attained with a forging pressure of 20 to 40 tsi and preform temperatures of 2000 0 F and above. At forging conditions which resulted in forgings with acceptable mechanical properties, complete die fill was accomplished at a forging ratio of 0.95, whereas incomplete die fill resulted at a forging ratio of 0.75. The response of P/M forgings to heat treatment was comparable to that for wrought materials, and the resultant tensile and yield strengths were equivalent to the strength values described for wrought 4640 steel in AMS specification 6317B. In addition, ductility and impact properties of P/M forgings with near theoretical density (99.5+ percent) were comparable to bar stock forgings

Microstructural characterization of dissimilar welds between Incoloy 800H and 321 Austenitic Stainless Steel

Energy Technology Data Exchange (ETDEWEB)

Sayiram, G., E-mail: sayiram.g@vit.ac.in; Arivazhagan, N.

2015-04-15

In this work, the microstructural character of dissimilar welds between Incoloy 800H and 321 Stainless Steel has been discussed. The microscopic examination of the base metals, fusion zones and interfaces was characterized using an optical microscope and scanning electron microscopy. The results revealed precipitates of Ti (C, N) in the austenitic matrix along the grain boundaries of the base metals. Migration of grain boundaries in the Inconel 82 weld metal was very extensive when compared to Inconel 617 weldment. Epitaxial growth was observed in the 617 weldment which increases the strength and ductility of the weld metal. Unmixed zone near the fusion line between 321 Stainless Steel and Inconel 82 weld metal was identified. From the results, it has been concluded that Inconel 617 filler metal is a preferable choice for the joint between Incoloy 800H and 321 Stainless Steel. - Highlights: • Failure mechanisms produced by dissimilar welding of Incoloy 800H to AISI 321SS • Influence of filler wire on microstructure properties • Contemplative comparisons of metallurgical aspects of these weldments • Microstructure and chemical studies including metallography, SEM–EDS • EDS-line scan study at interface.

Challenges in Special Steel Making

Science.gov (United States)

Balachandran, G.

2018-02-01

Special bar quality [SBQ] is a long steel product where an assured quality is delivered by the steel mill to its customer. The bars have enhanced tolerance to higher stress application and it is demanded for specialised component making. The SBQ bars are sought for component making processing units such as closed die hot forging, hot extrusion, cold forging, machining, heat treatment, welding operations. The final component quality of the secondary processing units depends on the quality maintained at the steel maker end along with quality maintained at the fabricator end. Thus, quality control is ensured at every unit process stages. The various market segments catered to by SBQ steel segment is ever growing and is reviewed. Steel mills need adequate infrastructure and technological capability to make these higher quality steels. Some of the critical stages of processing SBQ and the critical quality maintenance parameters at the steel mill in the manufacture has been brought out.

Die WTO in Hongkong: Zwischenergebnisse einer "Entwicklungsrunde"

OpenAIRE

Küblböck, Karin; Six, Clemens

2006-01-01

Die sechste Ministerkonferenz der Welthandelsorganisation (WTO), die von 13. bis 18. Dezember 2005 in Hongkong stattfand, war mit dem Anspruch angetreten, die Agenda der Doha-Entwicklungsrunde, also die B erücksichtigung der Interessen und ökonomischen Bedürfnisse der Entwicklungsländer und insbesondere der am wenigsten entwickelten Staaten, um wesentliche Schritte im Hinblick auf einen erfolgreichen Abschluss voranzubringen. Die Ergebnisse sind vor dem Hintergrund des Anspruches dieser Verha...

Research on the Effects of the Movable Die and its Counter Force on Sheet Hydroforming

International Nuclear Information System (INIS)

Zhou, Li X.; Zhang, Shi H.; Wang, Ben X.

2007-01-01

An improved Sheet Hydro-forming process was proposed, which was investigated in Institute of Metal Research, Chinese Academy of Sciences. ASAME system and FEM are used to analyze the forming process to explain some results that were found in the experiment. In the simulation, the effect of the movable die on the maximum principal stress is investigated in detail by using the FEM code LS-DYNA. For this case, the movable die changes the distribution of the maximum principal stress. For the sheet hydroforming without the movable die, the principal stress near the shoulder of the movable die arrives to the maximum value when t=0.0033s suddenly. But for the sheet hydroforming with the movable die, the maximum principal stress still lies in the die radius. The principal stress near the shoulder of the movable die is smaller. At the last stage contacting with the die, for the case without the movable die, the maximum principal stress near the shoulder of movable die is larger than that of the sheet hydroforming with the movable die. Moreover, the stress distribution near the shoulder of movable die for the case without the movable die is complicated. It is instable and very easy to occur wrinkling. The movable die delays the maximum thickness strain to the contacting die stage. So the formability of sheet metal can be remarkably improved by adopting the movable die. On a certain extent, the uniform distribution of thickness can be realized by increasing the counterforce of movable die. The minimum thickness reduction moves outside which is very helpful for the uniform thickness distribution. In this paper, two kinds of materials, soft steel and stainless steel, were investigated

Material pre-conditioning effects on the creep behaviour of 316H stainless steel

International Nuclear Information System (INIS)

Mehmanparast, A.; Davies, C.M.; Dean, D.W.; Nikbin, K.

2013-01-01

Material pre-conditioning by, for example, pre-strain through component bending and welding is known to alter the creep deformation and creep crack growth (CCG) behaviour of 316H stainless steel. Experimental test data on the creep deformation and crack growth behaviour of 316H weldment compact tension specimens at 550 °C, where the starter defect was introduced into the heat affected zone (HAZ), have been compared to those of obtained from similar specimens manufactured from parent material, which had been subjected to 8% compressive plastic pre-strain at room temperature. Similar degrees of accelerated cracking behaviour compared to parent material, for given values of C*, were exhibited in both 316H HAZ and pre-compressed parent materials. This acceleration has been attributed to the influence of material hardening effects and the reduction of creep ductility in the pre-conditioned materials. These results are discussed in terms of the potential for using material pre-conditioning to assist in predicting the long term cracking behaviour of high temperature 316H stainless steel plant components from shorter term laboratory CCG tests

Improved design and durability of aluminum die casting horizontal shot sleeves

Science.gov (United States)

Birceanu, Sebastian

The design and performance of shot sleeves is critical in meeting the engineering requirements of aluminum die cast parts. Improvement in shot sleeve materials have a major impact on dimensional stability, reproducibility and quality of the product. This investigation was undertaken in order to improve the life of aluminum die casting horizontal shot sleeves. Preliminary pin tests were run to evaluate the soldering, wash-out and thermal fatigue behavior of commercially available materials and coatings. An experimental rig was designed and constructed for shot sleeve configuration evaluation. Fabrication and testing of experimental shot sleeves was based upon preliminary results and manufacturing costs. Three shot sleeve designs and materials were compared to a reference nitrided H13 sleeve. Nitrided H13 is the preferred material for aluminum die casting shot sleeves because of wear resistance, strength and relative good soldering and wash-out resistance. The study was directed towards damage evaluation on the area under the pouring hole. This area is the most susceptible to damage because of high temperatures and impingement of molten aluminum. The results of this study showed that tungsten and molybdenum had the least amount of soldering and wash-out damage, and the best thermal fatigue resistance. Low solubility in molten aluminum and stability of intermetallic layers are main factors that determine the soldering and wash-out behavior. Thermal conductivity and thermal expansion coefficient directly influence thermal fatigue behavior. TiAlN nanolayered coating was chosen as the material with the best damage resistance among several commercial PVD coatings, because of relatively large thickness and simple deposition conditions. The results show that molybdenum thermal sprayed coating provided the best protection against damage under the pouring hole. Improved bonding is however required for life extension of the coating. TiAlN PVD coating applied on H13 nitrided

H12CN and H13CN excitation analysis in the circumstellar outflow of R Sculptoris

Science.gov (United States)

Saberi, M.; Maercker, M.; De Beck, E.; Vlemmings, W. H. T.; Olofsson, H.; Danilovich, T.

2017-03-01

Context. The 12CO/13CO isotopologue ratio in the circumstellar envelope (CSE) of asymptotic giant branch (AGB) stars has been extensively used as the tracer of the photospheric 12C/13C ratio. However, spatially-resolved ALMA observations of R Scl, a carbon rich AGB star, have shown that the 12CO/13CO ratio is not consistent over the entire CSE. Hence, it can not necessarily be used as a tracer of the 12C/13C ratio. The most likely hypothesis to explain the observed discrepancy between the 12CO/13CO and 12C/13C ratios is CO isotopologue selective photodissociation by UV radiation. Unlike the CO isotopologue ratio, the HCN isotopologue ratio is not affected by UV radiation. Therefore, HCN isotopologue ratios can be used as the tracer of the atomic C ratio in UV irradiated regions. Aims: We aim to present ALMA observations of H13CN(4-3) and APEX observations of H12CN(2-1), H13CN(2-1, 3-2) towards R Scl. These new data, combined with previously published observations, are used to determine abundances, ratio, and the sizes of line-emitting regions of the aforementioned HCN isotopologues. Methods: We have performed a detailed non-LTE excitation analysis of circumstellar H12CN(J = 1-0, 2-1, 3-2, 4-3) and H13CN(J = 2-1, 3-2, 4-3) line emission around R Scl using a radiative transfer code based on the accelerated lambda iteration (ALI) method. The spatial extent of the molecular distribution for both isotopologues is constrained based on the spatially resolved H13CN(4-3) ALMA observations. Results: We find fractional abundances of H12CN/H2 = (5.0 ± 2.0) × 10-5 and H13CN/H2 = (1.9 ± 0.4) × 10-6 in the inner wind (r ≤ (2.0 ± 0.25) ×1015 cm) of R Scl. The derived circumstellar isotopologue ratio of H12CN/H13CN = 26.3 ± 11.9 is consistent with the photospheric ratio of 12C/13C 19 ± 6. Conclusions: We show that the circumstellar H12CN/H13CN ratio traces the photospheric 12C/13C ratio. Hence, contrary to the 12CO/13CO ratio, the H12CN/H13CN ratio is not affected by UV

Hardness in high temperature of steels ABNT H11 and ABNT H11 modified with niobium

International Nuclear Information System (INIS)

Goncalves, R.A.

1984-01-01

A method to measure the hardness of metallic materials was developed. The heating was done by the Joule effect heat dissipation in the sample, that is like an electrical resistor. A diamond penetrator with a revolution paraboloid format was used, that assure a linear relation between the load applyed and the penetration deep. Hardness tests were make in the range of 25 - 600 0 C, in the steels ABNT H11 and ABNT H11 modified with niobium, with the simultaneous register of the applied force, penetration deep and temperature. (E.G.) [pt

Heat treatment of investment cast PH 13-8 Mo stainless steel: Part II. Isothermal aging kinetics

Science.gov (United States)

Robino, C. V.; Cieslak, M. J.; Hochanadel, P. W.; Edwards, G. R.

1994-04-01

The hardening response of investment cast PH 13-8 Mo stainless steel has been evaluated by hardness measurements following aging in the temperature range normally specified for this alloy (510 °C to 593 °C). A new relationship between fraction transformed and hardness was developed, and analysis of the data in terms of the kinetics of precipitation, in a manner similar to that frequently applied to other precipitation-hardenable martensitic steels, yielded low time exponents and a low value for the apparent activation energy. The values of the time exponents were 0.49, 0.37, 0.56, and 0.53 at 510 °C, 538 °C, 566 °C, and 593 °C, respectively, and that for the apparent activation energy was 139 kJ/mole. As has been proposed for other maraging type steels, these estimates suggest that Β-NiAl precipitates along or near dislocations and that growth of the precipitates is dominated by dislocation pipe diffusion. However, these predictions were neither supported nor refuted by transmission electron microscopy (TEM) because of difficulties in imaging the Β-NiAl precipitates at the aging times and temperatures used. Further, analysis of the data using the formalism of Wert and Zener for the growth of precipitates with interfering diffusion fields indicated that the estimates of fraction transformed from hardness data are not fully appropriate for maraging type steels. Consideration of the nature of the Avrami analysis and the electron microscopy results suggests that other phenomena, including dislocation recovery and reversion of martensite to austenite, occur at rates sufficient to convolute the Avrami analysis. It is further suggested that these results cast doubt on the fundamental implications of previous analyses of precipitation kinetics in age-hardening martensitic steels. Although the Avrami analysis was found not to provide a tenable description of the precipitation kinetics, it does provide a reasonable methodology for portrayal of the hardening response

Die rol van die blanke werker in die motivering van die swart werker

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G. J. Oosthuizen

1980-11-01

Opsomming Die motivering van die Swart werker kan nie in die huidige situasie in isolasie bestudeer word nie, omdat die Blanke werker steeds in die bestuursposisie is en daarom die motivering van die Swart werker kan beïnvloed. Hierdie ondersoek was daarop gerig om die rol van die Blanke werker in die motivering van die Swart werker nader te ondersoek. Die houding en die leierskapsbenadering van die Blanke werker teenoor die Swart werker is gemeet, asook die behoeftes wat volgens die Blanke werker by die Swart werker bestaan, bevredig is, of nie bestaan nie. Die behoeftes van Swart werkers, soos deur hulleself gesien, is ook ondersoek. Ten opsigte van sekere aspekte is beduidende verskille gevind.

Corrosive effect of oil's accompanying water polluted with H2S over steel (API 5L X-52)

International Nuclear Information System (INIS)

Cueli Corugedo, Alexander; Adames Montero, Yosmari; Rivera Beltran, Yischy; Davis Harriet, Juan

2013-01-01

The corrosion from the steel to the carbon in the sale oil pipage conduction, is a serious problem, due to the material and economical looses they cause, damaging even in some cases the productive field. The purpose of this study is to determine the aggressiveness of the oil's water layer, polluted with H 2 S ( g) , over the steel of pipelines' construction (API 5L X-52), taking into account the temperature variations which take place during the transportation of the oil, using the electrochemical techniques of polarisation resistance (LPR) and electrochemical noise. It is pretended to determine the velocity of steel corrosion in the oil's water layer polluted with H 2 S through electrochemical techniques. It was shown that the temperature increases and the concentration of H 2 S to 500 ppm in the oil's accompanying water emphasizes the corrosion phenomenon experienced by the steel (9, 188 0 mm/year to 70℃).The results of the electrochemical noise spectrums and the values of the localisation ?s index calculated, shown the presence of corrosion on the steel surface (API 5L X-52).This result was complemented through optic Microscopy which permits to corroborate the poor adherence of the sulphur layers deposited on the metal that increase the appearance of events found with the temperature increase and the concentration of H 2 S in the environment studied

Influence of surface mechanical activation of the X40Cr13 steel on roughness after ion and gas nitriding

International Nuclear Information System (INIS)

Jasinski, J.; Wojtal, A.; Jeziorski, L.; Radecki, A.; Ucieklak, S.

2003-01-01

The article describes the problem of the thermal and mechanical activation of the surface of the X40Cr13 steel on the state of the ion and gas nitriding. in order to determine the nitriding influence and make the analysis of results, the steel was subjected to: soft annealing, hardening with subsequent tempering at T = 550 o C and also mechanical activation of the surface consisting in peripheral grinding with abrasive papers of the grain size 60, 360, 1000 and mechanical polishing. The main aim of this work was to establish the influence of different surface geometrical structure, depending on X40Cr13 steel structure, on the roughness profile after ion and gas nitriding. With regard to the above, the examinations of basic roughness parameters prior to and after thermochemical processes and the analysis of utilitarian usefulness of activations applied were carried out. (author)

Oxidation Behavior of Carbon Steel: Effect of Formation Temperature and pH of the Environment

Science.gov (United States)

Dubey, Vivekanand; Kain, Vivekanand

2017-11-01

The nature of surface oxide formed on carbon steel piping used in nuclear power plants affects flow-accelerated corrosion. In this investigation, carbon steel specimens were oxidized in an autoclave using demineralized water at various temperatures (150-300 °C) and at pH levels (neutral, 9.5). At low temperatures ( 240 °C) as confirmed by scanning electron microscopy. Electrochemical impedance measurement followed by Mott-Schottky analysis indicated an increase in defect density with exposure duration at 150 °C at neutral pH but a low and stable defect density in alkaline environment. The defect density of the oxide formed at neutral pH at 150-300 °C was always higher than that formed in alkaline environment as reported in the literature.

Optimization of Minimum Quantity Lubricant Conditions and Cutting Parameters in Hard Milling of AISI H13 Steel

OpenAIRE

The-Vinh Do; Quang-Cherng Hsu

2016-01-01

As a successful solution applied to hard machining, the minimum quantity lubricant (MQL) has already been established as an alternative to flood coolant processing. The optimization of MQL parameters and cutting parameters under MQL condition are essential and pressing. The study was divided into two parts. In the first part of this study, the Taguchi method was applied to find the optimal values of MQL condition in the hard milling of AISI H13 with consideration of reduced surface roughness....

Tribological Behavior of Laser Textured Hot Stamping Dies

Directory of Open Access Journals (Sweden)

Andre Shihomatsu

2016-01-01

Full Text Available Hot stamping of high strength steels has been continuously developed in the automotive industry to improve mechanical properties and surface quality of stamped components. One of the main challenges faced by researchers and technicians is to improve stamping dies lifetime by reducing the wear caused by high pressures and temperatures present during the process. This paper analyzes the laser texturing of hot stamping dies and discusses how different surfaces textures influence the lubrication and wear mechanisms. To this purpose, experimental tests and numerical simulation were carried out to define the die region to be texturized and to characterize the textured surface topography before and after hot stamping tests with a 3D surface profilometer and scanning electron microscopy. Results showed that laser texturing influences the lubrication at the interface die-hot sheet and improves die lifetime. In this work, the best texture presented dimples with the highest diameter, depth, and spacing, with the surface topography and dimples morphology practically preserved after the hot stamping tests.

