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Sample records for aceros al cr-mo-v

  1. Repair by weld of steam and gas turbine rotors made of Cr-Mo-V steel; Reparacion por soldadura de rotores de turbinas de vapor y de gas fabricados con aceros al Cr-Mo-V

    Mazur C, Zdzislaw; Hernandez R, Alejando [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Orozco S, Julian; Banuelos P, Jose E. [Comision Federal de Electricidad (Mexico)

    2003-07-01

    In this article an analysis is presented of the typical damages in steam and gas turbine rotors made of Cr-Mo-V low alloy steels. An analysis of the weldability of the Cr-Mo-V steel is carried out and a classification of the possible types of repairs of the turbine rotors is presented, starting off from the causes and ways of presentation of the faults/deterioration of the rotor materials during the operation of the turbine. With base on the damages detected in the rotor of a gas turbine of 20.65 MW, the development of the repairing technology carried out by weld in site is presented. After the repair process, the rotor was put again in operation. [Spanish] En este articulo se presenta un analisis de los danos tipicos en rotores de turbinas de vapor y de gas fabricados con aceros de baja aleacion al Cr-Mo-V. Se lleva a cabo un analisis de la soldabilidad de los aceros al Cr-Mo-V y se presenta una clasificacion de los posibles tipos de reparaciones de los rotores de turbinas, partiendo de las causas y modos de presentacion de las fallas/deterioro del material de los rotores durante la operacion de la turbina. Con base en los danos detectados en el rotor de una turbina de gas de 20.65 MW, se presenta el desarrollo de la tecnologia de reparacion por soldadura llevada a cabo en sitio. Despues del proceso de reparacion, el rotor fue puesto nuevamente en servicio.

  2. The influences of the parameters in the welding process to the refinement of the zone by affected the temperature in the Cr-Mo-V steels; Influencia de los parametros del proceso de soldadura a la refinacion de la zona afectada por la temperatura en los aceros al Cr-Mo-V

    Mazur Czerwiec, Zdzislaw

    2001-07-01

    The Cr-Mo-V fissure of the unions by welding that operate at high temperature and elevated pressure is an important problem. The behavior of the unions by welding in both cases during the process of welding and during its operation, depends strictly on the microstructure of the zone affected by the temperature (ZAT) of the base metal, which for a given chemical composition of the material it is a function of the weld parameters and geometry of the union. A prediction methodology of the microstructure of the zone affected by the temperature (ZAT) in a fillet weld applied to the low alloy steel 1.25 Cr-1 Mo-0.25 V by the process of weld with protected electrical arc (SMAW) is presented. The bases for the development of the algorithm were the classic equations of heat transference to determine the welding thermal cycles, basic metallurgy including transformation of the phases and grains' growth, empirical relations to describe the correlation of the variables of the weld process and the dimensions of the weld fillet. By means of an experiment, it was analyzed and determined the variation of the geometry of the singular weld fillet applied to the 1.25 Cr-1 Mo-0.25 V steel by means of the SMAW process and the microstructure of the zone affected by the temperature (ZAT) based in function of the heat induction and the preheating temperature. The empirical results were used for the numerical prediction of the microstructure of the zone affected by the temperature (ZAT) based on the weld parameters. It was found that the prediction methodology of the microstructure of the zone affected by the temperature (ZAT) in a fillet weld applied to a heavy plate of the low alloy steel 1.25 Cr-1 Mo-0.25 V by the SMAW process, with base in the knowledge of the dimensions of the weld fillet variables of the weld process and basic metallurgy of the ZAT, predicts the distribution of the microstructure in the reasonable ZAT for certain parameters of the weld. It was also found that the

  3. Influencia del acabado superficial sobre el comportamiento tribológico de capas nitrocarburadas en acero X40CrMoV5 1

    Miguel, V.

    2005-12-01

    Full Text Available In this work the surface roughness behaviour in the forming of gaseous nitrocarburized layers has been analyzed. Ra values from 0.02 to 1.50 μm. has been considered. Obtained results prove a minor influence on layer thickness. A little increase of Ra has been observed. The abrasive wear resistance of nitrocarburized specimens was researched. The carbonitride ε is the only constituent in the about 6 μm thickness layers that have been carried out in this work. The tests revealed a minor wear resistance of the external part in the layers. This way, the external zone is less effective to wear phenomena than the internal. The specimens with small roughness parameters values show a higher poor wear resistance zone.

    En este trabajo se estudia la influencia que el acabado superficial del acero X40CrMoV5 1 tiene sobre la capa blanca o de combinación formada en el proceso de la nitrocarburación gaseosa. Se consideran acabados superficiales en el rango de 0,02 a 1,50 μm para Ra. Los resultados obtenidos indican que la rugosidad aumenta en todos los casos, aunque tiene poca influencia sobre el espesor de capa formada. También se ha investigado el comportamiento frente al desgaste abrasivo de las capas obtenidas que están constituidas en su totalidad por nitrocarburo ε y son de un espesor aproximado de 6 μm. Se ha encontrado un comportamiento diferenciado frente al desgaste de la zona externa de la capa frente a la zona subsuperficial. Los resultados revelan que la capa externa de la capa de combinación es poco efectiva frente al desgaste en relación con la capa subsuperficial. La zona de peor comportamiento es mayor para las probetas con acabados superficiales más finos.

  4. Estudio de la transformación martensítica, optimización de la microestructura y prevención de la rotura frágil en piezas coladas de acero X38CrMoV5-1 de alta resistencia

    Pastor Muro, Ana

    2015-01-01

    La presente tesis trata sobre el "Estudio de la transformación martensítica, optimización de la microestructura y prevención de la rotura frágil en piezas coladas de acero X38CrMoV5-1 de alta resistencia”. El acero X38CrMoV5-1/AISI H11 es un acero martensítico al cromo-vanadio-molibdeno para trabajo en caliente fácilmente endurecible, que se fabrica generalmente por moldeo con la consiguiente presencia de porosidad interdendrítica. La primera parte de la tesis consiste en una introducción don...

  5. Transformaciones de inequilibrio producidas por ciclos anisotérmicos en aceros inoxidables martensíticos tipo 13Cr y 14CrMoV

    Álvarez Moreno, Luisa Fernanda

    1991-01-01

    Diversas investigaciones en el campo de las transformaciones de inequilibrio en estado sólido han intentado buscar explicación a ciertos comportamientos atípicos observados en el desarrollo de la transformación martensítica de aceros aleados con elementos carburíqenos, tales como el cromo, molibdeno, vanadio y wolframio. En estos aceros aleados, la transformación anisotérmica de la austenita en rnartensita no se realiza de forma continua durante el enfriamiento en un intervalo determinado de ...

  6. High purity Cr-Mo-V steels for bolting applications

    A ductility trough is normally observed in Cr-Mo-V steels under creep at around 10 000 hrs at 5500C. Residual levels of lead and bismuth have been found to have a major effect on the ductility. By use of double vacuum melting (VIM-VAR) low residual levels are attained and the normal ductility trough is removed

  7. Hot cracking studies on CrMoV and NiCrMoV turbine rotor steels during welding

    Four different rotor materials, three CrMoV steels and a NiCrMoV steel, were investigated both with respect to solidification and HAZ liquation cracking. It involved the Varestraint testing using autogeneous gas tungsten arc welding at two different heat inputs, and metallographic examinations using optical, scanning and/or transmission electron microscopy. An increase in heat input/unit length (from 1.2 to 2.7 KJ/mm) or an increase in travel speed at the same low heat input (1.2 KJ/mm) tends to produce more solidification cracking. In the case of CrMoV steels, 1950s air melted rotors (Buck and the Gallatin rotors) showed worse solidification cracking susceptibility than the modern Bethlehem forging vacuum poured, 2A. The modern NiCrMoV forging, also vacuum-poured, 3A, however, showed worse solidification cracking susceptibility than the old air-melted Gallatin rotor. Therefore, the harmful effects of Ni on solidification cracking was confirmed. Its role is understood as having favored the austenite formation, thus resulting in more primary austenite solidification. This gives rise to heavy segregation of impurities such as S and P at the austenite grain boundaries. Detrimental effects of sulfur and phosphorus both on solidification and the HAZ hot cracking were confirmed. Addition of Ce or Ti to the Buck rotor with the greatest solidification cracking susceptibility helped improve cracking resistance

  8. Hot cracking studies on CrMoV and NiCrMoV turbine rotor steels during welding

    Yoo, S.Y.

    1986-01-01

    Four different rotor materials, three CrMoV steels and a NiCrMoV steel, were investigated both with respect to solidification and HAZ liquation cracking. It involved the Varestraint testing using autogeneous gas tungsten arc welding at two different heat inputs, and metallographic examinations using optical, scanning and/or transmission electron microscopy. An increase in heat input/unit length (from 1.2 to 2.7 KJ/mm) or an increase in travel speed at the same low heat input (1.2 KJ/mm) tends to produce more solidification cracking. In the case of CrMoV steels, 1950s air melted rotors (Buck and the Gallatin rotors) showed worse solidification cracking susceptibility than the modern Bethlehem forging vacuum poured, 2A. The modern NiCrMoV forging, also vacuum-poured, 3A, however, showed worse solidification cracking susceptibility than the old air-melted Gallatin rotor. Therefore, the harmful effects of Ni on solidification cracking was confirmed. Its role is understood as having favored the austenite formation, thus resulting in more primary austenite solidification. This gives rise to heavy segregation of impurities such as S and P at the austenite grain boundaries. Detrimental effects of sulfur and phosphorus both on solidification and the HAZ hot cracking were confirmed. Addition of Ce or Ti to the Buck rotor with the greatest solidification cracking susceptibility helped improve cracking resistance.

  9. A study on the continuous low cycle fatigue properties of 1%Cr-Mo-V steel and 12%Cr-Mo-V steel used in turbine rotors

    Continuous low cycle fatigue properties of 1%Cr-Mo-V steel and 12%Cr-Mo-V steel used in turbine rotors were investigated at 298, 773 and 873K in air atmosphere. The microstructure of 1%Cr-Mo-V steel and 12%Cr-Mo-V steel consisted of tempered upper bainite and tempered martensite, respectively. The experimental results show that the effect of the directionality of rotor on the fatigue life was rarely observed. The fatigue life of 1%Cr-Mo-V steel is significantly reduced at high temperature with decreasing plastic strain range, and the reason is considered to be the earlier crack initiation by oxidation damage. However, the effect of temperature on the fatigue life 12%Cr-Mo-V steel is known to be not existing throughout all the plastic strain range. This is suggested to be concerned with the increasing plastic ductility in tensile test with increasing test temperatures. (Author)

  10. Improved superclean NiCrMoV rotor steel

    Bodnar, R.L.; Hansen, S.S.; Michael, J.R.; Steigerwalt, R.E. (Bethlehem Steel Corp., PA (USA). Homer Research Lab.)

    1990-07-01

    Due to its excellent creep rupture properties and relative economy, silicon-deoxidized, tempered bainitic 1%CrMoV steel is currently used extensively for high-temperature steam turbine rotor forgings operating at temperatures up to 565{degree}C. However, there is considerable impetus to improve the toughness of this steel while maintaining its current level of creep rupture strength and vice versa. The toughness of 1%CrMoV steel is improved by lowering the bainite start (B{sub s}) temperature in a superclean' base composition which is essentially free of Mn, Si, P, S, Sb, As and Sn. The B{sub s} temperature can be lowered through the addition of alloying elements (i.e. C, Ni, Cr and Mo). Through suitable alloy additions, the 50% FATT of this grade was lowered from approximately 100{degree}C to below room temperature. This improved toughness provides the opportunity to eliminate the special precautionary procedures currently used in the startup and shutdown of steam turbines. In general, the creep rupture strengths of these new superclean' steels equal or exceed that of the standard 1%CrMoV steel. In addition, the superclean' steels have not been found to be susceptible to temper embrittlement, and have similar room temperature fatigue crack propagation characteristics and elevated tensile properties to the standard 1%CrMoV steel. The most promising steels in terms of a balance between creep rupture and toughness properties contain 2.5% Ni and 0.03%/0.04% Nb (for austenite grain refinement and enhanced tempering resistance), i.e. 2.5NiCrMoVNb steel. These new steels may also find application in combination high-temperature -- low-temperature rotors and gas turbine rotors. 106 refs., 34 figs., 10 tabs.

  11. Nonequilibrium grain-boundary cosegregation of nitrogen and chromium in NiCrMoV steel

    Zheng, Lei; Xu, Tingdong

    2005-12-01

    It is concluded in this article that nonequilibrium grain-boundary cosegregation (NCGS) of nitrogen and chromium occurs in NiCrMoV steel. That conclusion is reached from experimental observations of the parallel segregation isotherms and the maximum coverage of Cr and N at grain boundaries during the isotherms. This means that the nonequilibrium segregation of Cr induces that of N, in NiCrMoV steel.

  12. Structure optimization and damage behaviour of heat-resistant CrMoV-steels

    The object of the investigations was to optimize the heat treatment conditions of steel 12 CrMoV 4 3 (around 0,12% C; 1% Cr; 0,3% Mo; 0,25% V) on the basis of known structure-property relations of heat resistant steel-CrMoV in such way that the performance of this steel relating to its long-term heat resistance is completely utilized. Further, the influence of heat treatment or of the initial structure was analyzed as well as of further factors on the evolution of damages by formation of pores due to creep. (orig.)

  13. Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint

    In this paper, the fracture toughness and the related microstructure characteristics of dissimilarly welded joint manufactured by advanced 9Cr and CrMoV steels were systematically investigated. The dissimilarly welded joint was fabricated by narrow gap submerged arc welding (NG-SAW) applying multi-layer and multi-pass technique. Fracture toughness, as one of the most important property to assess the reliability of welded joint, was studied for different regions including CrMoV base metal (CrMoV-BM), heat affected zone (HAZ) of CrMoV side (CrMoV-HAZ), weld metal (WM), heat affected zone of 9Cr side (9Cr-HAZ) and 9Cr base metal (9Cr-BM). It was found that the fracture toughness of CrMoV-BM, CrMoV-HAZ and WM was better than that of 9Cr-HAZ and 9Cr-BM. In order to illustrate these results, the microstructure of the whole welded joint was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) detailedly. It was found that the fine high-temperature tempered martensite and bainite in WM, CrMoV-BM and CrMoV-HAZ contribute to the higher fracture toughness, while lower fracture toughness for 9Cr-BM and HAZ was caused by coarse tempered lath-martensite. Furthermore, the fracture morphology showed that ductile fracture occurred in WM and CrMoV side, while brittle fracture appeared in BM and HAZ of 9Cr side

  14. Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint

    Guo, Qian [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Fenggui, E-mail: Lfg119@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Xia [Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240 (China); Yang, Renjie [Shanghai Turbine Works Company, Shanghai 200240 (China); Cui, Haichao [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yulai, E-mail: ylgao@shu.edu.cn [State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai 200072 (China)

    2015-06-25

    In this paper, the fracture toughness and the related microstructure characteristics of dissimilarly welded joint manufactured by advanced 9Cr and CrMoV steels were systematically investigated. The dissimilarly welded joint was fabricated by narrow gap submerged arc welding (NG-SAW) applying multi-layer and multi-pass technique. Fracture toughness, as one of the most important property to assess the reliability of welded joint, was studied for different regions including CrMoV base metal (CrMoV-BM), heat affected zone (HAZ) of CrMoV side (CrMoV-HAZ), weld metal (WM), heat affected zone of 9Cr side (9Cr-HAZ) and 9Cr base metal (9Cr-BM). It was found that the fracture toughness of CrMoV-BM, CrMoV-HAZ and WM was better than that of 9Cr-HAZ and 9Cr-BM. In order to illustrate these results, the microstructure of the whole welded joint was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) detailedly. It was found that the fine high-temperature tempered martensite and bainite in WM, CrMoV-BM and CrMoV-HAZ contribute to the higher fracture toughness, while lower fracture toughness for 9Cr-BM and HAZ was caused by coarse tempered lath-martensite. Furthermore, the fracture morphology showed that ductile fracture occurred in WM and CrMoV side, while brittle fracture appeared in BM and HAZ of 9Cr side.

  15. Predicción numérica de la microestructura de la zona afectada por el calor (ZAC) durante el proceso de soldeo SMAW en el acero al Cr-Mo-V

    Mazur, Z.; Salazar, O.; González, G.; Urquiza, G.

    2001-01-01

    Cracking associated with welds operating in high temperatures and high pressure, is a problem of consideration. The performance of welded joints, both during fabrication and operation depends strictly upon the microstructure of the heat-affected zone (HAZ), which, in a steel of a given composition, is a function of welding conditions and joint geometry. The methodology of prediction of the dimensions of the zones containing different sizes in the HAZ grain of a single-bead weld of 1.25Cr-1Mo-...

  16. Predicción numérica del afino de los granos en la zona afectada por la temperatura (ZAC) para aportes de multipasadas durante el proceso de soldeo SMAW en el acero al Cr-Mo-V

    Mazur, Z.; González, G.; Urquiza, O.; Salazar, O.; Marino, C; Hernández, A,

    2002-01-01

    The methodology of prediction of the heat-affected zone (HAZ) microstructure in a multiple-bead welds of the two layers of 1.25Cr-1Mo-0.25V steel using SMAW deposition process is presented. A computer program was developed to calculate extension zones of interest of two layer multipass weld-beads HAZ and predict a percentage of HAZ coarse grains refinement for determined welding parameters, preheating temperature and weldbead overlap. The computer model has been validated by experiment deposi...

  17. Influence of phosphorus, aluminium and boron on the property profile of hot-work tool steel X38CrMoV5-1; Einfluss von Phosphor, Aluminium und Bor auf das Eigenschaftsprofil des Warmarbeitsstahls X38CrMoV5-1

    Ernst, C. [Edelstahl Witten-Krefeld GmbH, Werke Krefeld und Witten (Germany)

    1996-10-14

    The influence of P, Al, and B on various properties of the hot forging steel X38CrMoV5-1 has been investigated. Experimental results are given for hardness, toughness, and creep strength. It is shown that P additions lead to lower toughness in impact bending and notch impact bending testing. Increasing B concentration leads to deterioration in continuous casting and hot working. Al concentrations below 0.096% do not change steel properties.

  18. Metallographic etching and microstructure characterization of NiCrMoV rotor steels for nuclear power

    Liu, Peng; Lu, Feng-gui; Liu, Xia; Gao, Yu-lai

    2013-12-01

    The grain size of prior austenite has a distinct influence on the microstructure and final mechanical properties of steels. Thus, it is significant to clearly reveal the grain boundaries and therefore to precisely characterize the grain size of prior austenite. For NiCrMoV rotor steels quenched and tempered at high temperature, it is really difficult to display the grain boundaries of prior austenite clearly, which limits a further study on the correlation between the properties and the corresponding microstructure. In this paper, an effective etchant was put forward and further optimized. Experimental results indicated that this agent was effective to show the details of grain boundaries, which help analyze fatigue crack details along the propagation path. The optimized corrosion agent is successful to observe the microstructure characteristics and expected to help analyze the effect of microstructure for a further study on the mechanical properties of NiCrMoV rotor steels used in the field of nuclear power.

  19. Thermal Stability of Nanocrystalline Structure In X37CrMoV5-l Steel

    Skołek E.; Marciniak S.; Świątnicki W.A.

    2015-01-01

    The aim of the study was to investigate the thermal stability of the nanostructure produced in X37CrMoV5-1 tool steel by austempering heat treatment consisted of austenitization and isothermal quenching at the range of the bainitic transformation. The nanostructure was composed of bainitic ferrite plates of nanometric thickness separated by thin layers of retained austenite. It was revealed, that the annealing at the temperature higher than temperature of austempering led to formation of ceme...

  20. Comparison of the abrasion wear resistance of the X40CrMoV5-1 and 55NiCrMoV7 hot work tool steel with their surface layer enriched with the ceramic powders

    L.A. Dobrzański; E. Jonda; A. Polok

    2006-01-01

    Purpose: In the paper there are presented the results of the influence of laser remelting parameters on the properties of the surface layer of the X40CrMoV5-1 and 55NiCrMoV7 hot work steel, using the high power diode laser (HPDL).The aim of this work was to compare the abrasion wear resistance of the X40CrMoV5-1 and 55NiCrMoV7 hot work tool steel surface layers enriched with the TiC, WC and VC ceramic powders. The surface layers of hot work tool steel remelted with a diode laser beam have be...

  1. Crack propagation in X38CrMoV5 (AISI H11) tool steel

    Shah, Masood; Mabru, Catherine; Boher, Christine; Le Roux, Sabine; Rezaï-Aria, Farhad

    2009-01-01

    A method is proposed for the evaluation of surface fatigue damage of hot forming tools that undergo severe thermo mechanical loading. Fatigue crack propagation in a hot work tool steel X38CrMoV5-47HRC is investigated using single-edge cracked tension specimens (SET). The effect of thickness (ranging from 2,5mm to 0.10mm) and R values is investigated. Numerical simulation is performed by ABAQUS® Standard to evaluate J integral and stress intensity factor KI. The Paris curves are established. S...

  2. Microscopical investigation of steamside oxide on X20CrMoV121 superheater tubes

    Montgomery, Melanie; Hansson, Anette Nørgaard; Jensen, Søren A.;

    2011-01-01

    X20CrMoV121 is a 12%Cr martensitic steel which has been used in power plants in Europe for many decades. Superheater tubes exposed for various durations up to 135,000 hours in power plants in Denmark at steam temperatures varying from 450 to 575°C were investigated. Light optical and scanning...... electron microscopy was used to investigate steamside oxide morphologies. At all temperatures there is a double layered oxide, however, the inner:outer oxide thickness is not always equal. At the lower steam temperature range of...

  3. Welding repair of the steam and gas turbines rotors made of Cr-Mo-V steel

    An analysis of typical steam turbine and gas turbine rotor failures is carried out. On the base of the rotors different failure causes and their mode of occurring, an evaluation of the weldability of the Cr-Mo-V steels and the classification of the common turbine rotors repair possibilities is presented. The developing of specific in-situ welding repair process of the damaged 20.65 MW gas turbine rotor is described. After repair, the rotor was put back into service. (Author) 15 refs

  4. Analysis variations for steel 26 NiCrMoV 14 5

    Development of a new NiCrMoV steel containing 2.7% nickel and 2.5% chromium with very low susceptibility to temper brittleness as a material for the manufacture of large-diameter generator and turbine shafts. Tests with 6 m long shafts with 1900 and 1500 mm diameter. Shift of the transition temperature ΔFATT to about 00C. Yield strength values above 700 N/mm2. Transition temperature FATT (axial) -250C in the core and -1000C at the rim. (orig.)

  5. Investigation on Mechanical Properties of 9%Cr/CrMoV Dissimilar Steels Welded Joint

    Liu, Xia; Lu, Fenggui; Yang, Renjie; Wang, Peng; Xu, Xiaojin; Huo, Xin

    2015-04-01

    Advanced 9%Cr steel with good heat resistance and CrMoV with good toughness were chosen as candidate materials to fabricate combined rotor for steam turbine operating at over 620 °C. But the great difference in base metals properties presents a challenge in achieving sound defect-free joint with optimal properties in dissimilar welded rotor. In this paper, appropriate selection of filler metal, welding parameters, and post-weld heat treatment was combined to successfully weld 1100-mm-diameter 9%Cr/CrMoV dissimilar experimental rotor through ultra-narrow gap submerge arc welding. Some properties such as hardness, low-cycle fatigue (LCF), and high-cycle fatigue (HCF) combined with microstructural characterization qualify the integrity of the weld. Microstructural analysis indicated the presence of high-temperature tempered martensite as the phase responsible for the improved properties obtained in the weld. The Coffin-Manson parameters were obtained by fitting the data in LCF test, while the conditional fatigue strength was derived from the HCF test based on S-N curve. Analysis of hardness profile showed that the lowest value occurred at heat-affected zone adjacent to base metal which represents the appropriate location of fracture for the samples after LCF and HCF tests.

  6. Metallographic etching and microstructure characterization of NiCrMoV rotor steels for nuclear power

    Peng Liu; Feng-gui Lu; Xia Liu; Yu-lai Gao

    2013-01-01

    The grain size of prior austenite has a distinct influence on the microstructure and final mechanical properties of steels. Thus, it is significant to clearly reveal the grain boundaries and therefore to precisely characterize the grain size of prior austenite. For NiCrMoV rotor steels quenched and tempered at high temperature, it is really diffi cult to display the grain boundaries of prior austenite clearly, which limits a further study on the correlation between the properties and the corresponding microstructure. In this paper, an eff ective etchant was put forward and further optimized. Experimental results indicated that this agent was eff ective to show the details of grain boundaries, which help analyze fatigue crack details along the propagation path. The optimized corrosion agent is successful to observe the microstructure characteristics and expected to help analyze the eff ect of microstructure for a further study on the mechanical properties of NiCrMoV rotor steels used in the field of nuclear power.

  7. Experimental and numerical investigations of the creep behaviour of the dissimilar weldment GS-17 CrMoV 5 11 and X 20 CrMoV 12 1

    In the collaborative programme between MPA, Stuttgart, and the Institute for Materials Science and Welding Technology at the Technical University, Graz, within the framework of COST 505 'Materials for Steam Turbines', the creep-rupture behaviour of teh dissimilar weldment 1% CrMoV/12% CrMoV was investigated. Independent of the effects given by the welding process, weld metal and post weld heat treatment, the fine-grained zone in the HAZ of the lower alloyed steel grade was life-determining after long-time creep loading. The decarburized coarse grained HAZ near the fusion line is critical at higher stress levels, e.g. breakdowns. (orig.)

  8. Microstructural parameters and yielding in a quenched and tempered Cr-Mo-V pressure vessel steel

    In this work the plastic deformation behaviour of a Cr-Mo-V pressure vessel steel is studied at ambient and low temperatures. To produce a wide range of microstructures, different austenitizing, quenching and tempering treatments are performed. The microstructures, including grain and dislocation structures as well as carbides, are evaluated. A qualitative model is proposed for the martensitic and bainitic transformations explaining the morphology and crystallography of the transformation products. Based on microstructural observations of undeformed and deformed materials, as well as the tensile test results, the role of various obstacles to dislocation motion in plastic deformation is evaluated. Finally the strength increment, its temperature dependence and the effect due to combinations of various obstacles are analyzed. The results are intended to serve as basis for further fracture behaviour analyses. (author)

  9. Carbide precipitation, grain boundary segregation, and temper embrittlement in NiCrMoV rotor steels

    Bandyopadhyay, N.; Briant, C. L.; Hall, E. L.

    1985-05-01

    This paper presents a study of carbide precipitation, grain boundary segregation, and temper embrittlement in NiCrMoV rotor steels. One of the steels was high purity, one was doped with phosphorus, one was doped with tin, and one was commercial purity. In addition, two NiCrV steels, one high purity and one doped with phosphorus, were examined. Carbide precipitation was studied with analytical electron microscopy. It was found that after one hour of tempering at 600 ‡C only M3C carbides were precipitated in the NiCrMoV steels. These were very rich in iron. As the tempering time increased, the chromium content of the M3C carbides increased significantly, but their size did not change. Chromium rich M7C3 precipitates began to form after 20 hours of tempering, and after 50 hours of tempering Mo-rich M2C carbides were precipitated. Also, after 100 hours of tempering, the matrix formed bands rich in M3C or M7C3 and M2C particles. Tempering occurred more rapidly in the NiCrV steels. Grain boundary segregation was studied with Auger electron spectroscopy. It was found that the amount of phosphorus and tin segregation that occurred during a step-cooling heat treatment after tempering was less if a short time tempering treatment had been used. It will be proposed that this result occurs because the low temperature tempering treatments leave more carbon in the matrix. Carbon then compctes with phosphorus and tin for sites at grain boundaries. This compctition appears to affect phosphorus segregation more than tin segregation. In addition to these two impurity elements, molybdenum and nickel segregated during low temperature aging. The presence of molybdenum in the steel did not appear to affect phosphorus segregation. Finally, it will be shown that all of the steels that contain phosphorus and/or tin exhibit some degree of temper embrittlement when they are aged at 520 ‡C or are given a step-cooling heat treatment. Of the NiCrMoV steels, the phosphorus-doped steel showed

  10. Stress corrosion crack growth in NiCrMoV turbine disc steels

    Mcminn, A.; Lyle, F.F. Jr.; Leverant, G.R.

    1985-09-01

    The effects of metallurgical and environmental variables on stress corrosion crack growth rates in NiCrMoV turbine disc steels is examined. Steels with yield strengths of 627-1124 MPa were tested at 157 C in either pure water environments or in environments containing the ionic contaminants NaCl and NaOH and gaseous contaminants, such as air, oxygen, and carbon dioxide. The chemical composition of the metals tested and the test procedures are described. Maximum crack growth rates of all the materials in each environment are presented. The results revealed that yield strength, temper embrittlement, and the composition of the environment influence crack growth rate; however, the composition of the alloy is only significant in specific environments. Two proposed damage mechanisms for environmentally assisted cracking in low alloy steels, anodic dissolution and hydrogen embrittlement, are discussed. 28 references.

  11. The influence of chemical constitution on abrasive wear of alloy cast steel Cr, Mo, V, Cu, Ni type

    In the work were presented some elements of a wide research programme of the influence of alloying element contents such as Cr, Mo, V on the abrasive wear of hot working cast steel. The dependence between the mass decrement quantity and the element contents on cast steel structure were shown. (author)

  12. The abrasive wear dependence research on chemical constitution, hardness and resistance of alloy cast steel Cr-Mo-V-Cu-Ni type

    In the work there are research program elements, alloying elements contents influence on abrasive wear for hot work. The aim of research is to define the hardness influence, resistance and contents of Cr, Mo, V on alloy cast steel abrasive wear Cr-Mo-V-Cu-Ni. (author)

  13. Thermal Stability of Nanocrystalline Structure In X37CrMoV5-l Steel

    Skołek E.

    2015-04-01

    Full Text Available The aim of the study was to investigate the thermal stability of the nanostructure produced in X37CrMoV5-1 tool steel by austempering heat treatment consisted of austenitization and isothermal quenching at the range of the bainitic transformation. The nanostructure was composed of bainitic ferrite plates of nanometric thickness separated by thin layers of retained austenite. It was revealed, that the annealing at the temperature higher than temperature of austempering led to formation of cementite precipitations. At the initial stage of annealing cementite precipitations occurred in the interfaces between ferritic bainite and austenite. With increasing temperature of annealing, the volume fraction and size of cementite precipitations also increased. Simultaneously fine spherical Fe7C3 carbides appeared. At the highest annealing temperature the large, spherical Fe7C3 carbides as well as cementite precipitates inside the ferrite grains were observed. Moreover the volume fraction of bainitic ferrite and of freshly formed martensite increased in steel as a result of retained austenite transformation during cooling down to room temperature.

  14. On the overaging behaviour of tool steel X38 CrMoV 5-3

    In this study, a combination of small-angle neutron scattering, energy-filtered and conventional transmission electron microscopy and X-ray diffraction has been used to characterize the overaging behaviour of the hot-work tool steel X38 CrMoV 5-3. Hot-work tool steels are mainly used for hot-forging dies, casting dies and extruding tools where high strength is required at high service temperatures. As a consequence, thermal fatigue and softening play the most important role with regard to tool life, and they are strongly influenced by coarsening of the nanometer-sized secondary hardening carbides. The microstructural response to three different overaging treatments in the temperature range of 650-680 deg. C has been analyzed regarding precipitate types, particle size distributions and corresponding volume fractions. The combination of the different methods used in this study enables a very precise determination of these parameters. This allows for a profound discussion on the evolution of particles occurring in the analyzed samples

  15. On the overaging behaviour of tool steel X38 CrMoV 5-3

    Bischof, Michael [Montanuniversitaet, Department of Physical Metallurgy and Materials Testing, Franz Josef-Strasse 18, A-8700 Leoben (Austria)], E-mail: michael.bischof@hilti.com; Staron, Peter [GKSS Research Center, Max-Planck-Strasse 1, Geesthacht (Germany); Caliskanoglu, Devrim [Boehler Edelstahl GmbH, Mariazellerstrasse 25, Kapfenberg (Austria); Leitner, Harald; Scheu, Christina; Clemens, Helmut [Montanuniversitaet, Department of Physical Metallurgy and Materials Testing, Franz Josef-Strasse 18, A-8700 Leoben (Austria)

    2008-01-15

    In this study, a combination of small-angle neutron scattering, energy-filtered and conventional transmission electron microscopy and X-ray diffraction has been used to characterize the overaging behaviour of the hot-work tool steel X38 CrMoV 5-3. Hot-work tool steels are mainly used for hot-forging dies, casting dies and extruding tools where high strength is required at high service temperatures. As a consequence, thermal fatigue and softening play the most important role with regard to tool life, and they are strongly influenced by coarsening of the nanometer-sized secondary hardening carbides. The microstructural response to three different overaging treatments in the temperature range of 650-680 deg. C has been analyzed regarding precipitate types, particle size distributions and corresponding volume fractions. The combination of the different methods used in this study enables a very precise determination of these parameters. This allows for a profound discussion on the evolution of particles occurring in the analyzed samples.