Corrosion Inhibition and Adsorption Characteristics of Tarivid on Mild Steel in H2SO4

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N. O. Eddy

2010-01-01

Full Text Available The corrosion inhibition and adsorption characteristics of (+/--9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid (Tarivid on the corrosion of mild steel has been studied using thermometric and gasometric methods. The study reveals that tarivid inhibits the corrosion of mild steel in H2SO4. The values of inhibition efficiency of tarivid were found to increase as its concentration increased but decreased with increase in temperature. Activation energies of the inhibited corrosion of mild steel ranged from 39.05 to 50.61 kJ/mol. Values of enthalpy change and free energy of adsorption were negative which indicated exothermic and spontaneous adsorption process. Physical adsorption mechanism is proposed from the obtained kinetic and thermodynamic parameters. Langmuir adsorption isotherm model is obeyed from the fit of the experimental data.

An ALMA Survey of DCN/H{sup 13}CN and DCO{sup +}/H{sup 13}CO{sup +} in Protoplanetary Disks

Energy Technology Data Exchange (ETDEWEB)

Huang, Jane; Öberg, Karin I.; Qi, Chunhua; Andrews, Sean M.; Guzmán, Viviana V.; Loomis, Ryan A.; Wilner, David J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Aikawa, Yuri; Furuya, Kenji [Center for Computational Sciences, The University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Van Dishoeck, Ewine F., E-mail: jane.huang@cfa.harvard.edu [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

2017-02-01

The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed throughout the stages of star and planet formation. We present ALMA observations at ∼0.″6 resolution of DCO{sup +}, H{sup 13}CO{sup +}, DCN, and H{sup 13}CN in the full disks around T Tauri stars AS 209 and IM Lup, in the transition disks around T Tauri stars V4046 Sgr and LkCa 15, and in the full disks around Herbig Ae stars MWC 480 and HD 163296. We also present ALMA observations of HCN in the IM Lup disk. DCN, DCO{sup +}, and H{sup 13}CO{sup +} are detected in all disks, and H{sup 13}CN in all but the IM Lup disk. We find efficient deuterium fractionation for the sample, with estimates of disk-averaged DCO{sup +}/HCO{sup +} and DCN/HCN abundance ratios ranging from ∼0.02–0.06 and ∼0.005–0.08, respectively, which is comparable to values reported for other interstellar environments. The relative distributions of DCN and DCO{sup +} vary between disks, suggesting that multiple formation pathways may be needed to explain the diverse emission morphologies. In addition, gaps and rings observed in both H{sup 13}CO{sup +} and DCO{sup +} emission provide new evidence that DCO{sup +} bears a complex relationship with the location of the midplane CO snowline.

Inelastic Cyclic Deformation Behaviors of Type 316H Stainless Steel for Reactor Pressure Vessel of Sodium-Cooled Fast Reactor at Elevated Temperatures

International Nuclear Information System (INIS)

Yoon, Ji-Hyun; Hong, Seokmin; Koo, Gyeong-Hoi; Lee, Bong-Sang; Kim, Young-Chun

2015-01-01

Type 316H stainless steel is a primary candidate material for a reactor pressure vessel of a sodium-cooled fast (SFR) reactor which is under development in Korea. The reactor pressure vessel for a SFR is subjected to inelastic deformation induced by cyclic thermal stress. Fully reversed cyclic testing and ratcheting testing at elevated temperatures were performed to characterize the inelastic cyclic deformation behaviors of Type 316H stainless steel at the SFR operating temperature. It was found that cyclic hardening of Type 316H stainless steel was enhanced, and the accumulation of ratcheting deformation of Type 316H stainless steel was retarded at around the SFR operating temperature. The results of the tensile testing and the microstructural investigation for dislocated structures after the inelastic deformation testing showed that dynamic strain aging affected the inelastic cyclic deformation behavior of Type 316 stainless steel at around the SFR operating temperature.

Inhibition of Mild Steel Corrosion in Hydrochloric Acid Solution by New Coumarin

Directory of Open Access Journals (Sweden)

Abdul Amir H. Kadhum

2014-06-01

Full Text Available A new coumarin derivative, N,N′-((2E,2′E-2,2′-(1,4-phenylenebis (methanylylidenebis(hydrazinecarbonothioylbis(2-oxo-2H-chromene-3-carboxamide PMBH, was synthesized and its chemical structure was elucidated and confirmed using spectroscopic techniques (Infrared spectroscopy IR, Proton nuclear  magnetic resonance, 1H-NMR and carbon-13 nuclear magnetic resonance 13C-NMR. The corrosion inhibition effect of PMBH on mild steel in 1.0 M HCl was investigated using corrosion potential (ECORR, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS, and electrochemical frequency modulation (EFM measurements. The obtained results indicated that PMBH has promising inhibitive effects on the corrosion of mild steel in 1.0 M HCl across all of the conditions examined. Scanning electron microscopy (SEM was used to investigate the morphology of the mild steel before and after immersion in 1.0 M HCl solution containing 0.5 mM of PMBH. Surface analysis revealed improvement of corrosion resistance in presence of PMBH.

Inhibition of Mild Steel Corrosion in Hydrochloric Acid Solution by New Coumarin

Science.gov (United States)

Kadhum, Abdul Amir H.; Mohamad, Abu Bakar; Hammed, Leiqaa A.; Al-Amiery, Ahmed A.; San, Ng Hooi; Musa, Ahmed Y.

2014-01-01

A new coumarin derivative, N,N′-((2E,2′E)-2,2′-(1,4-phenylenebis(methanylylidene))bis(hydrazinecarbonothioyl))bis(2-oxo-2H-chromene-3-carboxamide) PMBH, was synthesized and its chemical structure was elucidated and confirmed using spectroscopic techniques (Infrared spectroscopy IR, Proton nuclear magnetic resonance, 1H-NMR and carbon-13 nuclear magnetic resonance 13C-NMR). The corrosion inhibition effect of PMBH on mild steel in 1.0 M HCl was investigated using corrosion potential (ECORR), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) measurements. The obtained results indicated that PMBH has promising inhibitive effects on the corrosion of mild steel in 1.0 M HCl across all of the conditions examined. Scanning electron microscopy (SEM) was used to investigate the morphology of the mild steel before and after immersion in 1.0 M HCl solution containing 0.5 mM of PMBH. Surface analysis revealed improvement of corrosion resistance in presence of PMBH. PMID:28788680

Influence of Mo addition on the tempered properties of 13Cr martensitic stainless steel

International Nuclear Information System (INIS)

Jung, Byong Ho; Ahn, Yong Sik

1998-01-01

In order to investigate the effect of Mo addition on the mechanical properties of 13Cr-0.2C martensitic stainless steel, tensile test and Charpy V-notch test were performed after tempering at the temperature range of 200∼700 .deg. C following austenitizing at 1100 .deg. C. The yield strength and hardness of the steel were increased with the increase of Mo content at all tempering conditions, because Mo causes retardation of precipitation and coarsening of carbides and solid solution strengthening of matrix. Except 500 .deg. C of tempering temperature, the Charpy impact energy was significantly increased with Mo content and showed the highest value at 1.5 wt% addition. The increase of impact energy of the steel containing Mo is thought to be caused by δ-ferrite formed in the tempered martensitic matrix. At 500 .deg. C tempering, Charpy impact energy was decreased drastically due to temper embrittlement and it was not possible to prevent it even though Mo was added up to 1.5 wt%

Influence of corrosion environment composition on crack propagation in high-strength martensitic steel

International Nuclear Information System (INIS)

Romaniv, O.N.; Nikiforchin, G.N.; Tsirul'nik, A.T.

1984-01-01

The 40 Kh steel is taken as an example to investigate the dependence of electrochemical parameters in the crack tip and characteristics of corrosion static cracking resistance of martensitic steel on the composition of environment. The tests are performed in acidic and alkaline solutions prepared by adding HC or NaOH in distilled water. It is established that growth of pH value of initial solutions trom 0 to 13 brings about linear increase of a threshold stress intensity factor. It is found that acidic medium in the crack tip preserves up to pH 13 of initial medium. The possibility of corrosion crack propagation in alkaline solutions according to the mechanism of hydrogen embrittlement is proved

Energy Saving Melting and Revert Reduction Technology: Improved Die Casting Process to Preserve the Life of the Inserts

Energy Technology Data Exchange (ETDEWEB)

David Schwam, PI; Xuejun Zhu, Sr. Research Associate

2012-09-30

The goal of this project was to study the combined effects of die design, proper internal cooling and efficient die lubricants on die life. The project targeted improvements in die casting insert life by: Optomized Die Design for Reduced Surface Temperature: The life of die casting dies is significantly shorter when the die is exposed to elevated temperature for significant periods of time. Any die operated under conditions leading to surface temperature in excess of 1050oF undergoes structural changes that reduce its strength. Optimized die design can improve die life significantly. This improvement can be accomplished by means of cooling lines, baffles and bubblers in the die. A key objective of the project was to establish criteria for the minimal distance of the cooling lines from the surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. The Uddeholm Dievar steel evaluated in this program showed superior resistance to thermal fatigue resistance. Based on the experimental evidence, cooling lines could be placed as close as 0.5" from the surface. Die Life Extension by Optimized Die Lubrication: The life of die casting dies is affected by additions made to its surface with the proper lubricants. These lubricants will protect the surface from the considerable temperature peaks that occur when the molten melt enters the die. Dies will reach a significantly higher temperature without this lubricant being applied. The amount and type of the lubricant are critical variables in the die casting process. However, these lubricants must not corrode the die surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. Chem- Trend participated in the program with die

Susceptibility to stress corrosion in stainless steels type AISI 321 and 12X18H10T used in PWR type reactors (WWER)

International Nuclear Information System (INIS)

Matadamas C, N.

1995-01-01

Titanium stabilized stainless steels have been utilized in sovietic pressurized water reactors (VVER) for avoid the susceptibility to Intergranular Corrosion (IGC) present in other austenitic stainless steels. However the Intergranular Corrosion resistance of this kind of materials has been questioned because of Intergranular Stress Corrosion Cracking failures (IGSCC) have been reported. This paper study the electrochemical behavior of the AISI 321 stainless steel in a H 3 BO 3 Solution contaminated with chlorides and its susceptibility to Intergranular Corrosion.Electrochemical prediction diagrams of the stainless steels AISI 321 and 12X18H10T (sovietic) sensitized (600 Centigrade, 3 h.) were compared. Cylindrical and conical samples were used in Slow Strain Rate Tests (SSRT), to determine the susceptibility to Stress Corrosion Cracking (SCC) in AISI 321 and 12X18H10T stainless steels. The results obtained showed that the temperature of the solution is a very important factor to detect this susceptibility. Fractography studies on the fracture surfaces of the samples obtained in the SSRT at high temperature were realized. Corrosion velocities of both AISI 321 and 12X18H10T stainless steels were determined using conical samples in the CERT system at high temperature. E.D.A.X. analysis was employed in both AISI 321 and 12X18H10T stainless steels in order to explain the degree of sensitization. (Author)

Multi criteria decision making of machining parameters for Die Sinking EDM Process

Directory of Open Access Journals (Sweden)

G. K. Bose

2015-04-01

Full Text Available Electrical Discharge Machining (EDM is one of the most basic non-conventional machining processes for production of complex geometries and process of hard materials, which are difficult to machine by conventional process. It is capable of machining geometrically complex or hard material components, that are precise and difficult-to-machine such as heat-treated tool steels, composites, super alloys, ceramics, carbides, heat resistant steels etc. The present study is focusing on the die sinking electric discharge machining (EDM of AISI H 13, W.-Nr. 1.2344 Grade: Ovar Supreme for finding out the effect of machining parameters such as discharge current (GI, pulse on time (POT, pulse off time (POF and spark gap (SG on performance response like Material removal rate (MRR, Surface Roughness (Ra & Overcut (OC using Square-shaped Cu tool with Lateral flushing. A well-designed experimental scheme is used to reduce the total number of experiments. Parts of the experiment are conducted with the L9 orthogonal array based on the Taguchi methodology and significant process parameters are identified using Analysis of Variance (ANOVA. It is found that MRR is affected by gap current & Ra is affected by pulse on time. Moreover, the signal-to-noise ratios associated with the observed values in the experiments are determined by which factor is most affected by the responses of MRR, Ra and OC. These experimental data are further investigated using Grey Relational Analysis to optimize multiple performances in which different levels combination of the factors are ranked based on grey relational grade. The analysis reveals that substantial improvement in machining performance takes place following this technique.

Hydrothermal Valorization of Steel Slags—Part I: Coupled H2 Production and CO2 Mineral Sequestration

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Camille Crouzet

2017-10-01

Full Text Available A new process route for the valorization of BOF steel slags combining H2 production and CO2 mineral sequestration is investigated at 300°C (HT under hydrothermal conditions. A BOF steel slag stored several weeks outdoor on the production site was used as starting material. To serve as a reference, room temperature (RT carbonation of the same BOF steel slag has been monitored with in situ Raman spectroscopy and by measuring pH and PCO2 on a time-resolved basis. CO2 uptake under RT and HT are, respectively, 243 and 327 kg CO2/t of fresh steel slag, which add up with the 63 kg of atmospheric CO2 per ton already uptaken by the starting steel slag on the storage site. The CO2 gained by the sample at HT is bounded to the carbonation of brownmillerite. H2 yield decreased by about 30% in comparison to the same experiment performed without added CO2, due to sequestration of ferrous iron in a Mg-rich siderite phase. Ferric iron, initially present in brownmillerite, is partitioned between an Fe-rich clay mineral of saponite type and metastable hematite. Saponite is likely stabilized by the presence of Al, whereas hematite may represent a metastable product of brownmillerite carbonation. Mg-rich wüstite is involved in at least two competing reactions, i.e., oxidation into magnetite and carbonation into siderite. Results of both water-slag and water-CO2-slag experiments after 72 h are consistent with a kinetics enhancement of the former reaction when a CO2 partial pressure imposes a pH between 5 and 6. Three possible valorization routes, (1 RT carbonation prior to hydrothermal oxidation, (2 RT carbonation after hydrothermal treatment, and (3 combined HT carbonation and oxidation are discussed in light of the present results and literature data.

Die Region braucht die Kultur - die Kultur braucht die Region

OpenAIRE

Klemm, Ulrich

1995-01-01

Die Region braucht die Kultur - die Kultur braucht die Region. - In: Region in Aktion - oder: Region im Abseits? - Boxberg-Wölchingen : Eigenständige Regionalentwicklung Baden-Württemberg, 1995. - S. 25 f.

DIE GESKIEDENIS VAN DIE PERSONEELFUNKSIE IN DIE SA ...

African Journals Online (AJOL)

stel (kortdiensstelsel). Met die uitbreek van die oorlog in 1939 het die. Unieverdedigingsmag uit 40% Staandemag en. 60% aktiewe Burgermag bestaan. Op 22 Sept. 1939 is magtiging aan die Aktiewe Burgermag- eenhede verleen om vrywilligers vir die duur van die oorlog te aanvaar. Agv beswaar dat die Verdedigingswet.

Aging degradation of cast stainless steel

International Nuclear Information System (INIS)

Chopra, O.K.; Chung, H.M.

1985-10-01

A program is being conducted to investigate the significance of in-service embrittlement of cast-duplex stainless steels under light-water reactor operating conditions. Data from room-temperature Charpy-impact tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450 0 C are presented and compared with results from other studies. Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or in reactor service have been characterized. The results indicate that at least two processes contribute to the low-temperature embrittleent of duplex stainless steels, viz., weakening of the ferrite/austenite phase boundary by carbide precipitation and embrittlement of ferrite matrix by the formation of additional phases such as G-phase, Type X, or the α' phase. Carbide precipitation has a significant effect on the onset of embrittlement of CF-8 and -8M grades of stainless steels aged at 400 or 450 0 C. The existing correlations do not accurately represent the embrittlement behavior over the temperature range 300 to 450 0 C. 18 refs., 13 figs

Effect of milling time and annealing temperature on nanoparticles evolution for 13.5% Cr ODS ferritic steel powders by joint application of XAFS and TEM

Science.gov (United States)

He, P.; Hoffmann, J.; Möslang, A.

2018-04-01

The characteristics of strengthening nanoparticles have a major influence on the mechanical property and irradiation resistance of oxide dispersion strengthened (ODS) steels. To determine how to control nanoparticles evolution, 0.3% Ti with 0.3% Y2O3 were added in 13.5%Cr pre-alloyed steel powders via different milling and consolidation conditions, then characterized by transmission electron microscopy (TEM) and X-ray absorption fine structure (XAFS) at synchrotron irradiation facility. The dissolution of Y2O3 is greatly dependent on the milling time at fixed milling speeds. After 24 h of milling, only minor amounts of the initially added Y2O3 dissolve into the steel matrix whereas TEM results reveal nearly complete dissolution of Y2O3 in 80-h-milled powder. The annealed powder FT-A800 (at 800 °C for 1 h) exhibits a structure near to the initially added Y2O3. The slightly deviation may be accounted for considerable lattice distortion related to the presence of atomic vacancies or formation of Y-Ti-O nucleus. The annealed powders FT-A1000 and FT-A1100 contain complex mixtures of Y-O/Y-Ti-O oxides, which cannot be fitted by any single thermally stable compounds. The coordination numbers of these first two shells in the annealed powders significantly raise as a function of the annealing temperature, indicating the formation of more ordered Y-O or Y-Ti-O particles. The extended X-ray absorption fine structure (EXAFS) spectrum could not necessarily distinguish the dominant oxide species.