  16. Thermal diffusivity of X153CrMoV12 - a methodological study

    Full text: The main target of a recent research project in cooperation with Boehler Edelstahl GmbH and Co KG is to compare different methods for thermal diffusivity measurements of highly alloyed steels. For this reason, thermal diffusivity is on one hand directly measured via Laser Flash Analysis (LFA) and, on the other hand, indirectly calculated from electrical resistivity using the Wiedemann-Franz-Law. Therefore, electrical resistivity (in the solid and the liquid states) needs to be known and is within the frame of this investigation measured using a fast pulse-heating apparatus. However, material-dependent lattice contributions of yet unknown magnitude need to be accounted for. A relation between direct and indirect methods is sought after to improve measurements and simulations using the Wiedemann-Franz-Law. As a first step, a X153CrMoV12 steel of industrial relevance is investigated using both mentioned methods. The measured diffusivity results will be compared and presented within this study. The examination of other alloys is in preparation and will possibly help to quantify these lattice contributions for selected groups of alloys. (author)

  17. Carbide evolution in temper embrittled NiCrMoV bainitic steel

    Wittig, J.E. [Vanderbilt Univ., Dept. of Electrical Engineering, Nashville, TN (United States); Sinclair, R. [Stanford Univ., Dept. of Materials Science, Palo Alto, CA (United States)

    2004-01-01

    Phosphorus segregation to prior austenite grain boundaries in low alloy steel from exposure to temperatures of 300 to 600 C results in a susceptibility for intergranular fracture referred to as ''temper embrittlement''. It has been observed that alloying steel with Mo greatly reduces the phosphorus segregation kinetics. Therefore changes in the ferrite matrix composition from carbide precipitation and evolution involving Mo can influence the segregation phenomenon and fracture properties. This study uses analytical electron microscopy of extraction replicas to characterize the changes in carbide chemistry of a NiCrMoV bainitic steel with 0.25 wt% C that accompany the phosphorus segregation during aging at 480 C for up to 3400 hr. The steel was doped with 0.02 wt% P and tempered at 650 C to two different hardness levels, i.e., two different initial carbide distributions. The amount of grain boundary phosphorus segregation produced by aging at 480 C correlates with the level of molybdenum that remains in solution in the ferritic matrix whereas changes in vanadium and chromium appear to have less influence on the temper embrittlement. (orig.)

  18. Comparison of the abrasion wear resistance of the X40CrMoV5-1 and 55NiCrMoV7 hot work tool steel with their surface layer enriched with the ceramic powders

    L.A. Dobrzański

    2006-02-01

    Full Text Available Purpose: In the paper there are presented the results of the influence of laser remelting parameters on the properties of the surface layer of the X40CrMoV5-1 and 55NiCrMoV7 hot work steel, using the high power diode laser (HPDL.The aim of this work was to compare the abrasion wear resistance of the X40CrMoV5-1 and 55NiCrMoV7 hot work tool steel surface layers enriched with the TiC, WC and VC ceramic powders. The surface layers of hot work tool steel remelted with a diode laser beam have been metallographically examined and analyzed with the use of a hardness testing machine.Design/methodology/approach: The high power diode laser (HPDL and ceramic powders WC, VC and TiC were used. Remelting and alloying processes were carried out at the constant remelting rate and focus shape, varying the laser beam power for the alloyed test pieces in the range from 1,2 – 2,3 kW.Findings: On the basis of the wear abrasion tests carried out on 55NiCrMoV7 and X40CrMoV5-1 steels it could be ascertained that each of those steels is characterized by different resistance for the same powders and the power of the laser beam. In the case of employing 1,2 kW laser, the surface layer formed using the majority of the investigated portions undergoes a total wear during the wear-rate test which also causes the wear of the initial material. When 2,3 kW is employed, the surface layers have crack and microcrack defections which decrease the resistance to the abrasion. The smallest mass loss for 55NiCrMoV7 steel among all the analyzed cases has been observed for the surface layers alloyed with TiC powder, at the of the laser beam power of 2,3 kW and for WC powder at 1,2 kW laser beam power. For the X40CrMoV5-1 steel the smallest mass decrement has been observed for the steel alloyed with WC powder at 1,2 kW laser beam power and VC powder at 1,6 kW laser beam power.Practical implications: The investigations showed that as a result of the applied laser processing there is the

  19. Experimental and numerical investigations of the creep behaviour of the dissimilar weldment GS-17 CrMoV 5 11 and X 20 CrMoV 12 1

    Buchmayr, B.; Cerjak, H.; Witwer, M. (Technische Univ., Graz (Austria). Abt. fuer Werkstoffkunde und Schweisstechnik); Maile, K.; Theofel, H.; Eckert, W. (Stuttgart Univ. (Germany, F.R.). Staatliche Materialpruefungsanstalt)

    1990-01-01

    In the collaborative programme between MPA, Stuttgart, and the Institute for Materials Science and Welding Technology at the Technical University, Graz, within the framework of COST 505 'Materials for Steam Turbines', the creep-rupture behaviour of teh dissimilar weldment 1% CrMoV/12% CrMoV was investigated. Independent of the effects given by the welding process, weld metal and post weld heat treatment, the fine-grained zone in the HAZ of the lower alloyed steel grade was life-determining after long-time creep loading. The decarburized coarse grained HAZ near the fusion line is critical at higher stress levels, e.g. breakdowns. (orig.).

  20. A study on life prediction and inelastic constitutive equation in creep-fatigue interaction of CrMoV rotor steel

    In this study, elevated temperature low cycle fatigue test were performed at operation temperature 550deg C under creep-fatigue interaction using the specimens of CrMoV steel for the turbine rotor manufactured by domestic. Life predicted by Linear Damage Summation Method and Strain Range Partitioning Method therefore it shows that the CrMoV rotor steel having a safety factor over 2 was possible. (Author)

  1. Oligocyclic fatigue resistance and time-dependent damage of 1CrMoV rotor steel; Resistenza a fatica oligociclica e danneggiamento tempo-dipendente di un acciaio per rotore 1CrMoV

    Be, C.A.; Bicego, V.; Ricci, N.; Ragazzoni, S.

    1988-12-31

    Results of extensive low cycle fatigue characterization of HP and LP stages of 1CrMoV steam turbine rotor steel are presented. The LP material showed a general inferior fatigue resistance, due to microstructural inhomogeneities which reduced material ductility. A softening behaviour was always observed which shortened the lives of specimens cycled at the lowest strain rates. In tests with long hold times, the presence of creep damage was recognized; this damage was effective in reducing endurances at least in low strain range tests.

  2. The effect of niobium contents on mechanical properties of the large forged Cr-Mo-V steel

    The effect of Niobium(Nb) contents on the mechanical properties of the CrMoV forgings was investigated as a preliminary study to manufacture large forgings having a low Fracture Appearance Transition Temperature(FATT) and high tensile strength. The experimental forgings were varied in the Nb contents as 0%(A), 003%(B) and 0.05%(C). The tensile strength at room temperature and 600 .deg. C were almost equal regardless of Nb contents, while the FATT lowered in order of alloy C(32 .deg. C), B(35 .deg. C), and A(62 .deg. C). These were resulted from the grain refining. The grain size of alloy A was ASTM no. 5.0 and those of B and C were ASTM no. 6.5 respectively. Based on the preliminary experimental results, large forgings containing 0.03%Nb(D) and 0.05%Nb(E) were manufactured from 30 ton ingot and then those mechanical properties were tested. The higher tensile strength was obtained in both D and E forgings, whereas, the FATT of D and E forgings were 33 deg. C and 67 .deg. C, respectively. The ductile fractured surfaces were developed in the forgings D, while serrated fractographes were alternately occurred with the eutectic niobium carbides and ductile dimples in the forgings E. The eutectic NbC and normal matrix were alternately developed in a severely Nb segregated region of the forgings E. The alternated structure might develop a serrate fracture surfaces, which caused forgings E to increase its FATT. Therefore, in order to manufacture large CrMoV forgings by adding Nb, Nb content to be added should be decided by considering segregation of Nb during solidification. The coarse eutectic niobium carbides were formed in the severely Nb segregated region. The serrated fracture might be caused to increase the FATT of large CrMoV forgings containing Nb

  3. Evolution of residual stresses during short time nitriding of 33CrMoV12-9 steel grade

    FALLOT, Guillaume; Jegou, Sébastien; Barrallier, Laurent

    2014-01-01

    The evolution of residual stresses during short time gas nitriding of 33CrMoV12-9 steel grade is studied. It aims understanding the influence of nitriding parameters (temperature T and nitriding potential Kn) on the generation and evolution of residual stresses in the very first stage of nitriding. The samples are gas nitrided using a thermobalance during 2h30 and 5 hours for various temperatures and nitriding potentials. Residual stress analyses are carried out by laboratory X-ray diffraction.

  4. The application of miniature disc testing for the assessment of creep damage in CrMoV rotor steel

    Parker, J.D.; Stratford, G.C. [University of Wales, Swansea (United Kingdom); Shaw, N.; Spink, G. [National Power plc (United Kingdom); Metcalfe, H. [Siemens Power Generation (United Kingdom)

    1998-12-31

    A range of critical experiments has been performed studying the creep and fracture behaviour of a typical CrMoV rotor steel. Initially, uniaxial tests were carried out to provide material with a predetermined level of creep damage. Then, miniature disc tests were undertaken under accelerated conditions in a similar manner to procedures used for post-exposure uniaxial testing of service components. Data analysis demonstrates that the miniature tests accurately reflect the damage present so that this approach can be used to support run/repair/replace decisions. (orig.) 8 refs.

  5. Structure and tribological behavior of surface layer of laser modified X40CrMoV5-1 steel

    L.A. Dobrzański; E. Jonda; K. Lukaszkowicz; A. Križ

    2006-01-01

    Purpose: The paper presents the effect of alloying with WC, TaC and TiC on structure and mechanical propertiesof the X40CrMoV5-1 steel surface layer using the HPDL (High Power Diode Laser).Design/methodology/approach: The microstructure of the alloyed layers which were formed on the surface ofthe investigated hot work steel was examined using optical microscope. The tribological wear relationships usingpin-on-disc test were specified for surface layers subject to laser treatment, determining ...

  6. Strain Energy Approach for Axial and Torsional Fatigue Life Prediction in Aged NiCrMoV Steels

    Song, Gee Wook; Hyun, Jung Seob; Ha, Jeong Soo

    Axial and torsional low cycle fatigue tests were performed for NiCrMoV steels serviced low-pressure turbine rotor of nuclear power plant. The results were used to evaluate multiaxial fatigue life models including Tresca, von Mises and Brown and Miller's critical plane. The fatigue life predicted by the multiaxial fatigue models didn't correspond with the experimental results in small strain range. We proposed the total strain energy density model to predict torsional fatigue life from axial fatigue data. The total strain energy density model was found to best correlate the experimental data with predictions being within a factor of 2.

  7. Development of a 2 1/4 Cr-Mo-V-Nb steel for heavy duty gas turbine rotor disk. Gas turbine disk yo 2 1/4 Cr-Mo-V-Nb tainetsuko no kaihatsu

    Tsuji, I.; Kadoya, Y. (Mitsubishi Heavy Industries, Ltd., Tokyo (Japan))

    1991-05-01

    A new low alloy steel for gas turbine rotor disk was menufactured as a trial and examined. A target of new low alloy steel development for disk was to have excellent stress rupture strength without taking account of creep below 400 centigrade, and to have excellent both high temperature strength (yield strength at 400 centigrade higher than 60kgf/mm {sup 2}) and fracture toughness (FATT lower than 40 centigrade) at bore of disk. An effect of chemical composition on mechanical properties and heat treatment characteristics of low allow steel were investigated. Consequently, a 2 {sup 1}/{sub 4} Cr-Mo-V-Nb steel containing low silicon manufactured by vacuum carbon deoxidization (VCD) or electroslag remelting (ESR) process showed the best performance for large size disk. On the basis of the results, the 2 {sup 1}/{sub 4} Cr-Mo-V-Nb steel disk for turbine was produced by commercial base. Tensile, impact, and metallurgical tests were conducted on the disk, and it was confirmed that the disk had excellent yield strength and impact properties at both rim and bore. 14 refs., 12 figs., 4 tabs.

  8. Melting of 3. 5% NiCrMoV superclean steel for extended operation temperatures. Hochreine Erschmelzung des 3,5%-NiCrMoV-Stahles zur Erweiterung der Einsatzgrenzen

    Berger, C. (Siemens AG Unternehmensbereich KWU, Muelheim an der Ruhr (Germany, F.R.). Bereich Technik, Werkstoffe); Mayer, K.H. (MAN Energie GmbH, Nuernberg (Germany, F.R.))

    1990-09-14

    The high-strength, ductile 3.5% NiCrMoV steel (26 NiCrMoV 14 5) which is used, for instance, for manufacturing turbine rotors and discs with diameters up to 2,800 mm, is susceptible to temper and long-term embrittlement at temperatures above 350deg C. This is due to the precipitation of P, Sn and Sb at the grain boundaries. The investigations were designed to show whether melting with low Mn, S, Si, P, Sn, Sb and As contents is possible for large rotors and could prevent this problem make it thus possible to extend the application range up to about 500deg C. Exposure tests of this superclean steel for periods of up to about 35,000 hours at 480deg C revealed no reduction of fracture toughness and a simultaneous increase in creep resistance and fatigue strength. Thus, this ductile and high-strength steel can be used to achieve a higher thermal efficiency, e.g. in low-pressure turbines, also at temperatures above 350deg C. In addition, the steel can be employed as a less expensive variant for service applications at temperatures up to 480 to 500deg C. (orig.).

  9. High temperature fatigue tests and crack growth in 40CrMoV13.9 notched components

    P. Gallo

    2015-10-01

    Full Text Available The present paper addresses experimentally the high temperature fatigue of 40CrMoV13.9 steel and the effect of surface roughness on fatigue strength and crack initiation. The 40CrMoV13.9 steel is widely used in different engineering high temperature applications among which hotrolling of metals, where, in order to assure a constant temperature, the rolls are provided with cooling channels. These are the most stressed zone of the rolls where cracks systematically initiate. In order to completely characterize the high temperature behaviour of this steel, firstly uniaxial-tension load controlled fatigue tests have been conducted at different temperatures up to 650°C. Two geometries are considered: plain specimens and plates weakened by symmetric V-notches. Subsequently, with the aim to investigate the influence of the cooling channels roughness on the high temperature behaviour and the cracks initiation, uniaxial-tension load controlled fatigue tests have been conducted on plate with central hole at the service temperature of 650°C varying the surface roughness. After a brief review of the recent literature, the experimental procedure is described in detail and the new data from un-notched and notched specimens are summarized in terms of stress range, at the considered temperatures. Finally, fatigue data from un-notched and notched specimens are re-analysed by means of the mean value of the Strain Energy Density (SED approach extended at high temperature.

  10. Effect of δ-ferrite on the low cycle fatigue behavior of 12CrMoV steel

    The 12CrMoV steel subjected to high temperature will inevitably contain some δ-ferrite. The presence of δ-ferrite in this steel has been known to lead to discontinuites in the mechanical properties because of compositional differences and lack of cohesin between δ-ferrite and tempered martensite matrix. The strain controlled fatigue test was carried out to investigate the effect of δ-ferrite on the low cycle fatigue behavior of the 12CrMoV steel at room temperature. Two different microstructures, tempered martensite with and without δ-ferrite, were developed by heat treatment schedules. The tensile properties for the two different specimen conditions were very similar. The cyclic behavior was characterized by softening and the plastic strain range vs. the number of reversals plots obeyed the Manson-Coffin relationship. The fatigue crack propagation mode was a transgranular. However, the specimen with δ-ferrite had a longer fatigue life than that without δ-ferrite. Introduction of δ-ferrite resulted in the increase of cyclic strain hardening exponent and the more plastic work required to failure. The δ-ferrite had influence on the crack path as a soft obstacle, which resulted that the crack passed around δ-ferrite. An excess energy was required to propagate the crack and led locally to a decrease in crack growth rate. Therefore, the presence of δ-ferrite in tempered martensite increased the resistance to crack propagation and resulted in the increase in fatigue life

  11. Tribological properties of anti-wear PVD coatings for elevated temperatures application deposited onto X37CrMoV5-1 type hot work steel

    The paper presents results of tribological and adhesion investigations of anti-wear PVD coatings TiN, TiN/(Ti,Al)N and CrN types deposited in ion plating PVD process onto X37CrMoV5-1 type hot work tool steel. It was found that damage mechanism during scratch test in all investigated coatings begins with multiple spallings located on the scratch edges followed by cracking and tool coatings delamination. Regarding to the coating types it can be seen different location of such damages and loads typical for them. According to this observations it can be stated that highest adhesion among investigated coating present, CrN monolayer coating and the lowest one multilayers Ti/(Ti,Al)N coating. The wear resistance was investigated by pin-on-disc method performed in room and elevated to 500 oC temperatures. It was found that the lowest wear in to fixed investigation conditions in both room and elevated temperatures shows TiN monolayer coating. Additionally one can see that TiN coatings application improve wear resistance some five times. (author)

  12. Effects of the pre-transformation microstructures on the grain refining of medium-carbon 5Cr-Mo-V steels; Chutanso 5Cr-Mo-V ko no gyaku hentai sairyuka ni oyobosu zenhentai soshiki no eikyo

    Mukauda, Y.; Shibata, T.; Ono, S.; Ishiguro, T. [Nippon Steel Works, Ltd., Tokyo (Japan)

    2000-07-01

    For the purpose of obtaining refined grains over full cross section for improved ductility in heavy-gage products of a medium carbon 5Cr- Mo-V steel, the effects of pre-transformation microstructures on the grain refining during austenitizing were investigated. Samples were prepared to possess either one of three different microstructures , pearlite, bainite and martensite. These samples were heated slowly to the desired austenitizing temperature followed by rapid cooling, and the formation of new austenite grains was examined. Though austenite grains were not refined in cases of martensite and bainite microstructures, these were remarkably refined in case of pearlite. Portions of pearlite were enriched with carbon, where the transformation temperature into austenite was lower, and this is considered to be the reason that finer austenite grains were formed.Above results show that arranging pearlite microstructure before quenching heat treatment is effective for obtaining refined grains over full cross section in heavy-gage products. (author)

  13. Strength and toughness of a shape-welded turbine shaft made of 20 NiCrMoV 14 5. Festigkeits- und Zaehigkeitseigenschaften einer formgeschweissten Turbinenwelle aus 20 NiCrMoV 14 5

    Kussmaul, K.; Imhof, W. (Stuttgart Univ. (Germany, F.R.). Staatliche Materialpruefungsanstalt)

    1989-04-01

    Shape welding, also known as shaping welding or shaping fusing, is a fabrication technology which allows to produce components of almost any shape, however preferably axially symmetrical, by built-up welding of layers on a dummy or auxiliary body. The report deals with mechanical-technological and fracture-mechanical properties of a shape-welded turbine shaft of 20 NiCrMoV 14 5. The results from fracture mechanical, notch impact and drop-weight tests, as well as mechanical brittle fracture and ductile fracture tests are presented and discussed. An increase of the values of toughness would be possible e.g. by reducing the share of not normalized, columnar structure ranges, which could be obtained by an optimized layer structure with flatter beads. (orig./MM).

  14. Comparison of the thermal fatigue surface layers of the X40CrMoV5-1 hot work tool steels laser alloyed

    L.A. Dobrzański; E. Jonda; A. Polok; A. Klimpel

    2007-01-01

    Purpose: The comparison of thermal fatigue and mechanical properties of the hot work tool steels alloyed with carbide powders has been presented. The effect of laser alloying with powders on the surface layers alloying with HPDL was evaluated.Design/methodology/approach: In this paper the result of laser surface alloying is discussed. The material used for investigation were hot work tool steels X40CrMoV5-1 and 55NiCrMoV7 alloyed with TiC or TaC using high power diode laser.Findings: Th...

  15. Microstructure Variation and Hardness Diminution During Low Cycle Fatigue of 55NiCrMoV7 Steel

    2007-01-01

    The influence of temperature and hardness level on the cyclic behavior of 55NiCrMoV7 steel, and the microstructure variation and hardness diminution during low cycle fatigue behavior were investigated. By means of SEM and XRD, the modality of carbides and the full-width half-maximum (FWHM) of martensite (211) [M(211)] of Xray diffraction spectrum in fatigue specimen were studied. The results showed that the cyclic stress response behavior generally showed an initial exponential softening for the first few cycles, followed by a gradual softening without cyclic softening saturation. The fatigue behavior of the steel is closely related to the hardness level. The hardnessdiminution and the variation of half-width M(211) are remarkably influenced by the interaction between the cyclic plastic deformation and the thermal loading when the fatigue temperature exceeds the tempering temperature of the steel.

  16. Type IIIa cracking at 2CrMo welds in 1/2CrMoV pipework

    Brett, S.J.; Smith, P.A. [National Power plc, Swindon (United Kingdom)

    1998-12-31

    The most common form of in-service defect found today on the welds of National Power`s 1/2CrMoV pipework systems is Type IV cracking which occurs in intercritically transformed material at the edge of the heat affected zone. However an alternate form of cracking, termed IIIa, which occurs close to the weld fusion line in fully grain refined heat affected zones, has also been observed. The incidence of Type IIIa cracking has increased in recent years and these defects now constitute a significant part of the total recorded crack population. This presentation describes Type IIIa cracking and compares and contrasts it with the better documented Type IV cracking. Particular reference is made to the role of carbon diffusion at the weld fusion line in promoting Type IIIa damage in preference to Type IV. (orig.) 5 refs.

  17. Stress corrosion cracking behavior of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    Maday, M.F.; Mignone, A.; Borello, A. (ENEA, Rome (Italy))

    1989-04-01

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) of two Ni-Cr-Mo-V Italian-made alloys that are materials used for low-pressure (LP) turbine discs in light water reactor (LWR) nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). The first set of experiments was conducted in pure deaerated caustic solutions in a static Ni autoclave system in order to determine the effects of temperature on NaOH concentration on the SCC behavior of these materials. In the second set of tests, the influence of dissolved oxygen on cracking in water was studied. Results showed that the minimum value of oxygen to promote SCC was lower for the heat with the higher Ni content and the larger grain size.

  18. Stress corrosion cracking behavior of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) of two Ni-Cr-Mo-V Italian-made alloys that are materials used for low-pressure (LP) turbine discs in light water reactor (LWR) nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). The first set of experiments was conducted in pure deaerated caustic solutions in a static Ni autoclave system in order to determine the effects of temperature on NaOH concentration on the SCC behavior of these materials. In the second set of tests, the influence of dissolved oxygen on cracking in water was studied. Results showed that the minimum value of oxygen to promote SCC was lower for the heat with the higher Ni content and the larger grain size

  19. Microstructural effects on the yield strength and its temperature dependence in a bainitic precipitation hardened Cr-Mo-V steel

    The plastic deformation behaviour of a precipitation hardened bainitic Cr-Mo-V steel is analyzed at ambient and low temperatures. The temperature dependent component of the yield strength is composed of the Peierls-Nabarro force and also partly of the strengthening contribution of the lath- and cell boundaries or the solid solution hardening. The temperature dependence below 230 K is in accordance with the models presented by Yanoshevich and Ryvkina as well as Dorn and Rajnak. The temperature independent component can be calculated merely from the dislocation density, which is stabilized by the vanadium-rich carbides. The linear additivity cannot be used for the superposition of the strengthening effects of various strengthening parameters, By using the phenomenological approach starting from the dislocation movement mechanisms upon yielding the laws for the superposition are discussed. (author)

  20. Analysis of life distribution by stress corrosion cracking of 3.5NiCrMoV steel forgings

    The stress corrosion cracking (SCC) life time of turbine rotors in actual nuclear and fossil power plants was analyzed by a statistical method and was estimated to obey an exponential probability distribution. Then, the laboratory accelerated test condition to exhibit such an exponential probability distribution was investigated using 3.5 NiCrMoV steel forgings which are being used most widely as a material for low pressure turbine rotors. The exposure of double U-bend specimens in liquid/gas interface of undeaerated 30% NaOH aqueous solution was found to be most fitted for the purpose. Under this condition, the effects of alloying elements and mechanical strength/microstructure on SCC life were studied. The reduction of P content and/or the addition of a small amount of Nb in steel and the reduction of mechanical strength were effective to prolong the SCC life of turbine rotors. (author)

  1. Analysis of life distribution by stress corrosion cracking of 3. 5NiCrMoV steel forgings

    Nakayama, Takenori; Fujiwara, Kazuo; Shimogori, Kazutoshi; Miyakawa, Mutsuhiro; Kinoshita, Shuji

    1988-01-01

    The stress corrosion cracking (SCC) life time of turbine rotors in actual nuclear and fossil power plants was analyzed by a statistical method and was estimated to obey an exponential probability distribution. Then, the laboratory accelerated test condition to exhibit such an exponential probability distribution was investigated using 3.5 NiCrMoV steel forgings which are being used most widely as a material for low pressure turbine rotors. The exposure of double U-bend specimens in liquid/gas interface of undeaerated 30% NaOH aqueous solution was found to be most fitted for the purpose. Under this condition, the effects of alloying elements and mechanical strength/microstructure on SCC life were studied. The reduction of P content and/or the addition of a small amount of Nb in steel and the reduction of mechanical strength were effective to prolong the SCC life of turbine rotors.

  2. Structure and tribological behavior of surface layer of laser modified X40CrMoV5-1 steel

    L.A. Dobrzański

    2006-08-01

    Full Text Available Purpose: The paper presents the effect of alloying with WC, TaC and TiC on structure and mechanical propertiesof the X40CrMoV5-1 steel surface layer using the HPDL (High Power Diode Laser.Design/methodology/approach: The microstructure of the alloyed layers which were formed on the surface ofthe investigated hot work steel was examined using optical microscope. The tribological wear relationships usingpin-on-disc test were specified for surface layers subject to laser treatment, determining the friction coefficient,and mass loss of the investigated surfaces. X-ray diffraction (XRD technique was used to investigate crystallinestructure and phases in the layers.Findings: The metallographic investigations on light microscope show that during alloying the X40CrMoV5-1hot work tool steel with the WC, TaC and TiC powder layer the obtained run face is characteristic of the highroughness, multiple pores, irregularity, and flashes at the borders. The changes of the surface layers hardnessformed as a result of remelting and alloying with ceramic powders containing carbides are accompanied withthe increased tribological properties.Research limitations/implications: In order to evaluate with more detail the possibility of applying thesesurface layers in tools, further investigations should be concentrated on the determination of the thermal fatigueresistance of the layers.Practical implications: The alloyed layers which were formed on the surface of the hot work steel have shownsignificant improvement. Good properties of the laser treatment make these layers suitable for various technicaland industrial applications.Originality/value: Structural and tribological behaviour of surface layer achieved by alloying and remeltingusing high diode power laser and selected ceramic powders were compared.

  3. Microstructure characteristics and temperature-dependent high cycle fatigue behavior of advanced 9% Cr/CrMoV dissimilarly welded joint

    Advanced 9% Cr and CrMoV steels chosen as candidate materials are first welded by narrow-gap submerged arc welding (NG-SAW) to fabricate the heavy section rotor. The present work focuses on studying the high-cycle fatigue (HCF) behavior of advanced 9% Cr/CrMoV dissimilarly welded joint at different temperatures. Conditional fatigue strength of this dissimilarly welded joint was obtained by HCF tests at room temperature (RT), 400 °C and 470 °C. It was observed that the failure occurred at the side of CrMoV base metal (BM), weld metal (WM) and heat affected zone (HAZ) of CrMoV side over 5×107 cycles for the specimens tested at RT, 400 °C and 470 °C. The detailed microstructures of BMs, WMs and HAZs as well as fracture appearance were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Precipitation and aggregation of carbides along the grain boundaries were clearly detected with the increase of temperature, which brought a negative effect on the fatigue properties. It is interesting to note that the inclusion size leading to crack initiation became smaller for the HCF test at higher temperature. Therefore, reduction in the inclusion size in a welded joint helps to improve the HCF performance at high temperature

  4. Influence of a sol–gel alumina coating on oxidation of X20CrMoV12-1 in air up to 650 °C

    The need for a more efficient coal power plant generation (e.g. oxyfuel technology) results in modified process parameters and enhanced corrosion. To reach the necessary service life of high temperature parts protective coatings may be a sufficient technical solution. A modified Yoldas sol (Al2O3 based) was used to coat X20CrMoV12-1 by spin coating. After appropriate heat treatments transition alumina coatings being about 400 nm thick were obtained. Oxidation studies were carried out in laboratory air at temperatures up to 650 °C for up to 500 h exposure time. In case of the uncoated sample a rough oxide layer formed on the surface and a remarkable weight gain (2.62 mg/cm2) were detected. The sol–gel alumina layer (mainly δ-Al2O3) demonstrated a high protection, i.e. a very low weight gain (0.05 mg/cm2). Diffusion of alloying elements into the coating was observed. No indication of spallation of the coating occurred. Local defects (2 μm–30 μm) in the coating led to the formation of iron-oxide islands. - Highlights: • Power plant steel X20 was coated with alumina by sol–gel method. • A 400 nm alumina layer provides good protection up to 650 °C. • Cr and Mn diffusion into Al2O3 supports coating adhesion and protective ability. • Improvement of the coating process must be directed to avoidance of local defects

  5. Comparison of the PVD gradient coatings deposited onto X40CrMoV5-1 and HS6-5-2 tool steel substrate

    K. Lukaszkowicz

    2008-03-01

    Full Text Available Purpose: The main aim of this research was investigation and comparison of selected properties of gradient coatings TiCN and AlSiCrN. In this paper both coatings were deposited by cathode arc evaporation physical vapour deposition (CAE-PVD method onto high speed steel HS6-5-2 and hot work tool steel X40CrMoV5-1.Design/methodology/approach: Observations of surface and structures of the deposited coatings were carried out on cross sections in the scanning electron microscope. The phase composition of the investigated coatings was determined by means of the X-ray diffractometer. Tests of the coatings’ adhesion to the substrate material were made using the scratch test. The microhardness tests of coatings were made with the ultra microhardness tester.Findings: The hard PVD gradient coatings deposited by cathodic arc evaporation method demonstrate the high hardness, adhesion and wear resistance. The critical load LC2, which is in the range 35-67 N, depends on the coating type and material substrate. The values of friction coefficient for the investigated coatings are changing within the range of 0.08-0.25.Research limitations/implications: In order to evaluate with more detail the possibility of applying these surface layers in tools, further investigations should be concentrated on the determination of the thermal fatigue resistance of the coatings.Originality/value: It should be emphasized that the mechanical properties of the PVD coatings obtained in this work are very encouraging and therefore their application for products manufactured at mass scale is possible in all cases where reliable, very hard and abrasion resistant coatings, deposited onto tools steel substrate are needed.

  6. Influence of Tempering Temperature on Cyclic Viscoplastic Behaviour of 55NiCrMoV7 Steel

    ZHANG Zhan-ping; DELAGNES Denis; BERNHART Gerard

    2004-01-01

    Low cycle fatigue behaviour of a steel 55NiCrMoV7 under four tempered conditions is reported. One special type of total strain controlled isothermal cyclic deformation tests were performed in the temperature range 20℃ to 600℃for the steel tempered 2h at 350℃, 460℃, 560℃ and 600℃. The influence of temperature on cyclic behaviour was investigated. Generally, the cyclic stress response shows an initial exponential softening for the first few cycles, followed by a gradual softening without cyclic softening saturation. At 10-2 strain rate, σmax. △σ/2 decrease with the test temperature for all hardness levels. They decrease linearly with tempering temperature when testing temperature is lower than that of tempering, but rest nearly constant when test temperature is equal to or exceed tempering temperature of steel. Cyclic softening intensity increases with testing temperature from 300℃ to 600℃, but the maximal softening intensity occurs at room temperature. The strain rate influences notably the cyclic behaviour when T≥500℃. The time dependence of cyclic behaviour is closely related to test temperature and the tempering history of the steel.

  7. The use of electrochemical and mechanical property correlations to monitor the degradation of Cr-Mo-V turbine casing steel

    In this study, virgin and degraded Cr-Mo-V alloys were used to investigate the effect of thermal aging on mechanical and electrochemical behavior. The results are also used to propose the electrochemical polarization method for measuring material degradation based upon a relation between the corrosion characteristics and mechanical properties. The electrochemical corrosion characteristics were investigated by the potentiodynamic anodic polarization and the reactivation methods in an 50 wt% Ca(NO3)2 electrolyte. Small punch tests were applied to examine the mechanical properties by using a miniaturized specimen. The first current density measured from material aged for 1000 h at 630 deg. C was higher than those obtained from other aged materials. In addition, the reactivated current density exhibited the greatest increase in value in material aged for 1000 h at 630 deg. C. These results indicate that the material aged for 1000 h at 630 deg. C exhibits the most severe material degradation and are consistent with results obtained from the small punch tests

  8. Stress corrosion cracking behaviour of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    Maday, M.F.; Mignone, A.; Borello, A.

    1987-01-01

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) behaviour of two NiCrMoV alloys of Italian production, that are materials used for low pressure (LP) turbine discs in LWR nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). A first set of experiments has been conducted in pure deaerated caustic solutions in a static NI autoclave system, in order to determine the effects of temperature and NaOH concentration on the SCC behaviour of these materials. In a second set of tests, the influence of the oxygen content on cracking was studied; for this purpose, specimens were strained to fracture at 200/sup 0/C in pure water with various amounts of oxygen; a refreshed autoclave system was used to permit a continuous monitoring of the chemical parameters. Both alloys showed a decreasing SCC susceptibility as NaOH concentration and temperature decreased. The alloy with lower Ni content seemed to behave slightly better in caustic solutions and somewhat worse in pure oxygenated water.

  9. Stress corrosion cracking behaviour of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) behaviour of two NiCrMoV alloys of Italian production, that are materials used for low pressure (LP) turbine discs in LWR nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). A first set of experiments has been conducted in pure deaerated caustic solutions in a static NI autoclave system, in order to determine the effects of temperature and NaOH concentration on the SCC behaviour of these materials. In a second set of tests, the influence of the oxygen content on cracking was studied; for this purpose, specimens were strained to fracture at 2000C in pure water with various amounts of oxygen; a refreshed autoclave system was used to permit a continuous monitoring of the chemical parameters. Both alloys showed a decreasing SCC susceptibility as NaOH concentration and temperature decreased. The alloy with lower Ni content seemed to behave slightly better in caustic solutions and somewhat worse in pure oxygenated water

  10. Deformation in 2CrMo-1/2CrMoV pressure vessel weldments at elevated temperature

    The elastic and creep deformation occurring in low alloy ferritic steel pipe to pipe weldments has been studied in pressure vessel experiments carried out at 838 K and a range of internal steam pressures. The welds were made in heavy section 1/2CrMoV parent pipe, using 2CrMo weld metal and tested in either the as-welded or stress relieved condition. The results obtained are analysed in terms of the deformations that occur in the hoop and axial direction of the parent pipe and weld metals. Elastically the parent pipe and weld metals behave identically, and both exhibit primary and steady state creep. The steady state behaviour of the parent pipe agrees with that expected from multi-axial creep deformation theory. The stress relieved welds behave similarly to the parent pipe in the hoop direction, but not in the axial direction. This is considered to be due to offloading of stress predominantly in the hoop direction. In the as-welded condition, the hoop and axial creep strains and strain rates are greater than in the parent pipe or stress relieved welds. The reasons for this are discussed in terms of welding residual stresses. (author)

  11. Microstructure of as-quenched 3. 5 NiCrMoV rotor steel. Pt. 2. Double diffraction

    Gates, J.D.; Atrens, A.; Smith, I.O.

    1987-06-01

    In a study of the microstructural features of 3.5 NiCrMoV steam turbine rotor steel in the as-quenched state, correct interpretation of selected area electron diffraction patterns has been found to be nontrivial. A major complicating factor is the widespread occurrence of double diffraction associated with micro-twins in the martensite. The resulting diffraction patterns are similar to those expected from cementite and may even suggest an orientation relationship consistent with the Bagaryatskii relationship. Moreover in the as-quenched steel they are the only well-developed diffraction patterns observed. Cases of failure to recognise double diffraction, with misinterpretation as evidence for the presence of cementite, have been brought to light. Double diffraction also occurs in regions containing retained austenite. A notation of the form d-dsub(hkl/sub ..cap alpha../) is proposed for diffraction spots due to double diffraction micro-twins, based on the observed relationship between the reciprocal lattice spacings of the double diffraction spots and those of the matrix spots.

  12. Stress corrosion cracking behavior of 3.5NiCrMoV steel in carbonated pure water

    SCC susceptibility of 3.5NiCrMoV steel in a carbonated pure water at 157 C decreased with the decrease of P content in steel. SCC susceptibility also decreased by the addition of Nb. It was also confirmed that the SCC cracks were primarily intergranular. An Auger electron spectroscopy (AES) analysis revealed that P segregation to grain boundary might play an essential role in accelerating SCC susceptibility, and Nb could suppress the P segregation to grain boundary. The role of Nb in raising resistance to SCC is thought to be attributed to the decreasing P segregation to grain boundary, resulting from increasing segregation interface due to fine NbC formation in steel. The measurement of anodic current decay in a carbonated solution with and without HPO42- ion showed that HPO42- ion accelerates the repassivation of a fresh surface, indicating that P segregation to grain boundary might be mainly attributed to the crack-sharpening effect due to repassivation by the formation of phosphate species at the crack tip

  13. Creep damage in welds of X 20 CrMoV 12 1 steel. Part 1 - Literature study and collection of experience; Krypskador i svetsar av X 20 CrMoV 12 1 staal. Etapp 1 - Litteraturstudie och erfarenhetsinsamling

    Storesund, Jan [Det Norske Veritas AB, Stockholm (Sweden); Borggreen, Kjeld [Sydtek AB, Malmoe (Sweden)

    2003-05-01

    The present project is a first part of a study of welded joints of the heat resistant steel X 20 CrMoV 12 1 in purpose to improve the methods for residual life assessment of this steel. A literature study and a collection of the experience of the area have been performed. There exists literature concerning damage development in welds to some extent, significantly less than for low alloy steels and in some areas hardly not at all. These areas are, for instance, published results of power plant investigations and metallographical investigations of retired welded components. However, the collection of experience from Danish plant gave amounts of information. It is shown in the literature that the damage development is quite like the typical one of low alloy steels but also that there are differences such as that the damage in a great amount also is formed in the interior of the grains. This can to some extent affect the way to evaluate observed damage. The existing damage scales presupposes intercrystal line damage but can essentially be used all the same. The experience from results of replica testing on components in service show a very slow growth of the damage at lower damage classes. The experience of higher damage classes in plant is small for this material but results of laboratory testing indicate a relatively fast growth. In the collection of experience it is observed that damage preferentially occurs in welds at terminals and nodes, such as T-joints, in the pipeline. Replica investigations should therefore be concentrated to such welds. An erroneous heat treatment resulting in dramatically reduced creep strength is quite frequent in pipeline components. It is recommended to investigate particularly bends systematically with the view to deciding if the microstructure is correct, latest after approximately 100,000 hours of operation. The following areas have been identified as important for the continued work: Finite element calculations using data on welds

  14. Anwendung der Thermomechanischen Behandlung mit Wärmebehandlung aus der Walzhitze für die Herstellung der Stabstahlsorte 15MnCrMoV4-8

    Voloskov, Sergey

    2014-01-01

    Zur Herstellung von Stabstahl der Sorte 15MnCrMoV4-8 ist die thermomechanische Behandlung erprobt worden. Diese erfolgte in Kombination mit der kosten- und energiesparenden Wärmebehandlung aus der Walzhitze. Dabei wurde besondere Aufmerksamkeit der chemischen Zusammensetzung gewidmet. Sie wird aus der Sicht kostenintensiver Legierungselemente, wie sie in Kombination mit Umformung und Abkühlung zum Erreichen eines mechanischen Eigenschaftsprofils führen, betrachtet. Das erforderliche Niveau de...

  15. Alloying the X40CrMoV5-1 steel surface layer with tungsten carbide by the use of a high power diode laser

    The paper presents the effect of alloying with tungsten carbide on properties of the X40CrMoV5-1 steel surface layer, using the high power diode laser (HPDL). Selection of laser operating conditions is discussed, as well as thickness of the alloying layer, and their influence on structure and chemical composition of the steel. Analysis of the influence of the process conditions on the thicknesses of the alloyed layer and heat-affected zone is presented

  16. Mechanical properties and structure of the Cr-Mo-V low-alloyed steel after long-term service in creep condition

    J. Dobrzański; A. Zieliński; H. Krztoń

    2007-01-01

    Purpose: of this paper is to present the changes of the mechanical properties and structure in material components of the power station boiler after long-term creep service made of Cr-Mo-V low-alloyed steel.Design/methodology/approach: The investigated material has been obtained from the Polish power stations. All examined elements have exceeded their assessed life of 100 000 hours. Mechanical properties and structure examinations were carried out on materials after long-term service in creep...

  17. Alloying the X40CrMoV5-1 steel surface layer with tungsten carbide by the use of a high power diode laser

    Dobrzanski, L.A. [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, 44-100 Gliwice, Konarskiego St. 18A (Poland); Bonek, M. [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, 44-100 Gliwice, Konarskiego St. 18A (Poland)]. E-mail: mb@zmn.mt.polsl.gliwice.pl; Hajduczek, E. [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, 44-100 Gliwice, Konarskiego St. 18A (Poland); Klimpel, A. [Welding Department, Silesian University of Technology, 44-100 Gliwice, Konarskiego St. 18A (Poland)

    2005-07-15

    The paper presents the effect of alloying with tungsten carbide on properties of the X40CrMoV5-1 steel surface layer, using the high power diode laser (HPDL). Selection of laser operating conditions is discussed, as well as thickness of the alloying layer, and their influence on structure and chemical composition of the steel. Analysis of the influence of the process conditions on the thicknesses of the alloyed layer and heat-affected zone is presented.

  18. Investigation of the effects of various surface treatments on properties of plastic mold steels X40CrMoV5-1

    C. Meran; Sarikaya, E

    2012-01-01

    Purpose: CrN coating, hard chrome plating and nitriding has been applied on commonly used thermoset plastic mould steel X40CrMoV5-1 (Materials number 1.2344). The effects of these surface treatments over wear behaviour, impact behaviour, hardness, tensile strength and corrosion behaviour experimentally investigated.Design/methodology/approach: Charpy test, tensile test, hardness measurements, wear tests, salt spray tests conducted over hard chrome plated, nitrided, CrN coated and uncoated X40...

  19. Surface-layer's structure of X40CrMoV5-1 steel remelted and/or WC alloyed with HPDL laser

    Dobrzanski, L.A.; Bonek, M. [Inst. of Engineering Materials and Biomaterials, Silesian Univ. of Technology, Gliwice (Poland); Klimpel, A.; Lisiecki, A. [Welding Dept., Silesian Univ. of Technology, Gliwice (Poland)

    2003-07-01

    Investigations included remelting and alloying experiments on the X40CrMoV5-1 hot-work steel with the high power diode laser. Tests have been made using the high power diode laser (HPDL) in the technological process of remelting and alloying the surface layer with the tungsten carbides. The surface remelting tests have been carried out for the X40CrMoV5-1 steel disk-shaped specimens, and surface alloying tests with tungsten carbide applied onto the steel in the form of paste. The effect of remelting and alloying parameters, and thickness of paste coatings applied onto the surface of the steel, on structure and properties of its surface layer, as well as on stresses, strains, and also remelting geometry and shape. The influence of alloying process parameters on the structure of substrate material are presented. Guidelines for remelting and alloying with the tungsten carbide of the X40CrMoV5-1 steel surface using the high power diode laser feature the outcome of the investigation aimed at obtaining its optimum mechanical and working properties. Results of test on spectrometer GDOS. (orig.)

  20. Impact tests on welded joints between the steel X 20 CrMoV 12 1 and 10 CrMo 9 10

    Dueren, C.; Jahn, E.; Langhardt, W.; Schleimer, W.

    1982-05-03

    In a joint study of four works the toughness behaviour in the heat affected zone of welded joints between the steels X 20 CrMoV 12 1 and 10 CrMo 9 10 has been investigated. For manual arc and submerged arc welds using filler metals similar to X 20 CrMoV 12 1 or 10 CrMo 9 10, impact values were measured at room temperature on these weld junction sides where the different metals partner butt, which were partly lower than the minimum value of 34 J on the DVM transverse specimen required for the parent metals. The cause was the carbon diffusion during tempering after welding which, at the interface between the two steels, lead to the formation of a decarburized zone in the steel and weld metal 10 CrMo 9 10 and of a carbide seam in the steel and weld metal X 20 CrMoV 12 1. This phenomenon was especially pronounced in welds using a filler metal similar to 10 CrMo 9 10. It was further intensified by quenching and tempering. THis decrease of toughness did not occur when, by using the high-nickel filler metal S-NiCr 15 FeMn, carbon diffusion was largely suppressed during usual tempering after welding.

  1. Mechanical properties of the surface layer of the laser alloyed 32CrMoV12-28 steel

    L.A. Dobrzański

    2008-01-01

    Full Text Available Purpose: In this paper it was investigated the influence of the laser treatment, first of all the laser power, to themechanical properties and structure of the steel surface layer alloyed with different ceramic powders. The purpose ofthis work was also to determine technological and technical conditions for remelting the surface layer with HPDL.Design/methodology/approach: This paper presents and discusses the main methodology results of newlaser treatment techniques applied in metal surface technology are. There is presented laser treatment withremelting of hot work tool steel 32CrMoV12-28 with ceramic powders especially carbides, oxides and nitrides aswell as results of laser remelting influence on structure and properties of the surface of the hot work steel, carriedout using the high power diode laser (HPDL. Optical and scanning electron microscopy was used to characterizethe microstructure and intermetallic phases occurred.Findings: A surface layer was coming into existence without cracks and defects as well as has a considerablyhigher hardness value compared to the non remelted material. The hardness value increases according to the laserpower used so that the highest power applied gives to highest hardness value in the remelted layer.Research limitations/implications: Four choused laser powers were applied for alloying and implicated by oneprocess speed rate. The powders which were used for alloying were of the particle size in the range of 5 to 10μm.Practical implications: This work helps to use the laser treatment technique for alloying and remelting of hotwork tool steel.Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvementof steel mechanical properties.

  2. On the relations between cyclic contraction ratio flowstress and deformation mechanisms in bainitic CrMoV steels

    The cyclic diametral strain and stress response of macroscopically untextured (nominally isotropic) bainitc Cr-Mo-V steels has been studied. The total axial strain amplitudes were controlled and chosen so that a range of ratios of plastic and elastic elongations were used extending from 0.04 to 5. The trend of the cyclic diametral strain was sometimes found to drastically deviate from the commonly used Poisson's ratio when the ratio of plastic and elastic elongation was around 3 for the uncycled material. The unusual initial increase in cyclic contraction ratio for these conditions was attributed to strain concentration and the decrease to strain decentration. A condition for these unpredictable macroscopic effects seems to be that the effective strengthening structure should be sufficiently unstable during the cyclic strain applied. At room temperature fatigue slip bands of high local density and number are created in these conditions. At elevated temperature applied strains larger than ∼ 0.3% give rise to an increasing mechanically activated dynamic recovery which operates despite a dense carbide dispersion. The amount of recovery and simultaneous dislocation annihilation increase and act to lower the flow strength with rising strain. Their extent depend on the strain rate. An apparent maximum in dynamic recovery was observed as a minimum in cyclic yield strength at the same strain for which the pronounced unpredictable diametral strain was observed. Similar diametral strain effects in monotonic tension tests on different materials reported in the published literature indicate that the effects are most probably related to the particular dominant mode of slip at strain levels for which the ratio of plastic and elastic strain (ep/eE) is around three. Slip is then dominantly planar. Careful shape control of the specimen gauge section is necessary for reproducible diametral strain because of the unstable nature of the material in the actual conditions of the cyclic

  3. Investigation of the effects of various surface treatments on properties of plastic mold steels X40CrMoV5-1

    C. Meran

    2012-11-01

    Full Text Available Purpose: CrN coating, hard chrome plating and nitriding has been applied on commonly used thermoset plastic mould steel X40CrMoV5-1 (Materials number 1.2344. The effects of these surface treatments over wear behaviour, impact behaviour, hardness, tensile strength and corrosion behaviour experimentally investigated.Design/methodology/approach: Charpy test, tensile test, hardness measurements, wear tests, salt spray tests conducted over hard chrome plated, nitrided, CrN coated and uncoated X40CrMoV5-1 specimens. Coating thickness and diffusion layers examined by Nikon Eclipse LV150 optical microscope.Findings: Highest micro hardness was observed in CrN coating, which is followed by nitriding and hard chrome plating. In wear tests, highest wear resistance was observed in CrN coating, then nitriding. Hard chrome plated samples were exposed abrasion more than uncoated ones. CrN coating and hard chrome plating didn’t affect the yield and tensile strength of material but increased the modulus of elasticity. It is observed that, nitriding decreased the tensile strength but increased the modulus of elasticity. Decrease in impact energy, and increase in brittleness was observed in descending order of nitriding, CrN coating and hard chrome plating.Research limitations/implications: Tensile test machine with hydraulic jaws can be used in further researches.Practical implications: Suitable surface treatment selection in X40CrMoV5-1 mold steels can be made more accurate by using spider diagrams which found in this research.Originality/value: This study was performed in the frame of the Pamukkale University Scientific Researches Projects Coordination Unit project no 2010FBE036 „Investigation of the Effect of Various Surface Treatments on Properties of Plastic Mold Materials”

  4. Cobalt-based superalloy layers deposited on X38CrMoV5 steel base metal by explosion cladding process

    LANGLOIS, Laurent; Bigot, Régis; ETTAQI, Saïd

    2008-01-01

    International audience A grade 25 cobalt-based superalloy in the form of a sheet 5 mm in thickness and a steel substrate of type X38CrMoV5 are joined by explosion cladding. The macrostructure and microstructure of the interface and of the co-based superalloy layers are studied. The interface presents the form of wavelets with a period of 1000 µm and an amplitude of 250 µm. The superalloy grains are deformed during the cladding process with several slip systems appearing. Near to the interf...

  5. MICROSTRUCTURAL STUDIES FOR OPTIMIZATION OF HEAT TREATMENT IN COMPONENTS OF STEEL X38CrMoV5-1 SUBJECTED TO HIGH STRESSES

    Vallés, Pilar; A. Pastor; Vilanova, O.; Medina, Sebastián F.; Gómez, Manuel

    2013-01-01

    This material X38CrMoV5-1 is an alloyed steel used for hot working, with good toughness and high resistance to thermal shock. The presence of Cr, Mo and V gives this steel a high resistance to wear, keeping its hardness properties at high temperature. Cr and Mo delay softening annealing and inhibit the grain growth. The great resistance to high temperatures of this type of steels is related with an easy martensitic transformation. This transformation happens even at low cooling speeds. The pr...

  6. Role of butter layer in low-cycle fatigue behavior of modified 9Cr and CrMoV dissimilar rotor welded joint

    Highlights: • Modified 9Cr–CrMoV dissimilar turbine rotor was successfully welded by NG-SAW. • LCF properties of both welded joints were approximate at smaller strain amplitude. • Tempered martensite with amounts of carbides in HAZ contributed to weakest zones. • Matched BL determined LCF properties of whole joint for dissimilar welded rotor. - Abstract: The present work aims at studying the role of butter layer (BL) in low-cycle fatigue (LCF) behavior of modified 9Cr steel and CrMoV steel dissimilar welded joint. The significant difference of the chemical composition of base metals (BMs) makes it a challenge to achieve sound welded joint. Therefore, buttering was considered to obtain a transition layer between the dissimilar steels. The LCF tests of two kinds of specimens without and with butter layer were performed applying strain-controlled cyclic load with different axial strain amplitudes. The test results indicated that the number of cycles at higher strain amplitudes of welded joint without butter layer was greatly higher than that of the joint with butter layer, while the fatigue lifetime to crack initiation (2Nf) became closer to each other at low and middle strain amplitudes. The failure was in the tempered heat affected zone (HAZ) at the CrMoV side for specimens without BL, while the fracture occurred at the tempered HAZ in the BL for specimens with BL. The microstructure details of BM, BL, HAZ and weld metals (WMs) were revealed by optical microscopy (OM). It was found that the tempered martensite was major microstructure for welded joint and much more carbides were observed in tempered HAZ than other parts due to the repeated tempering. Microhardness test indicated a softest zone existing tempered HAZ of BL and also there was a softer zone in tempered HAZ at the CrMoV side due to repeated tempering during welding and post weld heat treatment (PWHT). And scanning electron microscopy (SEM) was applied to observe the fractography. It was

  7. Isothermal aging test results (up to 100 000 h) of NiCrMoV steels for low-pressure steam turbine

    Tanaka, Yasuhiko; Azuma, Tsukasa; Yaegashi, Noriaki (Japan Steel Works Ltd., Muroran, Hokkaido (Japan). Muroran Plant)

    1994-01-01

    Isothermal aging test of NiCrMoV rotor steel was carried out up to 100 000h and change in the Charpy transition behavior was investigated. The test result revealed considerable embrittlement at 343[sup o]C and higher temperature enhanced embrittlement significantly. This behavior depends on the impurity of the materials and temper embrittlement parameter J factor or X characterize the temper embrittlement susceptibility. Based on these results, the amount of embrittlement can be estimated. A correlation between step cooling embrittlement and 100 000h embrittlement was also found. (author)

  8. SANS-study of the nano-defects in a NiCrMoV wheel of the axial compressor of a heavy duty gas turbine

    Rogante, M.; Ceschini, G.F.; Tognarelli, L.; Retfalvi, E.; Lebedev, V.T

    2005-05-15

    A wheel for nuclear/traditional energy applications is considered for the study of nano-defects by small angle neutron scattering (SANS). The constitutive material is a NiCrMoV steel with reference to the ASTM A 471 (type 2) norms. Measurements were performed using the SANS instrument of the Budapest Neutron Centre, at specific positions on the disc where the residual stresses in the lattice have also been analysed by neutron diffraction. The data obtained testify that the material has a low concentration of nano-defects when after thermal treatment compared with steels in which an intense formation of precipitates is usually induced.

  9. SANS-study of the nano-defects in a NiCrMoV wheel of the axial compressor of a heavy duty gas turbine

    A wheel for nuclear/traditional energy applications is considered for the study of nano-defects by small angle neutron scattering (SANS). The constitutive material is a NiCrMoV steel with reference to the ASTM A 471 (type 2) norms. Measurements were performed using the SANS instrument of the Budapest Neutron Centre, at specific positions on the disc where the residual stresses in the lattice have also been analysed by neutron diffraction. The data obtained testify that the material has a low concentration of nano-defects when after thermal treatment compared with steels in which an intense formation of precipitates is usually induced

  10. Stress corrosion cracking in high-purity water of 3-3 1/2% NiCrMoV tempering steels for steam turbine wheels and shafts. Final report. Spannungsrisskorrosion in hochreinem Wasser von 3-3 1/2 % NiCrMoV-Verguetungsstaehlen fuer Dampfturbinenradscheiben und Wellen. Abschlussbericht

    David, W.

    1987-01-01

    Stress corrosion cracking of 26 NiCrMoV 14 5 was investigated as a function of quality in the tempering state. Steels of similar chemical composition, as well as the steel 26 NiCrMoV 14 5 with a 0.2 limit > 1,200 Nmm/sup 2/ were taken into account. The interdependences between water chemistry and susceptibility to stress corrosion cracking were to be determined in a parameter study comprising crack initiation experiments, crack growth measurements and slow tensile tests (CERT experiments). The ultimate goal of the experiments was the optimisation of water chemistry as well as a better process technology in the steam circuit, so that stress corrosion cracking can be prevented. (orig.IHOE).

  11. The effect of dissolved hydrogen on the corrosion fatigue crack growth of 3.5NiCrMoV steel

    The effect of dissolved hydrogen on the corrosion Fatigue Crack Growth(FCG) behavior of 3.5NiCrMoV steel in pure water at 25 .deg. C and 150 deg. C was investigated. The corrosion fatigue crack growth rate measurements employing fracture mechanics specimens were performed in pure water. The water circulating loop system was used to control corrosion environment. The FCG rates highly increased in pure water with the large amount of the dissolved hydrogen (35 cc/kgH2O) at 25 .deg. C. However, it made no difference to FCG in pure water at 150 .deg. C regardless of the contents of the dissolved hydrogen(35 cc/kgH2O; 0.1 cc/kgH2O). The hydrogen embrittlement significantly influences the corrosion fatigue crack growth rate of 3.5NiCrMoV steel in pure water of 35 cc/kgH2O at 25 .deg. C

  12. Influencia del acabado superficial sobre el comportamiento tribológico de capas nitrocarburadas en acero X40CrMoV5 1

    Miguel, V.; Calatayud, A.; Coello, J.; Martínez, A.; Caminero, A.

    2005-01-01

    In this work the surface roughness behaviour in the forming of gaseous nitrocarburized layers has been analyzed. Ra values from 0.02 to 1.50 μm. has been considered. Obtained results prove a minor influence on layer thickness. A little increase of Ra has been observed. The abrasive wear resistance of nitrocarburized specimens was researched. The carbonitride ε is the only constituent in the about 6 μm thickness layers that have been carried out in this work. The tests revealed a minor wear re...

  13. EFECTO DEL PRECALENTAMIENTO Y LA SEVERIDAD DE TEMPLE SOBRE LA RESISTENCIA AL DESGASTE ADHESIVO DEL ACERO AUSTENÍTICO AL MANGANESO

    OSCAR FABIÁN HIGUERA COBOS

    2010-01-01

    Full Text Available En este trabajo de investigación se estudió el efecto del precalentamiento y la severidad de temple sobre la resistencia al desgaste adhesivo del acero austenítico al manganeso ASTM A 128 grado C. El material se sometió a ciclos térmicos de temple y revenido con y sin precalentamiento con el fin de evaluar su influencia sobre la resistencia al desgaste. Posteriormente el material fue sometido a prueba según norma ASTM G83 y se determinó que el acero Austenítico al manganeso, es un material que presenta una microestructura metaestable en condiciones estables y no debe ser sometido a tratamiento térmico de revenido a altas temperaturas debido que favorece la descomposición de esta a ferrita (fase blanda de los acero y por ende disminuye su resistencia al desgaste.

  14. The Effect of Stepped Austempering on Phase Composition and Mechanical Properties of Nanostructured X37CrMoV5-1 Steel

    Marciniak S.

    2015-04-01

    Full Text Available This paper presents the results of studies of X37CrMoV5-1 steel subjected to quenching processes with a one-step and a two-step isothermal annealing. The TEM observation revealed that steel after one-step treatment led is composed of carbide-free bainite with nanometric thickness of ferrite plates and of high volume fraction of retained austenite in form of thin layers or large blocks. In order to improve the strength parameters an attempt was made to reduce the austenite content by use of quenching with the two-step isothermal annealing. The temperature and time of each step were designed on the basis of dilatometric measurements. It was shown, that the two-step heat treatment led to increase of the bainitic ferrite content and resulted in improvement of steel's strength with no loss of steel ductility.

  15. High-temperature 9-10%-CrMoV materials for steam turbines - A status report on current research work in Germany

    The novel 10%-CrMoV materials developed under the roof of the European COST501 project have made it possible that advanced power plants with supercritical steam parameters could be designed. Operational experience so far with the new plants and the novel materials yielded information indicating possibilities or requirements for further enhancement or development work, and the German power plant industry translated this information to a catalogue of aspects and subjects for further research work. The resulting research programmes are performed by the universities and relevant research institutes, accompanied by management and coordination activities of a Task Force of the industry whose members are representatives of the companies Siemens, ABB, and Alstom Energie. (orig./CB)

  16. The effect of Mn and impurities on temper embrittlement for 3.5% NiCrMoV steel low pressure rotor forgings

    It is known that 3.5%NiCrMoV steel which is being used as one of power generation materials, temper embrittlement is caused under the conditions of long time service at high temperature because it contains small amount of impurities. P, Sn and Sb are known as the elements which affect the embrittlement in service, it is necessary to minimize the content of these elements in order to decrease the degree of the embrittlement. In addition, in case of low manganese content the steel properties against the embrittlement is improved, and it was recognized that high purity steel is very effective for the USC power generation rotors used at high temperature. The effects of the manganese content on the embrittlement in service of low pressure rotor forgings were studied to investigate the adequate manganese content considering the production cost

  17. Stress corrosion cracking in repair-welded 3.5 NiCrMoV steel in an actual turbine environment

    Hitomi, Itoh; Takashi, Shige [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center (Japan); Takashi, Momoo [Mitsubishi Heavy Industries, Ltd., Takasago Machinery Works (Japan)

    2001-07-01

    Temporary welding repairs are sometimes needed when damage occurs at the teeth of blade grooves in a low-pressure turbine rotor operated at the dry/wet boundary region. When repair welding has been performed for the 3,5 NiCrMoV steel used in low-pressure turbines, the soundness of the weld must be confirmed. For this reason, a laboratory investigation of susceptibility for stress corrosion cracking (SCC) was conducted for test specimens taken from simulated welds, and then an exposure test was conducted in an actual turbine environment for approximately 7,000 hours. As no SCC initiation was detected and also the propagation was extremely small, repair welding is deemed to be applicable. (author)

  18. Grain boundary composition effects on environmentally induced cracking of engineering materials. [SCC of austenitic stainless steel; HE of NiCrMoV low-alloy steel

    Bruemmer, S.M.

    1986-09-01

    There is now clear evidence that intergranular stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of engineering materials depend on grain boundary composition. Two examples are used to illustrate this interrelationship: (1) SCC of austenitic stainless steel in high-temperature water and (2) HE of NiCrMoV rotor steels in acidic solutions. Grain boundary compositions are characterized by analytical electron microscopy and scanning Auger electron spectroscopy. Environmental cracking susceptibility is indicated by slow-strain-rate tests in appropriate aqueous environments. Direct correlations are documented between measured grain boundary compositions and environmental cracking. The ability to establish these types of correlations enables diagnosis of embrittlement susceptibility and helps identify methods to control or eliminate embrittlement by bulk chemistry or processing modifications. 7 figs., 3 tabs.

  19. The effect of microstructural changes on the caustic stress corrosion cracking resistance of a NiCrMoV rotor steel

    Bandyopadhyay, N.; Briant, C. L.; Hall, E. L.