Die Parlamentswahlen 2008 in Malaysia

DEFF Research Database (Denmark)

Reher, Stefanie; Knirsch, Thomas

2008-01-01

aus diversen Parteien bestehende Oppositionsbündnis erfuhr überraschend eine klare Stärkung. Während die aus der UMNO und 13 weiteren Koalitionären bestehende BN unter dem Motto „Sicherheit, Frieden, Wohlstand” für Premier Badawi warb, führten die Oppositionsparteien DAP, PAS und PRK – letztere unter...

Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific and Design Methodology

Energy Technology Data Exchange (ETDEWEB)

Pankiw, Roman I; Muralidharan, G. (Murali); Sikka, Vinod K.

2006-06-30

The goal of this project was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and the upper use temperature by 86 to 140 degrees fahrenheit (30 to 60 degrees celsius). Meeting this goal is expected to result in energy savings of 35 trillion Btu/year by 2020 and energy cost savings of approximately $230 million/year. The higher-strength H-Series cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat treating industry, including radiant burner tubes. The project was led by Duraloy Technologies, Inc., with research participation by Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies.

Evaluation of the Effect of Different Plasma-Nitriding Parameters on the Properties of Low-Alloy Steel

Science.gov (United States)

Zdravecká, Eva; Slota, Ján; Solfronk, Pavel; Kolnerová, Michaela

2017-07-01

This work is concerned with the surface treatment (ion nitriding) of different plasma-nitriding parameters on the characteristics of DIN 1.8519 low-alloy steel. The samples were nitrided from 500 to 570 °C for 5-40 h using a constant 25% N2-75% H2 gaseous mixture. Lower temperature (500-520 °C) favors the formation of compound layers of γ' and ɛ iron nitrides in the surface layers, whereas a monophase γ'-Fe4 N layer can be obtained at a higher temperature. The hardness of this layer can be obtained when nitriding is performed at a higher temperature, and the hardness decreases when the temperature increases to 570 °C. These results indicate that pulsed plasma nitriding is highly efficient at 550 °C and can form thick and hard nitrided layers with satisfactory mechanical properties. The results show the optimized nitriding process at 540 °C for 20 h. This process can be an interesting means of enhancing the surface hardness of tool steels to forge dies compared to stamped steels with zinc coating with a reduced coefficient of friction and improving the anti-sticking properties of the tool surface.

DEVELOPMENT OF THE DOPING MATRIX FOR CREATION OF THE BELORUSSIAN INSTRUMENTAL STEELS ON THE BASIS OF STEEL 70K(Y7A PRODUCED BY RUP “BMZ” (view and investigation

Directory of Open Access Journals (Sweden)

D. M. Kukuj

2004-01-01

Full Text Available Theoretical and practical aspects of production of the Belorussian instrumental steels on the base of the steel of type 70K are considered. The ways of working out of the alloy complex for receiving of the die steels in the conditions of RUP “BMZ” are shown.

Influence of the supporting die structures on the fracture strength of all-ceramic materials.

Science.gov (United States)

Yucel, Munir Tolga; Yondem, Isa; Aykent, Filiz; Eraslan, Oğuz

2012-08-01

This study investigated the influence of the elastic modulus of supporting dies on the fracture strengths of all-ceramic materials used in dental crowns. Four different types of supporting die materials (dentin, epoxy resin, brass, and stainless steel) (24 per group) were prepared using a milling machine to simulate a mandibular molar all-ceramic core preparation. A total number of 96 zirconia cores were fabricated using a CAD/CAM system. The specimens were divided into two groups. In the first group, cores were cemented to substructures using a dual-cure resin cement. In the second group, cores were not cemented to the supporting dies. The specimens were loaded using a universal testing machine at a crosshead speed of 0.5 mm/min until fracture occurred. Data were statistically analyzed using two-way analysis of variance and Tukey HSD tests (α = 0.05). The geometric models of cores and supporting die materials were developed using finite element method to obtain the stress distribution of the forces. Cemented groups showed statistically higher fracture strength values than non-cemented groups. While ceramic cores on stainless steel dies showed the highest fracture strength values, ceramic cores on dentin dies showed the lowest fracture strength values among the groups. The elastic modulus of the supporting die structure is a significant factor in determining the fracture resistance of all-ceramic crowns. Using supporting die structures that have a low elastic modulus may be suitable for fracture strength tests, in order to accurately reflect clinical conditions.

Development of scientific and technological basis for the fabrication of thin film solar cells on the basis of a-Si:H and {mu}c-Si:H using the 'hot-wire' deposition technique. Final report; Entwicklung wissenschaftlicher und technischer Grundlagen fuer die Herstellung von Duennschichtsolarzellen auf der Basis des a-Si:H und {mu}c-Si:H mit der 'Hot-Wire'-Depositionstechnik. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Schroeder, B.

2002-01-22

Two new deposition systems were realized enabling the entire and respectively, large area deposition of a-Si:H based solar cells using the so called 'hot-wire' (HW) CVD. The deposition conditions for appropriate n- and p-doped a-Si:H and {mu}c-Si:H layers have been developed. For the first time in the world a-Si:H based pin solar cells were entirely deposited by the HWCVD method. A maximum initial conversion efficiency of {eta}{sub initial}=8.9% was obtained. After the development of a suitable p/n-tunnel/recombination junction pin-pin tandem structures with a-Si:H absorbers could be entirely fabricated by the HWCVD for the first time in the world, too. A conversion efficiency of {eta}=7% was measured for the tandem cell, after some structural degradation took place. In general, the stability of the HWCVD solar cells is not satisfactory, what could be attributed to a structural instability of the HWCVD-p-layers. For the first time we have deposited nip solar cells on stainless steel substrates entirely by HWCVD ({eta}{sub initial}>6%). The incorporation of {mu}c-Si:H absorber layers by HWCVD or ECWR-PECVD into pin solar cells was not successfull until now. Large area deposition of a-Si:H films has been performed in a simple vacuum vessel. Under consideration of appropriate filament and gas supply geometry as well as simulation calculations a good electronic quality and a film thickness uniformity of {delta}d={+-}2.5% of the material was obtained. i-layers for small area solar cells on an area of 20 x 20 cm{sup 2} have been deposited which could be completed to solar cells with very uniform conversion efficiencies of {eta}{sub initial} = 6,1{+-}0.2%. This result represents a proof of concept for the large area deposition of a-Si:H based solar cells using the HWCVD. Also for the first time the HWCVD was used for the deposition of emitter layers on c-Si-wafers to realize hetero solar cells. Hetero solar cells with amorphous, microcrystalline and epitaxial n

Smart Surfaces and Interfaces

Science.gov (United States)

2010-08-01

the piezoelecric thin film sensor is placed between the top tribological coating system and bottom of ferritic nirocarburized H13 die substrate to...11 Electrical Resistivity (Ω.cm) 109 1011- 1016 108 1011 Note: CTE  (10-6 K-1): 13 for H13 steel, 6 for Al2O3, 6.5 for TiAlN, and 10.1 for Ti...In contrary, at lower working pressures, collision frequency of ions is much lower and ions with high energy will impact the substrate introducing

Properties of 13HMF steel for steam pipelines as a result of impact and cracking resistance investigations; Wlasnosci stali 13HMF na rurociagi pary swiezej w swietle badan udarnosci i odpornosci na pekanie

Energy Technology Data Exchange (ETDEWEB)

Bilous, W.; Wasiak, J.; Hajewska, E.; Szteke, W.; Wagner, T. [Institute of Atomic Energy, Otwock-Swierk (Poland)

1996-12-31

Long lasting and safe exploitation of steam pipelines in energetics depends strongly on mechanical properties of material used for tubing production. Most of pipelines installed in polish energetics is made of Cr-Mo-V type steel. The investigation results of such steel (13MHF) concerning the influence of exploitation time on impact and cracking resistance have been presented, discussed and compared with the imported steel P91. 3 refs, 7 figs, 3 tabs.

Simultaneous visualization of pH and Cl"− distributions inside the crevice of stainless steel

International Nuclear Information System (INIS)

Nishimoto, Masashi; Ogawa, Junichiro; Muto, Izumi; Sugawara, Yu; Hara, Nobuyoshi

2016-01-01

Highlights: • A pH and Cl"− sensing plate was fabricated. • The pH and Cl"− distributions inside the crevice of stainless steel was visualized. • The initial morphology of crevice corrosion of stainless steel was pitting. • Gradual acidification and Cl"− accumulation occurred before pit initiation. • The generation of pit caused a sharp decrease in pH and an increase in Cl"− concentration. - Abstract: A sensing plate for the simultaneous measurements of pH and Cl"− concentration was fabricated. Terbium–dipicolinic acid complex (Tb–DPA) and quinine sulphate were used to measure the pH and Cl"− concentration, respectively. In the incubation period of the crevice corrosion, the pH inside the crevice gradually decreased from 3.0 to ca. 2.0, and the Cl"− concentration increases from 0.01 to ca. 0.18 M. The generation of the micro-pit led to a sharp decrease in pH to below 0.5 and an increase in the Cl"− concentration to above 4 M. This situation allowed the crevice corrosion to proceed without spontaneously stopping.

Phyllanthus muellerianus and C6H15NO3 synergistic effects on 0.5 M H2SO4-immersed steel-reinforced concrete: Implication for clean corrosion-protection of wind energy structures in industrial environment

Science.gov (United States)

Okeniyi, Joshua Olusegun; Omotosho, Olugbenga Adeshola; Popoola, Abimbola Patricia Idowu; Loto, Cleophas Akintoye

2016-07-01

This paper investigates Phyllanthus muellerianus leaf-extract and C6H15NO3 (triethanolamine: TEA) synergistic effects on reinforcing-steel corrosion-inhibition and the compressive-strength of steel-reinforced concrete immersed in 0.5 M H2SO4. This is to assess suitability of the synergistic admixture usage for wind-energy steel-reinforced concrete structures designed for industrial environments. Steel-reinforced concrete specimens were admixed with individual and synergistic designs of Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures and immersed in the 0.5 M H2SO4. Electrochemical monitoring of corrosion potential, as per ASTM C876-91 R99, and corrosion current were obtained and statistically analysed, as per ASTM G16-95 R04, for modelling noise resistance. Post-immersion compressive-strength testing then followed, as per ASTM C39/C39M-03, for detailing the admixture effect on load-bearing strength of the steel-reinforced concrete specimens. Results showed that while individual Phyllanthus muellerianus leaf-extract concentrations exhibited better inhibition-efficiency performance than C6H15NO3, synergistic additions of C6H15NO3 to Phyllanthus muellerianus leaf-extract improved steel-rebar corrosion-inhibition. Thus, 6 g Phyllanthus muellerianus + 2 g C6H15NO3 synergistically improved inhibition-efficiency to η = 84.17%, from η = 55.28% by the optimal chemical or from η = 74.72% by the optimal plant-extract admixtures. The study also established that improved compressive strength of steel-reinforced concrete with acceptable inhibition of the steel-rebar corrosion could be attained through optimal combination of the Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures.

‘Op de wijze van Kavafis’: Die voorbeeld van die digter uit Alexandrië

Directory of Open Access Journals (Sweden)

Phil van Schalkwyk

2014-12-01

Full Text Available Die Griekse digter K.P. Kavafis (1863–1933 word wêreldwyd deur lesers sowel as skrywers besonder hoog geag. Hy het nie net van die grootste twintigste-eeuse skrywers beïnvloed nie,maar is vanweë die buitengewone vertaalbaarheid van sy werk ook betreklik sterk teenwoordig in die letterkunde van meer tale as slegs Grieks en Engels. Vir baie – veral gay lesers, skrywers en kunstenaars – besit Kavafis ’n voorbeeldstatus, ten opsigte van die letterkunde sowel asdie lewe. W.H. Auden het beweer dat dit wat Kavafis onderskei, sy stemtoon is, een wat ’n persoon met ’n unieke perspektief op die wêreld openbaar. Hierdie bydrae, wat deel is van ’nnavorsingsprojek oor idiolektiese skrywersidentiteit, is daarop gerig om die onderskeidende kenmerke van Kavafis se werk, sowel in terme van vorm as inhoud, opnuut te ondersoek. Dit word gedoen binne die raamwerk van die breë kritiese diskoers oor Kavafis en met verwysing na enkele manifestasies/voorbeelde van Nederlandse en Afrikaanse kritiese en kreatieweperspektiewe op sy poësie, met die doel om spesifiek lig te werp op die besondere soortwysheid wat in Kavafis se werk oorgedra word.

Die Kardiomyopathie in der Friedreich-Ataxie

OpenAIRE

Reichert [geb. Florescu], Christiane Katharina

2018-01-01

Die Friedreich-Ataxie ist eine autosomal-rezessiv vererbte neurodegenerative Erkrankung, die sich meistens vor dem 20. Lebensjahr manifestiert. Der Erkrankung liegt eine GAA-Trinukleotid-Expansion im FXN-Gen (Chromosom 9q13) zu Grunde. Diese Mutation führt zu einer verminderten Bildung von Frataxin, wodurch es zur Eisenanreicherung in den Mitochondrien kommt. Diese Eisenakkumulation führt zu oxidativem Stress und mitochondrialer Dysfunktion, die sich vor allem in Gewebe mit einem hohen An...

Die posisie van die Helper in die sending

Directory of Open Access Journals (Sweden)

I. J. van der Walt

1972-05-01

Full Text Available Gedurende die aanvangsjare van die sending het die helper ’n onmisbare funksie vervul. Hulle het die onherbergsame binnelande geken, waardevolle kontakpunte vir die sendelinge geopen en hulle mense geestelik help voorlig en voorberei.

Study on the Surface Microstructure of a Modified STD61 Steel Mold Used for the Die Casting Process

Energy Technology Data Exchange (ETDEWEB)

Yu, Ha-Young; Lee, Seung-Joon; Kang, Minwoo; Lee, Suk-Jin; Lee, Young-Kook [Yonsei University, Seoul (Korea, Republic of); Yang, Won Jon [Korea Institute of Materials Science, Changwon (Korea, Republic of); Jeong, Jae Suk; Kim, Byung-Hoon [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

2016-09-15

The surface microstructure and crack formation of an aluminum die-casting mold were investigated. The mold was made of a modified STD61 steel, and was used for more than 165,000 cycles. The mold surface consisted of four layers; an oxidized layer, a decarburized layer, a network carbide layer and a tempered martensite matrix. The depth down to the hardest network carbide layer was ⁓200 μm. Inside the matrix, M{sub 3}C transition carbides were dissolved so that solute C joined pre-existing M{sub 2}3C{sub 6} and MC carbides to make them coarse. About 60% of thermal fatigue cracks had a depth less than 200 μm due to the hard network carbide layer, which obstructed the propagation of cracks. Cracks of over 200 μm were filled with oxide wedges of Al and Si which was which flown from the molten alloy as well as the Fe oxide.

Quantified pH imaging with hyperpolarized (13) C-bicarbonate.

Science.gov (United States)

Scholz, David Johannes; Janich, Martin A; Köllisch, Ulrich; Schulte, Rolf F; Ardenkjaer-Larsen, Jan H; Frank, Annette; Haase, Axel; Schwaiger, Markus; Menzel, Marion I

2015-06-01

Because pH plays a crucial role in several diseases, it is desirable to measure pH in vivo noninvasively and in a spatially localized manner. Spatial maps of pH were quantified in vitro, with a focus on method-based errors, and applied in vivo. In vitro and in vivo (13) C mapping were performed for various flip angles for bicarbonate (BiC) and CO2 with spectral-spatial excitation and spiral readout in healthy Lewis rats in five slices. Acute subcutaneous sterile inflammation was induced with Concanavalin A in the right leg of Buffalo rats. pH and proton images were measured 2 h after induction. After optimizing the signal to noise ratio of the hyperpolarized (13) C-bicarbonate, error estimation of the spectral-spatial excited spectrum reveals that the method covers the biologically relevant pH range of 6 to 8 with low pH error (< 0.2). Quantification of pH maps shows negligible impact of the residual bicarbonate signal. pH maps reflect the induction of acute metabolic alkalosis. Inflamed, infected regions exhibit lower pH. Hyperpolarized (13) C-bicarbonate pH mapping was shown to be sensitive in the biologically relevant pH range. The mapping of pH was applied to healthy in vivo organs and interpreted within inflammation and acute metabolic alkalosis models. © 2014 Wiley Periodicals, Inc.

Influence of traps on the deuterium behaviour in the low activation martensitic steels F82H and Batman

International Nuclear Information System (INIS)

Serra, E.

1997-01-01

A time dependent permeation method is used to measure the permeability, diffusivity and solubility of deuterium in the low activation martensitic steels F82H and Batman. The measurements cover the temperature range from 373 to 743 K which includes the onset of deuterium trapping effects on diffusivity and solubility. The results are interpreted using a trapping model. The number of trap sites and their average energies for deuterium in F82H and Batman steels are determined. (orig.)

Influence of traps on the deuterium behaviour in the low activation martensitic steels F82H and Batman

Science.gov (United States)

Serra, E.; Perujo, A.; Benamati, G.

1997-06-01

A time dependent permeation method is used to measure the permeability, diffusivity and solubility of deuterium in the low activation martensitic steels F82H and Batman. The measurements cover the temperature range from 373 to 743 K which includes the onset of deuterium trapping effects on diffusivity and solubility. The results are interpreted using a trapping model. The number of trap sites and their average energies for deuterium in F82H and Batman steels are determined.

The electrochemical behaviour of stainless steel AISI 304 in alkaline solutions with different pH in the presence of chlorides

International Nuclear Information System (INIS)

Freire, L.; Carmezim, M.J.; Ferreira, M.G.S.; Montemor, M.F.