    1985-07-01

    This paper presents a study of the effects of microstructural changes on the caustic stress corrosion cracking resistance of a NiCrMoV rotor steel. All tests were run in 9 M NaOH at 98 °C and at an electrochemical potential of -400 mVHg/Hgo. Different microstructures were obtained by tempering martensitic samples for different times at 600 °C or by using a slow controlled cool from the austenite to produce a bainitic structure. The results show that heat treatments which produced large, chromiumrich carbides are beneficial. These carbides are preferentially corroded and cause pits to form at the crack tip. We propose that these pits cause crack tip blunting and slow crack propagation. It is further shown that, although changes in microstructure can produce improvements in the susceptibility to stress corrosion cracking, these changes cannot compensate for the detrimental effects of phosphorus segregation to grain boundaries.

  20. Stress corrosion cracking in repair-welded 3.5 NiCrMoV steel in an actual turbine environment

    Temporary welding repairs are sometimes needed when damage occurs at the teeth of blade grooves in a low-pressure turbine rotor operated at the dry/wet boundary region. When repair welding has been performed for the 3,5 NiCrMoV steel used in low-pressure turbines, the soundness of the weld must be confirmed. For this reason, a laboratory investigation of susceptibility for stress corrosion cracking (SCC) was conducted for test specimens taken from simulated welds, and then an exposure test was conducted in an actual turbine environment for approximately 7,000 hours. As no SCC initiation was detected and also the propagation was extremely small, repair welding is deemed to be applicable. (author)

  1. Structure and adhesion of thin coatings deposited by PVD technology on the X6CrNiMoTi17-12-2 and X40CrMoV5-1 steel substrates

    K. Lukaszkowicz

    2011-09-01

    Full Text Available Purpose: The main aim of the research was the investigation of the structure and adhesion of AlTiCrN, CrAlSiN and TiAlSiN coatings deposited by physical vapour deposition technology on the X40CrMoV5-1 hot work tool steel and the X6CrNiMoTi17-12-2 austenitic stainless steel substrate.Design/methodology/approach: Observations of surface and microstructure of the deposited coatings were carried out on cross sections in the SUPRA 35 scanning electron microscope. The microhardness tests of coatings were made with the SHIMADZU DUH 202 ultra-microhardness tester. The cohesion and adhesion properties of the coatings were made using the scratch test on the CSEM REVETEST device.Findings: It was found that the coatings present a compact structure, without any visible delaminations or defects. The morphology of the fracture of coatings is characterized by a dense structure, in some cases there is a columnar structure. The coatings demonstrated good adhesion to the substrate. The critical load LC2 lies within the range of 39-47 N, depending on the coating and substrate type. The coatings demonstrate a high hardness (~40 GPa.Practical implications: The process of covering steels with the thin PVD coatings is currently the most commonly method used to extend their life. Investigations of those coatings determining their scratch-resistant properties and structure enable to pick out the optimum coatings for given industrial applications.Originality/value: The results of the investigation provide useful information on microstructure and scratch-resistant properties of the quaternary coatings deposited on the hot work tool steels and austenitic stainless steels.

  2. Functional properties of surface layers of X38CrMoV5-3 hot work tool steel alloyed with HPDL laser

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: Improvement of functional properties alloyed of hot work tool steel surface layers is one of the goals of this paper.Design/methodology/approach: The material used for investigation was the hot work tool steel X38CrMoV5-3. Remelting and alloying of surface layers were made using the HPDL high power diode laser Rofin DL 020 in the laser power range of 1.2-2.3 kW. The carbide powders were applied on specimens prepared and degreased in this way; the powder was mixed with the sodium glass as inorganic binder in proportion of 30% binder and 70% powder. Paste coating 0.5 mm thick was put down in each case.Findings: The hardness changes of the surface layers obtained by remelting and alloying with carbides using the high power diode laser are accompanied with the improved tribological properties compared to the conventionally heat treated steel. The highest abrasion wear resistance, more than 2.5 times higher than that of the base material, was revealed in case the steel alloyed with vanadium carbide.Research limitations/implications: These advantages are the result of features unique to the HPDL, such as: shorter wavelength (thus better beam absorption for most metallic materials, and smaller absorption length and better temporal beam stability (due to beam integration compared to Nd:YAG and CO2 lasers. HPDL materials processing is, therefore, expected to produce better quality and more consistent and repeatable results for applications requiring beam spot sizes larger than 0.5mm diameter. One of the issues of concern in the practical applications of the lasers in materials processing for mass production is the repeatability.Practical implications: The research results indicate to the feasibility and purposefulness of the practical use of remelting and alloying with the ceramic particles using the high power diode laser for manufacturing and regeneration of various tools from the X38CrMoV5-3 hot-work tool steel.Originality/value: The laser

  3. The effect of long-term service at elevated temperatures on structure and mechanical properties of Cr-Mo-V steel

    J. Ćwiek

    2011-05-01

    Full Text Available Purpose: of this paper is to reveal the microstructural changes in 13HMF steel exposed to long-term service at elevated temperatures. The degradation of bainite structure was determined and carbides morphology has been examined. The influence of carbides evolution was discussed in dependence of creep rupture strength and mechanical properties of the steel.Design/methodology/approach: Examinations were conducted on 273 mm diameter, 32 mm wall thickness tube made of 13HMF (14MoV6-3 steel. The tube was a segment of stem pipeline used in power plant at 540°C. The service time is 168,000 hours. Microstructure of the material has been examined with the use of light optical microscopy and scanning electron microscopy (SEM. The energy dispersive X-ray spectrometry (EDS analysis was used for phase chemical composition identification. Transmission electron microscopy (TEM of thin foils was used for carbides structure identification. The mechanical properties of the tube material were evaluated in static tensile tests at room temperature, hardness tests and impact Charpy U tests.Findings: Microstructure of 13HMF steel tube shows an advanced level of degradation - coagulation of carbides at ferrite grain boundaries and inside bainitic grains. Precipitates of carbides decorated grain boundaries in chain forms. The presence of M7C3, M23C6, M6C phases were revealed. After extended service M23C6 and M3C carbides were replaced by more stable carbides. This transformation did not occur until the end. This indicates the presence of mainly Mo2C carbide, and only sporadic occurrence of carbide M6C.Practical implications: Useability of the method for assessing the current degradation level and for predicting residual lifetime of creep-resistant tubes based on analysis of carbides morphology was confirmed for Cr-Mo-V steel.Originality/value: Information available in literature does not clearly indicate the influence of microstructure and mechanical properties of Cr-Mo-V

  4. Comportamiento del acero de baja aleación SA-508 y del acero al carbono A-410b en las condiciones de operación y parada del circuito primario de los reactores de agua ligera tipo PWR

    García-Redondo, María del Sol; Castaño-Marín, María Luisa; Gómez-Briceño, Dolores

    2000-01-01

    The corrosion rate of low alloy steel SA-508 and carbon steel A-410b in simulated operation and shutdown conditions of pressurized water reactor has been determined. Moreover potentiodynamic polarization curves and galvanic effect through coupling of AISI-304 have been carried out under shutdown simulated condition.

    En este trabajo se ha determinado la cinética de corrosión del acero de baja aleación SA-508 y del acero al carbono A-410b en condiciones que simulan la operaci...

  5. The assessment of the structural degradation level of an used thermoenergetic pipe made out of 12CrMoV3 Steel, using the metallographical replica method

    Andreea Bobic

    2005-10-01

    Full Text Available Generally, the metallographical replica method is applied on the external surface of the energetic pipes in order to assess the structural degradation. This nondestructive method allows to obtain information regarding the grow and sheroidization of carbides, as well as the propagation of cavities leading to cracks. Considering the analysed pipe a thick-walled cylinder, from the theory of maximum tangential unit stress, the permanent deformations appear, firstly, in the neighborhood of the cylinder internal surface. Thereby, the aim of the paper is to evaluate and compare the structural degradation of the external and, respectively internal surface of a pipe made out from 12CrMoV3 steel, with the dimensions of 273x38mm, using the metallographical replica method. The pipe worked at the temperature of 5400C and the pressure of 140 bar, for 44,827 hours. The obtained results showed that the structural degradation level of the internal surface is higher with about 11 – 18 % than the structural degradation level of the pipe external surface. Thus, by applying the metallographical replica method, a certain level of structural degradation of the material external surface is established; the degradation level at the internal surface of the pipe is equal or higher than the one determined on the external surface.

  6. Atom probe study of the carbon distribution in a hardened martensitic hot-work tool steel X38CrMoV5-1.

    Lerchbacher, Christoph; Zinner, Silvia; Leitner, Harald

    2012-07-01

    The microstructure of the hardened common hot-work tool steel X38CrMoV5-1 has been characterized by atom probe tomography with the focus on the carbon distribution. Samples quenched with technically relevant cooling parameters λ from 0.1 (30 K/s) to 12 (0.25 K/s) have been investigated. The parameter λ is an industrially commonly used exponential cooling parameter, representing the cooling time from 800 to 500 °C in seconds divided with hundred. In all samples pronounced carbon segregation to dislocations and cluster formation could be observed after quenching. Carbon enriched interlath films with peak carbon levels of 6-10 at.%, which have been identified to be retained austenite by TEM, show a thickness increase with increasing λ. Therefore, the fraction of total carbon staying in the austenite grows. This carbon is not available for the tempering induced precipitation of secondary carbides in the bulk. Through all samples no segregation of any substitutional elements takes place. Charpy impact testing and fracture surface analysis of the hardened samples reveal the cooling rate induced microstructural distinctions. PMID:22391101

  7. Short-term creep behavior of an X 37 Cr Mo V 5-1 hot-work tool steel with almost bainitic and fully martensitic microstructures

    Wurmbauer, H. [Department Physical Metallurgy and Material Testing, Montanuniversitaet Leoben (Austria); Materials Center Leoben Forschung GmbH, Leoben (Austria); Leitner, H. [Department Physical Metallurgy and Material Testing, Montanuniversitaet Leoben (Austria); Christian Doppler Laboratory of Early Stages of Precipitation, Montanuniversitaet Leoben (Austria); Panzenboeck, M.; Clemens, H. [Department Physical Metallurgy and Material Testing, Montanuniversitaet Leoben (Austria); Scheu, C. [Department of Chemistry and Biochemistry, Ludwig-Maximilians-University Munich (Germany)

    2010-07-15

    In this study two different heat treatments were conducted on an X 37 Cr Mo V 5-1 hot-work tool steel, resulting either in a tempered fully martensitic matrix or a matrix almost consisting of tempered bainite. Short-term creep tests were performed at a high stress level of 800 MPa and at temperatures in the range from 450 C to 500 C. Creep specimens consisting of a tempered fully martensitic microstructure exhibited a three times longer creep-to-rupture time, than those consisting of a tempered almost bainitic microstructure. Microstructural investigations of creep specimens were performed by transmission electron microscopy. Results of these investigations revealed that due to a lower cooling rate, which is necessary to form bainite, the tempered bainitic microstructure consists of large former bainitic plates, whereas tempered martensite shows fine former martensitic laths. Tempered bainite also exhibits a higher number density of large M{sub 3}C, M{sub 7}C{sub 3} and MC carbides than tempered martensite. Small M{sub 2}C carbides appear in both microstructures in the same quantity, however, nanometer-sized MC carbides could only be found in tempered martensite. Thus poor short-term creep behavior of the tempered almost bainitic microstructure can be explained by the lesser amount of strengthening relevant precipitates, a smaller size-effect due to distance of bainitic interfaces as well as lower solid solution hardening. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  8. Mechanical properties of the PVD gradient coatings deposited onto the hot work tool steel X40CrMoV5-1

    K. Lukaszkowicz

    2007-10-01

    Full Text Available Purpose: The aim of the research is the investigation of the mechanical properties of gradient coatings deposited by PVD technique (cathodic arc evaporation method onto the substrate from the X40CrMoV5-1 hot work steel.Design/methodology/approach: The microhardness tests were made on the dynamic ultra-microhardness tester. Tests of the coatings’ adhesion to the substrate material were made using the scratch test. The wear and friction tests were performed on a standard pin-on-disc device.Findings: The hard PVD gradient coatings deposited by cathodic arc evaporation method demonstrate the high hardness, adhesion and wear resistance. The critical load LC2, which is in the range 46-59 N, depends on the coating type. The friction coefficient for the investigated coatings is within the range of 0.30-0.90.Research limitations/implications: In order to evaluate with more detail the possibility of applying these coatings in tools steel, further investigations should be concentrated on the determination of the mechanical and tribological properties of the coatings.Originality/value: It should be stressed that the mechanical properties of the PVD coatings obtained in this work are very encouraging and therefore their application for products manufactured at mass scale is possible in all cases where reliable, very hard and abrasion resistant coatings, deposited onto tools steel substrate are needed.

  9. High-temperature cast steel GS-17 CrMoV 5 11 - a contribution to the behaviour of simulated HAZ structures

    Different heat-affected-zone structures of two creep-resistant cast-steel materials containing 1% CrMoV (spec. according to DIN 17245 or ASTM A 356) are simulated by using the welding simulator GLEEBLE 1500. The conversing attitude in the heat-affected zone was investigated and illustrated by means of a welding time temperature transition curve. The mechanical behaviour of the heat-affected-zone structures was determined by means of thermal tension tests at 5500C and thoughness tests. The material according to the ASTM specifications shows a better toughness behaviour. The influence of different thermal treatments on the toughness behaviour of the coarse grain zone was investigated. Best values of toughness were achieved at annealing temperatures of 700 and 7250C. Tests on stress relief cracking revealed that both materials are susceptible to cracking in the temperature range from 550 to 6500C. The precipitation condition of the coarse grain zone after various thermal treatments was investigated by using the electron microscope. Fine MX and M2C precipitations of the mixed carbides of the type M23C6 M7C3 were detected in dependence on the annealing temperature. (orig./MM)

  10. Changes occurring in the chemical composition of the precipitates in the steel X 20 CrMoV 12 1 during long-term high temperature service

    The steel X 20 CrMoV 12 1 exhibits a tempered martensitic microstructure, when it is hardened and tempered in accordance with the appropriate material standards. At very low austenitizing temperatures the amount of carbon going into solution is small. The undissolved, relatively coarse carbides at these temperatures inhibit grain growth of the austenite. The martensite forming from such an austenite is very fine and often cannot be recognized as such, when examined by optical microscopy. The nonequilibrium structures resulting from the heat treatment will be progressively transformed to thermally more stable structures during high temperature service. The reactions taking place at high temperatures lead to an enrichment of the carbides with the alloying elements, the equilibrium compositions of the carbides being dependent on the temperature. Thus, for example, the composition of the carbide M23C6 is characteristic of heat treatment or service temperatures. The initial arrangement of various phases in the microstructure remains largely unaltered, despite the various precipitation reactions occurring during service. Metallographic examination enable one to determine the heat treatment of the components but they are not sufficient to assess the service conditions and, especially, the residual life of the components. (orig.)

  11. High-resolution diffraction for residual stress determination in the NiCrMoV wheel of an axial compressor for a heavy-duty gas turbine

    Rogante, M.; Török, G.; Ceschini, G. F.; Tognarelli, L.; Füzesy, I.; Rosta, L.

    2004-07-01

    The wheel of an axial compressor for a heavy-duty gas turbine has been investigated for residual stresses (RS) evaluation of the teeth-section where SANS measurements have previously been performed. Such a component can contain internal RS, either due to the manufacturing process, or to the operating cycles fatigue. The constitutive material is a NiCrMoV steel to ASTM A 471 (type 2) norms (equivalent to B50A420B10); this material is usually adopted in the manufacturing of forged components for gas turbines. Internal radial and hoop RS have been determined, whose values are under the limit of 200kPa. Hoop RS, in general, resulted in higher value than the radial ones. The present experiment represents a particularly important step in the RS determination for gas turbine components, since the measurements reveal that the fatigue of the wheel is also a lifetime limiting factor although, in the same technological field, the available data in the actual neutron techniques literature mainly concern turbine buckets.

  12. High-resolution diffraction for residual stress determination in the NiCrMoV wheel of an axial compressor for a heavy-duty gas turbine

    The wheel of an axial compressor for a heavy-duty gas turbine has been investigated for residual stresses (RS) evaluation of the teeth-section where SANS measurements have previously been performed. Such a component can contain internal RS, either due to the manufacturing process, or to the operating cycles fatigue. The constitutive material is a NiCrMoV steel to ASTM A 471 (type 2) norms (equivalent to B50A420B10); this material is usually adopted in the manufacturing of forged components for gas turbines. Internal radial and hoop RS have been determined, whose values are under the limit of 200 kPa. Hoop RS, in general, resulted in higher value than the radial ones. The present experiment represents a particularly important step in the RS determination for gas turbine components, since the measurements reveal that the fatigue of the wheel is also a lifetime limiting factor although, in the same technological field, the available data in the actual neutron techniques literature mainly concern turbine buckets

  13. High-resolution diffraction for residual stress determination in the NiCrMoV wheel of an axial compressor for a heavy-duty gas turbine

    Rogante, M.; Toeroek, G.; Ceschini, G.F.; Tognarelli, L.; Fuezesy, I.; Rosta, L

    2004-07-15

    The wheel of an axial compressor for a heavy-duty gas turbine has been investigated for residual stresses (RS) evaluation of the teeth-section where SANS measurements have previously been performed. Such a component can contain internal RS, either due to the manufacturing process, or to the operating cycles fatigue. The constitutive material is a NiCrMoV steel to ASTM A 471 (type 2) norms (equivalent to B50A420B10); this material is usually adopted in the manufacturing of forged components for gas turbines. Internal radial and hoop RS have been determined, whose values are under the limit of 200 kPa. Hoop RS, in general, resulted in higher value than the radial ones. The present experiment represents a particularly important step in the RS determination for gas turbine components, since the measurements reveal that the fatigue of the wheel is also a lifetime limiting factor although, in the same technological field, the available data in the actual neutron techniques literature mainly concern turbine buckets.

  14. Influence of cooling rate on the structure and mechanical properties of G17CrMoV5 – 10 cast steel

    G. Golański

    2009-07-01

    Full Text Available The paper presents results of research on the influence of cooling rate on the structure and properties of G17CrMoV5 – 10 (L17HMF cast steel. The material for research was a section taken out from an outer cylinder of a steam turbine body after about 250 000 hours of operation at the temperature of 535°C and pressure 9 MPa. The investigated cast steel was subjected to heat treatment which consisted in cooling at the rates corresponding to the processes, such as: bainitic hardening, normalizing and full annealing. Tempering after the process of cooling from austenitizing temperature was carried out at the temperatures of: 700, 720 and 740°C. Performed research has proved that structures obtained after bainitic hardening and normalizing are characterized by a large strength margin which allows to apply high temperatures of tempering. It has been shown that the cast steel of bainitic structure, with similar mechanical properties as the cast steel of bainitic – ferritic structure, is characterized by almost twice as high impact energy. Full annealing and tempering of the examined cast steel ensures only the required impact strength, with mechanical properties comparable to those after service.

  15. The effect of temperature, specimen size, and geometry on the fracture toughness of a 3 Pct NiCrMoV low pressure turbine disc steel

    The variation of fracture toughness with temperature and specimen size of a 3 pct NiCrMoV LP disc steel has been investigated over the temperature range -100 to +1000C using compact tension and single-edge-notched bend geometries. A number of large 'half-disc' three point bend specimens were also tested. Toughness increased up to a transition temperature coinciding with the onset of stabl ductile tearing prior to instability. Below this temperature fracture could be described by established linear elastic or post yield fracture analyses. Above this temperature failure was by plastic collapse. The transition temperature decreased with decreasing specimen size, and at similar thicknesses was lower for the bend geometry than for the compact tension so that it was not possible to predict th fracture behavior of the full size service component from small scale tests in the transition region. A further complicating feature was the extreme scatter of some duplicate test results below the transition temperature. The implications for toughness testing in the transition region are discussed. The data obtained in this work have been combined with published data for similar steels to derive an equation which describes the variation of fracture toughness with temperature for steels of this type

  16. Stress corrosion cracking in 3,5 NiCrMoV steel in a 403 K potential-PH diagram

    Hitomi, Itoh [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center, (Japan); Takashi, Momoo [Mitsubishi Heavy Industries Ltd., Takasago Machinery Works, (Japan)

    2001-07-01

    3,5 NiCrMoV steel is used in low-pressure turbine rotors and discs. It has been pointed out that intergranular stress corrosion cracking may occur in this material in the wet region at temperatures of about 400 K. Accordingly, the authors focused on the environmental conditions under which stress corrosion cracking (SCC) occurs. A potential-pH diagram was used to investigate the region in which SCC occurs in the high strength materials that are particularly susceptible to SCC. The investigation found that SCC is initiated in this material not only in the high caustic region but in the neutral region as well. The investigation also found that initiation and propagation were accelerated in dissolved oxygen environments with increased chemical potential in the neutral region. Since careful observation of the starting point of cracks has shown that corrosion pits trigger SCC, subsequent immersion tests under constant potential were conducted. The results showed that corrosion pits are generated at the high potential range. These results led to the development of an acceleration test environment for laboratory to determine the susceptibility of SCC in field turbine disc and rotor materials. (author)

  17. Stress corrosion cracking in 3,5 NiCrMoV steel in a 403 K potential-PH diagram

    3,5 NiCrMoV steel is used in low-pressure turbine rotors and discs. It has been pointed out that intergranular stress corrosion cracking may occur in this material in the wet region at temperatures of about 400 K. Accordingly, the authors focused on the environmental conditions under which stress corrosion cracking (SCC) occurs. A potential-pH diagram was used to investigate the region in which SCC occurs in the high strength materials that are particularly susceptible to SCC. The investigation found that SCC is initiated in this material not only in the high caustic region but in the neutral region as well. The investigation also found that initiation and propagation were accelerated in dissolved oxygen environments with increased chemical potential in the neutral region. Since careful observation of the starting point of cracks has shown that corrosion pits trigger SCC, subsequent immersion tests under constant potential were conducted. The results showed that corrosion pits are generated at the high potential range. These results led to the development of an acceleration test environment for laboratory to determine the susceptibility of SCC in field turbine disc and rotor materials. (author)

  18. The Effect of Temperature, Specimen Size, and Geometry on the Fracture Toughness of a 3 Pct NiCrMoV Low Pressure Turbine Disc Steel

    Shaw, N. B.; Spink, G. M.

    1983-03-01

    The variation of fracture toughness with temperature and specimen size of a 3 pct NiCrMoV LP disc steel has been investigated over the temperature range -100 to +100 °C using compact tension and single-edge-notched bend geometries. A number of large ‘half-disc’ three point bend specimens were also tested. Toughness increased up to a transition temperature coinciding with the onset of stable ductile tearing prior to instability. Below this temperature fracture could be described by established linear elastic or post yield fracture analyses. Above this temperature failure was by plastic collapse. The transition temperature decreased with decreasing specimen size, and at similar thicknesses was lower for the bend geometry than for the compact tension so that it was not possible to predict the fracture behavior of the full size service component from small scale tests in the transition region. A further complicating feature was the extreme scatter of some duplicate test results below the transition temperature. The implications for toughness testing in the transition region are discussed. The data obtained in this work have been combined with published data for similar steels to derive an equation which describes the variation of fracture toughness with temperature for steels of this type.

  19. Effect of dissolved oxygen on the stress corrosion cracking behavior of 3.5NiCrMoV steels in high temperature water

    Slow Strain Rate Tests (SSRT) were carried out to investigate the effect of environmental factors on the Stress Corrosion Cracking (SCC) susceptibility of 3.5NiCrMoV steels used in discs for Low-Pressure (LP) steam turbines in electric power generating plants. The influences of dissolved oxygen on the stress corrosion cracking of turbine steel were studied. For this purpose, specimens were strained at variously oxygenated conditions at 150 .deg. C in pure water. When the specimen was strained with 1 x 10-7 s-1 at 150 .deg. C in pure water, increasing concentration of dissolved oxygen decreased the elongation and the UTS. The corrosion potential and the corrosion rate increased as the amounts of dissolved oxygen increased. The increase of the SCC susceptibility of the turbine steel in a highly dissolved oxygen environment is due to the non protectiveness of the oxide layer on the turbine steel surface and the increase of the corrosion current. These results clearly indicate that oxygen concentration increases Stress Corrosion Cracking susceptibility in turbine steel at 150 .deg. C

  20. An observation concerning the contribution of temperature on the behaviour of grain boundary segregants for varied microstructures in a NiCrMoV steel

    Misra, R.D.K. (Defence Metallurgical Research Lab., P.O. Kanchanbagh, Hyderabad-500 258 (IN))

    1991-01-01

    In this paper, the authors examine thermodynamic interactions amongst trace and alloying elements at the grain boundaries of low alloy steels through measurement of grain boundary segregation isotherms and determination of time-temperature space plots (interaction maps). In a more recent work, a rational of the effects of microstructure on grain boundary segregation behaviour in a low alloy, NiCrMoV steel, was attempted. In this paper the effects of microstructure (martensitic, bainitic, ferrite-pearlite) on grain boundary segregation processes were elucidated by defining a parameter, referred as interaction severity, Q, which gives an idea of the magnitude of interaction between the two elements. The interaction severity, Q, for a cooperative interaction process was defined as the ratio of the grain boundary coverage of the interacting elements (e.g. for Cr-N, cooperative interaction process, Q = {theta}{sub N}/{theta}{sub Ce}, where {theta} is the grain boundary coverage of the interacting element) and for site-competitive process, it was defined as the sum of the grain boundary coverage of the interacting elements (e.g. for S-Sn site competitive interaction process, Q = {theta}{sub S} + {theta}{sub SN}).

  1. Effect of laser alloying on thermal fatigue and mechanical properties of the 32CrMoV12-20 steel

    L.A. Dobrzański

    2006-09-01

    Full Text Available Purpose: The reason of this work was to determine the thermal fatique resistance, the laser treatment parameters, particularly the laser power, to achieve a high value of layer hardness for protection of this hot work tool steel from losing their work stability and to make the tool surface more resistant for work. The purpose of this work was also to determine technological and technical conditions for remelting the surface layer with HPDL.Design/methodology/approach: In this paper the results of new laser treatment techniques applied in metal surface technology are presented and discussed. There is presented laser treatment with remelting of hot work tool steel 32CrMoV12-28 with ceramic powders especially carbide - TaC, as well as results of laser remelting influence on structure and properties of the surface of the hot work steel, carried out using the high power diode laser (HPDL. Special attention was devoted to monitoring of the layer morphology of the investigated material and on the particle occurred. Optical and scanning electron microscopy was used to characterize the microstructure and intermetallic phases occurred.Findings: The layer is without cracks and defects as well as has a considerably higher hardness value compared to the non remelted material. The hardness value increases according to the laser power used so that the highest power applied gives to highest hardness value in the remelted layer.Research limitations/implications: The results present only four choused laser powers by one process speed rate. Also one powder in form of TaC was used for alloying with the particle size of 10µm.Practical implications: The aim of this work is the determination of laser treatment technique for alloying and remelting of hot work tool steel.Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvement of steel mechanical properties.

  2. Modelling of gradient layer properties of the 32CrMoV12-27 surface layer alloyed with WC powder

    A. Klimpel

    2007-01-01

    Full Text Available Purpose: The reason of this work was to determine the thermal fatique resistance, the laser treatment parameters,particularly the laser power, to achieve a high value of layer hardness for protection of this hot work tool steelfrom losing their work stability and to make the tool surface more resistant for work. The purpose of this workwas also to determine technological and technical conditions for remelting the surface layer with HPDL.Design/methodology/approach: In this paper the results of new laser treatment techniques applied in metalsurface technology are presented and discussed. There is presented laser treatment with remelting of hot worktool steel 32CrMoV12-28 with ceramic powders especially carbide - WC, as well as results of laser remeltinginfluence on structure and properties of the surface of the hot work steel, carried out using the high powerdiode laser (HPDL. Special attention was devoted to monitoring of the layer morphology of the investigatedmaterial and on the particle occurred. Optical and scanning electron microscopy was used to characterize themicrostructure and intermetallic phases occurred.Findings: The layer is without cracks and defects as well as has a considerably higher hardness value comparedto the non remelted material. The hardness value increases according to the laser power used so that the highestpower applied gives to highest hardness value in the remelted layer.Research limitations/implications: The results present only four choused laser powers by one process speedrate. Also one powder in form of WC was used for alloying with the particle size of 10μm.Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvementof steel mechanical properties.

  3. Comparison of 32CrMoV12-28 steel alloyed with WC, VC and TaC powder using HPDL laser

    L.A. Dobrzański

    2008-10-01

    Full Text Available Purpose: This work presents the investigation results of laser remelting and alloying especially the laser parameters and its influence on the structure and properties of the surface of the 32CrMoV12-28 hot work steel, using the high power diode laser (HPDL. In this paper there are presented the investigation results of mechanical properties and microstructure with ceramic particle powders vanadium carbide VC, tungsten carbide WC and tantalum carbide TaC. The purpose of this work was also to determine the laser treatment conditions for surface layer treatment of the investigated steels.Design/methodology/approach: The purpose of this work was the determination of technological conditions for alloying and remelting of the surface layer particularly the laser power. There is studying the influence of treatment on the remelting depth of the surface layer to achieve high layer hardness for protection of the steel and also make the surface more resistant for work.Findings: As a result structure changes in form of fragmentation were determined. For alloying the tungsten carbide, tantalum carbide and vanadium carbide powders were used. Three phases of carbides: TaC, VC and WC, were observed.Research limitations/implications: The remelted layers which were formed on the surface of the investigated hot work steel were examined metallographically and analyzed using a hardness and micro hardness testing, X-ray diffraction, EDS microanalysis, electron scanning microscope.Practical implications: This work helps to use the new developed laser treatment technique for alloying and remelting of hot work tool steel tools for hot working conditions.Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvement of steel mechanical properties as well the thermal fatigue and wear resistance.

  4. Modelling of surface layer of the 32CrMoV12-28 tool steel using HPDL laser for alloying with TiC powder

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: In this work are presented the performed investigation for the reason to determine the laser treatment parameters, for example the laser power to achieve a high value of layer hardness for protection of this hot work tool steel from losing their work stability and to make the tool surface more resistant for work. The purpose of this work was also to determine technological conditions for remelting the surface layer with HPDL.Design/methodology/approach: The research way results of new laser treatment methodology applied in metal surface technology are presented and discussed. There is presented laser treatment with remelting of hot work tool steel 32CrMoV12-28 with ceramic powders especially titanium carbide - TiC, as well as results of laser remelting influence on structure and properties of the surface of the hot work steel, carried out using the high power diode laser (HPDL. Special attention was devoted to monitoring of the layer morphology of the investigated material and on the particle occurred. Optical and scanning electron microscopy was used to characterize the microstructure and intermetallic phases occurred.Findings: A surface layer was comming into existence without cracks and defects as well as has a considerably higher hardness value compared to the non remelted material. The hardness value increases according to the laser power used so that the highest power applied gives to highest hardness value in the remelted layer.Research limitations/implications: Four laser powers were choused and implicated by one process speed rate. Also one powder in form of TiC was used for alloying with the particle size of 10µm.Practical implications: The investigation helps to use the laser treatment technique for alloying of hot work tool steel with different ceramic particles.Originality/value: The scientific reason of this work is the applying of High Power Diode Laser (HPDL for improvement of steel mechanical properties, especially the

  5. Caustic stress corrosion cracking of NiCrMoV rotor steels—The effects of impurity segregation and variation in alloy composition

    Bandyopadhyay, N.; Briant, C. L.