2011-01-01

Highlights: → The passivation and passivation breakdown of AISI 304 in alkaline solutions with different pH was studied. → The electrochemical behaviour and the corrosion resistance in chloride environments were evaluated using d.c. potentiodynamic polarization and electrochemical impedance spectroscopy. → The results were modelled using a hierarchically distributed circuit and revealed a more susceptible surface at pH 9. → The passive film characterization was carried out by SEM and EDS analysis, revealing the existence of MnS inclusions and the increase of Cr/Fe ratio in the attacked areas, preferably the vicinity of those inclusions. - Abstract: Nowadays, stainless steel reinforcements appear as an effective solution to increase the durability of reinforced concrete structures exposed to very aggressive environments. AISI 304 is widely used for this purpose. Although the improved durability of reinforcing AISI 304, when compared to carbon steel, there is a high probability of pitting susceptibility in the presence of chlorides. Thus, the present work aims at studying the passivation and passivation breakdown of AISI 304 in alkaline solutions of different pH (pH from 13 to 9), simulating the interstitial concrete electrolyte. These solutions were contaminated with different concentrations of chloride ions (3% and 10%, as NaCl). The electrochemical behaviour was evaluated by d.c. potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The morphological features and the changes observed in the surface composition were evaluated by Scanning Electron Microscopy (SEM) together with EDS chemical analysis. The results evidence that pH plays an important role in the evolution of the film resistance and charge transfer processes. Moreover, the effect is highly dependent upon the chloride content and immersion time.

Corrosion of carbon steel and low-alloy steel in diluted seawater containing hydrazine under gamma-rays irradiation

International Nuclear Information System (INIS)

Nakano, Junichi; Yamamoto, Masahiro; Tsukada, Takashi

2014-01-01

Seawater was injected into reactor cores of Units 1, 2, and 3 in the Fukushima Daiichi nuclear power station as an urgent coolant. It is considered that the injected seawater causes corrosion of steels of the reactor pressure vessel and primary containment vessel. To investigate the effects of gamma-rays irradiation on weight loss in carbon steel and low-alloy steel, corrosion tests were performed in diluted seawater at 50°C under gamma-rays irradiation. Specimens were irradiated with dose rates of 4.4 kGy/h and 0.2 kGy/h. To evaluate the effects of hydrazine (N 2 H 4 ) on the reduction of oxygen and hydrogen peroxide, N 2 H 4 was added to the diluted seawater. In the diluted seawater without N 2 H 4 , weight loss in the steels irradiated with 0.2 kGy/h was similar to that in the unirradiated steels, and weight loss in the steels irradiated with 4.4 kGy/h increased to approximate 1.7 times of those in the unirradiated steels. Weight loss in the steels irradiated in the diluted seawater containing N 2 H 4 was similar to that in the diluted seawater without N 2 H 4 . When N 2 was introduced into the gas phase in the flasks during gamma-rays irradiation, weight loss in the steels decreased. (author)

Effect of 0.2 and 0.5% Ti on the microstructure and mechanical properties of 13Cr supermartensitic stainless steel

Science.gov (United States)

Lian, Yong; Huang, Jinfeng; Zhang, Jin; Zhang, Cheng; Gao, Wen; Zhao, Chao

2015-11-01

The effect that a 0, 0.2, and 0.5 wt.% titanium content has on the microstructure and mechanical properties of 13Cr supermartensitic stainless steel was investigated using an optical microscope, transmission electron microscope, and X-ray diffraction. The resultant microstructures of the three steels were tempered martensite with a reversed austenite dispersed throughout the matrix. Additionally, the formation of Cr-rich carbides was suppressed by stable Ti(C, N), which improved the strength without severely decreasing in the Ti-microalloyed steel toughness. Nano-precipitation of Ni3Ti was found for the 0.5 wt.% Ti steel during tempering, which significantly increased the strength, but decreased the toughness. The reversed austenite volume fraction also significantly influenced the mechanical properties.

die ontstaan en die ontwikkeling van die skoolkadette-stelsel in die rsa

African Journals Online (AJOL)

toe algemene diensplig ingestel is. Die diens- plig het intussen sy volle beslag gekry en in. Weermagkringe het die gedagte posgevat dat skoolkadette. 'n deeglike ondersoek vereis ten einde die skoolgaande seun vir sy komende nasionale diensplig te orienteer. Tydens kadetopleldlng leer die seuns al die fynere kunsles ...

Study of corrosion resistance properties of nitrided carbon steel using radiofrequency N{sub 2}/H{sub 2} cold plasma process

Energy Technology Data Exchange (ETDEWEB)

Bouanis, F.Z. [Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Jama, C., E-mail: charafeddine.jama@ensc-lille.f [Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Traisnel, M. [Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Bentiss, F. [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco)

2010-10-15

C38 carbon steel have been plasma-nitrided using a radiofrequency cold plasma discharge treatment in order to investigate the influence of gas composition on corrosion behaviour of nitrided substrates. The investigated C38 steel was nitrided by a RF plasma discharge treatment using two different gas mixtures (75% N{sub 2}/25% H{sub 2} and 25% N{sub 2}/75% H{sub 2}) at different times of plasma-treatment on non-heated substrates. Electron Probe Microanalysis (EPMA) showed that the nitrided layer formed using 75% N{sub 2}/25% H{sub 2} gas mixture was thicker compared to those formed in the case of 25% N{sub 2}/75% H{sub 2} or pure N{sub 2}. The modifications of the corrosion resistance characteristics of plasma-nitrided C38 steel in 1 M HCl solution were investigated by weight loss measurements and ac impedance technique. The results obtained from these two evaluation methods were in good agreement. It was shown that the nitriding treatment in both cases (75% N{sub 2}/25% H{sub 2} and 25% N{sub 2}/75% H{sub 2}) improves the corrosion resistance of investigated carbon steel, while the better performance is obtained for the 75% N{sub 2}/25% H{sub 2} gas mixture. X-ray photoelectron spectroscopy (XPS) was carried out before and after immersion in corrosive medium in order to establish the mechanism of corrosion inhibition using N{sub 2}/H{sub 2} cold plasma nitriding process.

pH effect on pit potential and protection potential of stainless steels AISI-304, 310 and 316 in NaCl solution

International Nuclear Information System (INIS)

Cabral, U.Q.; Sathler, L.; Mariano Neto, F.

1973-06-01

For three austenitic stainless steels, AISI 304, 310 and 316, the pH influence on the rupture, protection and corrosion potentials was studied in a 0,5N NACl solution. The pit potentials determined by the chronogalvonometric method, are pH independent within the acid range. They showed a rough linear variation within the basic range having a maximum corresponding to the pH value of 8.8. The electrochemical hysteresis method, employed for determining the protection potential, presented a total pH independence for the AISI 316. The other steels showed a small dependence within the basic range but with a tendency for the protection potential to become slightly more active with increasing pH, within the acid range. It was also noted for the three steels studied that the corrosion potental became more active with increasing pH, within the basic range [pt

A Study on the Corrosion Behavior of Carbon Steel Exposed to a H2S-Containing NH4Cl Medium

Science.gov (United States)

Wang, Hai-bo; Li, Yun; Cheng, Guang-xu; Wu, Wei; Zhang, Yao-heng

2018-04-01

NH4Cl corrosion failure often occurs in the overhead systems of hydrotreaters, and this failure is always accompanied by the appearance of H2S. A combination of electrochemical and surface spectroscopic (SEM/EDS, AFM, XRD) techniques was used to investigate the effect of different factors, including the surface roughness, temperature, dissolved oxygen, pH and H2S concentration, on the corrosion behavior of carbon steel in an NH4Cl environment with the presence of H2S. The effect of H2S concentrations (at the ppm level) on the corrosion behavior of carbon steel was systematically revealed. The experimental results clearly indicated that the corrosion rate reached a minimum value at 10 ppm H2S. The steel surface was covered by a uniform corrosion product film in a 10 ppm H2S environment, and the corrosion product film was tight and protective. The ammonia from NH4Cl helped maintaining the protectiveness of the corrosion films in this environment. Dissolved oxygen mainly accelerated the cathodic reaction. The cathodic limiting current density increased with increasing temperature, and the anodic branch polarization curves were similar at different temperatures. The anodic current density decreased as the pH decreased, and the cathodic current density increased as the pH decreased. The absolute surface roughness (R a) of carbon steel increased from 132.856 nm at 72 h to 153.973 nm at 144 h, and the rougher surface resulted in a higher corrosion rate. The critical innovation in this research was that multiple influential factors were revealed in the NH4Cl environment with the presence of H2S.

A Study on the Corrosion Behavior of Carbon Steel Exposed to a H2S-Containing NH4Cl Medium

Science.gov (United States)

Wang, Hai-bo; Li, Yun; Cheng, Guang-xu; Wu, Wei; Zhang, Yao-heng

2018-05-01

NH4Cl corrosion failure often occurs in the overhead systems of hydrotreaters, and this failure is always accompanied by the appearance of H2S. A combination of electrochemical and surface spectroscopic (SEM/EDS, AFM, XRD) techniques was used to investigate the effect of different factors, including the surface roughness, temperature, dissolved oxygen, pH and H2S concentration, on the corrosion behavior of carbon steel in an NH4Cl environment with the presence of H2S. The effect of H2S concentrations (at the ppm level) on the corrosion behavior of carbon steel was systematically revealed. The experimental results clearly indicated that the corrosion rate reached a minimum value at 10 ppm H2S. The steel surface was covered by a uniform corrosion product film in a 10 ppm H2S environment, and the corrosion product film was tight and protective. The ammonia from NH4Cl helped maintaining the protectiveness of the corrosion films in this environment. Dissolved oxygen mainly accelerated the cathodic reaction. The cathodic limiting current density increased with increasing temperature, and the anodic branch polarization curves were similar at different temperatures. The anodic current density decreased as the pH decreased, and the cathodic current density increased as the pH decreased. The absolute surface roughness ( R a) of carbon steel increased from 132.856 nm at 72 h to 153.973 nm at 144 h, and the rougher surface resulted in a higher corrosion rate. The critical innovation in this research was that multiple influential factors were revealed in the NH4Cl environment with the presence of H2S.

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

Science.gov (United States)

Bellanger, G.; Rameau, J. J.

1996-02-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive -transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique.

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

Energy Technology Data Exchange (ETDEWEB)

Bellanger, G. [CEA Centre d`Etudes de Valduc, 21 - Is-sur-Tille (France); Rameau, J.J. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Saint-Martin-d`Heres (France)

1996-02-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive-transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique. (orig.).

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

International Nuclear Information System (INIS)

Bellanger, G.; Rameau, J.J.

1996-01-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive-transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique. (orig.)

Reformed austenite transformation during fatigue crack propagation of 13%Cr-4%Ni stainless steel

Energy Technology Data Exchange (ETDEWEB)

Thibault, Denis, E-mail: thibault.denis@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Bocher, Philippe, E-mail: philippe.bocher@etsmtl.ca [Ecole de technologie superieure, 1100, rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3 (Canada); Thomas, Marc, E-mail: marc.thomas@etsmtl.ca [Ecole de technologie superieure, 1100, rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3 (Canada); Lanteigne, Jacques, E-mail: lanteigne.jacques@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Hovington, Pierre, E-mail: hovington.pierre@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Robichaud, Patrice, E-mail: patrice.robichaud@riotinto.com [Centre de recherche et de developpement Arvida (CRDA), 1955, boul. Mellon, Jonquiere, Quebec, G7S 4K8 (Canada)

2011-08-15

Highlights: {yields} Reformed austenite in 13%Cr-4%Ni stainless steel transforms during fatigue crack growth. {yields} Low cycle fatigue tests showed that this transformation to martensite is gradual. {yields} XRD spectrums obtained on the fracture surface and have been correlated to LCF results. - Abstract: In the as-quenched state, 13%Cr-4%Ni martensitic stainless steels are essentially 100% martensitic. However, a certain amount of austenite is formed during the tempering of this alloy. This reformed austenite is thermally stable at room temperature but can transform to martensite under stress. This transformation is known to happen during impact testing but it has never been established if it occurs during fatigue crack propagation. This study presents the results of X-ray diffraction measurements of reformed austenite before and after crack growth testing. It has been found that reformed austenite does transform to martensite at the crack tip and that this transformation occurs even at a low stress intensity factor. Low-cycle fatigue tests were conducted to verify austenite transformation under cyclic straining. It was found that reformed austenite transforms only partially during the first strain reversal but that essentially all austenite has disappeared after 100 cycles. The relation between austenite transformation under low-cycle fatigue and its transformation during crack growth is also discussed.

Reformed austenite transformation during fatigue crack propagation of 13%Cr-4%Ni stainless steel

International Nuclear Information System (INIS)

Thibault, Denis; Bocher, Philippe; Thomas, Marc; Lanteigne, Jacques; Hovington, Pierre; Robichaud, Patrice

2011-01-01

Highlights: → Reformed austenite in 13%Cr-4%Ni stainless steel transforms during fatigue crack growth. → Low cycle fatigue tests showed that this transformation to martensite is gradual. → XRD spectrums obtained on the fracture surface and have been correlated to LCF results. - Abstract: In the as-quenched state, 13%Cr-4%Ni martensitic stainless steels are essentially 100% martensitic. However, a certain amount of austenite is formed during the tempering of this alloy. This reformed austenite is thermally stable at room temperature but can transform to martensite under stress. This transformation is known to happen during impact testing but it has never been established if it occurs during fatigue crack propagation. This study presents the results of X-ray diffraction measurements of reformed austenite before and after crack growth testing. It has been found that reformed austenite does transform to martensite at the crack tip and that this transformation occurs even at a low stress intensity factor. Low-cycle fatigue tests were conducted to verify austenite transformation under cyclic straining. It was found that reformed austenite transforms only partially during the first strain reversal but that essentially all austenite has disappeared after 100 cycles. The relation between austenite transformation under low-cycle fatigue and its transformation during crack growth is also discussed.

Reinforcement steel corrosion in passive state and by carbonation: Consideration of galvanic currents and interface steel - concrete defaults

International Nuclear Information System (INIS)

Nasser, A.

2010-01-01

This thesis aims to study the durability of nuclear waste deep storage structures. The work carried out is essentially an experimental study, and focuses on the corrosion of steel in the passive state with aerated or non-aerated conditions on the one hand, and the corrosion of steel in carbonated concrete during the propagation phase on the other hand. Indeed, the pore solution of concrete in contact with the metal is alkaline (pH between 12 and 13). Under these conditions, steel reinforced concrete remains passive by forming a stable and protective oxide layer (corrosion of steel in the passive state). This passive layer limits the steel corrosion rate at very low values (negligible on a short life time) but not null. For the nuclear waste storage structures due to a very long life time (up to several hundred years), this low corrosion rate can become a risk. Therefore, it is necessary to study the evolution of the oxide layer growth over time. The objectives of the thesis are to study the influence of the steel-concrete interface quality on reinforcement corrosion in passive and active state, and the possible occurrence of galvanic corrosion currents between different reinforcement steel areas. (author)

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Ho

1994-02-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H 2 O 2 played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively

Microstructure and mechanical properties of annealed SUS 304H austenitic stainless steel with copper

Energy Technology Data Exchange (ETDEWEB)

Sen, Indrani [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Amankwah, E. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Department of Materials Science, African University of Science and Technology, Abuja (Nigeria); Kumar, N.S. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Fleury, E. [Center for High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Oh-ishi, K.; Hono, K. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Ramamurty, U., E-mail: ramu@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India)

2011-05-25

Research highlights: {yields} SUS 304H austenitic stainless steel containing 3 wt.% Cu was annealed at 700 deg. C for up to 100 h. {yields} Microstructure and mechanical properties of annealed alloys are examined. {yields} Nano-sized Cu-rich precipitation upon annealing. {yields} Strength of the alloy remains invariant with annealing whereas ductility improves. {yields} Fatigue crack growth threshold of 3 wt.% Cu added alloy increases with annealing. - Abstract: An experimental investigation into the effect of Cu on the mechanical properties of 0 and 3 wt.% Cu added SUS 304H austenitic stainless steel upon annealing at 700 deg. C for up to 100 h was conducted. Optical microscopy reveals grain coarsening in both the alloys upon annealing. Observations by transmission electron microscopy revealed the precipitation of nanometer-sized spherical Cu particles distributed within the austenitic grains and the presence of carbides at the dislocations. Both the yield and ultimate tensile strengths of the alloys were found to remain invariant with annealing. Tensile ductility and the threshold stress intensity factor range for fatigue crack growth for 3 wt.% Cu added alloy increase with annealing. These are attributed to the grain coarsening with annealing. In all, the addition of Cu to SUS 304H does not affect the mechanical performance adversely while improving creep resistance.

Die funksie van die skeppingstradisie in die boek Jeremia

African Journals Online (AJOL)

gedeeites voor wat sterk ooreenkomste toon met die beskrywings van die skep pingsgebeure in die boek Jeremia. • Volgpns Von Rad (1957:144-146) het daar wel 'n groep bestaan wat belange ge- had liet by die oorlewering van die skeppingstradisies. Dit was waarskynlik die. Sadokitiese priesters wat om twee redes aan ...

Die binding van die konfessie

Directory of Open Access Journals (Sweden)

P. J. Coetzee

1970-05-01

Full Text Available Ons moet waak teen twee uiterstes. Aan die een kant het die dogma as onversoenlike vyand die dogmatisme en aan die ander kant die antidogmatisme — dit hou enersyds die gevaar in van verabsolutering (oorskatting, en ander- syds die gevaar van relativisme (onderskatting.

Joining of cemented carbides to steel by laser beam welding

Energy Technology Data Exchange (ETDEWEB)

Barbatti, C.; Garcia, J.; Pyzalla, A. [Max-Planck-Institut fuer Eisenforschung GmbH, 40237 Duesseldorf (Germany); Liedl, G. [TU Wien, Institut fuer Umform- und Hochleistungslasertechnik (IFLT), 1040 Vienna (Austria)

2007-11-15

Welding of dissimilar materials such as steel and cemented carbides (hardmetals, cermets) is particularly challenging e.g. because mismatches in their thermal expansion coefficients and thermal conductivities result in residual stress formation and because of the formation of brittle intermetallic phases. Laser beam welding of cemented carbides to steel appears as an attractive complementary technique to conventional brazing processes due to its high precision, high process speed, low heat input and the option of welding without filler. Here a laser welding process including pre-heat treatment and post-heat treatment was applied successfully to joining as-sintered and nitrided hardmetals and cermets to low alloyed steel. The microstructure and mechanical properties of the welds are investigated by microscopy, X-ray diffraction, microhardness measurements, and bending tests. The results reveal that the three-step laser beam welding process produced crack-free and non-porous joints. Nitridation of the cemented carbides results in a significant reduction of the amount of brittle intermetallic phases. The mechanical properties of the joints are competitive to those of the conventional brazed steel-cemented carbide joints. (Abstract Copyright [2007], Wiley Periodicals, Inc.) [German] Das Schweissen von ungleichartigen Werkstoffen wie z. B. Staehlen mit Hartmetallen und Cermets stellt eine erhebliche Herausforderung dar, u. a. infolge der unterschiedlichen thermischen Ausdehnungskoeffizienten und Waermeleitfaehigkeiten, welche die Bildung von Eigenspannungen zur Folge haben, sowie aufgrund der Bildung sproeder intermetallischer Phasen. Das Laserstrahlschweissen von Hartmetallen/Cermets mit Stahl erscheint als attraktives komplementaeres Verfahren zum ueblicherweise verwendeten Loeten, da es die Herstellung von Verbindungen mit hoeherer Praezision, hoeherer Geschwindigkeit sowie geringerem Waermeeintrag erlaubt und die Verwendung eines Zusatzwerkstoffs nicht notwendig ist

Scale structure of aluminised F82H-mod. steel after HIP treatment

International Nuclear Information System (INIS)

Glasbrenner, H.; Stein-Fechner, K.; Konys, J.

2000-01-01

Coatings on low activation steels are required in fusion technology in order to reduce the tritium permeation rate through the steel into the cooling water system by a factor of at least 100. Alumina seems to be a promising coating material. However, an appropriate coating system must also have the potential for self-healing since the ceramic alumina scale tends to fail if mechanical stress is applied. A technology is introduced to form a ductile Al enriched surface scale on F82H-mod steel (Fe-7.7% Cr) and on top of it alumina. This technology consists of two main process steps. Hot dip aluminising has been performed at 700 deg. C for 30 s to the steel in order to introduce Al to the surface near zone by an easy way. The very hard intermetallic scale Fe 2 Al 5 which forms during the immersion process gets completely transformed into FeAl 2 , FeAl and α-Fe(Al) phases during a subsequent HIP process step at high pressure at 1040 deg. C and 30 min. The pressure chosen for the HIP experiment was 3000 bar. Compared to a heat treatment without superimposed high pressure pores formation due to the Kirkendall effect could be suppressed successfully. The influence of the high pressure on the heat treatment (1040 deg. C, 30 min) will be discussed in this paper

A study of enhanced diffusion during high dose high flux pulsed metal ion implantation into steel and aluminium

International Nuclear Information System (INIS)

Zhang Tonghe; Ji Chengzhou; Shen Jinghua; Chen Jun

1992-01-01

The depth profiles of metal ions implanted into steel and aluminium were measured by Rutherford backscattering (RBS). The ions of Mo, W and Y, produced by a metal vapour vacuum are ion source (MEVVA) were implanted at an energy range from 25 to 50 keV for doses of (2-5)x10 17 cm -2 into H13 steel and aluminium. Beam currents were from 0.5 to 1.0 A. The beam flux is in the range of 25 to 75 μAcm -2 . In order to simulate the profiles, a formula which includes the sputtering yield, diffusion coefficients and reaction rate was obtained. The results demonstrate that the penetration depth and retained dose increase with increasing beam flux for Mo implanted into aluminium. The peak concentration of Mo implanted H13 steel increases with increasing ion flux. In contrast to this for Y implantation into steel, the peak concentration of Y decreases with increasing ion flux. For an ion flux of 25 μAcm -2 for Mo, Y and W implantation into steel, the penetration depth and retained dose are 3-5 times greater than the theoretical values. The diffusion coefficients are about 10 -16 to 10 -15 s -1 . If the ion flux is greater than 47 μAcm -2 , the penetration depth and retained dose are 5 to 10 times greater than the theoretical values for Mo implanted aluminium. The diffusion coefficients increase with increasing ion flux for Mo implanted aluminium. The diffusion coefficients hardly change with increasing ion flux for Y and Mo implanted H13 steel. The retained dose increases 0.43 to 1.16 times for Y implanted steel for an ion flux of 25 μAcm -2 . Finally, the influence of phases precipitates, reaction rate and diffusion on retained dose, diffusion coefficient and penetration depth are discussed. (orig.)

Benefits Analysis of Past Projects. Volume 2. Individual Project Assessments.

Science.gov (United States)

1984-11-01

010 inch. Chemical milling was found to be an effective method for removing the surface enrichment. Also 4140 and H13 steel dies were found to result... tooling surface due to the reaction r,* it;nium and t . 22-4-9 steel toolin,. Oxidation and leveling .I ,.. Jevelope in this project yielded tool life...dimensions without expensive tool rework. The process has a potential for reducing mold inclusions since the mold surfaces in contact with the metal can

Effect of post-weld heat treatment and neutron irradiation on a dissimilar-metal joint between F82H steel and 316L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Fu, Haiying, E-mail: haigirl1983@gmail.com [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); Nagasaka, Takuya [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); National Institute for Fusion Science, Toki (Japan); Kometani, Nobuyuki [Nagoya University, Nagoya (Japan); Muroga, Takeo [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); National Institute for Fusion Science, Toki (Japan); Guan, Wenhai; Nogami, Shuhei; Yabuuchi, Kiyohiro; Iwata, Takuya; Hasegawa, Akira [Tohoku University, Sendai (Japan); Yamazaki, Masanori [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University (Japan); Kano, Sho; Satoh, Yuhki; Abe, Hiroaki [Institute for Materials Research, Tohoku University, Sendai (Japan); Tanigawa, Hiroyasu [Japan Atomic Energy Agency, Rokkasho (Japan)

2015-10-15

Highlights: • Significant hardening after neutron irradiation at 300 °C for 0.1 dpa was found in the fine-grain HAZ of F82H for the dissimilar-metal joint between F82H and 316L. • The possible hardening mechanism was explained from the viewpoint of carbon behavior. • However, the significant hardening did not degrade the impact property significantly. - Abstract: A dissimilar-metal joint between F82H steel and 316L stainless steel was fabricated by using electron beam welding (EBW). By microstructural analysis and hardness test, the heat-affected zone (HAZ) of F82H was classified into interlayer area, fine-grain area, and coarse-carbide area. Post-weld heat treatment (PWHT) was applied to control the hardness of HAZ. After PWHT at 680 °C for 1 h, neutron irradiation at 300 °C with a dose of 0.1 dpa was carried out for the joint in Belgian Reactor II (BR-II). Compared to the base metals (BMs) and weld metal (WM), significant irradiation hardening up to 450HV was found in the fine-grain HAZ of F82H. However, the impact property of F82H-HAZ specimens, which was machined with the root of the V-notch at HAZ of F82H, was not deteriorated obviously in spite of the significant irradiation hardening.

Die nabyheid van die Koninkryk

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W.J. Snyman

1963-03-01

Full Text Available Vanweë die belangrikheid daarvan volg hier ’n breër bespreking van die proefskrif van dr. Tjaart van der Walt oor die nabyheid van die Koninkryk as wat in ’n gewone resensie kan geskied. Die vraagstuk wat onder oë gesien word is so oud as die kerk en die teologie, soms minder en soms meer op die voorgrond. Tans kan gesê word, staan dit in die middelpunt. Daarby is dit nie maar ’n akademiese vraagstuk nie, maar ’n vraagstuk waarvoor elke nadenkende leser van die Skrif te staan kom.

Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

Directory of Open Access Journals (Sweden)

Jianbo Sun

2016-03-01

Full Text Available The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels.

Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

Science.gov (United States)

Sun, Jianbo; Sun, Chong; Lin, Xueqiang; Cheng, Xiangkun; Liu, Huifeng

2016-01-01

The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH)3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels. PMID:28773328

Mechanical and fatigue properties of martensitic 20X13 and austenitic 12X18H10T at interaction with lead nad lead-bismuth melts

International Nuclear Information System (INIS)

Yas'kiv, O.I.; Fedirko, V.M.

2013-01-01

The effect of Pb and Pb-Bi melts on mechanical properties and fatigue of Fe-13Cr and Fe-18Cr-10Ni-Ti steels in temperature interval 250...750 deg C has been investigated. It was shown that metal melts lead to increasing of strength of Fe-13Cr steel on 10...20 % as compared with vacuum and this effect increases with temperature rising. Fe-13Cr steel is prone to liquid metal embrittlement in temperature interval 350...450 deg C, particularly in Pb-Bi melt. Mechanical properties of Fe-18Cr-10Ni-Ti are not affected by metal melts. Both Pb and Pb-Bi assist in reducing of fatigue life of steels and this effect is more significant in Pb-Bi

Temperature Effects on Stainless Steel 316L Corrosion in the Environment of Sulphuric Acid (H2SO4)

Science.gov (United States)

Ayu Arwati, I. G.; Herianto Majlan, Edy; Daud, Wan Ramli Wan; Shyuan, Loh Kee; Arifin, Khuzaimah Binti; Husaini, Teuku; Alfa, Sagir; Ashidiq, Fakhruddien

2018-03-01

In its application, metal is always in contact with its environment whether air, vapor, water, and other chemicals. During contact, chemical interactions emerge between metals and their respective environments such that the metal surface corrodes. This study aims to determine the corrosion rate of 316L stainless steel sulphuric acid environment (H2SO4) with weight loss and electrochemical methods. The corrosion rate (CR) is value of 316L stainless steel by weight loss method with sulfuric acid (H2SO4) with concentration of 0.5 M. The result obtained in conjunction with the increase of temperature the rate of erosion obtained appears to be larger, with a consecutive 3 hour the temperature of 50°C is 0.27 mg/cm2h, temperature 70°C 0.38 mg/cm2h, and temperature 90 °C 0.52 mg/cm2h. With the electrochemical method, the current value increases by using a C350 potentiostal tool. The higher the current, the longer the time the corrosion rate increases, where the current is at 90 °C with a 10-minute treatment time of 0.0014736 A. The 316L stainless steel in surface metal morphology is shown by using a Scanning Electron Microscope (SEM).

Microstructural evolution in 13Cr-8Ni-2.5Mo-2Al martensitic precipitation-hardened stainless steel

International Nuclear Information System (INIS)

Ping, D.H.; Ohnuma, M.; Hirakawa, Y.; Kadoya, Y.; Hono, K.

2005-01-01

The microstructure of 13Cr-8Ni-2.5Mo-2Al martensitic precipitation-hardened (PH) stainless steel has been investigated using transmission electron microscopy, three-dimensional atom probe and small-angle X-ray scattering. A high number density (∼10 23-25 m -3 ) of ultra-fine (1-6 nm) β-NiAl precipitates are formed during aging at 450-620 deg. C, which are spherical in shape and dispersed uniformly with perfect coherency with the matrix. As the annealing temperature increases, the size and concentration of the precipitates increase concurrently while the number density decreases. The Mo and Cr segregation to the precipitate-matrix interface has been detected and is suggested to suppress precipitate coarsening. In the sample aged for 500 h at 450 deg. C, the matrix decomposes into Cr-rich (α') and Cr-poor (α) regions. The decrease in the strength at higher temperature (above 550 deg. C) is attributed to the formation of larger carbides and reverted austenite

Evaluation of rolling contact fatigue of induction heated 13Cr-2Ni-2Mo Stainless steel bar with Si3N4-ball

Science.gov (United States)

Yadoiwa, Ariyasu; Mizobe, Koshiro; Kida, Katsuyuki

2018-03-01

13Cr % martensitic stainless steels were used in various industry, because they have excellent corrosion resistance and high hardness among other stainless steels. They are also expected as a bearing material, however, the research on rolling contact fatigue (RCF) is not enough. In this study, 13Cr-2Ni-2Mo stainless steels were quenched by induction heating and their RCF lives were evaluated. A Si3N4-ball was used in order to apply higher stress (Pmax = 5.6 GPa) than our previous tests (Pmax=5.3 GPa), in a single-ball RCF testing machine. It was found that the basic life (L10) was 2.20×106 cycles and Median life (L50) was 6.04×106 cycles. In addition, Weibull modulus became higher than the previous tests.

Annealing of chromium oxycarbide coatings deposited by plasma immersion ion processing (PIIP) for aluminum die casting

International Nuclear Information System (INIS)

Peters, A.M.; He, X.M.; Trkula, M.; Nastasi, M.

2001-01-01

Chromium oxycarbide coatings have been investigated for use as non-wetting coatings for aluminum die casting. This paper examines Cr-C-O coating stability and non-wetability at elevated temperatures for extended periods. Coatings were deposited onto 304 stainless steel from chromium carbonyl [Cr(CO) 6 ] by plasma immersion ion processing. The coatings were annealed in air at an aluminum die casting temperature of 700 deg. C up to 8 h. Coatings were analyzed using resonant ion backscattering spectroscopy, nanoindentation and pin-on-disk tribometry. Molten aluminum was used to determine coating wetting and contact angle. Results indicate that the surface oxide layer reaches a maximum thickness of 900 nm. Oxygen concentrations in the coatings increased from 24% to 34%, while the surface concentration rose to almost 45%. Hardness values ranged from 22.1 to 6.7 GPa, wear coefficients ranged from 21 to 8x10 -6 mm 3 /Nm and contact angles ranged from 156 deg. to 127 deg

Hydrothermal Valorization of Steel Slags—Part I: Coupled H{sub 2} Production and CO{sub 2} Mineral Sequestration

Energy Technology Data Exchange (ETDEWEB)

Crouzet, Camille [University Grenoble Alpes, University Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, Grenoble (France); LRCS and RS2E, CNRS-UMR7314, University Picardie Jules Verne, Amiens (France); Aix Marseille University, CNRS, Centrale Marseille, M2P2, Marseille (France); Brunet, Fabrice, E-mail: fabrice.brunet@univ-grenoble-alpes.fr; Montes-Hernandez, German [University Grenoble Alpes, University Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, Grenoble (France); Recham, Nadir [LRCS and RS2E, CNRS-UMR7314, University Picardie Jules Verne, Amiens (France); Findling, Nathaniel [University Grenoble Alpes, University Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, Grenoble (France); Ferrasse, Jean-Henry [Aix Marseille University, CNRS, Centrale Marseille, M2P2, Marseille (France); Goffé, Bruno [Aix-Marseille University, CNRS, IRD, Coll. de France, CEREGE, Aix-en-Provence (France)

2017-10-30

A new process route for the valorization of BOF steel slags combining H{sub 2} production and CO{sub 2} mineral sequestration is investigated at 300°C (HT) under hydrothermal conditions. A BOF steel slag stored several weeks outdoor on the production site was used as starting material. To serve as a reference, room temperature (RT) carbonation of the same BOF steel slag has been monitored with in situ Raman spectroscopy and by measuring pH and P{sub CO2} on a time-resolved basis. CO{sub 2} uptake under RT and HT are, respectively, 243 and 327 kg CO{sub 2}/t of fresh steel slag, which add up with the 63 kg of atmospheric CO{sub 2} per ton already uptaken by the starting steel slag on the storage site. The CO{sub 2} gained by the sample at HT is bounded to the carbonation of brownmillerite. H{sub 2} yield decreased by about 30% in comparison to the same experiment performed without added CO{sub 2}, due to sequestration of ferrous iron in a Mg-rich siderite phase. Ferric iron, initially present in brownmillerite, is partitioned between an Fe-rich clay mineral of saponite type and metastable hematite. Saponite is likely stabilized by the presence of Al, whereas hematite may represent a metastable product of brownmillerite carbonation. Mg-rich wüstite is involved in at least two competing reactions, i.e., oxidation into magnetite and carbonation into siderite. Results of both water-slag and water-CO{sub 2}-slag experiments after 72 h are consistent with a kinetics enhancement of the former reaction when a CO{sub 2} partial pressure imposes a pH between 5 and 6. Three possible valorization routes, (1) RT carbonation prior to hydrothermal oxidation, (2) RT carbonation after hydrothermal treatment, and (3) combined HT carbonation and oxidation are discussed in light of the present results and literature data.