    1983-10-01

    This paper reports a study of the effects of phosphorus, tin, and molybdenum on the caustic stress corrosion cracking susceptibility of NiCrMoV rotor steels. Constant load tests were performed on these steels in 9M NaOH at 98 ± 1 °C at a controlled potential of either -800 mVHg/Hgo or -400 mVHg/Hgo. Times to failure were measured. The results show that at a potential of -400 mVHg/Hgo the segregation of phosphorus to grain boundaries lowers the resistance of these steels to caustic stress corrosion cracking. When molybdenum is removed from a steel that has phosphorus segregated to the grain boundaries, the steel’s resistance to stress corrosion cracking is improved. High purity alloys, both with and without molybdenum, show very good resistance to caustic cracking at this potential. At-800 mVHg/Hgo segregated phophorus has no effect; only molybdenum additions lower the resistance of the steel to caustic stress corrosion cracking. Segregated tin has little effect at either potential. Metallographic examination shows that one explanation for these results is that molybdenum and phosphorus, probably as anions precipitated from solution, aid in passivating the sides of the crack and thus help keep the crack tip sharp. This sharpness will increase the speed with which the crack will propagate through the sample. Furthermore, removal of molybdenum greatly increases the number of cracks which nucleate. This higher crack density would increase the relative area of the anode to the cathode and thus act to decrease the crack growth rate.

  6. Effects of preheating temperature on cold cracks, microstructures and properties of high power laser hybrid welded 10Ni3CrMoV steel

    Research highlights: → A Y-groove cold cracking test is designed to assess the laser hybrid welded joints. → As preheating temperature increases, the crack rate decreases and then increases. → Thermal cycles of different preheating temperatures illustrate crack resistance. → The preheating temperature changes the microstructures of laser welded joints. -- Abstract: Laser hybrid welding has become one of the most promising welding methods for high strength low alloy steels due to combining the advantage of the laser and arc. A novel Y-groove cold cracking test adapted to laser hybrid welding is designed to assess the weldability of 10Ni3CrMoV steels at room temperature and different preheating temperatures. The experimental results show that the orientation of the predominant root cracks generally follows the contour of the fusion line. As the temperature increases from 25 oC to 150 oC, at first the root crack rate decreases and then slightly increases at 150 oC. The root crack rate obtained at 120 oC is the lowest. The fracture model changes from a brittle cleavage fracture to a mixture fracture with quasi-cleavage facets and dimples. The thermal cycle curves of laser hybrid welding obtained by temperature measurement systems are used to evaluate the crack resistance and microstructure transformation. The microstructures of welded joints obtained at different temperatures are analyzed by optical microscope (OM). The results reveal that the microstructures of the coarse grained region and the fusion zone at 120 oC have higher cold crack resistance and good impact toughness. Mechanical properties of the welded joint obtained at 120 oC and 150 oC are comprehensively evaluated by microhardness test, uniaxial tensile test and charpy V-notch impact test with side notches. Fractographs of the impact specimens are studied by scanning electron microscopy (SEM). The test results show that the welded joints obtained at 120 oC have satisfactory mechanical properties

  7. Mejora de la tenacidad de un acero de ultraalto contenido en carbono nnediante unión por laminación con un acero al cromo y molibdeno

    Pozuelo, M.

    2005-12-01

    Full Text Available Laminated composite materials containing five layers of ultrahigh carbon steel, 1.35%C, and five layers of a Cr-Mo steel were processed by roll bonding. The rolling procedure improves the bonding of layers and refines the microstructure, diminishing grain size and removing the pearlitic zones. Charpy impact tests were carried out to evaluate the impact properties. Toughness of the laminated composite was highly improved respect to the ultrahigh carbon steel. Moreover, it was double than that of the Cr-Mo steel in the arrester orientation. These results reveal the important role of the interfaces in the mechanical properties of the composite materials.

    Se procesaron mediante unión por laminación, dos materiales compuestos laminados de 10 capas: cinco capas de un acero de ultraalto contenido en carbono con 1,35 % C, alternadas con otras cinco de un acero al cromo y molibdeno. La laminación en caliente consolida la unión entre las capas y afina la microestructura, reduciendo el tamaño de grano y eliminando las zonas de perlita presentes inicialmente. Se realizaron ensayos de impacto Charpy para evaluar su resistencia al impacto. El material compuesto laminado mejoró sustancialmente la tenacidad del acero de ultraalto carbono, además de duplicar la resiliencia del acero al cromo y molibdeno en la orientación "en serie". Estos resultados ponen de manifiesto la importancia de las intercaras en las propiedades mecánicas de los materiales compuestos.

  8. INFLUENCIA DE LAS INCLUSIONES DE AZUFRE EN LA FATIGA DE UN ACERO AL MEDIO CARBÓN.

    Banderas Morales, Juan Joel

    2012-01-01

    La fabricación de acero puro es un proceso trabajoso y caro. Las propiedades mecánicas del acero, en particular la solidez, son considerablemente más altas que las del hierro puro. Uno de los problemas del acero es la presencia de inclusiones (sulfuros) en el producto final, que disminuyen las propiedades mecánicas del acero y el control de las inclusiones no-metálicas, que precipitan en fases aisladas durante la solidificación del acero líquido como productos de reacción, form...

  9. Effect of impurities, Si and Mn contents on long term isothermal temper embrittlement of 3. 5%NiCrMoV steel forgings for turbine rotors. Teiatsu turbine rotor yo 3. 5%NiCrMoV ko no chojikan koon yakimodoshi zeika ni oyobosu fujunbutsu genso oyobi Si, Mn ryo no eikyo

    Kono, M.; Tsuchiyama, T.; Miyakawa, M.; Kinoshita, S.; Suzuki, A. (Kobe Steel, Ltd., Kobe (Japan))

    1993-03-25

    An embrittlement treatment test was carried out on 3.5%NiCrMoV steel forgings as a low-pressure turbine rotor material to find effects of amounts of impurities, Si and Mn on temper embrittlement that may occur during use. A Charpy impact test was performed after the embrittlement treatment, where the shift in 50% fracture appearance transition temperature was used as an embrittlement amount. The embrittlement treatment consists of a step cooling and an isothermal aging processes. Temper embrittlement as a result of isothermal aging at 375[degree]C to 450[degree]C decreased with decrease in impurity elements, Si and Mn, and fall in the quench cooling rates and embrittling temperatures. Effects of impurity elements are large and most important. A considerable amount of time is required until a steel reaches 90% saturated embrittlement. The embrittlement rate is faster with higher temperature, but the saturated embrittlement grows more intensely when temperature is low. Embrittlement at 375[degree]C is less than at other temperatures even under as long period storage as about 20 years. If an embrittlement coefficient is assumed K [le] 0.78, temper embrittlement in a rotor with a diameter of 1,800 mm having been used for 20 years is considered to be 24[degree]C on the surface and 16[degree]C or lower at the center. No problems were observed in its tenacity. 21 refs., 12 figs., 1 tab.

  10. Effect of microstructure on statistical scatter of crack initiation and growth lives in NiCrMoV cast steel. NiCrMoV chuko ni okeru kiretsu no hasseiter dot denpa jumyo no baratsuki ni oyobosu zairyo bishi soshiki no eikyo

    Ishii, A.; Ochi, Y.; Sasaki, S.; Nakamura, H. (The University of Electro-Communications, Tokyo (Japan))

    1991-05-15

    In order to clarify the cause of statistical scatter of crack initiation lives and growth lives in NiCrMoV cast steel for large-size turbine rotor shafts, the initial crack growth behavior and crack initiation sites were studied in detail. Rotating bending fatigue tests were carried out for four kinds of stress amplitudes including one just above a fatigue limit in air at room temperature, and fatigue process was divided into several ones according to a crack length range. By analyzing the number of cycles required for crack growth in each range, the crack length affecting strongly scatter of fatigue lives was examined. Since from scanning electron microscopic observation of crack initiation sites, most of the cracks were initiated from inclusions, the relation between the initiation lives and the size, shape and depth of inclusions was also examined. In addition, the crack length range sensitive to microstructure was considered on the basis of the correlation between a crack growth rate and stress intensity factor on log-log relation. 9 refs., 10 figs., 4 tabs.

  11. Effect of composition, heat treatment and processing technologies on the microstructure and properties of HP and IP rotors of large steam turbines from 1CrMoV steels

    Tchizhik, A.A. [The Polzunov Central Boiler and Turbine Institute, Department the Fatigue Life of Materials for Power Plant Equipment, St. Petersburg (Russian Federation)

    1998-12-31

    In the presentation the evolution of the technology manufacturing of the large forging from the 1CrMoV steels and the results complex of the long time investigations rotors on virgin state and after different operation times is analyzed. Among the information there are the criterion of the optimization of the composition steel service properties, especially super long - term creep resistance, creep fracture and long time cracks resistance. Two safety coefficients: stress (SSC) and time safety coefficient (TSC) must be used for calculations of the possibility prolongation service life of HP and IP rotors for large steam turbines. (orig.) 11 refs.

  12. Application of a constitutive material law for description of creep behaviour at 550 C in pipe bends consisting of the material X20CrMoV12-1

    A model has been developed describing the multiaxial creep deformation and the resulting damage due to pore formation. The model has been modified to incorporate results from uniaxial creep rupture tests, and has been integrated into an FE program and applied to numerical verification of a creep rupture test at 550 C in a pipe bend consisting of the material X 10 CrMoV 12 1. The results show satisfactory agreement between experimental and numerical results and demonstrate the applicability of the model for calculation of the creep-to-rupture data of components. (orig./CB)

  13. Hydrogen-induced crack formation in the low-alloy steel 26 NiCrMoV 145 with a yield strength of approx. 850 N/mm/sup 2/

    David, W.; Schleithoff, K.; Schmitz, F.

    1986-06-01

    In recent years intergranular stress corrosion cracking has occurred worldwide in the shrink-fitted discs of low-pressure turbine rotors made of low-alloy steels. Both anodic stress corrosion cracking and hydrogen-induced crack formation have been mentioned in the literature as possible failure mechanisms. Clarification of the role of hydrogen induced cracking was sought by carrying out a variety of tests with the low-alloy steel 26NiCrMoV 14 5. The results indicate that hydrogen plays a decisive role in the failure mechanism, provided it is available in sufficiently high quantities.

  14. "Estudio tribologico de aceros para moldes. Aplicacion al moldeo por inyeccion de polibutilentereftalato reforzado con fibra de vidrio"

    Martinez Mateo, Isidoro Jose

    fabricacion del molde, tienen una gran influencia sobre su comportamiento en servicio a lo largo de la vida util del molde. En la primera parte del presente estudio, a partir de ensayos punzon sobre disco, se ha determinado la relacion entre la resistencia al desgaste y la dureza de aceros para moldes obtenidos a partir de bloques de gran espesor, estudiando los principales mecanismos de desgaste que tienen lugar. A continuacion, con el fin de determinar el dano superficial que sufren los aceros para moldes en condiciones reales de inyeccion, se han estudiado distintos tipos de aceros utilizados comercialmente en moldes de inyeccion de polimeros y materiales compuestos, seleccionando las condiciones de operacion para determinar la variacion de la rugosidad superficial del acero en funcion del material inyectado, del numero de operaciones sucesivas de inyeccion y de la orientacion del flujo de inyeccion, mediante tecnicas de perfilometria optica y microscopia electronica de barrido. Ademas del dano superficial sufrido por el acero con el numero de piezas inyectadas, tambien se ha determinado la evolucion de la rugosidad superficial de los materiales inyectados, polibutilentereftalato (PBT) puro y materiales compuestos derivados de PBT por adicion de un 20 o un 50% en peso de fibra de vidrio. En el caso de las piezas inyectadas, se ha caracterizado su microestructura en funcion del flujo de inyeccion y de la densidad de fibra, se han determinado sus propiedades termicas y dinamico-mecanicas, asi como la variacion de la rugosidad superficial de las piezas inyectadas con el numero de operaciones de inyeccion y con la geometria de las distintas secciones de las piezas. Finalmente, se ha evaluado la resistencia a la abrasion de PBT reforzado con un 50% de fibra, en funcion del numero de piezas inyectadas y de la direccion de rayado con respecto a la orientacion del flujo de inyeccion.

  15. Effect of ETA treatment on corrosion fatigue in rotors and blades and stress corrosion cracking in 3.5 NiCrMoV steel low-pressure turbine discs

    In recent years, to increase the reliability and reduce the amount of feed water iron to prevent of fouling of steam generator tubes, ethanolamine (ETA) treatment has been adopted into the secondary system. In this investigation, the authors verified that ethanolamine treatment does not adversely affect the susceptibility of either stress corrosion cracking (SCC) in the turbine discs that are the principal units in the secondary system or corrosion fatigue (CF) in rotors and blades. In the first stage, a laboratory investigation was made of (1) SCC initiation and propagation in 3,5 NiCrMoV steel and (2) CF in 3,5 NiCrMoV steel and blade steels, in both cases using deaerated water to which had been added ethanolamine with few organic acids that is 10 times the estimated concentration. It was confirmed that the ethanolamine treatment had almost no effect. In the second stage, test pieces (removed from the disc steel inserted into the turbine extraction chamber before the ethanolamine treatment was started) were used to observe the initiation and propagation of SCC. Even after long-term observation, ethanolamine treatment into the secondary system was found to have almost no effect on the susceptibility of SCC in discs. (author)

  16. Properties of surface layer of X40CrMoV5-1 in the relation to remelting conditions by the use of a high power diode laser

    Investigations included remelting experiments on the X40CrMoV5-1 hot-work steel with the high power diode laser. Tests have been made using the high power diode laser (HPDL) in the technological process of remelting. The effect of remelting parameters on structure and properties of its surface layer, as well as on remelting geometry and shape. The influence of the technological conditions and their effect on the mechanical properties of the surface layer, and especially its hardness has been tested. Dependence of the microhardness changes, on the degree of the laser beam influence on the treated surface, and mostly on the hardness increase in the remelted layer is presented. The influence of remelting process parameters on the structure of substrate material is presented. Guidelines for remelting of the X40CrMoV5-1 steel surface using the high power diode laser feature the outcome of the investigation aimed at obtaining its optimum mechanical and working properties. (author)

  17. Effect of ETA treatment on corrosion fatigue in rotors and blades and stress corrosion cracking in 3.5 NiCrMoV steel low-pressure turbine discs

    Hitomi, Itoh [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center (Japan); Takashi, Momoo [Mitsubishi Heavy Industries, Ltd., Takasago Machinery Works (Japan); Takayuki, Shiomi [Kansai Electric Power Co., Inc., Osaka (Japan)

    2001-07-01

    In recent years, to increase the reliability and reduce the amount of feed water iron to prevent of fouling of steam generator tubes, ethanolamine (ETA) treatment has been adopted into the secondary system. In this investigation, the authors verified that ethanolamine treatment does not adversely affect the susceptibility of either stress corrosion cracking (SCC) in the turbine discs that are the principal units in the secondary system or corrosion fatigue (CF) in rotors and blades. In the first stage, a laboratory investigation was made of (1) SCC initiation and propagation in 3,5 NiCrMoV steel and (2) CF in 3,5 NiCrMoV steel and blade steels, in both cases using deaerated water to which had been added ethanolamine with few organic acids that is 10 times the estimated concentration. It was confirmed that the ethanolamine treatment had almost no effect. In the second stage, test pieces (removed from the disc steel inserted into the turbine extraction chamber before the ethanolamine treatment was started) were used to observe the initiation and propagation of SCC. Even after long-term observation, ethanolamine treatment into the secondary system was found to have almost no effect on the susceptibility of SCC in discs. (author)

  18. Creep damage in welds of X 20 CrMoV 12 1 steel. Part 2 - Studies of long term service exposed material and damage data base and calculation of damage distribution and damage resistance; Krypskador i svetsar av X 20 CrMoV 12 1 staal. Etapp 2 - Studier av lingtidspiverkat material och skadedatabas samt berakning av skadefordelning och skadetilighet

    Storesund, Jan; Borggreen, Kjeld; Weilin Zang; Nilsson, Henrik; Samuelson, Aake

    2004-09-01

    The present project has been consisted of the following pieces of work on welds of X20 CrMoV 12 1: Analysis of, by use of replica testing, creep damage development in 368 welds in 11 Danish high pressure steam lines with operation up to 200,000 h. Metallographic investigations of four welds from a retired live steam line with approximately 182 000 h in operation. - Evaluation of the influence of the two most common etching methods on the interpretation of creep cavitation. Analysis of the time security of the material, i.e. influence of enhanced temperature or stress on creep life time. Finite element simulations of the creep behaviour of X20 welds where effects of HAZ creep properties, system stresses and degree of multiaxiality in the rupture criterion are studied. In addition a literature study on publications of creep life time in X20 steel was performed in a first, already reported part of the project. The results of the comprehensive replica testing and the metallographic investigations show clear-cut that welds of this material have an excellently long creep life that indeed will reach 200,000 h. The creep damage at that time is in general very limited. The typical creep life for welds of X20 can be evaluated to at least 250,000 h. The reason for that it is not possible to evaluate an even longer creep life is the fact that creep testing and finite element simulations show that creep elongation and creep damage will accelerate considerably later in the creep life than some low alloy steels. In the worst case this acceleration could start already just after 200,000 h. It is also demonstrated that welds of the X20 steel can stand system stresses much better than low alloy steels. Recommendations for how and when inspections and testing of welds of the current material should be performed have been issued. They have been adapted to the findings in the project. The recommendations can, as long as severe damage is absent, allow for longer inspection intervals

  19. Experimental investigation of cutting parameters influence on surface roughness and cutting forces in hard turning of X38CrMoV5-1 with CBN tool

    H Aouici; M A Yallese; A Belbah; M F Ameur; M Elbah

    2013-06-01

    This experimental investigation was conducted to determine the effects of cutting conditions on surface roughness and cutting forces in hard turning of X38CrMoV5-1. This steel was hardened at 50 HRC and machined with CBN tool. This is employed for the manufacture of helicopter rotor blades and forging dies. Combined effects of three cutting parameters, namely cutting speed, feed rate and depth of cut, on the six performance outputs-surface roughness parameters and cutting force components, are explored by analysis of variance (ANOVA). Optimal cutting conditions for each performance level are established. The relationship between the variables and the technological parameters is determined through the response surface methodology (RSM), using a quadratic regression model. Results show how much surface roughness is mainly influenced by feed rate and cutting speed. The depth of cut exhibits maximum influence on cutting force components as compared to the feed rate and cutting speed.

  20. Estudio tribológico de aceros austeníticos tipo Hadfield: influencia del manganeso en su respuesta frente al desgaste

    Camba, C.

    2010-12-01

    Full Text Available This study analyzes the wear behavior of austenitic Hadfield steels with different manganese contents (4 to 6% of manganese. The tribological analysis has been carried out by pin on disk tests according to ASTMG99-05 standard. The results have been related to the hardness and to the microstructure of every sample. The wear resistance of these steels depends on the hardness of the material and is very influenced by the type and distribution of the precipitates.

    En este estudio se analiza la respuesta frente al desgaste de aceros austeníticos tipo Hadfield, en función del contenido de manganeso, partiendo de aceros con proporciones dentro del intervalo del 4 al 6 % de manganeso. El análisis tribológico se ha realizado mediante ensayos pin on disk, según norma ASTM G99-05, y los resultados obtenidos se han relacionado con la dureza y con la microestructura de cada muestra determinándose que, para este tipo de aceros, la resistencia al desgaste no sólo depende de la dureza del material sino que se ve muy influida por el tipo y distribución de precipitados existentes.

  1. Magnolias de acero (1989)

    Galache Montero, Aurora

    2009-01-01

    [ES] Magnolias de Acero (1989) acerca a los espectadores al lado humano de la enfermedad. Los pone en contacto con la capacidad de lucha de algunos enfermos por llevar una vida normal ante un proceso crónico ni las repercusiones negativas sobre su salud. La protagonista, que padece una diabetes, se esfuerza por vivir una vida sin limitaciones batallando constante con las barreras que su enfermedad le va poniendo constantemente, anteponiendo siempre su felicidad a las consecuencias fatales que...

  2. Origen y endurecimiento por dispersión de carbonitruros en un acero comercial microaleado al niobio y laminado en caliente

    Valencia, E.

    1998-12-01

    Full Text Available Throughout this work, a study on niobium carbonitrides formation and its hardening effect in a commercial hot strip microalloyed steel is presented. Optic and electron micrographs were obtained while mechanical tests and indirect models allow to predict samples yield strength, taking into account the steel composition and its structural characteristics. The results showed an extended precipitation on austenite boundary cells during the last thermomechanical processing stages, which probably achieved a considerable contribution to the hardening by dispersion in the material studied. Otherwise, no evidence of precipitation in ferrite by means of transmission electron microscopy (TEM was observed. A poor interphase precipitation was detected in about 10 per cent of the total observed zones with no appreciated contribution to the steel hardness.

    Se presenta un estudio sobre el origen de los carbonitruros de niobio y su efecto en el endurecimiento de un acero comercial microaleado y laminado en caliente. Para tal fin se utilizaron micrografías ópticas y electrónicas; así como también ensayos mecánicos y modelos indirectos que permitieron predecir el límite elástico teniendo en cuenta la composición del acero y sus características estructurales. Los resultados mostraron una extensa precipitación en la austenita durante las últimas fases del proceso de laminación siendo ésta responsable del principal aporte al endurecimiento por dispersión en el material investigado. No hubo evidencias de precipitación en la ferrita por observaciones al microscopio electrónico de transmisión y sólo una escasa precipitación interfásica fue detectada en un 10 % de las zonas observadas sin una apreciable contribución al endurecimiento del acero.

  3. RESISTENCIA A LA CORROSIÓN DE LAS MULTICAPAS DE [TIN/ALTIN]n DEPOSITADAS SOBRE ACERO AL CARBONO AISI 1045

    WILLIAM APERADOR

    2011-01-01

    Full Text Available En este artículo se presenta el mejoramiento frente a la corrosión de los recubrimientos multicapas de [TiN/AlTiN]n con periodos de 2, 6, 12 y 24 bicapas depositados mediante la técnica de PVD magnetrón Sputtering sobre acero al carbono AISI 1045. La evaluación electroquímica se realizó mediante las técnicas espectroscopia de impedancia electroquímica (EIS y curvas de polarización Tafel, en una solución de 0.5M de H2SO4 + 3.5% wt. de NaCl. La resistencia a la corrosión aumentó de forma gradual en función del número de bicapas en comparación al sustrato encontrando valores de velocidad de corrosión de 18.51 mpy para el sustrato sin recubrir y de 1x10 6 mpy para la muestra con 24 bicapas. Los resultados electroquímicos revelan el efecto positivo en cuanto a la protección superficial del acero 1045 con el incremento del periodo en las multicapas de [TiN /AlTiN]n.

  4. Procedimientos y análisis END y ED de soldaduras a tope SMAW, MAG y TIG, de acero al carbono F-114 para construcción

    CLIMENT BALBASTRE, JUAN JOSÉ

    2011-01-01

    Trabajo científico técnico.El objeto del proyecto es la comparación entre tres chapas. Cada una de las chapas tiene un procedimiento de soldadura diferente: Chapa 1. Método SMAW. Chapa 2. Método MAG. Chapa 3. Método TIG. Una vez estas han sido soldadas, se procederá mediante ensayos no destructivos y ensayos destructivos a descubrir las características de estas. Al final de la realización de todos estos ensayos, se concluirá con la elección de la soldadura más apropiada para este acero. La...

  5. Empleo de la cáscara de arroz en la fundición de piezas de acero al carbono//Using of rice husk in the carbon steel casting parts process

    Juan Carlos Cruz-Pérez; Jesús Eduardo González-Ruiz; Lorenzo Perdomo-González; Pantaleón Rodríguez-González

    2012-01-01

    Los materiales auxiliares desempeñan un papel importante en el aumento de la eficiencia tecnológica del proceso de fundición de piezas de acero al carbono. En este artículo se exponen los primeros resultados del empleo de la cáscara de arroz como material termoaislante en la obtención de piezas fundidas de acero al carbono. En los experimentos se evaluó la influencia  de seis combinaciones de las variables espesor de pared del casquillo y capa de cobertura. En la confección de los casquillos ...

  6. Investigation of changes in toughness of the steel X 20 CrMoV 12 1 due to long-term loading and renewed tempering treatment - reason and procedure

    The aim of the project is to check whether renewing the impact notch work by renewed tempering after long-term loading leads to statistically secure and long-term improvement of toughness and how the creep behaviour is affected by this. The main part in carrying out the project as regards effort and duration is the long-term (20,000 hour) storage experiment on a pipe made of optimised (S, P Lowered) X 20 CrMoV 12 1 material (400 mm diameter x 21 wall thickness, 2500 mm long) with three identical circular seams at 550deg C with an internal pressure of 12.5 MPa. The main point of the material investigations is determining the toughness behaviour for the material conditions: initial state (BOL), under internal pressure for material stored at 550deg C, under internal pressure for material stored at 550deg C tempered again. There is an accompanying check of the creep behaviour and electron optical micro-structure examination (cut-outs, compound) of these material conditions. (orig./DG)

  7. Acero de alto silicio producido por inmersión en Al-Si y recocido de difusión

    Ros-Yáñez, Tanya

    2000-10-01

    Full Text Available It is difficult to process steel sheet with a high Si content (>3.5%Si, mainly because of its brittleness and the appearance of cracks during rolling and oxidation. However, there is a market for this steel in electrical applications because of the favourable influence of Si on magnetostriction and electrical resistivity. As an alternative process, 3% Si-steel substrates were coated with hypereutectic Al-Si-alloys in a "hot-dip simulator" using different preheating and dipping times. The obtained layers were characterised by SEM and EDS analysis. Diffusion annealing experiments were performed to obtain sufficient amount of Si in the steel. It was observed that:

    • intermetallic phases appear in the coating layers as according to the ternary Fe-Si-Al diagram
    • with a double dipping primary silicon crystals are formed in the surface layer
    • the ordered DO3 structure is present if the dipping and/or diffusion time is long enough
    • homogeneous silicon gradients in the whole substrate thickness have not yet been achieved
    • theoretic calculations show that Si-gradient, also have beneficial effects on magnetic behaviour


    Es difícil procesar aceros eléctricos de alto contenido en silicio (>3,5 % Si. Esto se debe principalmente, a problemas de fragilidad, aparición de grietas durante la laminación y oxidación. Sin embargo, existe un importante mercado para este tipo de acero en aplicaciones eléctricas debido a la favorable influencia que ejerce el Si sobre la magnetoestricción, las pérdidas eléctricas y la resistividad eléctrica. Como proceso alternativo, se sumergieron substratos de acero con 3 % de silicio en una aleación hipereutéctica Al-25 % Si, en un simulador de recubrimiento por inmersión en caliente. En los ensayos se utilizaron diferentes tiempos de precalentamiento y de inmersión. En la segunda fase de la investigación se llevaron a cabo recocidos de difusión en el

  8. Aplicación y caracterización físico-química de varios tratamientos superficiales realizados al acero inoxidable 316L para aplicaciones biomédicas

    Mañá, M.; Valentí, J.; Mestre Vinardell, Aleix; Gil Mur, Francisco Javier

    2008-01-01

    La biocompatibilidad de los metales utilizados en implantología está íntimamente relacionada con las características superficiales de los implantes tanto desde un punto de vista químico como topográfico. El objetivo de este trabajo es aplicar varios tratamientos superficiales al acero inoxidable 316 L y caracterizar, posteriormente, la superficie físico-químicamente. La superficie pulida de varios discos de acero 316 L fue tratada mediante los procesos de: granallado, variando el tamaño y la...

  9. Aplicación y caracterización físico-química de varios tratamientos superficiales realizados al acero inoxidable 316 L para aplicacions biomédicas

    Mañá, M.; Valentí, J.; Mestre Vinardell, Aleix; Gil Mur, Francisco Javier

    2008-01-01

    La biocompatibilidad de los metales utilizados en implantología está íntimamente relacionada con las características superficiales de los implantes tanto desde un punto de vista químico como topográfico. El objetivo de este trabajo es aplicar varios tratamientos superficiales al acero inoxidable 316 L y caracterizar, posteriormente, la superficie físico-químicamente. La superficie pulida de varios discos de acero 316 L fue tratada mediante los procesos de: granallado, variando el tamaño y l...

  10. Diagrama de Recristalización-Precipitación-Tiempo-Temperatura (RPTT de un acero microaleado al vanadio

    Quispe, A. B.

    1997-12-01

    Full Text Available A method developed in the CENIM is described which allows to study the interaction recrystallization-induced precipitation by the deformation of vanadium microalloyed steel. By means of torsión test and applying the back extrapolation method, has been determined the recristallized fraction to diferent temperatures. When the precipitation begins, the recristallized fraction is separated of the Avrami's equation and this allows to know the instant the precipitation begins (Ps and the instant the precipitation finishes (Pf. Thereby can be traced the Recrystallization- Precipitation-Time-Temperature (PTT diagrams, which graphically show the interaction Recrystallization-Precipitation and simultaneously allows the determination of the static recrystallization critical temperature (SCRT. The mentioned temperature represents the limit between the two phases, before and after of the precipitation.

    Se describe un método desarrollado en el CENIM, que permite estudiar la interacción de la recristalización- precipitación inducida por deformación de un acero microaleado al vanadio. Mediante ensayos de torsión, y aplicando el método back extrapolation, se ha determinado la fracción recristalizada a diferentes temperaturas. Cuando la precipitación comienza, la fracción recristalizada se desvía de la ecuación de Avrami y esto permite conocer el instante en que la precipitación comienza (Ps y el instante en que termina (Pf. De este modo, se pueden trazar los diagramas Recristalización- Precipitación- Tiempo-Temperatura (RPTT, que muestran gráficamente la interacción Recristalización-Precipitación y que simultáneamente permiten la determinación de la temperatura crítica de recristalización estática (SCRT. Dicha temperatura crítica representa el límite entre las dos fases, antes y después de la precipitación.

  11. 新型Fe-Cr-Mo-V系热强耐蚀钢的热处理工艺%Heat treatment of a new type of thermal strengthening and corrosion resistance steel Fe-Cr-Mo-V

    刘海亮; 朱景川; 来忠红; 侯杨; 董晓林

    2009-01-01

    The Fe-Cr-Mo-V thermal strengthening and corrosion resistance steel is a newly developed special steel with has better mechanical properties and corrosion resistance.The heat treatment process of this steel was investigated through microstructure observation and hardness test with appropriate quenching and tempering.The results show that the optimum heat treatment process for the steel is water quenching at 1 120℃ and tempering at 560℃ for 2 h.After such processing,the tensile strength of the steel is 1 607 MPa,impact value is 8.2J,reduction of area is 30.56% and elongation is 4.4%.%新型Fe-Cr-Mo-V系热强耐蚀钢是一种新开发的具有高硬度,红硬性和一定耐腐蚀性的特种钢材.通过对淬火和回火试样的微观组织观察和硬度测试,研究了该钢种的热处理工艺.结果表明,该钢种的最佳热处理工艺为1 120℃水淬,560℃回火2 h,经该工艺处理后材料的拉伸强度为1 607 MPa、冲击功为8.2J、断面收缩率为30.56%,伸长率为4.4%.

  12. Retained Austenite Decomposition and Carbide Formation During Tempering a Hot-Work Tool Steel X38CrMoV5-1 Studied by Dilatometry and Atom Probe Tomography

    Lerchbacher, Christoph; Zinner, Silvia; Leitner, Harald

    2012-12-01

    The microstructural development of a hot-work tool steel X38CrMoV5-1 during continuous heating to tempering temperature has been investigated with the focus on the decomposition of retained austenite (Stage II) and carbide formation (Stages III and IV). Investigations have been carried out after heating to 673.15 K, 773.15 K, 883.15 K (400 °C, 500 °C, 610 °C) and after a dwell time of 600 seconds at 883.15 K (610 °C). Dilatometry and atom probe tomography were used to identify tempering reactions. A distinctive reaction takes place between 723.15 K and 823.15 K (450 °C and 550 °C) which is determined to be the formation of M3C from transition carbides. Stage II could be evidenced with the atom probe results and indirectly with dilatometry, indicating the formation of new martensite during cooling. Retained austenite decomposition starts with the precipitation of alloy carbides formed from nanometric interlath retained austenite films which are laminary arranged and cause a reduction of the carbon content within the retained austenite. Preceding enrichment of substitutes at the matrix/carbide interface in the early stages of Cr7C3 alloy carbide formation could be visualised on the basis of coarse M3C carbides within the matrix. Atom probe tomography has been found to be very useful to complement dilatational experiments in order to characterise and identify microstructural changes.