DIE SPRACHE VON "BAŠĆANSKA PLOČA" (DIE STEINTAFEL VON BAŠKA

Directory of Open Access Journals (Sweden)

Stjepan Damjanović

1990-01-01

Full Text Available In einer Mehrzahl von Abhandlungen über Bašćanska ploča berücksichtigen die Verfasser auch die Sprache, in der Regel kurz, nur in einem oder zwei Sätzen. Die größten Bemühungen sind auf die Rekonstruirung der unlesbaren Teilen gerichtet, dagegen nicht weinger interessanter lesbarer Teil regte eine Sprachanalyse selten an. Gewöhnlich wird festgestellt, daß die Tafel in der kroatischen Sprache geschrieben ist, während die philologisch gut unterrichtete Forscher vermeiden diesartige Nenunngen, indem sie das Vorhandensein der altslawischen und altkroatischen Sprachelemente entdeckten. Man versuchte noch nicht in einer Analyse sprachliche Grundschichte und darauf geschichtete Sprachelemente zu bestimmen. Nach dem ersten Eindruck wurde bestimmt, ob es sich um "die kroatische Srpache mit den Elementen der alten slawischen liturgischen Sprache" handelt oder um "die altslawische in der manche kroatische Spracheigenschaften hereingekommen sind". Die Analyse mancher Spracheinzelheiten (Halblaute und "Jat" weist auf altslawische Grundschicht hin. Der Verfasser hat sich trotzdem nicht entschieden den Fachausdruck "kroatische Redaktion des altslawischen" zu verwenden, weil er neue Analyse und neue Begriffsbestimmungen als nötig hält, wie z.B. "Redaktion", "Rezension" usw, um mit Sicherkeit sagen zu können, ob es um kroatische Redaktion des altslawischen oder um andere Formen der altslawischen - alt kroatischen Interferenz geht.

Damascus steel ledeburite class

Science.gov (United States)

Sukhanov, D. A.; Arkhangelsky, L. B.; Plotnikova, N. V.

2017-02-01

Discovered that some of blades Damascus steel has an unusual nature of origin of the excess cementite, which different from the redundant phases of secondary cementite, cementite of ledeburite and primary cementite in iron-carbon alloys. It is revealed that the morphological features of separate particles of cementite in Damascus steels lies in the abnormal size of excess carbides having the shape of irregular prisms. Considered three hypotheses for the formation of excess cementite in the form of faceted prismatic of excess carbides. The first hypothesis is based on thermal fission of cementite of a few isolated grains. The second hypothesis is based on the process of fragmentation cementite during deformation to the separate the pieces. The third hypothesis is based on the transformation of metastable cementite in the stable of angular eutectic carbide. It is shown that the angular carbides are formed within the original metastable colony ledeburite, so they are called “eutectic carbide”. It is established that high-purity white cast iron is converted into of Damascus steel during isothermal soaking at the annealing. It was revealed that some of blades Damascus steel ledeburite class do not contain in its microstructure of crushed ledeburite. It is shown that the pattern of carbide heterogeneity of Damascus steel consists entirely of angular eutectic carbides. Believe that Damascus steel refers to non-heat-resistant steel of ledeburite class, which have similar structural characteristics with semi-heat-resistant die steel or heat-resistant high speed steel, differing from them only in the nature of excess carbide phase.

„… höher als die Liebe zur Wissenschaft steht die Treue zum eigenen Vaterland …“: Hallenser Romanisten im Ersten Weltkrieg

Directory of Open Access Journals (Sweden)

Annette Schiller

2014-12-01

Full Text Available Die 1914 verbreitete Kriegsbegeisterung nahm auch die Romanisten nicht aus. Briefe und Tagebuchnotizen aus der Zeit zeigen, wie Lehrende und Studenten unseres Faches, deren gemeinsamer Bezug die Zugehörigkeit zum Romanischen Seminar Halle war, vom „Großen Krieg“ betroffen waren und führen uns die Situation und Geisteshaltung der Professoren und Studenten und die Rückwirkungen des Krieges auf das Fach vor Augen.

Endurance in Al Alloy Melts and Wear Resistance of Titanium Matrix Composite Shot-Sleeve for Aluminum Alloy Die-casting

International Nuclear Information System (INIS)

Choi, Bong-Jae; Kim, Young-Jig; Sung, Si-Young

2012-01-01

The main purpose of this study was to evaluate the endurance against Al alloy melts and wear resistance of an in-situ synthesized titanium matrix composite (TMC) sleeve for aluminum alloy die-casting. The conventional die-casting shot sleeve material was STD61 tool steel. TMCs have great thermal stability, wear and oxidation resistance. The in-situ reaction between Ti and B4C leads to two kinds of thermodynamically stable reinforcements, such as TiBw and TiCp. To evaluate the feasibility of the application to a TMCs diecasting shot sleeve, the interfacial reaction behavior was examined between Al alloys melts with TMCs and STD61 tool steel. The pin-on-disk type dry sliding wear test was also investigated for TMCs and STD61 tool steel.

Die invloed van doelwitstelling op prestasie

Directory of Open Access Journals (Sweden)

J. G. A. Louw

1985-11-01

Ofskoon die meeste navorsing Locke se doelwitstellingsteorie ondersteun, is bepaalde afwykings teengekom wat nie op 'n bevredigende wyse verklaar kan word nie. Die resultate van hierdie studie dui daarop dat 'n toename in doelwitmoeilikheidsgraad nie altyd tot ‘n ooreenstemmende toename in prestasie lei nie. Hierdie resultaat kon ook nie op grond van 'n gebrek aan doelwitaanvaarding verklaar word nie. Daar is voorts gevind dat die wyse waarop 'n nie-spesifieke doelwit gestel word, 'n beduidende invloed op prestasie kan hê. Finansiële aansporings blyk ook 'n onafhanklike invloed op prestasie te hê. Bepaalde aspekte van Locke se teorie word dus deur bogenoemde resultate bevraagteken. Aanbevelings vir verdere navorsing word ten slotte gedoen.

Idiopathic combined, autoantibody-mediated ADAMTS-13/factor H deficiency in thrombotic thrombocytopenic purpura-hemolytic uremic syndrome in a 17-year-old woman: a case report

Directory of Open Access Journals (Sweden)

Patschan Daniel

2011-12-01

Full Text Available Abstract Introduction Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome is a life-threatening condition with various etiopathogeneses. Without therapy approximately 90% of all patients die from the disease. Case presentation We report the case of a 17-year-old Caucasian woman with widespread hematomas and headache. Due to hemolytic anemia, thrombocytopenia, and schistocytosis, thrombotic thrombocytopenic purpura-hemolytic uremic syndrome was suspected and plasma exchange therapy was initiated immediately. Since her thrombocyte level did not increase during the first week of therapy, plasma treatment had to be intensified to a twice-daily schedule. Further diagnostics showed markedly reduced activities of both ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 - also known as von Willebrand factor-cleaving protease and factor H. Test results for antibodies against both proteins were positive. While plasma exchange therapy was continued, rituximab was given once weekly for four consecutive weeks. After the last dose, thrombocytes and activities of ADAMTS-13 and factor H increased into the normal range. Our patient improved and was discharged from the hospital. Conclusions Since no clinical symptoms/laboratory findings indicated a malignant or specific autoimmune-mediated disorder, the diagnosis made was thrombotic thrombocytopenic purpura-hemolytic uremic syndrome due to idiopathic combined, autoantibody-mediated ADAMTS-13/factor H deficiency.

Improvement of impact toughness by modified hot working and heat treatment in 13%Cr martensitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Srivatsa, Kulkarni, E-mail: srivatsa.kulkarni@kcssl.com; Srinivas, Perla; Balachandran, G.; Balasubramanian, V.

2016-11-20

Improvement of the general mechanical properties and in particular sub-zero impact toughness in a 0.2%C-13%Cr martensitic stainless steel has been explored by varying the hot deformation and heat treatment conditions. The deformation conditions include hot rolling an ingot in one case and cogging the ingot to a semis followed by hot rolling in another case. The bars made from both routes were subjected to a single hardening heat treatment at 980 °C and 1040 °C oil quenched and a double hardening heat treatment at 1040 °C followed by 980 °C oil quenched. The hardened steels were subjected to a standard two stage tempering at 710 °C followed by 680 °C. The impact toughness was found to be doubled in the cogged and rolled steel in double hardened condition. Other processing conditions show varying impact toughness levels. The toughness observed was correlated to the grain size and the carbide distribution in the matrix and the fractography features.

Die histologie en ultrastruktuur van die hepatopankreas van die bloukurper Oreochromis mossambicus

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M. M. Nel

1990-07-01

Full Text Available Die histologie en ultrastruktuur van die hepatopankreas van die bloukurper Oreochromis mossambicus word beskryf. ’n Dun bindweefselkapsel omring die lewer. Die hepatosietrangskikking vertoon as lobules, met die koorde van hepatosiete wat vanaf ’n sentrale vene uitradieer en met mekaar anastomaseer. Indiwiduele lewerlohules vertoon nie duidelike grense nie, maar enkele duidelike triades word wel in die lewer van O. mossambicus aangetref. Die hepatosiete bevat ’n enkele ronde kern met ’n duidelike nukleolus en die growwe endoplasmiese retikula kom in twee of meer rye om die kerne en teen die selgrense van die hepatosiete voor. Die ander sitoplasmiese organelle kom verspreid in die hepatosietsitoplasma voor. Die eksokriene pankreasselle is om die portale venes gesetel. Die kerne van hierdie selle is rond en is hasaal in die kubies- tot silindervormige selle gelee. ’n Goedontwikkelde growwe endoplasmiese retikulum — vesikulêr, tubulêr en sirkulêr in vorm — en sektretoriese granules wat apikaal in die sel gelee is, kom voor.

Surface quality analysis of die steels in powder-mixed electrical discharge machining using titan powder in fine machining

Directory of Open Access Journals (Sweden)

Banh Tien Long

2016-06-01

Full Text Available Improving the quality of surface molds after electrical discharge machining is still being considered by many researchers. Powder-mixed dielectric in electrical discharge machining showed that it is one of the processing methods with high efficiency. This article reports on the results of surface quality of mold steels after powder-mixed electrical discharge machining using titanium powder in fine machining. The process parameters such as electrode material, workpiece material, electrode polarity, pulse on-time, pulse off-time, current, and titanium powder concentration were considered in the research. These materials are most commonly used with die-sinking electrical discharge machining in the manufacture of molds and has been selected as the subject of research: workpiece materials were SKD61, SKT4, and SKD11 mold steels, and electrode materials were copper and graphite. Taguchi’s method is used to design experiments. The influence of the parameters on surface roughness was evaluated through the average value and ratio (S/N. Results showed that the parameters such as electrical current, electrode material, pulse on-time, electrode polarity, and interaction between the electrode materials with concentration powder mostly influence surface roughness and surface roughness at optimal parameters SRopt = 1.73 ± 0.39 µm. Analysis of the surface layer after powder-mixed electrical discharge machining using titanium powder in optimal conditions has shown that the white layer with more uniform thickness and increased hardness (≈861.0 HV, and amount and size of microscopic cracks, is reduced. This significantly leads to the increase in the quality of the surface layer.

Review of Research Work on Ti-BASED Composite Coatings

Science.gov (United States)

Gabbitas, Brian; Salman, Asma; Zhang, Deliang; Cao, Peng

The service life of industrial components is limited predominantly by Chemical corrosion/mechanical wear. The project is concerned with the investigation of the capability of Ti(Al,O)/Al2O3 coatings to improve the service life of tool steel (H13) used for dies in aluminium high pressure die casting. This paper gives a general review on the research work conducted at the University of Waikato on producing and evaluating the titanium/alumina based composite coatings. The powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO2 powders in two different molar ratios followed by a thermal reaction process. The feedstocks were then thermally sprayed using a high velocity air-fuel (HVAF) technique on H13 steel substrates to produce a Ti(Al,O)/Al2O3 composite coatings. The performance of the coating was assessed in terms of thermal shock resistance and reaction kinetics with molten aluminium. The composite powders and coatings were characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD).

Comparative studies on ultrasonic, friction, laser and resistance pressure welding of NiTi shape memory alloys with high-alloy steels. Final report; Vergleichende Untersuchungen zum Ultraschall-, Reib-, Laserstrahl- und Widerstandspressschweissen von NiTi-Shape-Memory-Metall mit hochlegierten Staehlen. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Zuckschwerdt, K.

2000-04-01

The suitability of different welding techniques for welding of NiTi shape memory alloys with high-alloy steel (C12CrNi17-7, X5CrNiNb19-9, X20Cr13) was investigated. The quality of the welds was analyzed using mechanical-technological, fractographic, metallographic and electron microscopy analysis. [German] Ziel dieses Forschungsvorhabens ist es, die Eignung der einzelnen Schweissverfahren fuer das Fuegen von NiTi-Formgedaechtnislegierungen mit hochlegiertem Stahl (X12CrNi17-7, X5CrNiNb19-9, X20Cr13) darzustellen und zu beurteilen. Die Qualitaet der Fuegeverbindungen wird mit Hilfe mechanisch-technologischer, fraktographischer, metallographischer und elektronenmikroskopischer Untersuchungen bewertet.

die impak van metodologie op die verstaan van die nuwe testament

African Journals Online (AJOL)

voorbeeld eers een maal deur die bril van die vorm- en redaksiekritiek na die Evangelies gekyk het, dink jy vir altyd anders oor hulle tot- standkoming. Inderdaad, nuwe metodes lei tot nuwe perspektiewe! Dit is dan ook waar die fokus van hierdie artikel val: die impak van metodologie op die verstaan van die Nuwe ...

Long-term behaviour of heat-resistant steels and high-temperature materials

International Nuclear Information System (INIS)

1987-01-01

This book contains 10 lectures with the following subjects: On the effect of thermal pretreatment on the structure and creep behaviour of the alloy 800 H (V. Guttmann, J. Timm); Material properties of heat resistant ferritic and austenitic steels after cold forming (W. Bendick, H. Weber); Investigations for judging the working behaviour of components made of alloy 800 and alloy 617 under creep stress (H.J. Penkalla, F. Schubert); Creep behaviour of gas turbine materials in hot gas (K.H. Kloos et al.); Effect of small cold forming on the creep beahviour of gas turbine blades made of Nimonic 90 (K.H. Keienburg et al.); Investigations on creep fatigue alternating load strength of nickel alloys (G. Raule); Change of structure, creep fatigue behaviour and life of X20 Cr Mo V 12 1 (by G. Eggeler et al.); Investigations on thermal fatigue behaviour (K.H. Mayer et al.); Creep behaviour of similar welds of the steels 13 Cr Mo 4 4, 14 MoV 6 3, 10 Cr Mo 910 and GS-17 Cr Mo V 5 11 (K. Niel et al.); Determining the creep crack behaviour of heat resistant steels with samples of different geometry (K. Maile, R. Tscheuschner). (orig.,/MM) [de

Die vrede van Münster / Westfale en die betekenis daarvan vir die ...

African Journals Online (AJOL)

In die Suid-Afrikaanse kerkgeskiedenis egter is die Vrede van Münster as epogmakende gebeure tot dusver nie net in die algemeen verwaarloos nie, maar boonop is die direkte verband tussen hierdie sentrale historiese baken aan die een kant en aan die ander kant die vestiging van die VOC se verversingspos aan die ...

P. S. D DIE TEOLOGIESE HOOFGEDAGTES IN KIERKEGAARD SE ...

African Journals Online (AJOL)

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D.Phil. DIE TEOLOGIESE HOOFGEDAGTES IN KIERKEGAARD SE. STRYD TEEN DIE HEGELSE SISTEEM. A. INLEIDENDE OPMERKING. Ons is van oordeel dat dit ongetwyfeld paslik is om in ons waardering van die persoon en werk van prof. H. P. Wolmarans, oor die Deense denker en digter, Kierkegaard, te skrywe.

Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires.

Science.gov (United States)

Hobbelink, Marieke G; He, Yan; Xu, Jia; Xie, Huixu; Stoll, Richard; Ye, Qingsong

2015-01-01

The aim of this study was to investigate the corrosive behaviour of stainless steel archwires in a more clinically relevant way by bending and exposing to various pH. One hundred and twenty pieces of rectangular stainless steel wires (0.43 × 0.64 mm) were randomly assigned into four groups. In each group, there were 15 pieces of bent wires and 15 straight ones. Prior to measurements of the wires, as individual experimental groups (group 1, 2, and 3), the wires were exposed to artificial saliva for 4 weeks at pH 5.6, 6.6, and 7.6, respectively. A control group of wires (group 4) remained in air for the same period of time before sent for measurements. Surface roughness (Ra-value) was measured by a profilometer. Young's modulus and maximum force were determined by a four-point flexural test apparatus. Scanning electron microscopy was used to observe the surface morphology of straight wire. Differences between groups were examined using a two-way analysis of variance (ANOVA). Mean surface roughness values, flexural Young's moduli, and maximum force values of bent wires are significantly different from those of the straight wires, which was the main effect of wire bending, ignoring the influence of pH. A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape. There was a significant interaction effect of bending and pH on flexural Young's moduli of stainless steel archwires, while pH did not show much impact on the maximum force values of those stainless steel wires. Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values. Surface depth (Rz) was more sensitive than Ra in revealing surface roughness, both measured from 3D reconstructed SEM images. Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer. Bending has a significant influence on surface roughness and mechanical

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

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Wen-Tao Yu

2016-08-01

Full Text Available The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix during hot processing as demonstrated by the determination of extracted carbides from the steel matrix. Meanwhile, titanium suppressed the precipitation of secondary carbides during annealing. The appropriate amount of titanium addition decreased the size and fraction of primary carbides in the as-cast ingot, and improved the mechanical properties of the annealed steel.

die pers as bron oor die geskiedenis van die eerste vrydeidsoorlog

African Journals Online (AJOL)

dood agv wonde wat hy tydens die slag opgedoen het. Dit was vir die Britse volk onaanvaarbaar dat slegs twee Boere gedood is nadat daar tussen. 20 000 en 30 000 rondtes op die Boere afgevuur is. Die pers kon net nie die ware syfers publiseer nie, want dit sou na 'n onwaarheid Iyk. Het die. Britse volk egter die Boere ...

Die partypolitiek en die toekoms van die Afrikaanse volkskultuur

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A.P. Treurnicht

1970-03-01

Full Text Available Reeds in 1853 het die Zuid Afrikaan hom soos volg uitgelaat: „Dis ’n dwaling wat ons reeds meermale bestry het dat ons as Britse onderdane verplig sou wees, om die Britse nasionaliteit ons s’n te maak. Die Kolonis van Hollandse oorsprong kan geen Engelsman word nie, en moet ook geen Nederlander wil wees nie. Wanneer hy weet om sy standpunt te waardeer, dan sal hy as verligte kolonis die grondtrekke van die Engelse volkskarakter met dié van die Nederlandse harmonies leer verenig en daardeur word wat hy as Kapenaar moet word.”

5-[(3,5-Dimethyl-1-phenyl-1H-pyrazol-4-ylmethylene]-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H-dione

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Salman A. Khan

2010-03-01

Full Text Available The title compound, 5-[(3,5-dimethyl-1-phenyl-1H-pyrazol-4-ylmethylene]-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H-dione, has been synthesized by condensation of 1,3-diethyl-2-thiobarbituric acid and 3,5-dimethyl-1-phenylpyrazole-4-carbaldehyde in ethanol in the presence of pyridine. The structure of this new compound was confirmed by elemental analysis, IR, 1H-NMR, 13C-NMR and EI-MS spectral analysis.

Characteristics of Pilger Die Materials for Nuclear Zirconium Alloy Tubes

International Nuclear Information System (INIS)

Park, Ki Bum; Kim, In Kyu; Park, Min Young; Kahng, Jong Yeol; Kim, Sun Doo

2011-01-01

KEPCO Nuclear Fuel Company's (KEPCO NF) tube manufacturing facility, Techno Special Alloy (TSA) Plant, has started cold pilgering operation since 2008. It is obvious that the cold pilgering process is one of the key processes controlling the quality and the characteristics of the tubes manufactured, i.e. nuclear zirconium alloy tube in KEPCO NF. Cold pilgering is a rolling process for forming metal tubes in which diameter and wall thickness are reduced in a number of forming steps, using ring dies at outside of the tube and a curved mandrel at inside to reduce tube cross sections by up to 90 percent. The OD size of tube is reduced by a pair of dies, and ID size and wall thickness is controlled simultaneously by mandrel. During the cold pilgering process, both tools are the critical components for providing qualified tube. Development of pilger die and mandrel has been a significant importance in the zirconium tube manufacturing and a major goal of KEPCO NF. The objective of this study is to evaluate the life time of pilger die during pilgering. Therefore, a comparison of the heat treatment and mechanical properties of between AISI 52100 and AISI H13 materials was made in this study

Improvement of Strength-Toughness-Hardness Balance in Large Cross-Section 718H Pre-Hardened Mold Steel

Science.gov (United States)

Liu, Hanghang; Fu, Paixian; Liu, Hongwei; Li, Dianzhong

2018-01-01

The strength-toughness combination and hardness uniformity in large cross-section 718H pre-hardened mold steel from a 20 ton ingot were investigated with three different heat treatments for industrial applications. The different microstructures, including tempered martensite, lower bainite, and retained austenite, were obtained at equivalent hardness. The microstructures were characterized by using metallographic observations, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron back-scattered diffraction (EBSD). The mechanical properties were compared by tensile, Charpy U-notch impact and hardness uniformity tests at room temperature. The results showed that the test steels after normalizing-quenching-tempering (N-QT) possessed the best strength-toughness combination and hardness uniformity compared with the conventional quenched-tempered (QT) steel. In addition, the test steel after austempering-tempering (A-T) demonstrated the worse hardness uniformity and lower yield strength while possessing relatively higher elongation (17%) compared with the samples after N-QT (14.5%) treatments. The better ductility of A-T steel mainly depended on the amount and morphology of retained austenite and thermal/deformation-induced twined martensite. This work elucidates the mechanisms of microstructure evolution during heat treatments and will highly improve the strength-toughness-hardness trade-off in large cross-section steels. PMID:29642642

Improvement of Strength-Toughness-Hardness Balance in Large Cross-Section 718H Pre-Hardened Mold Steel

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Hanghang Liu

2018-04-01

Full Text Available The strength-toughness combination and hardness uniformity in large cross-section 718H pre-hardened mold steel from a 20 ton ingot were investigated with three different heat treatments for industrial applications. The different microstructures, including tempered martensite, lower bainite, and retained austenite, were obtained at equivalent hardness. The microstructures were characterized by using metallographic observations, scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, and electron back-scattered diffraction (EBSD. The mechanical properties were compared by tensile, Charpy U-notch impact and hardness uniformity tests at room temperature. The results showed that the test steels after normalizing-quenching-tempering (N-QT possessed the best strength-toughness combination and hardness uniformity compared with the conventional quenched-tempered (QT steel. In addition, the test steel after austempering-tempering (A-T demonstrated the worse hardness uniformity and lower yield strength while possessing relatively higher elongation (17% compared with the samples after N-QT (14.5% treatments. The better ductility of A-T steel mainly depended on the amount and morphology of retained austenite and thermal/deformation-induced twined martensite. This work elucidates the mechanisms of microstructure evolution during heat treatments and will highly improve the strength-toughness-hardness trade-off in large cross-section steels.

die heidelbergse kategismus en die kategesemateriaal van die ned

African Journals Online (AJOL)

subjek, objek, leerstof en die metodiek van die senior kategese. Bloemfontein: Algemene Jeugkommissie Sondagskoolboekhandel. de rAAd oer ned ger kerken in Zuid AfrikA. 1921. De zevende vergadering: handelinge. 1925. De negende vergadering: handelinge. de villierS, d. W. 1957. Die Kategese in die Ned. Geref.

Heat Treatment Optimization and Properties Correlation for H11-Type Hot-Work Tool Steel

Science.gov (United States)

Podgornik, B.; Puš, G.; Žužek, B.; Leskovšek, V.; Godec, M.

2018-02-01

The aim of this research was to determine the effect of vacuum-heat-treatment process parameters on the material properties and their correlations for low-Si-content AISI H11-type hot-work tool steel using a single Circumferentially Notched and fatigue Pre-cracked Tensile Bar (CNPTB) test specimen. The work was also focused on the potential of the proposed approach for designing advanced tempering diagrams and optimizing the vacuum heat treatment and design of forming tools. The results show that the CNPTB specimen allows a simultaneous determination and correlation of multiple properties for hot-work tool steels, with the compression and bending strength both increasing with hardness, and the strain-hardening exponent and bending strain increasing with the fracture toughness. On the other hand, the best machinability and surface quality of the hardened hot-work tool steel are obtained for hardness values between 46 and 50 HRC and a fracture toughness below 60 MPa√m.

Damping capacity of unstable steels on chromium-nickel-manganese base

Energy Technology Data Exchange (ETDEWEB)

Kochkin, L.I.; Rudakov, A.A. (Kirovskij Politekhnicheskij Inst. (USSR))

1982-02-01

The paper deals with results of a study on the energy scattering in OKh13N3G8, 20Kh13N3G4 and 30Kh13N3G4 unstable steels. It is shown that the development of microplastic strains most easily occurs in low-carbon steel having a two-phase structure in the initial state. The proceeding of microplastic deformations in carbon unstable steels is limited by the interstitial atom effect on the dislocation movement. It is established that in OKh13N3G8 steel the martensite ..cap alpha --> gamma..- transformation begins under the cyclic stress amplitudes below the yield point of this steel. The steels studied possess a high vibrostrength.

Compound effect of CaCO3 and CaSO4·2H2O on the strength of steel slag: cement binding materials

International Nuclear Information System (INIS)

Qi, Liqian; Liu, Jiaxiang; Liu, Qian

2016-01-01

In this study, we replaced 30% of the cement with steel slag to prepare binding material; additionally, small amounts of CaCO 3 and CaSO 4 ·2H 2 O were added. This was done to study the compound effect of CaCO 3 and CaSO 4 ·2H 2 O on the strength of steel slag-cement binding materials. The hydration degree of the steel slag cementitious material was analyzed by XRD, TG and SEM. The results showed that the optimum proportions of CaCO 3 and CaSO 4 ·2H 2 O were 3% and 2%, respectively. Compared with the steel slag-cement binders without adding CaCO 3 and CaSO 4 ·2H 2 O, the compressive strength increased by 59.9% at 3 days and by 17.8% at 28 days. Acting as the nucleation matrix, CaCO 3 could accelerate the hydration of C 3 S. In addition, CaCO 3 was involved in the hydration reaction, generating a new hydration product, which could stably exist in a slurry. Meanwhile, CaSO 4 ·2H 2 O could increase the number of AFt. The compound effect of CaCO 3 and CaSO 4 ·2H 2 O enhanced the intensity of steel slag-cement binding materials and improved the whole hydration behavior. (author)

Structural changes of radial forging die surface during service under thermo-mechanical fatigue

International Nuclear Information System (INIS)

Nematzadeh, Fardin; Akbarpour, Mohammad Reza; Kokabi, Amir Hosein; Sadrnezhaad, Seyed Khatiboleslam

2009-01-01

Radial forging is one of the modern open die forging techniques and has a wide application in producing machine parts. During operation at high temperatures, severe temperature change associated with mechanical loads and the resultant wearing of the die surface lead to intense variation in strain on the die surface. Therefore, under this operating condition, thermo-mechanical fatigue (TMF) occurs on the surface of the radial forging die. TMF decreases the life of the die severely. In the present research, different layers were deposited on a 1.2714 steel die by SMAW and GTAW, with a weld wire of UDIMET 520. The microstructure of the radial forging die surface was investigated during welding and service using an optical microscope and scanning electron microscope. The results revealed that, after welding, the structure of the radial forging die surface includes the γ matrix with a homogeneous distribution of fine semi-spherical carbides. The weld structure consisted mostly of columnar dendrites with low grain boundaries. Also, microstructural investigation of the die surface during operation showed that the weld structure of the die surface has remained without any considerable change. Only dendrites were deformed and broken. Moreover, grain boundaries of the dendrites were revealed during service.

Die invloed van die neo-marxistiese kultuuranalise op die Wêreldraad van Kerke en die Gereformeerde Kerke van Nederland

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J. M. Vorster

1979-05-01

Full Text Available Toe die studente dwarsoor die VSA en Europa in die laat sestigerjare ’n plotselinge en radikale verset openbaar het teen die bestaande orde, het hulle die deur geopen vir ’n nuwe mededinger om die hart van die Westerse kultuur. Dit is die nou reeds bekende neo-Marxisme. Sedertdien het hierdie jongeling sy voetspore op vele vlakke van die Westerse kultuur gelaat.

Adsorption study of CO and H2O on carbon materials, Ni and stainless steel

International Nuclear Information System (INIS)

Kato, S.

1991-01-01

Adsorption of CO and water vapor on single crystalline graphite, diamond and an amorphous carbon film at room temperature was investigated by low energy ion scattering (ISS) and compared with stainless steel and nickel surfaces. Even for a CO exposure up to 10 4 L, the C intensity stayed constant and no O peak appeared in the ISS spectra from graphite while Ni and O intensities from Ni surface changed strikingly. Intensities of FE and O signals from stainless steel seriously decrease and increase with increasing exposure of H 2 O, respectively, but did not reach saturation even at an exposure of 10 3 L. On the other hand, C and O intensities from carbon surfaces changed moderately to reach saturation at an exposure of some 100 L. These results indicate that CO and H 2 O do not adsorb significantly on carbon surfaces in contrast to nickel and stainless steel surfaces. As a by-product survival probabilities of scattered He + ions from graphite for the primary energy of 0.6-2 keV were measured to be in a range of 10 -4 to 10 -2 and the survival parameter was deduced to be 5.0 x 10 7 cm s -1 . (author)

Problems in repair-welding of duplex-treated tool steels

OpenAIRE

T. Muhič; J. Tušek; M. Pleterski; D. Bombač

2009-01-01

The present paper addresses problems in laser welding of die-cast tools used for aluminum pressure die-castings and plastic moulds. To extend life cycle of tools various surface improvements are used. These surface improvements significantly reduce weldability of the material. This paper presents development of defects in repair welding of duplex-treated tool steel. The procedure is aimed at reduction of defects by the newly developed repair laser welding techniques. Effects of different repa...

Die regsposisie van die gemolesteerde kind 1

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P.J. Schabort

1991-03-01

Full Text Available Hoe reik die reg uit na die seksueel gemolesteerde kind? As na die reg in wye verband gekyk word, sou dit alie wetgewing en alle gemeneregsbeginsels en alle regsprosedures insluit waardeur die Staat poog om molestering te voorkom en die gemolesteerde kind in beskerming te neem. Dit le baie wyd en sou byvoorbeeld die maatreels insluit van die Kindenvet 33 van 1960; die Wet op Egskeiding 70 van 1979; die Wet op Kindersorg 74 van 1983; die Wet op die Status van Kinders 82 van 1987 en die Wet op Bemiddeling in Sekere Egskeidingsaangeleenthede 24 van 1987. Eersdaags sal dit moontlik ook ’n Manifes vir die Regte van Kinders insluit wat vermoedelik geskoei sal wees op die W O se Konvensie vir die Regte van die Kind (1989 w a arv an die RSA tan s nog nie ’n ondertekenaar is nie.

Corrosion inhibition of carbon steel XC70 in H 2 SO 4 solution by ...

African Journals Online (AJOL)

In this work, we studied the efficiency of corrosion inhibition of carbon steel XC70 in H2SO4 0.5 M aqueous solution using ferrocenyl derivatives synthesized in our laboratory, this compound is: 3-(ferrocenylmethylamine)benzonitrile. The inhibitory potential of this compound was determined by electrochemical techniques ...

Inhibitor for the Corrosion of Mild Steel in H 2 SO 4 | Patel | South ...

African Journals Online (AJOL)

An extract of Terminalia chebula fruits was investigated as a corrosion inhibitor of mild steel in 0.5 M H2SO4 by means of conventional mass loss, electrochemical polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The mass loss results showed that the extract of Terminalia chebula is ...

Inhibition by Ginkgo leaves extract of the corrosion of steel in HCl and H{sub 2}SO{sub 4} solutions

Energy Technology Data Exchange (ETDEWEB)

Deng Shuduan, E-mail: dengshuduan@163.com [Faculty of Materials Engineering, Southwest Forestry University, Kunming 650224 (China); Li Xianghong [Faculty of Science, Southwest Forestry University, Kunming 650224 (China)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Ginkgo leaves extract (GLE) acts as a good inhibitor for steel in HCl and H{sub 2}SO{sub 4} media. Black-Right-Pointing-Pointer The inhibition efficiency follows the order: HCl > H{sub 2}SO{sub 4}. Black-Right-Pointing-Pointer The adsorption of GLE on steel surface obeys Langmuir adsorption isotherm. Black-Right-Pointing-Pointer GLE behaves as a mixed-type inhibitor in 1.0 M HCl, while cathodic inhibitor in 0.5 M H{sub 2}SO{sub 4}. - Abstract: The inhibition effect of Ginkgo leaves extract (GLE) on the corrosion of cold rolled steel (CRS) in 1.0-5.0 M HCl and 0.5-2.5 M H{sub 2}SO{sub 4} solutions was investigated for the first time by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) methods. The results show that GLE is a good inhibitor, and exhibits more efficient in 1.0 M HCl than 0.5 M H{sub 2}SO{sub 4}. The adsorption of GLE on CRS surface obeys Langmuir adsorption isotherm. GLE acts as a mixed-type inhibitor in 1.0 M HCl, while a cathodic inhibitor in 0.5 M H{sub 2}SO{sub 4}.

Mechanistic model of stress corrosion cracking (scc) of carbon steel in acidic solution with the presence of H2s

International Nuclear Information System (INIS)

Asmara, Y P; Juliawati, A; Sulaiman, A; Jamiluddin

2013-01-01

In oil and gas industrial environments, H 2 S gas is one of the corrosive species which should be a main concern in designing infrastructure made of carbon steel. Combination between the corrosive environment and stress condition will cause degradation of carbon steel increase unpredictably due to their simultaneous effects. This paper will design a model that involves electrochemical and mechanical theories to study crack growth rate under presence of H 2 S gas. Combination crack and corrosion propagation of carbon steel, with different hydrogen concentration has been investigated. The results indicated that high concentration of hydrogen ions showed a higher crack propagation rate. The comparison between corrosion prediction models and corrosion model developed by researchers used to verify the model accuracy showed a good agreement

Plasma assisted nitriding for micro-texturing onto martensitic stainless steels*

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Katoh Takahisa

2015-01-01

Full Text Available Micro-texturing method has grown up to be one of the most promising procedures to form micro-lines, micro-dots and micro-grooves onto the mold-die materials and to duplicate these micro-patterns onto metallic or polymer sheets via stamping or injection molding. This related application requires for large-area, fine micro-texturing onto the martensitic stainless steel mold-die materials. A new method other than laser-machining, micro-milling or micro-EDM is awaited for further advancement of this micro-texturing. In the present paper, a new micro-texturing method is developed on the basis of the plasma assisted nitriding to transform the two-dimensionally designed micro-patterns to the three dimensional micro-textures in the martensitic stainless steels. First, original patterns are printed onto the surface of stainless steel molds by using the dispenser or the ink-jet printer. Then, the masked mold is subjected to high density plasma nitriding; the un-masked surfaces are nitrided to have higher hardness, 1400 Hv than the matrix hardness, 200 Hv of stainless steels. This nitrided mold is further treated by sand-blasting to selectively remove the soft, masked surfaces. Finally, the micro-patterned martensitic stainless steel mold is fabricated as a tool to duplicate these micro-patterns onto the plastic materials by the injection molding.