  13. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo.

    R. Collazo Carceller; H. López Salinas; A. Días Romero

    2009-01-01

    El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuesta tecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Se determinó la influencia de los parámetros, energía introducida (Hi), número de capas (Nc) y ancho del depósito (Ad), en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizando el electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuesta tecnológicaThis work, ...

  14. Utilización del mineral de manganeso (pirolusita) en la producción de aceros al carbono

    Aerles Batista-Cabrera; Efraín Navas-Medina

    2003-01-01

    Los métodos tradicionales de producción de acero utilizan el ferromanganeso para obtener el porcentaje de Mn en la marca establecida según la norma cubana, pero este compuesto es altamente costoso. Se ensayó, en la producción del Ac 35, sustituir el ferromanganeso por el mineral pirolusita (MnO2) con el fin de reducir los costos. Se evaluaron dos variantes de sustitución: la primera consiste en añadir el mineral con virutas de aluminio y coque (o residuos de electrodos) sobre la escoria del m...

  15. Aceros patinables (Cu, Cr, Ni): resistencia a la corrosión atmosférica y soldabilidad

    Cano Cuadro, Heidis Patricia

    2013-01-01

    La utilización del acero mantiene una posición predominante en la ingeniería de los materiales. Concretamente, los aceros de alto comportamiento tienen un desarrollo creciente a nivel mundial, especialmente los denominados aceros patinables, que se corresponden con aceros de baja aleación y alto límite elástico. Los aceros patinables (“low alloy steels o “weathering steels”) son aceros suaves con un contenido en carbono inferior al 0,2% en peso, a los que se han adicionado como elementos ...

  16. Evolución microestructural y comportamiento mecánico de aceros fundidos resistentes al calor sometidos a alta temperatura de servicio

    Garin, J. L.

    2008-08-01

    Full Text Available The microstructure and mechanical properties evolution were determined in two cast heat-resistant steels upon annealing processes to induce sigma-phase formation. The research analyzed the influence of heating time at 1053 K on the formation of sigma and its relationship with selected mechanical properties, in HC-type steels (28,6Cr- 1,9Ni-0,4C and HD-type steels (28,3Cr-5,8 Ni-0,4. The obtained results evidenced formation of sigma-phase initially along ferrite-austenite grain boundaries, but at longer times sigma precipitates in the bulk of the ferrite grains, reaching maximum values of approximately 25 % and 55 % in HC and HD respectively, after 120 hours treatment. Precipitation of sigma in both alloys resembled the Johnson-Mehl-Avrami’s mechanism stated for nucleation and growth. The mechanical behavior mainly depicted a strong decrease of toughness and a moderated increase of hardness.

    Se determinaron los cambios producidos en la microestructura y en las propiedades mecánicas de dos aceros fundidos resistentes al calor, al ser sometidos a recocidos para inducir la formación de la fase sigma. La investigación analizó la influencia del tiempo de calentamiento a 1.053 K, en la formación de la fase sigma y su consecuente relación con algunas propiedades mecánicas seleccionadas, de aceros tipo HC (28,6Cr-1,9Ni-0,4C y HD (28,3Cr-5,8 Ni-0,4C. Los resultados obtenidos evidenciaron la formación de fase sigma, inicialmente, en los bordes de grano austenita-ferrita avanzando, luego, masivamente hacia el seno de la matriz ferrítica, para alcanzar valores extremos de aproximadamente 25 % y 55 % en HC y HD, respectivamente, al cabo de 120 h de tratamiento. La precipitación de sigma en ambos materiales exhibió un mecanismo de nucleación y crecimiento del tipo Jonson-Mehl-Avrami. El comportamiento mecánico se caracterizó, principalmente, por una drástica disminución en la tenacidad y un aumento de la dureza.

  17. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo.

    R. Collazo Carceller

    2009-09-01

    Full Text Available El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuesta tecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Se determinó la influencia de los parámetros, energía introducida (Hi, número de capas (Nc y ancho del depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizando el electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuesta tecnológicaThis work, sumarises the study and the analisys developed, to prupose the Zuazaga cut cane thecnology recuperation, in aur sugar mills. The parameters influency was determinated, Heat input (Hi, Number of layers (Nc and the Cord whith (Ad, in the mofology and the abrasive wear resistance increase, using the cromiun steel UTP DUR - 600. The economical calculation of the thecnology was done.

  18. Application of digital image processing to determine the causes of failures in SAE 1018 carbon steel; Aplicacion del procesamiento digital de imagenes para la determinacion de las causas que provocan fallas en el acero al carbono SAE 1018

    Bolanos-Rodriguez, E [Escuela Superior de Tizayuca, Universidad Autonoma del Estado de Hidalgo, Tizayuca, Hidalgo (Mexico)]. E-mail: bola7112@yahoo.com.mx; Gonzalez-Islas, J.C. [Universidad Tecnologica de Tulancingo, Tulancingo, Hidalgo (Mexico)]. E-mail: juanc.gonzalez@utec-tgo.edu.mx; Felipe-Riveron, E.M. [Centro de Investigacion en Computacion, Instituto Politecnico Nacional, Mexico, D.F. (Mexico)]. E-mail: edgardo@cic.ipn.mx

    2013-03-15

    The research is focused on determining the causes of failures in the SAE 1018 carbon steel that is used in pipes carrying drinking water. Digital processing of images captured by photomicrographs by scanning electron microscopy coupled with the technique of X-ray microanalysis. The results demonstrate that the low quality of the raw materials and the manufacturing process of steel are the reasons for the occurrence of cracks observed in the material. [Spanish] La investigacion se centra en determinar las causas que provocan fallas en el acero al carbono SAE 1018 que es utilizado en tuberias que transportan agua potable. Se emplea el procesamiento digital de imagenes de las microfotografias captadas por medio de microscopia electronica de barrido, unido a la tecnica de microanalisis de rayos X. Los resultados obtenidos demuestran que la baja calidad de las materias primas y el proceso de manufactura del acero son las razones de la ocurrencia de fisuras observadas en el material.

  19. Comparación de la corrosividad atmosférica del acero al carbono en Colombia y Cuba

    Delgado Lastra, Juan

    2001-06-01

    Full Text Available Samples of structural carbon steel were exposed to the atmosphere in a number of sites in Colombia and Cuba for periods of 2, 3, 6, 12 and 24 months. Corrosion rate was determined by mass loss measurements, and cause-effect relationship to exposure time and pollutants (deposited chloride and sulfur oxides were calculated. Analysis let to adjust models by the multiple regression method. Also, comparison of atmospheric corrosion rates between Colombia and Cuba were done using covariance analysis.

    Se expusieron a la atmósfera probetas de aceros estructurales de bajo contenido de carbono, en varios sitios de Colombia y Cuba, que se retiraron a intervalos de 2, 3, 6, 12, 18 y 24 meses. Se determinó la corrosión por pérdida de masa y se buscaron relaciones de causalidad con el tiempo de exposición y las cantidades de cloruro y óxidos de azufre depositados. El análisis permitió ajustar modelos de regresión múltiple y también, a través de variables dicótomas, realizar la comparación de la corrosión atmosférica entre Colombia y Cuba, mediante análisis de covarianza.

  20. un acero importado

    Wilson A. Hormaza R.

    2007-01-01

    Full Text Available Este trabajo busca determinar las causas que llevaron al deterioro superficial de un conjunto de láminas y bobinas importadas de acero. Lo anterior implica precisar el tipo de deterioro de los componentes, es decir, si este se presentó durante el transporte marítimo o durante el almacenamiento. Los ensayos realizados fueron: análisis visual, análisis de espectrofotometría de infrarrojo y comparativo de los cristales de Cloruro de Sodio (NaCl, análisis de la morfología de la superficie deteriorada a través de microscopia óptica, análisis químico, metalografía y dureza. Los análisis determinaron la presencia de cristales de NaCl, los cuales, al disociarse, generan iones de Cl- (Cloruros y Na+ (Sodio, responsables del proceso de corrosión, indicándose, así la presencia de un ambiente marino

  1. “CARACTERIZACIÓN Y SOLDABILIDAD DE UN ACERO AVANZADO DE ALTA RESISTENCIA MICROALEADO CON BORO.”

    Alatorre Torres, Norma

    2012-01-01

    L os aceros micro-aleados, como es el caso de los Aceros Avanzados de Alta Resistencia (AHSS), presentan ventajas en relación a los aceros estructurales al carbón y de baja aleación, respecto al costo y a la mejora en propiedades mecánicas (límites elásticos hasta cuatro veces superiores a los aceros laminados tradicionales), que se obtienen mediante un tratamiento termo-mecánico controlado. Este hecho se ve reflejado en el aumento en la demanda de este acero (entre 10 y 15%...

  2. Producción de aceros al carbono en hornos de arco eléctrico en condiciones de mineral de manganeso. // Steel production in electric arc furnaces in the condition of use of manganese.

    E. E. Navas Medina

    2007-05-01

    Full Text Available El presente trabajo constituye una segunda etapa de investigación relacionada con la producción de acero en hornos de arcoeléctrico con revestimiento básico en condiciones de utilización de mineral de manganeso como sustituto del ferromanganeso.En la investigación se caracteriza el acero producido utilizando el mineral de manganeso en dos variantes tecnológicasdiferentes y se determinan parámetros importantes, tales como la estructura del acero obtenido, la influencia de lacomposición química y la temperatura en la reducción del Mn. Adicionalmente, se determina la composición química de laescoria, su basicidad e influencia en el aprovechamiento del Mn del mineral, así como, lo que significa la sustitución delFeMn en la problemática medioambiental.Palabras claves: Producción de aceros al carbono, hornos de arco eléctricos, mineral de manganeso.______________________________________________________________________________Abstract:This present work constitutes the second stage of investigation in relation with the steel production bymeans of electric arc furnaces in the condition of use of manganese ores as a substitute of theferromanganese. In the investigation, the steel manufactured is analyzed the manganese ore in twodifferent technological variants and some important parameters are determined such as: the chemicalcomposition's structure of the steel, the influence of temperature in the reduction of Mn. Moreover, ananalysis of the chemical composition of the slag and the influence in the environmental is realized.Key words: Carbon steel production, electric arc furnaces, manganese mineral.

  3. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo. // Proposal for Recuperation of Sugar Mill Cut Cane by Using Chromium Steel Electrodes.

    R. Collazo-Carceller; H López-Salinas; A. Días-Romero.

    2009-01-01

    El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuestatecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Sedeterminó la influencia de los parámetros, energía introducida (Hi), número de capas (Nc) y anchodel depósito (Ad), en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizandoel electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuestatecnológica.Palabras claves...

  4. Estudio de la degradación de elementos refractarios de alúmina en la sinterización de aceros modificados con Mn

    Peña, P.; Sicre-Artalejo, J.; Campos, M; Torralba Castelló, José Manuel; Zbiral, J.; Danniger, H.

    2008-01-01

    [ES] En este trabajo se estudia la degradación de los refractarios de un horno de sinterización, cuando están involucrados en el proceso aceros de baja aleación con adición de manganeso. Dada la elevada Pvapor del manganeso y las atmósferas habituales de sinterización para este tipo de aceros, se produce su sublimación durante el ciclo térmico. Se proporciona así, una fase gaseosa, que pudiendo ser beneficiosa para la difusión en las muestras de acero, puede alterar la composición de los refr...

  5. Soldabilidad de un acero de blindaje con electrodos de acero inoxidable austenitico

    GIRALDO BARRADA, JORGE ENRIQUE

    2005-01-01

    Se evaluaron las propiedades mecánicas y la microestructura de las soldaduras obtenidas con diferentes electrodos para unir platinas de un acero, templado y revenido, de alta dureza y baja aleación producido bajo la especificación MIL A46100, el cual es usado en la fabricación de estructuras blindadas. Se determinó el efecto que tiene el material de aporte (aceros inoxidables austeníticos, E307 y E308Mo, y dúplex, E312 y Eutectic 680),aplicado con proceso de soldadura al arco con electr...

  6. Diseño de aleaciones maestras para la sinterización con fase líquida de aceros al Mn-Si

    Oro Calderón, Raquel de

    2012-01-01

    Los aceros pulvimetalúrgicos han competido con éxito durante años con las piezas fabricadas por moldeo, debido a la posibilidad de fabricar mediante esta técnica piezas complejas, en grandes series y con un bajo coste. En las últimas décadas, el precio de los elementos de aleación comúnmente utilizados en la pulvimetalúrgia de aceros de baja aleación (cómo el Cu, Ni y Mo) ha experimentado continuas fluctuaciones y, globalmente, un aumento creciente. Se plantea en esta situación el reto de enc...

  7. Empleo de la cáscara de arroz en la fundición de piezas de acero al carbono//Using of rice husk in the carbon steel casting parts process

    Juan Carlos Cruz-Pérez

    2012-05-01

    Full Text Available Los materiales auxiliares desempeñan un papel importante en el aumento de la eficiencia tecnológica del proceso de fundición de piezas de acero al carbono. En este artículo se exponen los primeros resultados del empleo de la cáscara de arroz como material termoaislante en la obtención de piezas fundidas de acero al carbono. En los experimentos se evaluó la influencia  de seis combinaciones de las variables espesor de pared del casquillo y capa de cobertura. En la confección de los casquillos se utilizó cáscara de arroz triturada, la que posteriormente fue aglutinada con silicato de sodio, apisonada y endurecida con CO2, mientras que la cobertura se utilizó sin procesamiento previo. El mayor nivel de entrega de acero se obtuvo al emplear un espesor de casquillo de 65 mm y una altura de cobertura de 85 mm. El valor del ASAF generado por las variantes experimentales resultó igual o inferior a 0,48. Palabras claves: casquillo termoaislante, polvo de cobertura, cáscara de arroz, acero fundido.______________________________________________________________________________ Abstract Feeding auxiliary materials perform a very important role in improves technological efficiency of carbon steel casting parts process. In this article are exposing the first results in the rice husk using as an insulating material in such process. The variables sleeve thickness and covering thickness’ influence were evaluated in six combinations by means of experiments. In sleeves preparation was used crushed rice husk, which was agglutinated with sodium silicate, compacted and hardened with CO2, meanwhile as covering it was uses without previous preparation. The mayor liquid steel delivering level was get employing 65 mm sleeve thickness and 85 mm covering thickness. The ASAF value generated for experimental variants was equal or inferior to 0.48. Key words: insulating sleeve, riser sleeve, hot topping, rice husk, steel cast.

  8. Corrosión atmosférica de aceros patinables de nueva generación

    Díaz Ocaña, Iván

    2012-01-01

    Los aceros patinables, "low alloy steels" o "weathering steels" como se les denomina en la literatura sajona, describen una clase de aceros estructurales de baja aleación y alto límite elástico, que experimentan en atmósferas de baja agresividad (rural, urbana e industrial ligera)menor corrosión que el acero al carbono y además poseen superiores propiedades mecánicas, por lo que constituyen un material idóneo para sustituir al acero al carbono en estructuras de larga duración.De forma genéric...

  9. Influencia del revenido en la estructura y las propiedades de dureza, resistencia a la tracción y resiliencia del acero cubano al cromomanganeso- silicio-níquel. // Influence of tempering on structure and hardness, strength and resilience properties of ch

    G. Tourón-Alonso; A. Jénez-Señor; N. Caballero-Stevens; A. J. Estenoz-Mojena

    2009-01-01

    La actual demanda de herramientas y accesorios para maquinarias agrícolas se presenta comofuente creciente de nuevas aplicaciones del acero al Cr-Mn-Si-Ni. Este criterio justifica la práctica detratamientos térmicos, para conseguir distintos valores de propiedades mecánicas, que orienten almaterial hacia las exigencias y circunstancias de aplicaciones concretas. El trabajo tiene comoobjetivo conocer la estructura del acero, heredadas de las transformaciones de fase en diferentesregímenes de t...

  10. Estudio de la interacción precipitación-recristalización de un acero microaleado al vanadio con 0,35 % C

    Quispe, A. B.

    1998-05-01

    Full Text Available A method is described which allows to study the interaction recrystallization-induced precipitation by the deformation of vanadium microalloyed steel and 0.35 % C. By means of torsion tests and applying the Back Extrapolation method, the recristallized fraction at different temperatures has been determined. When the precipitation begins, the recristallized fraction does not follow the Avrami's equation. This allows to know the instant when precipitation starts (Ps and the instant when precipitation finishes (Pf. Therefore, Recrystallization-Precipitation-Time-Temperature (RPTT diagrams can be obtained, which graphically show the interaction Recrystallization-Precipitation and simultaneously allows the determination of the static recrystallization critical temperature (SRCT. This temperature represents the limit between the two phases, before and after precipitation.

    Se describe un método que permite estudiar la interacción de la recristalización-precipitación inducida por deformación de un acero microaleado al vanadio y 0,35 % C. Mediante ensayos de torsión, y aplicando el método Back Extrapolation, se ha determinado la fracción recristalizada a diferentes temperaturas. Cuando la precipitación comienza, la fracción recristalizada se desvía de la ley de Avrami y esto permite conocer el instante en que la precipitación comienza (Ps y el instante en que termina (Pf. De este modo, se pueden trazar los diagramas Recristalización-Precipitación-Tiempo- Temperatura (RPTT, que muestran gráficamente la interacción Recristalización-Precipitación y que simultáneamente permiten la determinación de la temperatura crítica de recristalización estática (SRCT. Dicha temperatura crítica representa el límite entre las dos fases, antes y después de la precipitación.

  11. Sinterabilidad y propiedades del acero pulvimetalúrgico HCx diluido con aceros inoxidables

    Gordo, E.

    2005-12-01

    Full Text Available HCx is a powder metallurgy steel developed to combine the corrosion resistance of stainless steel with the wear resistance of tool steels. Therefore, HCx appears to be a suitable material for wear applications in aggressive environments, as valve seat inserts in automotive engines. In this work dilution of HCx with two stainless steels, one ferritic (430 and another austenitic (316L, in percentages up to 15 % in mass, has been studied to improve process conditions, especially compressibility. The sinterability of diluted materials was studied through vacuum sintering at temperatures from 1.200 °C to 1.260 °C. Finally, properties of sintered materials were determined. The results are discussed in relation to the microstructure evolution.

    El acero pulvimetalúrgico HCx ha sido desarrollado para combinar la resistencia a corrosión de los aceros inoxidables con la resistencia al desgaste de los aceros de herramientas. Aparece así como un material adecuado para componentes sometidos a desgaste en un ambiente agresivo, como los asientos de válvulas en motores de automóviles. En este trabajo se estudia la dilución del HCx con dos aceros inoxidables, uno ferrítico (430 y otro austenítico (316L, en porcentajes hasta 15 % en masa, para mejorar las condiciones de procesado, especialmente la compresibilidad. La sinterabilidad de los materiales diluidos se ha estudiado mediante sinterización en vacío, a temperaturas entre 1.200 °C y 1.260 °C, y se han determinado las propiedades de los materiales sinterizados. Los resultados se discuten en relación a la evolución microestructural.

  12. Influencia del revenido en la estructura y las propiedades de dureza, resistencia a la tracción y resiliencia del acero cubano al cromo-manganeso-silicio-níquel.

    G. Tourón Alonso

    2009-09-01

    Full Text Available La actual demanda de herramientas y accesorios para maquinarias agrícolas se presenta como fuente creciente de nuevas aplicaciones del acero al Cr-Mn-Si-Ni. Este criterio justifica la práctica de tratamientos térmicos, para conseguir distintos valores de propiedades mecánicas, que orienten al material hacia las exigencias y circunstancias de aplicaciones concretas. El trabajo tiene como objetivo conocer la estructura del acero, heredadas de las transformaciones de fase en diferentes regímenes de tratamiento térmico de revenido, y la correlación entre dicha estructura y sus propiedades de dureza, resistencia a la tracción y resiliencia. Las observaciones al microscopio óptico de las muestras revenidas sugieren, en unos casos, una estructura compuesta por martensita revenida, en otros, indican la presencia de partículas de ferrita y cementita. Los ensayos de dureza y tracción revelaron una disminución de la dureza y de la resistencia a la tracción con el aumento de la temperatura de revenido. El ensayo de impacto reveló un aumento de la resiliencia con el aumento de la temperatura de revenido, aunque aparecen dos intervalos de temperatura en que la resiliencia disminuye.Specimens were tempered after being hardened into oil. Tempered specimens for tension tests, were heated from 200 to 500ºC, in an interval of 100ºC; while, specimens for hardness and resilience tests, were heated from 200 to 550ºC, in an interval of 50ºC. Tempering time, for tension and resilience tests, depends on specimens’ thickness, while, for hardness tests is 30, 60 and 90 minutes. Tempered specimens microstructures at 200 and 300ºC indicate the presence of carbide particles; it suggests a tempering martensite structure. Tempered specimens microstructures at 500ºC indicate the presence of ferrite and cementite particles. Both, hardness and strength decrease when the tempering temperature increases. The resilience increase with tempering temperature, but

  13. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo. // Proposal for Recuperation of Sugar Mill Cut Cane by Using Chromium Steel Electrodes.

    R. Collazo-Carceller

    2009-09-01

    Full Text Available El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuestatecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Sedeterminó la influencia de los parámetros, energía introducida (Hi, número de capas (Nc y anchodel depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizandoel electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuestatecnológica.Palabras claves: morfología, desgaste abrasivo, parámetro de soldadura, dendrites._____________________________________________________________________________AbstractThis work, sumarises the study and the analisys developed, to prupose the Zuazaga cut canethecnology recuperation, in aur sugar mills. The parameters influency was determinated, Heatinput (Hi, Number of layers (Nc and the Cord whith (Ad, in the mofology and the abrasive wearresistance increase, using the cromiun steel UTP DUR - 600. The economical calculation of thethecnology was done.Key words: morphology abrasive wear, welding parameters. dendrites, modeling

  14. ESTUDIO DE LA SOLDABILIDAD Y CORROSIÓN DEL ACERO INOXIDABLE AISI 904L CON LOS AGENTES UTILIZADOS EN LA LIXIVIACIÓN DEL COBRE

    Ramón Cortés P; Jaime Villanueva A; Ernesto Ponce L; Manuel Rojas M; Eduardo Rojas Z

    2004-01-01

    La alta agresividad de las soluciones utilizadas en el proceso de lixiviación del cobre y los cuidados especiales que se debe tener para evitar la formación de fases sensibles a estos agentes en la soldadura de aceros inoxidables, ha exigido el desarrollo de nuevos aceros inoxidables que sean más resistentes a la corrosión, manteniendo las propiedades de resistencia a la tracción, al impacto y ductilidad. Es el caso de acero inoxidable AISI 904L, un acero super austenítico de última generació...

  15. Comportamiento frente a corrosión bajo tensión en ambiente marino de armaduras de acero inoxidable dúplex

    Fernández Robles, José Jaime

    2015-01-01

    La utilización de barras corrugadas de acero inoxidable en estructuras de hormigón armado, se está mostrando como una alternativa con gran futuro en estructuras expuestas a ambientes muy agresivos o que requieran vidas en servicio muy elevadas. Estos aceros inoxidables cuentan con similares propiedades mecánicas que los aceros al carbono pero un comportamiento muy mejorado frente a la corrosión, especialmente frente a cloruros. Dentro de los aceros inoxidables, los del tipo dúplex tienen ...

  16. Análisis de soldabilidad de aceros inoxidables con aceros de medio y bajo carbono por SMAW

    José Luddey Marulanda Arevalo

    2013-12-01

    Full Text Available Se presenta un estudio de la soldabilidad de aceros inoxidables austeníticos AISI 304 y AISI 316 con aceros de bajo y medio carbono AISI 1020 – AISI 1045, empleando como materiales de aporte los electrodos EutecTrode® 52 NG, 54 NG y 57 NG, mediante el proceso de arco eléctrico con electrodo revestido (SMAW. Para analizar la soldabilidad de estos electrodos cuando se realiza la unión de aceros inoxidables con aceros al carbono, se practicaron pruebas metalográficas y ensayos mecánicos de dureza, doblez y tracción, con el fin de observar el comportamiento tanto de la zona afectada térmicamente como del cordón de soldadura, a partir del cambio en las propiedades mecánicas y metalúrgicas en las diferentes regiones de las uniones soldadas. Durante el proceso de soldadura se siguió una especificación del procedimiento de soldadura (WPS, para que los resultados fueran repetibles, minimizando los problemas de agrietamiento en caliente, agrietamiento en frío, formación de fase sigma y precipitación de carburos.

  17. Aceros aluminotérmicos. Nuevas aplicaciones

    Duart Blay, J. M.

    2004-02-01

    Full Text Available The metallothermy is a process based on physical ' chemistry possibility of metallic oxides reduction (Fe, Cr, Mn, Cu for oxygen strong affinity metals, like Al, Mg and Ti. The reaction is highly exothermic giving place to a metallic phase and slag separation by refining and reduction process simultaneously. The technological developed patent initially by Thermit - and improved for other Companies - works well by more than 50 years; today it is employed almost exclusively for obtaining steels and coppers for complex welded joints unions. Particular application or interest presents in the Railways technology for building continuous tracks, practically implanted in all the word and in welding copper cable rope - steel rail employed for traffic signals control. This work displays the fundamental thermodynamic principles of the aluminothermics of iron and their application to the complex weld of crossrail, dilation joints and bypass in Railways, that combine Hadfield steels, stainless steels and pearlitic steels of different mechanical properties. The unions should be compact, with strength and hardness in the levels that are cited in the work, according to requirements demanded by high speed (350 km/ h. lines, now in construction in Spain, but they result of general use to whatever class of less demanding lines and to mining railroads.

    La metalotermia es un proceso físicoquímico basado en la posibilidad de reducción de óxidos metálicos (hierro, cromo, manganeso, cobre por metales altamente afines por el oxígeno, como son aluminio, magnesio y titanio. La reacción es altamente exotérmica dando lugar a un caldo metálico separado de su escoria, por un proceso de reducción y afino combinados. La patente tecnológica, desarrollada inicialmente por Thermit y perfeccionada por otras Compañías, lleva en vigor más de 50 años; se aplica hoy, casi exclusivamente, a la obtención de aceros y cobres para uniones soldadas complejas

  18. Estudio del comportamiento a fluencia de un acero calidad ARMCO evaluado en el estado ferrítico

    Hernández Expósito Ana, Ana

    2015-01-01

    En el presente estudio se evalúa el comportamiento a fluencia en tibio y en caliente de un acero calidad ARMCO, teniendo en cuenta el diferente magnetismo que presenta en función de las condiciones de deformación. En este sentido, pocas investigaciones versan sobre el tratamiento termomecánico en el rango de temperaturas ferríticas en un acero de bajo o ultrabajo carbono; así como su control microestructural comparado con aceros al carbono de alta y baja aleación evaluados en e...

  19. Influencia del tiempo interpaso, la deformación y la temperatura final sobre la tensión acumulada en la austenita para un acero microaleado al vanadio

    Gómez, M.

    2005-12-01

    Full Text Available Non-recrystallization temperature (Tnr and phase transformation temperature during cooling (Ar3 of a medium carbon, vanadium-microalloyed steel have been determined by means of hot rolling simulation under different conditions of strain applied and interpass time. The stress accumulated in the austenite at temperatures between Tnr and Ar3 (Δσ has been measured on MFS curve and the influence of the deformation conditions on Tnr and Δσ values has been studied. Tnr and Ar3 are the temperature limits where last passes of industrial rolling should be accomplished in order to obtain a strengthened austenite leading to a finer final microstructure.

    La temperatura de no-recristalización (Tnr y la temperatura de transformación de fase durante el enfriamiento (Ar3 de un acero microaleado al vanadio de medio carbono han sido determinadas mediante simulación de laminación en caliente bajo diferentes condiciones de deformación aplicada y tiempo interpaso. Sobre la curva MFS se ha determinado la tensión acumulada en la austenita (Δσ a temperaturas comprendidas entre Tnr y Ar3 y se ha estudiado la influencia de las condiciones de deformación sobre el valor de Tnr y de Δσ. Las temperaturas Tnr y Ar3 establecen el intervalo donde deberían efectuarse los últimos pasos de la laminación industrial, con vistas a obtener una austenita endurecida que conducirá a una microestructura final más fina.

  20. Estudio del efecto de los elementos microaleantes en un acero HSLA

    Illescas Fernández, Silvia

    2007-01-01

    El presente Proyecto Final de Carera tiene como objeto de estudio un acero HSLA que es aquel que contiene cantidades no superiores a l0.15% de elementos de microaleación(V, Nb,TiyAl).Estos elementos generan un afino de grano y endurecimiento del material por lo que se consiguen elevados límites elásticos sin necesidad de añadir grandes cantidades de elementos aleantes, y por lo tanto sin un elevado coste addicional. Por ejemplo, respecto a un acero estructural, gracias a la pequeña cantidad d...

  1. Estudio de la corrosión del acero embebido en concreto aas sometido a cloruros

    ROBINSON TORRES GÓMEZ; WILLIAM APERADOR; ENRIQUE VERA; RUBY MEJÍA DE GUTIÉRREZ; CÉSAR ORTIZ

    2011-01-01

    Se presenta un estudio sobre el comportamiento frente a la corrosión de barras de acero de refuerzo de un concreto de escoria activado alcalinamente. La escoria de alto horno fue activada mediante el uso de silicato sódico al 5% obteniéndose un material con buenas propiedades cementantes. Las probetas de concreto fueron fabricadas a partir de este cemento, después de mezclar con los agregados fueron reforzadas con barras de acero sismo-resistente ASTM-A706. Las probetas de concreto reforzado ...

  2. Procesos metalúrgicos de aceros microaleados de alta resistencia 450 EMZ tipo II en la zona afectada térmicamente debido al efecto multipasada en soldaduras por arco sumergido

    González-Palma, R.

    2006-08-01

    Full Text Available A considerable number of crack tip opening displacement tests in the heat affected zone (HAZ of multipass welds, performed in accordance with standards BS 5762 and EEMUA, are rejected since the crack is not inside the coarse grain region at 0.5 mm from the fusion border, as well as the quantity of the crack length in percentage, that the crack goes through the intercritical region instead of in the grain coarse region as it would correspond. This circumstance make advisable to carry out a metallographic study of the intercritical zone in the HAZ as well as the corresponding tests, in order analyze the intercritical region brittleness reasons. The study is performed on a HSLA 75 mm thick panel 450 EMZ type II, welded under a SAW process with heat input and welded parameters controlled, without any post weld heat treatment

    La falta de cumplimiento de las normas BS 5762 y EEMUA, en considerables casos, invalida los ensayos de mecánica de la fractura, al no encontrarse la grieta en la región de grano grueso a 0,5 mm de la línea de fusión, así como en la cantidad expresada en porcentaje de longitud de grieta que atraviesa la región intercrítica, en lugar de hacerlo en la región de grano grueso. Esta circunstancia, conduce a realizar un estudio metalográfico de dicha región intercrítica de la zona afectada térmicamente así como los correspondientes ensayos, con objeto de analizar las causas de su fragilidad. Este estudio se realiza sobre un panel de chapa de acero microaleado de alto límite elástico, calidad EMZ 450 tipo II, de 75 mm de espesor, soldado bajo un proceso por arco sumergido, con energía calorífica aportada y parámetros de soldadura controlados, sin tratamiento térmico post-soldeo.

  3. Comportamiento frente al desgaste y fricción de aceros empleados en líneas de manutención aérea ensayados con y sin lubricación

    Castro Regal, G.

    2005-06-01

    Full Text Available The sliding friction and wear behaviour of different steel qualities were investigated with and without lubrication conditions. Steel qualities tested are normally used in the overhead conveyor system of many industrial fields, like the automotive sector. Sliding wear tests have been conducted by means of a pin-on-disk machine. A 100Cr6 steel similar to that used within the overhead conveyor trolleys has been employed as a pin. Friction coefficient values obtained under lubrication conditions were three times smaller than those obtained without lubrication. The mechanism that controls wear behaviour under lubrication conditions is an abrasive one and the wear values obtained are almost worthless. On the other hand, mechanism controlling wear during non lubrication tests, was a combination of abrasion and adhesion

    Se ha evaluado el comportamiento frente a fricción y el desgaste de distintas calidades de acero ensayadas bajo condiciones de lubricación y sin lubricación. Las calidades de acero seleccionadas son las que normalmente se emplean en los sistemas de manutención aérea de numerosos procesos de producción, como la fabricación de automóviles. Se han realizado ensayos de desgaste tipo punzón-disco mediante un punzón de acero de calidad100Cr6, empleado en los carros que circulan por las líneas de manutención aérea. Se ha observado que el valor del coeficiente de fricción obtenido bajo condiciones de lubricaciones, aproximadamente, tres veces menor que el obtenido sin lubricación. Por otro lado, el mecanismo que controla el proceso de desgaste de los aceros ensayados con lubricación es un mecanismo de desgaste abrasivo y los valores de desgaste obtenidos son prácticamente despreciables. El desgaste de los aceros ensayados sin lubricación se produjo por combinación de dos mecanismos de desgaste: abrasión y adhesión.

  4. Estudio del comportamiento a fluencia en caliente de un acero avanzado de alta resistencia de bajo contenido en carbono NiCrVCu microaleado con boro

    González Sala, Sara

    2009-01-01

    Una de las líneas de investigación prioritarias en el contexto internacional es el desarrollo de aceros avanzados de alta resistencia (AHSS) con excelentes propiedades de resistencia y tenacidad para aplicaciones en la industria automotriz, naval, aeronáutica y de generación de energía, que permitan disminuir el peso de los componentes y sustituyan aceros tradicionales de contenidos mayores de carbono. Los aceros AHSS microaleados al boro, debido a sus cualidades, tecnología de...

  5. Comparison of the CrN and TiN/(Ti,Al)N PVD coatings deposited onto plasma nitrited steel

    M. Polok-Rubiniec; L.A. Dobrzański

    2012-01-01

    Purpose: The paper presents the results of the mechanical and tribological properties of the CrN and TiN/(Ti,Al)N PVD coatings deposited onto plasma nitrided hot work tool steel X37CrMoV5-1 type.Design/methodology/approach: Tests of the coatings’ adhesion to the substrate material were made using the scratch test. The surfaces’ topography, structure of the PVD coatings were observed on the scanning electron microscopy. Wear resistance tests with the pin-on-disc method were carried out on the ...

  6. Aceros al molibdeno sinterizados con gradiente funcional

    Cisneros Belmonte, Manuel; Ruiz Román, José Manuel; Sánchez Fernández, Miguel; García Cambronero, Luis Enrique

    2014-01-01

    Las propiedades que se solicitan a las piezas y productos exigen, la mayoría de las veces, una combinación de materiales que respondan a requerimientos específicos en función de su posición. La fabricación de materiales compuestos y materiales con gradiente funcional proporciona grandes posibilidades de respuesta a las necesidades demandas, tanto de satisfacción de requerimientos como de reducción de materias primas necesarias. En este sentido, satisfacer las propiedades demandadas, de manera...

  7. SIMULACIÓN EXPERIMENTAL Y NUMÉRICA DE UN PROCESO DE TREFILADO HÚMEDO DE UN ALAMBRE DE ACERO AL CARBONO EXPERIMENTAL AND NUMERICAL SIMULATION OF THE DAMP WIRE DRAWING PROCESS OF A CARBON STEEL

    Ennio L Rojas

    2008-06-01

    Full Text Available En este trabajo se presenta un análisis experimental y numérico para la descripción del comportamiento mecánico de un alambre de acero al carbono durante un proceso industrial de trefilado húmedo. En primer lugar, se hizo una campaña experimental de mediciones de fuerza de trefilado de las doce reducciones presentes en el proceso. En segundo lugar, se llevaron a cabo ensayos de tracción con objeto de caracterizar el comportamiento mecánico del material en cada etapa de reducción. En estos ensayos se obtuvieron curvas de tensión-deformación que, en conjunto a las respuestas calculadas a partir de la simulación de los ensayos, permitieron derivar la evolución de los parámetros elásticos y plásticos característicos del material a medida que se reduce su diámetro. De dicha evolución se constató el gran endurecimiento que experimenta el material durante el proceso el que, a su vez, condiciona fuertemente su trefilabilidad. Las simulaciones se realizaron por medio de un modelo elastoplástico de grandes deformaciones implementado en un programa de cálculo preexistente, basado en el método de elementos finitos, denominado VULCAN. Luego, los parámetros del material obtenidos en los ensayos de tracción fueron considerados en la simulación del proceso de deformación que ocurre durante el paso del alambre a través de los dados. Los resultados de la simulación se consideran aceptables y representativos del comportamiento del alambre en el proceso.This paper presents an experimental and numerical analysis for the description of the mechanical behaviour of a carbon steel wire during an industrial process of damp drawing. Firstly, an experimental procedure aimed at measuring wire drawing forces in the twelve reductions present in the process was performed. Secondly, tensile tests were carried out in order to characterize the mechanical behavior of the material for each reduction step. The resulting stress-strain curves together with

  8. Laser treatment of the surface layer of 32CrMoV12-28 and X40CrMoV5-1 steels

    L.A. Dobrzański; K. Labisz; E. Jonda

    2008-01-01

    Division of Materials Processing Technology, Management and ComputerTechniques in Materials Science, Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

  9. Laser treatment of the surface layer of 32CrMoV12-28 and X40CrMoV5-1 steels

    L.A. Dobrzański

    2008-07-01

    Full Text Available Division of Materials Processing Technology, Management and ComputerTechniques in Materials Science, Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

  10. Influencia del Calor Aportado y Metal de Aporte Sobre las Propiedades Mecánicas y la Microestructura de Juntas Soldadas por FCAW de Acero Microaleado de Alta Resistencia

    César Marconi; María José Castillo; Leonardo Boccanera; Mabel Ramini

    2015-01-01

    ResumenActualmente, los aceros microaleados son ampliamente utilizados en reemplazo de los aceros al C y C-Mn por sus ventajas en cuanto a propiedades mecánicas, resistencia a la corrosión y soldabilidad, permitiendo una reducción de peso de los vehículos y estructuras sin detrimento de su resistencia. Cuando estos aceros son soldados, el ciclo térmico de la soldadura provoca cambios microestructurales que modifican sus propiedades originales. El calor aportado (HI: heat input) es una de las ...

  11. Influencia del revenido en la estructura y las propiedades de dureza, resistencia a la tracción y resiliencia del acero cubano al cromomanganeso- silicio-níquel. // Influence of tempering on structure and hardness, strength and resilience properties of ch

    G. Tourón-Alonso

    2009-09-01

    Full Text Available La actual demanda de herramientas y accesorios para maquinarias agrícolas se presenta comofuente creciente de nuevas aplicaciones del acero al Cr-Mn-Si-Ni. Este criterio justifica la práctica detratamientos térmicos, para conseguir distintos valores de propiedades mecánicas, que orienten almaterial hacia las exigencias y circunstancias de aplicaciones concretas. El trabajo tiene comoobjetivo conocer la estructura del acero, heredadas de las transformaciones de fase en diferentesregímenes de tratamiento térmico de revenido, y la correlación entre dicha estructura y suspropiedades de dureza, resistencia a la tracción y resiliencia. Las observaciones al microscopioóptico de las muestras revenidas sugieren, en unos casos, una estructura compuesta por martensitarevenida, en otros, indican la presencia de partículas de ferrita y cementita. Los ensayos de dureza ytracción revelaron una disminución de la dureza y de la resistencia a la tracción con el aumento dela temperatura de revenido. El ensayo de impacto reveló un aumento de la resiliencia con elaumento de la temperatura de revenido, aunque aparecen dos intervalos de temperatura en que laresiliencia disminuye.Palabras claves: revenido, estructura, dureza, resistencia, resiliencia____________________________________________________________________________AbstractSpecimens were tempered after being hardened into oil. Tempered specimens for tension tests,were heated from 200 to 500ºC, in an interval of 100ºC; while, specimens for hardness andresilience tests, were heated from 200 to 550ºC, in an interval of 50ºC. Tempering time, for tensionand resilience tests, depends on specimens’ thickness, while, for hardness tests is 30, 60 and 90minutes. Tempered specimens microstructures at 200 and 300ºC indicate the presence of carbideparticles; it suggests a tempering martensite structure. Tempered specimens microstructures at500ºC indicate the presence of ferrite and cementite particles

  12. Development of Zn-Al-Cu coatings by hot dip coated technology: preparation and characterization; Obtencion y caracterizacion de recubrimientos Zn-Al-Cu por inmersion en caliente sobre aceros de bajo carbono

    Cervantes, J.; Barba, A.; Hernandez, M. A.; Salas, J.; Espinoza, J. L.; Denova, C.; Torres-Villasenor, G.; Conde, A.; Covelo, A.; Valdez, R.

    2013-07-01

    In the present study, research concerning Zn-Al-Cu coatings on low carbon steels has been conducted in order to characterize different properties obtained by a hot-dip coated process. The results include preparation procedure as well as the processing parameters of the coatings. The obtained coatings were subjected to a cold rolling process followed by an anneal heat treatment at different temperatures and under different time conditions. The structural characteristics of coatings have been investigated by optical and electron microscopy. The mechanical properties were obtained by using micro-hardness testing, deep drawing and wear tests whereas chemical analyses were carried out using the SEM/EDAX microprobe. The corrosion properties were achieved by using a salt spray fog chamber and potentiodynamic tests in a saline solution. The coatings are resistant to corrosion and wear in the presence of sodium chloride, therefore, the coatings could be an attractive alternative for application in coastal areas, and adequate wear adhesive resistance. (Author)

  13. Modelo de comportamiento del contacto entre el hormigón y el acero a altas temperaturas en vigas metálicas parcialmente embebidas

    Ramos Gavilán, A.B.; Piloto, P. A. G.; Mesquita, L.M.R.

    2007-01-01

    Las vigas formadas por perfiles de acero laminado en caliente parcialmente embebidos en hormigón son elementos estructurales empleados cada vez con mayor incidencia. Los bloques de hormigón que recubren lateralmente el alma aportan al perfil mayor rigidez y resistencia al fuego. La influencia del contacto entre el hormigón y el acero en el comportamiento de este tipo de elementos a elevadas temperaturas nos lleva a la necesidad de obtener un modelo numérico, validado mediante e...

  14. Estudio de la susceptibilidad de un acero inoxidable dúplex del tipo 22Cr5NiMoN al dañado por hidrógeno en condiciones estáticas (HIC y bajo carga (SSC

    Gutiérrez de Saiz-Solabarría, S.

    1998-05-01

    Full Text Available The behavior to hydrogen damage caused by corrosion in a H2S medium is studied in a molded ferrite- austenite (52-48 % duplex stainless steel 22Cr5NiMoN type (UNS-J9.22.05 under both, static (damaging mechanism called Hydrogen Induced Cracking (HIC and sustained load (damaging mechanism called Sulfide Stress Cracking (SSC, conditions.

    Se estudia el comportamiento de un mismo acero moldeado inoxidable dúplex austeno-ferrítico (48-52 % del tipo 22Cr5NiMoN (UNS-J9.22.05 frente al dañado por hidrógeno generado por corrosión en medio H2S, tanto en condiciones estáticas, mecanismo de dañado conocido como HIC (Hydrogen Induced Cracking, como bajo carga de tracción, mecanismo de dañado conocido como SSC (Sulfide Stress Cracking.

  15. Influencia sobre los tratamientos térmicos del contenido de aluminio de aceros no aleados

    Carreras, L.

    1999-08-01

    Full Text Available The main purpose of this article is to determine the optimal level of aluminum content in plain steels to have the optimal mechanical properties by means of surface heat treatments. Various plain steels with different aluminium content have been studied. The importance of treatment temperature is analyzed. The influence of other factors, like nitrogen content or the homogenous distribution of particles, is evaluated. It is concluded that the aluminum composition of plain steels that are subjected to heat treatments should not exceed 0.02 %.

    El objetivo de este trabajo es determinar el intervalo óptimo de contenidos de aluminio en aceros no aleados para los que se consiguen las propiedades mecánicas óptimas mediante tratamientos térmicos de superficie. Se estudian diferentes coladas de acero en las que varía el contenido de aluminio y las temperaturas de tratamiento. Se evalúa la importancia de otros factores tales como el contenido de nitrógeno y la homogeneidad en la distribución de partículas endurecedoras. Se llega a la conclusión de que los aceros no aleados destinados a tratamientos térmicos no deben tener un contenido de aluminio superior al 0,02 %.

  16. ESTUDIO DE LA CORROSIÓN DEL ACERO EMBEBIDO EN CONCRETO AAS SOMETIDO A CLORUROS

    ROBINSON TORRES GÓMEZ

    2010-01-01

    Full Text Available Se presenta un estudio sobre el comportamiento frente a la corrosión de barras de acero de refuerzo de un concreto de escoria activado alcalinamente. La escoria de alto horno fue activada mediante el uso de silicato sódico al 5% obteniéndose un material con buenas propiedades cementantes. Las probetas de concreto fueron fabricadas a partir de este cemento, después de mezclar con los agregados fueron reforzadas con barras de acero sismoresistente ASTMA706. Las probetas de concreto reforzado estuvieron sometidas en ambientes contaminados con iones cloruro para simular condiciones marinas. La evaluación electroquímica se realizo aplicando las técnicas de resistencia a la polarización lineal (LPR y espectroscopia de impedancia electroquímica (EIS. Se logra determinar el comportamiento de la capa pasiva del acero y electroquímico del metal cuando está inmerso en estos materiales cerámicos novedosos.

  17. 高温条件下NiCrMoV转子钢焊接接头的高周疲劳性能研究%INVESTIGATION ON HIGH TEMPERATURE HIGH CYCLE FATIGUE PROPERTY OF THE WELDING JOINT FOR NiCrMoV ROTOR STEEL

    刘鹏; 芦凤桂; 刘霞; 高玉来

    2013-01-01

    The fatigue crack initiation and propagation of the simulated rotor (30Cr2Ni4MoV) used in steam turbine was investigated by the repeated high-cycle tensile and compressive test with stress ratio R =-1.The fatigue fracture morphology was observed by the scanning electron microscope (SEM),and the composition of the selected zone was analyzed by the energy dispersive spectroscopy (EDS).For the welded rotor steel of 30Cr2Ni4MoV,the inclusions basically consisted of oxides,such as Al2O3,CaO,MgO and SiO2,etc.The results revealed that the fatigue crack generally occurred at the inclusions and pores,leading to fish-eye propagation around the defects.In addition,the effective projected area parameter model was applied to calculate the critical size of the defect causing crack initiation.Based on the present results,in order to improve the fatigue property of rotor steel,some effective measures should be adopted to control the size,shape and distribution of the defects.%通过应力比R=-1的拉压高周疲劳实验,研究了在370℃条件下汽轮机转子模拟件焊接接头的高周疲劳裂纹的萌生和扩展过程.通过扫描电子显微镜(SEM)和能谱(EDS)分析了疲劳断口的形貌特征和微区成分.研究结果表明:对于30Cr2Ni4MoV转子钢焊接接头而言,夹杂物主要成分为氧化物(Al2O3、CaO、MgO和SiO2等),疲劳裂纹往往萌生于夹杂物和气孔等内部缺陷.采用有效投影面积模型计算出母材和焊缝区域组织对应的临界缺陷尺寸,建立了夹杂物尺寸和疲劳裂纹萌生区域之间的关系.基于该研究结果,采取适当措施减少其内部的缺陷尺寸,并优化其形态和分布,以提高转子钢材料的抗疲劳性能.

  18. NiCrMoV型转子钢焊接接头组织与高周疲劳性能研究%INVESTIGATION ON THE STRUCTURE AND HIGH CYCLE FATIGUE PROPERTY OF THE WELDED JOINT MADE OF NiCrMoV ROTOR STEEL

    刘鹏; 刘霞; 芦凤桂; 高玉来

    2013-01-01

    采用应力比R=-1的拉压高周疲劳实验,研究了汽轮机焊接模拟转子试样的高周疲劳裂纹的萌生与扩展过程,并通过扫描电子显微镜(SEM)和能谱(EDS)观察与分析了疲劳断口的形貌特征和微区成分.结果表明:疲劳裂纹常在夹杂物和气孔等缺陷处萌生,进而以此为裂纹源,逐渐发生扩展,直至材料最终断裂失效.对于30Cr2Ni4MoV转子钢,夹杂物性质主要为氧化物(如CaO、SiO2、Al2O3和MgO等),因此应严格控制钢中O、A1、Si、Mg、Ca等元素的含量.%The initiation and propagation of fatigue crack of the simulation rotor used in steam turbine was investigated by employing the repeated high cycle tension and compression test with stress ratio R = - 1. The fatigue fracture morphology was observed by the scanning electron microscope ( SEM) , and the composition was analyzed by the energy dispersive spectroscopy ( EDS). The results showed that the fatigue crack was initiated in the zone where inclusion and/or pores existed, and then the fatigue crack propagated until its fracture failure. In particular, the inclusions in 30Cr2Ni4MoV rotor steel mainly consisted of oxides such as CaO, SiO2, A12O3 and MgO etc. So the content of O、 Al、Si、Mg and Ca element in rotor steel should be controlled strictly.

  19. Efecto de la predeformación en la vida a fatiga de un acero inoxidable austenítico metaestable

    Durán Avilés, Ana María

    2009-01-01

    Los aceros de tipo 301LN son aceros inoxidables austeníticos metaestables de baja aleación que pueden transformar a martensita por deformación. Esta transformación tiene lugar por mecanismos cristalográficos, al producirse un movimiento colectivo de átomos por cizalladura. El desplazamiento de los átomos es inferior a las distancias interatómicas, de manera que aunque los mecanismos de difusión no intervienen se observa un cambio de volumen. La cantidad de austenita transfor...

  20. Desarrollo y caracterización de recubrimientos MCrAlY obtenidos mediante técnicas láser para aplicaciones de barrera térmica en aceros inoxidables

    PEREIRA FALCON, JUAN CARLOS

    2015-01-01

    [EN] The coaxial laser cladding process is an excellent tool to obtain quality coatings, achieving complete melting and deposition of alloys with high melting point on complex 3D surfaces. In this work we have studied the coaxial laser cladding parameters for MCrAlY coatings (where M = Ni, Co, Fe or combinations of these), commonly used as bond coats in thermal barrier systems, among them: NiCoCrAlYTa, NiCoCrAlY, NiCrAlY and CoNiCrAlY; selecting the laser parameters that allow to obtain over...

  1. Ductilidad en caliente y mecanismos de fractura de un acero de construcción

    Calvo, J.

    2006-02-01

    Full Text Available The hot ductility of a structural steel produced from scrap recycling has been studied to determine the origin of the transverse cracks in the corners that appeared in some billets. Samples extracted both from a billet with transverse cracks and from a billet with no external damage were tested. To evaluate the influence of residual elements and inclusions, the steel was compared to another one impurity free. Reduction in area of the samples tensile tested to the fracture was taken as a measure of the hot ductility The tests were carried out at temperatures ranging from 1000ºC to 650ºC and at a strain rate of 1·10- 3 s-1. The fracture surfaces of the tested samples were observed by scanning electron microscopy in order to determine the embrittling mechanisms that could be acting. The steel with residuals and impurities exhibited lower ductility values for a wider temperature range than the clean steel. The embrittling mechanisms also changed as compared to the impurity free steel.

    Se evaluó la ductilidad en caliente de un acero de construcción procedente del reciclaje de chatarra con el fin de determinar el origen de las grietas transversales que aparecen en las esquinas de algunas palanquillas. Para ello, se extrajeron probetas de dos palanquillas de una misma calidad de acero. Una de las palanquillas había presentado agrietamiento transversal al ser colada y, la otra, no. Para conocer la influencia de los elementos residuales e inclusiones en la ductilidad en caliente, otro acero, con la misma composición pero sin impurezas, se fabricó en laboratorio y fue sometido al mismo análisis que los aceros comerciales. La ductilidad en caliente se midió como la reducción del área de las probetas ensayadas a tracción hasta la rotura. Las condiciones a las que se realizaron los ensayos fueron temperaturas de 1.000 a 650 ºC y a una velocidad de deformación de 1·10-3 s-1. Las superficies de fractura de las probetas ensayadas se

  2. Diseño de nuevos aceros bainíticos.

    Caballero, F. G.

    2002-02-01

    Full Text Available Mixed microstructures consisting of fine plates of upper bainitic ferrite separated by thin films of stable retained austenite have seen many applications in recent years because of their impressive combination of strength and toughness. There may also be some martensite present in the microstructure, but its formation can be controlled increasing the stability of the retained austenite. On the other hand, carbides are avoided by the judicious use of silicon as an alloying element. The aim of the present work was to see how far these concepts can be extended in order to achieve the highest ever combination of strength and toughness in bulk-samples subjected to continuous cooling transformation. Three alloys were proposed and manufactured, and the results of metallographic characterisation and mechanical tests have shown that the designed steels have the highest ever combination of strength and toughness for bainitic microstructures, matching even the maraging steels which are at least thirty times more expensive. The experimental results confirm the alloy design procedures.

    En los últimos años se han diseñado aceros con microestmcturas formadas por placas de ferrita bainítica superior y finas regiones de austenita retenida que, por su excelente combinación de propiedades de resistencia y tenacidad, han sido empleados para numerosas aplicaciones. Aunque en estas microestructuras puede haber algo de martensita, su formación puede controlarse aumentando la estabilidad de la austenita retenida. Por otra parte, la presencia de carburos en la bainita, causa de importantes disminuciones de tenacidad en los aceros bainíticos convencionales, se evita gracias al uso del silicio como elemento de aleación. El objetivo de este trabajo es estudiar la posibilidad de optimizar la citada combinación de propiedades, generalmente antagónicas, en muestras masivas para aplicación industrial sujetas a transformaciones por enfriamiento continuo. Para

  3. Short-term creep behavior of a CrMoV hot-work tool steel

    Wurmbauer, Harald [Materials Center Leoben Forschung GmbH, Leoben (Austria); Dept. Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben (Austria); Leitner, Harald; Panzenboeck, Michael; Clemens, Helmut [Dept. Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben (Austria); Scheu, Christina [Dept. of Chemistry and Biochemistry, Ludwig-Maximilians-Univ., Munich (Germany)

    2009-08-15

    Hot-work tool steels are used for die casting, extrusion molding and drop forging tools and thus are exposed to high temperatures and elevated stresses during application. To get insight into the materials' behavior under those conditions, short-term creep tests are performed at temperatures in the range of 550 - 590 C and at stress levels ranging from 400-750 MPa. A steady-state creep range is not observed. Instead only a minimum strain rate appears. This minimum is followed by an extended tertiary creep range. Based on the observed stress exponent at 590 C recovery-controlled dislocation creep has been identified as the dominant creep mechanism. During creep carbide coarsening, recovery and recrystallization occur, as observed by scanning electron microscopy and transmission electron microscopy. (orig.)

  4. Effect of service exposure on mechanical properties of 1CrMoV turbine rotor steel

    Mechanical property tests were conducted on high pressure - intermediate pressure (HP-IP) Steam turbine rotor steel to establish extent of deterioration in properties resulting from the aging as a function of operating temperature. The samples were obtained from various locations of the rotor exposed to temperatures ranging from 560 to 8020K (550-9850F) for 223,000 hours. The results indicated that the material softened and temper embrittled in service due to aging. Extent of softening was directly related to the operating temperature above 6720K (7500F) and maximum softening occurred at the hottest location of the rotor. Unlike softening, maximum increase in the fracture appearance transition temperature (FATT) was observed at the location exposed to intermediate temperature around 6720K (7500F). The deterioration of properties has significant impact on the reliability and remaining life estimation of the rotor

  5. Effects of material and environmental factors on SCC of NiCrMoV rotor steels

    This paper summarizes the results of some parametric studies concerning the stress corrosion cracking (SCC) initiation and crack growth on shrunk-on wheel and mono-block rotor materials. The data were obtained through the long-term tests of 45,000 hours at the maximum in purified saturated steam, based on the parameters classified by factors, such as material, stress and environment. For the SCC initiation and crack growth, the effects of material strengths (750 through 1,150 MPa class), chemical compositions (Ni, P and S contents), temperatures (90 through 190C), oxygen contents (deaeration and 20 ppm) and stress conditions were evaluated. From a viewpoint of materials, in particular, some guidelines were established

  6. Stress corrosion crack growth rates in NiCrMoV turbine disc steels

    Stress corrosion crack growth rates were obtained from precracked WOL specimens in simulated turbine environments - pure NaOH solutions, dilute NaOH-NaCl solutions and pure water. Tests were performed at 157 C on steels with yield strength in the range 706-1124 MPa

  7. Stress corrosion cracking of 3.5 NiCrMoV turbine steels

    This paper describes a research program conducted to determine susceptibility of steels used in low-pressure (LP) turbine rotors of power plants to stress corrosion cracking (SCC) in LP turbine environments. Results indicate cracking occurs under specific conditions of temperature and electrode potential. Transgranular cracking occurred in chloride solutions and in oxygenated water. Cracking in dilute caustic-chloride solutions was both transgranular and intergranular. Results of constant-load tests were found to depend upon procedures followed in establishing test conditions

  8. El acero que nunca se fundió. Una reseña sobre Stalin

    Iñaki Oneca Agurruza

    2004-02-01

    Full Text Available Era el 5 de marzo de 1953 cuando murió el fetiche, el gurú, el símbolo. Stalin significa “acero”, y precisamente una de las cosas que se reprochó al joven revolucionario, tras la adopción de este apodo, era que el acero era duro pero también frío. Así iniciamos esta breve nota sobre la figura de uno de los personajes clave del siglo XX.

  9. Corrosión en láminas y bobinas de un acero importado

    Wilson A. Hormaza R.

    2007-01-01

    Este trabajo busca determinar las causas que llevaron al deterioro superficial de un conjunto de láminas y bobinas importadas de acero. Lo anterior implica precisar el tipo de deterioro de los componentes, es decir, si este se presentó durante el transporte marítimo o durante el almacenamiento. Los ensayos realizados fueron: análisis visual, análisis de espectrofotometría de infrarrojo y comparativo de los cristales de Cloruro de Sodio (NaCl), análisis de la morfología de la su...

  10. Resistencia a la corrosión marina en aceros austeníticos tipo fermanal (15,8Mn – 6,45Al –5,56Cr – 0,358C

    William Aperador Chaparro

    2011-07-01

    Full Text Available Given the huge potential that the Fe-Mn-Al alloys shows in the use of corrosion resistant alloys that are similar to the family of stainless steels Fe-Cr-Ni it has been proposed the study of marine corrosion of the alloy 22,6Mn – 6,3Al – 3,1Cr – 0,675C (AF and a stainless steel AISI 316 (AI. The study of the corrosion behavior was conduced trough the use of Tafel Polarization Curves and Galvanostatic Pulse Technique, obtaining the values of corrosion current density of 1,7 and 0,1 µA/cm2 and the corrosion rate of 0,54 and 0,04 mpy for fermalloy steel and stainless steel, respectively. The simulation of the marine environment was achieved using a solution of 3,5% wt. of NaCl non-aerated.

  11. Estudio de la susceptibilidad de un acero inoxidable austenítico estabilizado con niobio al dañado por tensocorrosión en medio H2S (SSC y corrosión intergranular (IGC en otros medios agresivos

    Gutiérrez de Saiz-Solabarría, S.

    1998-05-01

    Full Text Available Behavior to hydrogen damage caused by stress corrosion in a H2S medium (SSC and to intergranular corrosion (IGC in different mediums, such as oxalic acid (C2H2O4-2H20, iron sulphate-50 % sulfuric acid [Fe2(SO43-50 % H2SO4], nitric acid (HNO3, copper sulphate-16 % sulfuric acid (CuSO4-5H2O-16 % H2SO4 and cooper sulphate-50 % sulfuric acid (CuSO4-5H2O-50 % H2SO4, is studied in an AISI 347 austenitic stainless steel stabilized with 0.61 mass % Nb and hot rolled to a seamless pipe with 273.1 mm in diameter and 18.2 mm in thickness.

    Se estudia el comportamiento de un acero inoxidable austenítico del tipo AISI 347 estabilizado con un 0,61 % en masa de Nb, laminado en caliente para producir una tubería sin soldadura de 273,1 mm de diámetro y 18,2 mm de espesor, frente al dañado por hidrógeno generado por tensocorrosión en medio H2S (SSC y frente a la corrosión intergranular (IGC en diferentes medios agresivos tales como ácido oxálico (C2H2O4∙2H2O, sulfato de hierro-50% ácido sulfúrico [Fe2 (SO43-50 % H2SO4], ácido nítrico (HNO3, sulfato de cobre-16% ácido sulfúrico (CuSO4-5H2O-16 % H2SO4 y sulfato de cobre-50 % ácido sulfúrico (CuSO4-5H2O-50 % H2SO4, respectivamente.

  12. Estudio de la susceptibilidad de un acero inoxidable dúplex del tipo 22Cr5NiMoN al dañado por hidrógeno en condiciones estáticas (HIC) y bajo carga (SSC)

    Gutiérrez de Saiz-Solabarría, S.; San Juan, J. M.; Valea, A.

    1998-01-01

    The behavior to hydrogen damage caused by corrosion in a H2S medium is studied in a molded ferrite- austenite (52-48 %) duplex stainless steel 22Cr5NiMoN type (UNS-J9.22.05) under both, static (damaging mechanism called Hydrogen Induced Cracking (HIC)) and sustained load (damaging mechanism called Sulfide Stress Cracking (SSC)), conditions.

    Se estudia el comportamiento de un mismo acero moldeado inoxidable dúplex austeno-ferrítico (48-52 %) del tipo 2...

  13. Evaluación del comportamiento físico del acero Hadfield sometido a cargas explosivas

    Carlos Vinardell-García; Miguel A. Caraballo-Núñez

    2004-01-01

    Se investigó el efecto que produce la detonación de una sustancia explosiva en el comportamiento físico del acero al alto manganeso (Hadfield); para ello se emplearon técnicas de difracción de Rayos X y ensayo metalográfico con microscopía óptica, que permitieron describir el mecanismo de deformación del material. Se revelaron las fases presentes en la estructura, las particularidades de su comportamiento y evidencias de deformación plástica, el tamaño promedio del grano y su influencia en el...

  14. Aceros de baja aleación y alto rendimiento

    Campos, M.

    2008-02-01

    Full Text Available A highly demanding automobile market requires an intensification of the efforts on increasing the performance and reducing costs of sintered steels, in order to stay in such a competitive market. Final properties of sintered parts and their cost depend on two main factors, density and the alloying system. The growing interest for Cr and Mn as alloying elements is due to both price, more suitable than Mo, and the excellent level of properties which are achieved in assintered parts as well as after the heat treatments. In this work, the possible techniques which lead to an enhancement of density are discussed, such as warm and high velocity compaction, or high temperature sintering; moreover it is important to study the synergy between the proposed techniques which may be compatible.

    Las nuevas demandas en el sector del automóvil están haciendo que se intensifiquen los esfuerzos en aumentar las prestaciones y reducir los costes de los aceros sinterizados, para poder mantenerse en este mercado tan competitivo. Las propiedades finales de los componentes sinterizados y su coste dependen de dos factores principales, la densidad y el sistema de aleación. El creciente interés por el cromo y el manganeso como elementos de aleación se debe tanto al precio, más ventajoso que, por ejemplo, el molibdeno, como al nivel excelente de propiedades que se pueden conseguir tanto en estado sinterizado como después de los tratamientos térmicos. En este trabajo, se discuten además las posibles técnicas que conducen a una mejora de la densidad del componente, como la compactación de polvos precalentados, la compactación por propagación de ondas de impacto, o la sinterización a alta temperatura; además, es importante estudiar los efectos sinérgicos entre las técnicas propuestas que sean compatibles.