Numerical investigation of the effect of friction conditions to increase die life

Science.gov (United States)

Mutlu, M. O.; Guleryuz, C. G.; Parlar, Z.

2017-02-01

The standard die materials in aluminium extrusion offer good mechanical properties like high tempering resistance, high strength and ductility. On the other hand, they struggle with the problem of sliding wear. As a result, there is a growing interest in using surface treatment techniques to increase the wear resistance of extrusion dies. In this study, it is aimed to observe the effects of the different friction conditions on material flow and contact pressure in extrusion process. These friction conditions can be obtained with the application of a variety of surface treatment. In this way, it is expected to decrease the friction force on the die bearing area and to increase the homogeneity of the material flow which will result in the increase of the quality of the extrudate as well as the improvement of the process economically by extending die life. For this purpose, an extrusion process is simulated with a finite element software. A die made of 1.2344 hot work tool steel-commonly used die material for aluminium extrusion process- has been modelled and Al 1100 alloy used as billet material. Various friction factor values defined on the die surface under the same process parameters and effects of changing frictional conditions on the die and the extrusion process have been discussed.

Behaviour of F82H mod. stainless steel in lead-bismuth under temperature gradient

Science.gov (United States)

Gómez Briceño, D.; Martín Muñoz, F. J.; Soler Crespo, L.; Esteban, F.; Torres, C.

2001-07-01

Austenitic steels can be used in a hybrid system in contact with liquid lead-bismuth eutectic if the region of operating temperatures is not beyond 400°C. For higher temperatures, martensitic steels are recommended. However, at long times, the interaction between the structural material and the eutectic leads to the dissolution of some elements of the steel (Ni, Cr and Fe, mainly) in the liquid metal. In a non-isothermal lead-bismuth loop, the material dissolution takes place at the hot leg of the circuit and, due to the mass transfer, deposition occurs at the cold leg. One of the possible ways to improve the performance of structural materials in lead-bismuth is the creation of an oxide layer. Tests have been performed in a small natural convection loop built of austenitic steel (316L) that has been operating for 3000 h. This loop contains a test area in which several samples of F82Hmod. martensitic steel have been tested at different times. A gas with an oxygen content of 10 ppm was bubbled in the hot area of the circuit during the operation time. The obtained results show that an oxide layer is formed on the samples introduced in the loop at the beginning of the operation and this layer increases with time. However, the samples introduced at different times during the loop operation, are not protected by oxide layers and present material dissolution in some cases.

Behaviour of F82H mod. stainless steel in lead-bismuth under temperature gradient

International Nuclear Information System (INIS)

Gomez Briceno, D.; Martin Munoz, F.J.; Soler Crespo, L.; Esteban, F.; Torres, C.

2001-01-01

Austenitic steels can be used in a hybrid system in contact with liquid lead-bismuth eutectic if the region of operating temperatures is not beyond 400 deg. C. For higher temperatures, martensitic steels are recommended. However, at long times, the interaction between the structural material and the eutectic leads to the dissolution of some elements of the steel (Ni, Cr and Fe, mainly) in the liquid metal. In a non-isothermal lead-bismuth loop, the material dissolution takes place at the hot leg of the circuit and, due to the mass transfer, deposition occurs at the cold leg. One of the possible ways to improve the performance of structural materials in lead-bismuth is the creation of an oxide layer. Tests have been performed in a small natural convection loop built of austenitic steel (316L) that has been operating for 3000 h. This loop contains a test area in which several samples of F82Hmod. martensitic steel have been tested at different times. A gas with an oxygen content of 10 ppm was bubbled in the hot area of the circuit during the operation time. The obtained results show that an oxide layer is formed on the samples introduced in the loop at the beginning of the operation and this layer increases with time. However, the samples introduced at different times during the loop operation, are not protected by oxide layers and present material dissolution in some cases

Improvement of formability of high strength steel sheets in shrink flanging

International Nuclear Information System (INIS)

Hamedon, Z; Abe, Y; Mori, K

2016-01-01

In the shrinkage flanging, the wrinkling tends to occur due to compressive stress. The wrinkling will cause a difficulty in assembling parts, and severe wrinkling may leads to rupture of parts. The shrinkage flange of the ultra-high strength steel sheets not only defects the product by the occurrence of the wrinkling but also causes seizure and wear of the dies and shortens the life of dies. In the present study, a shape of a punch having gradual contact was optimized in order to prevent the wrinkling in shrinkage flanging of ultra-high strength steel sheets. The sheet was gradually bent from the corner of the sheet to reduce the compressive stress. The wrinkling in the shrink flanging of the ultra-high strength steel sheets was prevented by the punch having gradual contact. It was found that the punch having gradual contact is effective in preventing the occurrence of wrinkling in the shrinkage flanging. (paper)

Die hervertolking van die paradigma in verband met die ...

African Journals Online (AJOL)

Kerkorde van De Mist en die Algemene Reglement van 1816, wat onderskeidelik vir die Kaapse Kerk en die .... Een van die eerstes was Sam Freiherr von Pufendorf (1632-1694) wat in sy werk De habitu religionis ..... Koning was weer aan bewind (vgl Diepenhorst sj:74w; De Visser 1926/1927 lll:202w). 43.1 JD Janssen ...

Damping capacity of unstable steels on chromium-nickel-manganese base

International Nuclear Information System (INIS)

Kochkin, L.I.; Rudakov, A.A.

1982-01-01

The paper deals with results of a study on the energy scattering in OKh13N3G8, 20Kh13N3G4 and 30Kh13N3G4 unstable steels. It is shown that the development of microplastic strains most easily occurs in low-carbon steel having a two-phase structure in the initial state. The proceeding of microplastic deformations in carbon unstable steels is limited by the interstitial atom effect on the dislocation movement. It is established that in OKh13N3G8 steel the martensite α→γ- transformation begins under the cyclic stress amplitudes below the yield point of this steel. The steels studied possess a high vibrostrength [ru

Die Behandlung des Akustikusneurinoms mit dem Gamma-Knife

OpenAIRE

Hempel, Elizabeta

2005-01-01

Das Akustikusneurinom ist mit ca. 6% der häufigste intrakranielle Tumor und hat eine jährliche Inzidenz von 1:100000. Die durchschnittliche Wachstumsrate beträgt 2 mm pro Jahr, wobei es auch Akustikusneurinome gibt, die sehr viel schneller wachsen können. Bei der Behandlung des Schwannoms stehen uns zwei Modalitäten zur Verfügung. Die konventionelle Chirurgie und die stereotaktische Radiochirurgie, zu der die Gamma-Knife Therapie und der Linearbeschleuniger zählen. Sorgfältig ausgesuchte P...

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

OpenAIRE

Wen-Tao Yu; Jing Li; Cheng-Bin Shi; Qin-Tian Zhu

2016-01-01

The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix duri...

Die 2004 senior Harmony Suid-Afrikaanse Wiskunde- olimpiade: ’n Analise van die resultate van die senior groep, tweede ronde

Directory of Open Access Journals (Sweden)

J. G. Maree

2004-09-01

Full Text Available Suid-Afrikaanse leerders se ontoereikende wiskundeprestasie is ’n bron van kommer vir elkeen wat betrokke is by leerfasilitering i wiskunde. Belanghebbendes soek ernstig na moontlike wyses waarop leerders se insig rakende en prestasie in wiskunde verbeter ka word ten einde leerders toe te rus met wiskundige vaardighede en hulle op hierdie wyse te help om ’n beter kans te hê op lewensukse In hierdie verband word wiskunde-olimpiades wêreldwyd beskou as ’n uitnemende meganisme, enersyds om talentvolle leerders identifiseer en leerders se probleemoplossingsvaardighede in wiskunde te verbeter, en andersyds om leerders voor te berei op wiskundig studierigtings in die algemeen. In hierdie artikel word enkele aspekte van die pas afgelope Harmony Suid-Afrikaanse Wiskunde olimpiade ontleed en enkele aanbevelings gemaak. ’n Belangrike gevolgtrekking wat gemaak word, is dat die Harmony Suid-Afrikaans Wiskunde-olimpiade in ’n groot mate in sy doel slaag, maar nie naastenby soveel leerders en opvoeders bereik as waarop ’n mens so wou hoop nie. Die ideale van die Harmony Suid-Afrikaanse Wiskunde-olimpiade kan waarskynlik slegs bereik word indien alle sko van toereikende fasiliteite voorsien word en die standaard van wiskundeonderrig op nasionale vlak terselfdertyd toepaslik verbete word. Spoedige en indringende gesprek en herbesinning deur alle betrokke partye is daarom dringend noodsaaklik.

Microstructure in HIP-bonded F82H steel and its mechanical properties after irradiation

International Nuclear Information System (INIS)

Furuya, K.; Wakai, E.

2006-01-01

A first primary blanket structure is composed of the low-activation steel, e.g. F82H, and is fabricated by using a solid hot isostatic pressing (HIP) bonding method. A partial mock-up of such a blanket structure was successfully fabricated. The tensile specimen including HIP-bonded region possessed a sufficient strength and elongation under a non-irradiated condition as reported in our previous studies. In this study, the microstructures of HIP interface before irradiation were observed by a TEM, and the effects of irradiation on mechanical properties of the HIP-bonded region were also examined. TEM observation and elemental analysis of the HIP-bonded region before the irradiation were performed by using a FE-TEM of HF-2000 equipped with EDX spectroscopy. Tensile specimens (type SS-3) were prepared from a HIP-bonded region and a plate region of the mock-up block. Neutron irradiation was performed up to about 1.9 dpa at about 523 K in JMTR. After the irradiation, tensile test was performed at temperatures of 295 and 523 K. After the tensile test, OM observation at the rupture region and SEM observation at the fracture surface were conducted, respectively. TEM observation and analytical results revealed that the HIP interface possessed many precipitates, and enriched peak spectrum of chromium was detected from the precipitates. In addition, aspect of the spectrum was qualitatively equivalent to that of M23C6 in grain boundaries of F82H steel. In result, the HIP boundary has many M23C6 which were generally seen in grain boundaries of F82H steel, and it can be mentioned that the HIP interface is, in this sense, a new grain boundary. Obvious HIP boundary was seen at rupture region of tensile specimens sampled from the HIP-bonded region, by the macroscopic observation. It means that rupture do not occur in the HIP interface. In result, it can be mentioned that bondability of the HIP interfaces is kept under the irradiation and testing conditions. The strength and

New 1H-pyrrole-2,5-dione derivatives as efficient organic inhibitors of carbon steel corrosion in hydrochloric acid medium: Electrochemical, XPS and DFT studies

International Nuclear Information System (INIS)

Zarrouk, A.; Hammouti, B.; Lakhlifi, T.; Traisnel, M.; Vezin, H.; Bentiss, F.

2015-01-01

Highlights: • 1H-pyrrole derivatives act as good corrosion inhibitors for carbon steel in 1 M HCl. • Adsorption of the inhibitors on carbon steel surface obeys Langmuir’s isotherm. • XPS showed that the inhibitors are chemisorbed on the metal surface. • Quantum chemical parameters were correlated with experimental results. - Abstract: New 1H-pyrrole-2,5-dione derivatives, namely 1-phenyl-1H-pyrrole-2,5-dione (PPD) and 1-(4-methylphenyl)-1H-pyrrole-2,5-dione (MPPD) were synthesised and their inhibitive action against the corrosion of carbon steel in 1 M HCl solution were investigated at 308 K by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results showed that the investigated 1H-pyrrole-2,5-dione derivatives are good corrosion inhibitors for carbon steel in 1 M HCl medium, their inhibition efficiency increased with inhibitor concentration, and MPPD is slightly more effective than PPD. Potentiostatic polarization study showed that PPD and MPPD are mixed-type inhibitors in 1 M HCl. Impedance experimental data revealed a frequency distribution of the capacitance, simulated as constant phase element. The results obtained from electrochemical and weight loss studies were in reasonable agreement. The adsorption of MPPD and PPD on steel surface obeyed Langmuir’s adsorption isotherm. Thermodynamic data and XPS analysis clearly indicated that the adsorption mechanism of 1H-pyrrole-2,5-dione derivatives on carbon steel surface in 1 M HCl solution is mainly controlled by a chemisorption process. Quantum chemical calculations using the Density Functional Theory (DFT) were performed on 1H-pyrrole-2,5-dione derivatives to determine the relationship between molecular structures and their inhibition efficiencies

Effects of Cryogenic Treatment on the Strength Properties of Heat Resistant Stainless Steel (07X16H6)

Science.gov (United States)

Nadig, D. S.; Bhat, M. R.; Pavan, V. K.; Mahishi, Chandan

2017-09-01

Cryogenic treatment on metals is a well known technology where the materials are exposed to cryogenic temperature for prolonged time duration. The process involves three stages viz. slow cooling, holding at cryogenic temperature and warming to room temperature. During this process, hard and micro sized carbide particles are released within the steel material. In addition, soft and unconverted austenite of steel changes to strong martensite structure. These combined effects increase the strength and hardness of the cryotreated steel. In this experimental study, the effects of cryogenic treatment, austenitising and tempering on the mechanical properties of stainless steel (07X16H6) have been carried. After determining the strength properties of the original material, the specimens were cryotreated at 98K for 24 hours in a specially developed cryotreatment system. The effects of austenitising prior to cryogenic treatment and tempering post cryotreatment on the mechanical properties of steel samples have been experimentally determined and analysed.

Effect of boron control of environment on corrosion and resistance to low-cycle corrosion fatigue in structural steels

International Nuclear Information System (INIS)

Babej, Yu.I.; Zhitkov, V.V.; Zvezdin, Yu.I.; Liskevich, I.Yu.; Nazarov, A.A.

1982-01-01

Tests of the specimens on total, contact and crevice corrosion, corrosion cracking and low-cycle fatigue are conducted for determination of corrosion and corrosion-fatigue characteristics in the 15Kh3NMFA, 10N3MFA, 10Kh16N4B, 05Kh13N6M2 structural steels, used in energetics. The environment is subjected to boron control and contacting with atmosphere for simulation of stop and operation modes of the facility. The experiments are carried out in the distilled water with 12g/l H 3 BO 3 and 10 mg/l Cl' at 25, 60, 100 deg C under contacting with atmosphere. It is established, that the pearlitic steels 15Kh3NMFA, 10N3MFA, as well as transition and martensitic 05Kh13N6M2 and 10Kh16N4B steels are highly stable to total, crevice and contact corrosion at the high parameters of aqueous boron-containing medium. Steel resistance to low-cycle fracture decreases slightly under the conditions similar to the operation ones, in the water with 12 g/l H 3 BO 3 . Durability of the pearlitic steels at the simulation of stop conditions decreases more noticeably, crack formation as a rule, initiating from corrosion spots

Mu opioid receptor availability in people with psychiatric disorders who died by suicide: a case control study

Directory of Open Access Journals (Sweden)

Scarr Elizabeth

2012-08-01

Full Text Available Abstract Background Mu opioid receptors have previously been shown to be altered in people with affective disorders who died as a result of suicide. We wished to determine whether these changes were more widespread and independent of psychiatric diagnoses. Methods Mu receptor levels were determined using [3 H]DAMGO binding in BA24 from 51 control subjects; 38 people with schizophrenia (12 suicides; 20 people with major depressive disorder (15 suicides; 13 people with bipolar disorder (5 suicides and 9 people who had no history of psychiatric disorders but who died as a result of suicide. Mu receptor levels were further determined in BA9 and caudate-putamen from 38 people with schizophrenia and 20 control subjects using [3 H]DAMGO binding and, in all three regions, using Western blots. Data was analysed using one-way ANOVAs with Bonferroni’s Multiple Comparison Test or, where data either didn’t approximate to a binomial distribution or the sample size was too small to determine distribution, a Kruskal-Wallis test with Dunn’s Multiple Comparison Test. Results [3 H]DAMGO binding density was lower in people who had died as a result of suicide (p3 H]DAMGO binding densities, but not mu protein levels, were significantly decreased in BA9 from people with schizophrenia who died as a result of suicide (p Conclusions Overall these data suggest that mu opioid receptor availability is decreased in the brains of people with schizophrenia who died as a result of suicide, which would be consistent with increased levels of endogenous ligands occupying these receptors.

Iridium Oxide pH Sensor Based on Stainless Steel Wire for pH Mapping on Metal Surface

Science.gov (United States)

Shahrestani, S.; Ismail, M. C.; Kakooei, S.; Beheshti, M.; Zabihiazadboni, M.; Zavareh, M. A.

2018-03-01

A simple technique to fabricate the iridium oxide pH sensor is useful in several applications such as medical, food processing and engineering material where it is able to detect the changes of pH. Generally, the fabrication technique can be classified into three types: electro-deposition iridium oxide film (EIrOF), activated iridium oxide film (AIROF) and sputtering iridium oxide film (SIROF). This study focuses on fabricating electrode, calibration and test. Electro-deposition iridium oxide film is a simple and effective method of fabricating this kind of sensor via cyclic voltammetry process. The iridium oxide thick film was successfully electrodeposited on the surface of stainless steel wire with 500 cycles of sweep potential. A further analysis under FESEM shows detailed image of iridium oxide film which has cauliflower-liked microstructure. EDX analysis shows the highest element present are iridium and oxygen which concluded that the process is successful. The iridium oxide based pH sensor has shown a good performance in comparison to conventional glass pH sensor when it is being calibrated in buffer solutions with 2, 4, 7 and 9 pH values. The iridium oxide pH sensor is specifically designed to measure the pH on the surface of metal plate.

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