  15. Recomendaciones europeas para el empleo de tornillos de alta resistencia en las estructuras de acero

    Batanero, J.

    1962-10-01

    Full Text Available Con el enlace de los perfiles de acero por medio de tornillos de alta resistencia, pretensados, se ha introducido en la construcción metálica un nuevo tipo de uniones, que resisten por rozamiento. Los tomillos de alta resistencia (exceptuados los calibrados deberán quedar en el agujero con una cierta holgura; y, mediante apretadura de la tuerca o de la cabeza, tensarse en forma que las superficies de contacto de las piezas unidas quedan fuertemente presionadas, una contra otra, muy especialmente en las proximidades del agujero. Con ello el esfuerzo que actúa perpendicularmente al eje del tomillo es resistido por el rozamiento estático entre las superficies unidas; en tanto que, como consecuencia, la espiga del tomillo queda sometida a una tracción axil y a una torsión.

  16. Efectos del tratamiento térmico en la fractura de aceros

    Héctor Hernández A.

    2011-01-01

    Full Text Available No obstante de los avances logrados en otros tipos de aleaciones, los aceros se siguen utilizando en forma extensiva en la construcción de elementos estructurales, porque con una adecuada selección y tratamiento técnico, los aceros permiten obtener una conveniente combinación de propiedades mecánicas ante unas exigencias específicas de servicio. La fractura en elementos de máquinas frecuentemente se encuentra asociada a una discontinuidad, la cual provoca una concentración de esfuerzo, lo que puede originar sitios de iniciación de una falla por fractura. La carga límite de fractura es afectada por parámetros geométricos, naturaleza y tipo de carga y propiedades mecánicas del material. La mayoría de fallas por fractura de elementos de máquinas son fallas por fatiga; por lo general una fractura por fatiga tiene lugar por una progresiva generación y crecimiento de grietas hasta obtenerse una condición crítica de fractura súbita de la sección residual resistente. Frecuentemente en una fractura por fatiga se observan marcas de playa, las cuales son evidencias de la posición del frente de grietas antes que se alcance la condición de fractura súbita final. En este trabajo se muestra como el tratamiento térmico de temple y revenido de los aceros afecta el esfuerzo límite de falla por fractura para carga de tracción estática y carga de fatiga uniaxial con la presencia de una entalla severa. También se estudia el efecto del tratamiento térmico en la tenacidad de fractura, propiedad que cuantifica la resistencia al crecimiento súbito de una grieta bajo carga estática.

  17. Evaluación del trabajo esencial de fractura en chapa de un acero de alta resistencia de fase dual

    Gutiérrez, D.

    2013-02-01

    Full Text Available Fracture toughness of advanced high strength steels (AHSS, can be used to optimize crash behavior of structural components. However it cannot be readily measured in metal sheet because of the sheet thickness. In this work, the Essential Work of Fracture (EWF methodology is proposed to evaluate the fracture toughness of metal sheets. It has been successfully applied in polymers films and some metal sheets. However, their information about the applicability of this methodology to AHSS is relatively scarce. In the present work the fracture toughness of a Dual Phase (strength of 800 MPa and drawing steel sheets has been measured by means of the EWF. The results show that the test requirements are met and also show the clear influence of notch radii on the measured values, specially for the AHSS grade. Thus, the EWF is postulated as a methodology to evaluate the fracture toughness in AHSS sheets.

    La tenacidad de fractura de aceros de alta resistencia (AHSS, es una propiedad interesante para optimizar el comportamiento a impacto, pero su caracterización experimental en chapas metálicas es compleja debido a su espesor. En este trabajo se plantea el método del Trabajo Esencial de Fractura (TEF, como alternativa al cálculo de la tenacidad. Este método ya ha sido utilizado con éxito en polímeros y aceros dúctiles, aunque la información sobre su aplicación en AHSS es escasa. Se ha evaluado la tenacidad en un acero de fase dual de 800 MPa de resistencia y se ha comparado con la de un acero de embutición. Los resultados muestran que se cumplen los requisitos del método y ponen en evidencia la influencia del radio de entalla en el valor obtenido de TEF, especialmente para AHSS. Con todo ello, el método TEF se puede usar para caracterizar la tenacidad de AHSS en formato chapa.

  18. An evaluation of the properties of rotor forgings made from 26NiCrMoV115 steel: Ocena lastnosti izkovkov za rotorje iz jekla 26NiCrMoV115:

    Balcar, Martin; Bažan, Jiří; Fila, Pavel; Kešner, Dušan; Martínek, Ludvík; Němeček, Stanislav; Sochor, Libor; Turecký, Václav

    2008-01-01

    The development and verification of production technology for the rotor forgings of compressors and generators demonstrate the significant effect of the forming of the input ingot on the final properties of the forgings. The measured yield strength and the strength limit show a trend of dependence on the sample's position in the rotor. Significant differences in the longitudinal as well as in the transversal directions over the cross-section of a forging have been found, especially for the tr...

  19. Modelling of the solidification process and the chemical heterogeneity of a 26NiCrMoV115 steel ingot: Modeliranje procesa strjevanja in kemične heterogenosti ingota iz jekla 26NiCrMoV115:

    Balcar, Martin; Bažan, Jiří; Fila, Pavel; Martínek, Ludvík; Železný, Rudolf

    2007-01-01

    Steel making at ŽĎAS, a.s. using secondary metallurgy technology makes it possible to produce liquid metal with high levels of metallurgical cleanliness. During the casting and subsequent cooling of forging ingots, the steel solidification takes place. Directional material solidification, grain size, chemical heterogeneity and discontinuities can have a negative effect on the products' final properties. The comparison of the chemical composition based on a numerical calculation with the heter...

  20. Procesos de conversión de acero y efecto de variables en convertidores tipo L.B.E.

    Blanco, C.

    1995-10-01

    Full Text Available In order to determine control equations based on qualitative and quantitative changes of the raw materials, an analysis of the efficiency of the steel production process was carried out in converters under specified operation conditions. Empirical equations to obtain the final composition of the steel as a function of the additives, the initial concentrations of the hot metal and the blowing oxygen patterns are established. The resulting relationships depend on the considered variables and therefore could be used to determine operational strategies in order to obtain steels of a certain quality.

    Se analiza la eficacia de los procesos de transformación en convertidores en condiciones de trabajo determinadas, para deducir relaciones aplicables al control basadas en la modificación de cantidades y composiciones de las materias primas. Se plantean ecuaciones empíricas para determinar la composición final del acero como función de los aditivos y de las concentraciones iniciales del arrabio tratado, así como el patrón de soplado de oxígeno. Las relaciones obtenidas establecen las dependencias entre cada una de las variables consideradas y, por tanto, permiten determinar estrategias de operación para obtener aceros con unas calidades finales dadas.

  1. Comportamiento termomecánico de aceros AISI 304

    El Wahabi, M.

    2001-04-01

    Full Text Available The hot deformation behaviour of three AISI 304 (H, L and HP austenitic stainless steel with different carbon contents has been studied. An analysis of the parameters describing their hot flow curves was carried out. No heavy effect of the carbon content was found on most of the latter parameters. However, the work hardening and dynamic recovery behaviour showed clear differences depending on the given alloy, especially at high temperatures and low strain rates where the high carbon steel displayed larger work hardening and dynamic recovery rates than the other steels. The high purity steel (interstitial free displayed the lower stress levels as its hardening rate was slower than in the other two steels.

    Se llevó a cabo un estudio del comportamiento termomecánico de tres aceros inoxidables austeníticos tipo AISI 304 (H, L y HP con diferentes contenido en carbono, mediante la determinación de los parámetros que describen las etapas de deformación en caliente. No se notó un fuerte efecto del carbono en dichos parámetros, excepto en los que describen los procesos de endurecimiento y de restauración dinámica que muestran una cierta dependencia con la composición química, especialmente a bajos valores del parámetro de Zener-Hollomon, donde el acero de alto carbono (304H endurece y restaura más rápido que el de bajo carbono (304L, alcanzándose valores de tensión de pico similares en ambos casos. El material de alta pureza (libre de intersticiales toma valores de tensión de pico más bajos que los otros aceros, endureciendo más lentamente y con una velocidad de restauración similar a la del 304H.

  2. Effect of impurities on the proneness to temper embrittlement of heat resistant Cr-Mo-V steel

    The authors investigated the effect of most alloying elements which are traditionaly regarded as dangerous in low-alloy structural steels--sulfur, phosphorus, copper, arsenic, antimony, tin--on the proneness to temper embrittlement of steel 25Kh1M1F which is used for making large all-forged rotors of fixed and transport medium-pressure steam turbines. On the basis of the obtained results it may be concluded that from among the investigated alloying elements only phosphorus and antimony have a statistically significant effect on the proneness of fine-grained steel 25Kh1M1F to temper embrittlement, and the embrittling effect of phosphorus is much stronger than the embrittling effect of antimony

  3. Phase Diagram in the Iron-rich Corner of the Fe-Cr-Mo-V-C system below 1000 K

    Kroupa, Aleš; Havránková, Jitka; Coufalová, M.; Svoboda, Milan; Vřešťál, J.

    2001-01-01

    Roč. 22, č. 3 (2001), s. 312-323. ISSN 1054-9714. [International Symposium on User Aspects of Phase Diagrams. Sendai, 19.09.2001-21.09.2001] R&D Projects: GA ČR GA106/00/0174; GA ČR GA106/00/0855 Institutional research plan: CEZ:AV0Z2041904 Keywords : phase diagram * calculation * steels Subject RIV: BJ - Thermodynamics Impact factor: 0.553, year: 2001

  4. Segregation of phosphorus in Cr-Mo-V steel and cast steel after long time service at elevated temperature

    Steel and cast steel after long time service in the temperatures range 500-530oC have been investigated. In the areas close to the grain boundaries diffusion of phosphorus causes an occurrence the stable layers of ferrite enriched in phosphorus. The relation ship between the concentration of phosphorus in the alloy and the width of the enriched layers have been established.The width of the phosphorus enriched layers are independent of the grain size. The results suggest that diffusion of phosphorus is controlled by the bulk mechanism from the interior to the grain boundary and takes place only in the area near the grain boundary. Grain boundary etching method by using of picric acid is a useful as a technique analyzing grain boundary concentration of phosphorus. The good method of investigation is the measurement of the width of the etching grooves as the grain boundaries on the SEM microstructures. Segregation of phosphorus in the vicinity of grain boundaries drastically decreases the notch impact fracture toughness and increases the brittle fracture transition temperature of the alloy. Desegregation of phosphorus from the area close to the grain boundaries to the interior grains is long-time process and takes a few hours annealing in the temperature range 650-700oC. Desegregation of phosphorus from area close to the grain boundaries into the interior of grains there is observed an enrichment in the phosphorus of the ferrite around the interphase carbides/matrix boundaries. The notch impact fracture toughness of steel is related to the changes in time and temperature of phosphorus desegration process. (author)

  5. Effects of irradiation at lower temperature on the microstructure of Cr-Mo-V-alloyed reactor pressure vessel steel

    Grosse, M.; Boehmert, J.; Gilles, R. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1998-10-01

    The microstructural damage process due to neutron irradiation [1] proceeds in two stages: - formation of displacement cascades - evolution of the microstructure by defect reactions. Continuing our systematic investigation about the microstructural changes of Russian reactor pressure vessel steel due to neutron irradiation the microstructure of two laboratory heats of the VVER 440-type reactor pressure vessel steel after irradiation at 60 C was studied by small angle neutron scattering (SANS). 60 C-irradiation differently changes the irradiation-induced microstructure in comparison with irradiation at reactor operation temperature and can, thus, provide new insights into the mechanisms of the irradiation damage. (orig.)

  6. The elastic plastic behaviour of a 1/2% Cr Mo V steam turbine steel during high strain thermal fatigue

    High strain fatigue problem in steam turbine. Cyclic stress strain hysteresis loops and stress relaxation behaviour in 16 h dwell period tests. Variation of stress and strain during tests under nominally strain controlled conditions. Definition of test conditions and of criteria for crack initiation and failure. Comparison of reverse bend and push pull failure data. (orig.) 891 RW/orig. 892 RKD

  7. Structure and properties of the laser alloyed 32CrMoV12-28 with ceramic powder

    L.A. Dobrzański; K. Labisz; Klimpel, A

    2009-01-01

    Purpose: The work was performed for the reason to determine the laser treatment parameters, particularly the laser power, to achieve a high value of layer hardness for protection of this hot work tool steel from losing their work stability and to make the tool surface more resistant for work. The purpose of this work was also to determine technological and technical conditions for remelting the surface layer with HPDL.Design/methodology/approach: The main methodology results of new laser trea...

  8. Mechanical properties and structure changes of the laser alloyed 32CrMoV12-28 steel

    L.A. Dobrzański; K. Labisz; Klimpel, A

    2006-01-01

    Purpose: The reason of this work was to determine the laser treatment parameters, particularly the laser power, to achieve a high value of layer hardness for protection of this hot work tool steel from losing their work stability and to make the tool surface more resistant for work. The purpose of this work was also to determine technological and technical conditions for remelting the surface layer with HPDL.Design/methodology/approach: In this paper the results of new laser treatment techniq...

  9. Evaluation of intergranular corrosion techniques to determine phosphorus segregation in NiCrMoV rotor steel

    Several chemical and electrochemical etching techniques have been evaluated for the indirect measurement of grain boundary phosphorus segregation. A picric acid based solution was found to promote intergranular attack proportional to the grain boundary phosphorus composition measured by Auger Electron Spectroscopy. Preliminary results indicate this solution may enable the nondestructive evaluation of a rotor steel's susceptibility to temper embrittlement and IGSCC

  10. Effect of dissolved oxygen for corrosion fatigue behavior in 3.5NiCrMoV steel

    The corrosion fatigue behaviour of low alloy steel in a simulated low pressure steam turbine environment in pure water at 25 and 150 has been examined as an effect of dissolved oxygen concentration, 8 ppm and 10 ppb respectively. In pure water at 25 crack propagation rates are similar regardless of dissolved oxygen concentration. However, in pure water at 150 .deg. C crack propagation rate of 8 ppm (DO) concentration is faster than that of 10 ppb(DO) concentration

  11. Integridad estructural de vigas roblonadas de acero estructural antiguo

    Moreno Revilla, Jesús

    2005-01-01

    Son numerosas las estructuras construidas con hierro pudelado o acero forjado durante el siglo XIX y principios del XX que todavía permanecen en uso. Las cargas actuales y los daños existentes hacen necesarias evaluaciones de integridad estructural para extender su vida útil, adaptar su uso y establecer programas de vigilancia y mantenimiento. Los análisis de este tipo realizados hasta ahora son recientes y consideran que el componente dañado de un elemento estructural roblonada no interaccio...

  12. Nuevos tratamientos para inducir acero austenítico con granos ultrafinos

    Sacre, Charles-Henry

    2012-01-01

    Los aceros del grado AISI 301 LN son aceros de baja aleación de tipo austenítico metaestable, es decir la estructura austenítica es susceptible de transformarse en martensita bajo solicitación mecánica. En este proyecto se ha estudiado un acero AISI 301 LN C1050, el cual ha sufrido un 25% de reducción por laminación en frío, lo que hace que contenga un porcentaje de martensita de 28%. El proyecto tiene un doble objetivo: - Primero se ha investigado el tratamiento de reversió...

  13. Estudio del fenómeno de Strain Ageing en el acero inoxidable metaestable 301 LN

    Hevin, Lucas

    2014-01-01

    Un acero inoxidable metaestable es una aleación que presenta el efecto TRIP: Transformation Induced Plasticity. El acero estudiado, EN 1.4318/AISI 301 LN, tiene una estructura austenítica que puede transformarse en martensita por deformación. Tiene una buena resistencia a corrosión, buena conformabilidad, y una combinación de límite elástico y de deformación máxima muy superior a otros aceros. Con dicha transformación martensítica se puede aumentar el límite elástico y la resistencia a tracci...

  14. Incidencia de la adición de fibras metálicas y poliméricas sobre el proceso corrosivo del acero en el concreto reforzado con la inclusión de aditivos inhibidores de corrosión ante ambiente salino

    Rodríguez Quiroga, José Luis

    2014-01-01

    El principal objetivo de la investigación es determinar el impacto de la adición de fibras metálicas y poliméricas sobre la corrosión del acero en el concreto reforzado ante un ambiente salino, al usar aditivos inhibidores de corrosión. Sobre vigas de concreto con refuerzo de acero, se compararon concretos con y sin macrofibras (metálicas y poliméricas). Se evaluaron cuatro tipos de aditivos inhibidores de corrosión: nitratos, nitritos, aminoalcoholes y un impermeabilizante bloqueador de p...

  15. Reciclado de los residuos siderúrgicos de fabricación de acero. Nueva alternativa

    Fernández López, Miguel

    2001-08-01

    Full Text Available A brief description of a new process for recycling hot electric steelmaking wastes of high iron oxides content, from ministeel mills that produce common and special steels is made. The new process is designed to get the best treatment cost for the residues recycling. It is based in the application of the principles of technologies experienced in ministeel industries. This is possible because the following improvements are obtained: a obtention of a commercial product of high zinc oxide content; b avoidance of new toxic wastes; c use of low cost process energy; d increase of metallic yield in the residues; and e treatment of residues in the mill ("in situ", or from other ministeel mill ("off site". Previous technologies precedents of the new process, are given and a comparative study between the new recycling process and the same recycling process without heating pretreatment using the same furnace is made. Electric steel making wasts. Recycling

    Se presenta una breve descripción de un nuevo procedimiento de reciclado de residuos, de alto contenido en óxidos de hierro, generados en miniacerías fabricantes de acero por hornos eléctricos de arco (común y especial, dentro y/o fuera de las instalaciones del generador (“in situ” y ''off site''. El procedimiento pretende, la reducción de los costes de reciclado de dichos residuos, respecto a procedimientos actuales, al incluir las siguientes mejoras: a obtención de un producto comercializable rico en ZnO; b ausencia de residuos tóxicos necesitados de tratamiento; c utilización de energía de proceso de bajo coste, en sustitución parcial de energía eléctrica; d aumento de la recuperación de metales en los residuos; y e versatilidad para poder reciclar los residuos ”in situ'' u ''off site", según procedan de una o de varias miniacerías, respectivamente. Se describen los fundamentos y sus precedentes tecnológicos, así como un breve an

  16. COMPORTAMIENTO DEL ACERO AISI-SAE 1025 NITRURADO MEDIANTE DESCARGA DE BARRERA DIELÉCTRICA A PRESIÓN ATMOSFÉRICA

    Héctor Jaime Dulce Moreno; Germán Contreras de la Ossa

    2009-01-01

    Se presenta la implementación de una descarga de barrera dieléctrica a presión atmosférica, para utilizarla en tratamiento de nitruración del acero AISI-SAE 1025.Para tal tratamiento se genera un pulso positivo generado por un transformador de alto voltaje (bobina), con el acople de una fuente de señal de 24 V y frecuencia de 15.58 KHZ. Los tratamientos de duración 10, 15,y 30 minutos respectivamente con sesiones de 5 minutos y reposo de 2 minutos, dando como resultado un aumento en la dureza...

  17. Análisis experimental de la pérdida de adherencia hormigón-acero en hormigones sometidos a altas temperaturas

    Varona Moya, Francisco de Borja; Baeza de los Santos, Francisco Javier; Ivorra Chorro, Salvador; Bru Orts, David

    2015-01-01

    En el conjunto de materiales de construcción habituales en la edificación y las obras de ingeniería, el hormigón destaca entre otras razones por su excelente comportamiento frente a las altas temperaturas y la exposición al fuego. El presente estudio se centra en la adherencia residual entre el hormigón y las barras de acero corrugado soldable tras exponer probetas a altas temperaturas y enfriarlas hasta temperatura ambiente por convección natural. El estudio incluye hormigones de resistencia...

  18. CARACTERIZACIÓN DE ACEROS ALONIZADOS RESISTENTES A LA CORROSIÓN UTILIZADOS EN LA INDUSTRIA DEL PETRÓLEO

    Ramón Cortés; Regina Rodríguez; Andre Capra

    2004-01-01

    En el proceso de refinamiento del petróleo la deterioración por corrosión de las instalaciones metálicas es debido a la presencia de ácido sulfhídrico con gas nafténico, siendo más crítico el daño provocado por el hidrógeno. Una forma de protección contra estos medios corrosivos es la utilización de revestimiento de aluminio. Ese revestimiento representa protección pasiva y activa. Además, la presencia de una región ínter metálica de Fe/Al en la zona de ligación entre el aluminio y el acero, ...

  19. Recubrimientos de (ti,aln sobre acero aisi 4140 por sputtering reactivo

    DANNA GARCIA

    2007-01-01

    Full Text Available Empleando la técnica de Pulverización catódica con radiofrecuencia y magnetrón (Magnetron Sputtering RF, se prepararon películas de (Ti,AlN sobre sustratos de acero AISI 4140. Se utilizó un blanco formado con polvos metálicos de Ti y Al, con composición nominal 60% Ti y 40% Al (porcentaje en átomos y una razón de presiones parciales de nitrógeno - argón, PN2/PAr de 0,1 aproximadamente; la temperatura del sustrato se varió entre 260 y 330 ºC y el tiempo de deposición entre 2 y 4,5 horas para obtener películas con diferentes espesores. La composición química de las películas se determinó mediante la técnica de energía dispersada de rayos X (EDX, y su topografía mediante microscopía de fuerza atómica (AFM. Igualmente se midió micro dureza, y se determinó su comportamiento electroquímico mediante espectroscopia de impedancia electroquímica EIS y ensayos TAFEL. Las películas obtenidas presentaron granos globulares, uniformes y de pequeño diámetro, con características electroquímicas de protección al sustrato frente a procesos de corrosión.

  20. Inhibición del acero galvanizado en medio salino mediante tricloruro de cerio

    Serrano, F.

    1998-05-01

    Full Text Available The addition of small amounts of cerous chloride, as inhibitor of hot dip galvanised steel corrosión in aerated 3,5% NaCl solutions is studied. The results found so far, carried out by electrochemical techniques and accelerated tests, show a clear decrease in the zinc dissolution rate. The analysis of polarization curves and specimen surface suggest, in accordance with literature, that cerium acts as a cathodic inhibitor, blocking the oxygen reduction centers. Alternate immersion tests developed an excellent behaviour of specimens pre-treated in cerium containing solutions, compared to those without treatments. A rich cerium film is responsible of the improvement in the protective properties. These results prove the possibilities of cerium as an alternative treatment to those based on chromates, which are very effective on these materials but highly toxic.

    Se estudia la adición de pequeñas cantidades de tricloruro de cerio, como inhibidor de la corrosión de aceros galvanizados, en disoluciones aireadas de NaCl al 3,5 %. Los resultados encontrados hasta la fecha, obtenidos mediante técnicas electroquímicas y ensayos acelerados en laboratorio, muestran una clara reducción de la velocidad de disolución del cinc. Del análisis de los diagramas de polarización y de la superficie del electrodo, se deduce, de acuerdo con la bibliografía, que el cerio se comporta como un inhibidor catódico, bloqueando los centros de reducción de oxígeno disuelto. Los ensayos de inmersión alternada revelaron un excelente comportamiento de las probetas pretratadas en disoluciones que contenían cloruros de cerio, frente a aquellas que carecían de tratamiento. La formación de una película rica en cerio es la responsable del aumento de la capacidad protectora del acero galvanizado. Estos resultados confirman las posibilidades del cerio como posible sustituto de los tratamientos basados en cromatos, muy efectivos en estos materiales, pero altamente

  1. Técnicas para revelar el borde de grano austenítico en aceros microaleados

    García de Andrés, Carlos

    2001-08-01

    Full Text Available The prior austenite grain size (PAGS exerts an important influence on the microstructures forged by continuous cooling in the steel and on their mechanical properties. Since microalloyed steels have received considerable attention in the last years and enormous difficulties have been repetitively to reveal the austenite grain boundaries in these steels, this work analyzes the different techniques effective in that sense, which enable thus an accurate determination of the PAGS. This paper presents results obtained applying different conventional techniques such us chemical etching of quenched microstructures, the application of thermal cycles that enable the formation of phases around the prior austenite grain boundaries or oxidation etching which reveals the austenite grain boundaries by the preferential accumulation of oxides. Finally, an innovative and effective technique to reveal the prior austenite grain boundaries is presented. This technique is based on the preferential transfer of matter from the grain boundaries to the surrounding austenite by complicated mechanisms such as evaporation-condensation and volume and surface diffusion of atoms.

    El tamaño de grano austenítico (TGA tiene una gran influencia sobre la microestructura final y sobre las propiedades mecánicas de los productos obtenidos por transformación anisotérmica del acero. Debido a la considerable atención que se está prestando a los aceros microaleados en los últimos años y a las dificultades que se encuentran en muchos casos para poder revelar los bordes de grano austenítico de estos aceros, en este trabajo se han analizado las técnicas que lo hacen posible, permitiendo así la determinación fiable del TGA. En este sentido, se presentan los resultados obtenidos al aplicar aislada y combinadamente distintas técnicas tradicionales, como el ataque químico de microestructuras obtenidas directamente por temple, la aplicación de diferentes tipos de ciclos t

  2. Transferencia de calor en la colada continua de aceros. II parte. Enfriamiento secundario

    Cicutti, C.

    1997-12-01

    Full Text Available Once the strand leaves the mold, the solidification of steel progresses due to the heat extracted in the secondary cooling zone of the continuous casting machine. In this zone, heat is extracted mainly by: the incidence of water from sprays, radiation to surroundings contact with rolls and run out water accumulated between rolls and strand. In this work, all these mechanisms are evaluated and, when it is possible, they are quantified. Methods which are usually employed to measure solidification profiles in the continuous casting machine are also reviewed. Finally, the incidence of secondary cooling on the quality of cast products is discussed.

    La solidificación del acero iniciada en el molde continúa en la zona de enfriamiento secundario de la máquina donde el calor es extraído, principalmente por la incidencia del agua de los rociadores, la radiación al medio ambiente, el contacto con los rodillos y el agua acumulada en ellos. En este trabajo se revisa cada uno de estos mecanismos determinando, en los casos en que es posible, valores cuantitativos de los mismos. Además, se analizan los distintos métodos empleados para medir el avance del espesor solidificado en la máquina de colada continua. Por último, se discute la incidencia del enfriamiento secundario en la calidad final de los productos colados.

  3. Identificación y cuantificación de fases en acero inoxidable ASTM A743 grado CA6NM mediante la técnica de difracción de rayos x

    Rojas Marín, Jessika Viviana

    2009-01-01

    La técnica de difracción de rayos X a altas temperaturas fue aplicada al estudio de las transformaciones de fase en el acero inoxidable martensítico ASTM A743 grado CA6NM, material ampliamente usado en la fabricación de componentes hidráulicos por las excelentes propiedades mecánicas que ofrece. Mediante la técnica de difracción de rayos X y en el intervalo de temperaturas entre 25-860°C se estudió la dilatación térmica del acero durante el calentamiento, se identificaron las temperaturas de ...

  4. Evaluación del empleo de aceros de bajo contenido de carbono en la fabricación del cuerpo de cilindros oleohidráulicos. // Low carbon steel evaluation for oleohydraulic cylinders manufacturing.

    V. Gómez Rodríguez

    2003-05-01

    Full Text Available En el trabajo se realiza una evaluación del empleo de aceros de bajo contenido de carbono en la fabricación del cuerpo decilindros oleohidráulicos de producción nacional. Se estudia la influencia del cambio de material en la calidad superficial,la resistencia al desgaste y el comportamiento desde el punto de vista de la corrosión.Palabras claves: Cilindros oleohidráulicos, resistencia superficial, corrosión, acero._________________________________________________________________________________Abstract.In this paper, an evaluation of the use of low carbon steel used to manufacture the hydraulic homemade cylinders body iscarried out. The influence of change of material in surface quality, the wear resistance and the behaviour from the corrosionpoint of view, are studied.Key words: Oleohydraulic cylinders, superficial strength, corrosion, steel.

  5. Propiedades mecánicas de las uniones por láser de aceros inoxidables dúplex

    Amigó, V.

    2005-04-01

    Full Text Available The welded joints of stainless steels always present problems for the microstructural modifications that occur in the heat affected zone. Particularly, duplex stainless steels present very important changes when the weld pool solidifies forming fundamentally ferritic structures with some austenite in grain boundaries. These microstructural modifications, and those which occur in the HAZ, justify the mechanical properties of the joint and mainly those of plasticity, being all of them influenced by the processing conditions. In this work the influence of the laser welding speed on the tensile behaviour of duplex stainless steel welded joints is presented. The microstructure of the obtained seams and of the heat affected zone will be evaluated by means of optic and scanning electron microscopy. Also, different microhardness profiles have been obtained to evaluate the modifications in the mechanical properties both in the seam and the zone of thermal affection.

    Las uniones soldadas de aceros inoxidables siempre presentan problemas por las modificaciones microestructurales que suceden en la zona afectada por el calor. Particularmente, los aceros inoxidables dúplex presentan cambios microestructurales muy importantes al solidificar el cordón y formar estructuras, fundamentalmente ferríticas, con formación de austenita en borde de grano. Estas modificaciones microestructurales, junto a las que suceden en la ZAC, son las que justifican las propiedades mecánicas de la unión y fundamentalmente las de plasticidad. Y todo ello en función de las condiciones de procesado. En este trabajo se presenta la influencia de la velocidad de soldeo en las propiedades a tracción de uniones soldadas por láser de chapas de acero inoxidables dúplex. La microestructura de los cordones obtenidos y de la zona afectada por el calor se ha evaluado mediante microscopía óptica y electrónica de barrido, y se han obtenido diferentes perfiles de microdureza que

  6. Influencia del Calor Aportado y Metal de Aporte Sobre las Propiedades Mecánicas y la Microestructura de Juntas Soldadas por FCAW de Acero Microaleado de Alta Resistencia

    César Marconi

    2015-06-01

    Full Text Available ResumenActualmente, los aceros microaleados son ampliamente utilizados en reemplazo de los aceros al C y C-Mn por sus ventajas en cuanto a propiedades mecánicas, resistencia a la corrosión y soldabilidad, permitiendo una reducción de peso de los vehículos y estructuras sin detrimento de su resistencia. Cuando estos aceros son soldados, el ciclo térmico de la soldadura provoca cambios microestructurales que modifican sus propiedades originales. El calor aportado (HI: heat input es una de las principales variables a tener en cuenta cuando se evalúan estas modificaciones. Las propiedades finales de la unión soldada también se definen por el tipo de consumible utilizado. El objetivo de este trabajo es analizar las propiedades mecánicas y la microestructura de juntas soldadas a tope de un acero microaleado con dos grados de metal de aporte y diferentes HI. Como resultado del trabajo se observó un aumento considerable de tamaño de grano en la ZAC adyacente a la línea de fusión para todas las condiciones, siendo este efecto más marcado cuando se soldó con alto HI; y un ablandamiento en la ZAC de grano fino. Prácticamente se mantuvieron los valores de resistencia a la tracción al soldar con ambos consumibles, con un mejor desempeño cuando se soldó con bajo HI. La tenacidad en la ZAC mejoró con la disminución del HI.

  7. Influencia de la ductilidad de las armaduras de acero en el comportamiento y la seguridad de losas de hormigón armado

    Ortega, H.

    1999-10-01

    Full Text Available This work is based on the results and basic conclusions of author's doctoral thesis, directed by Professor José Calavera. On the one hand, a new form to measure the ductility of those steels used like reinforcement of concrete, is proposed, in order to be compared and classified in accordance with this one. On the other hand it has been studied the results of the tests on 12 continuous slabs of two equal spans, reinforced with four different steel types chosen so that, in the more requested section the steel will reach, in first place, its collapse (situation in the 2 domain, A pivot. The reinforcement to allow the mentioned extent, is provided with same nominal resistance steels and same diameter, but with - different ductility. The results of this experimental study, reveals the importance of the steel ductility concerning the behaviour and real security of the structure in front of the collapse, and furnish a group of conclusions and proposals concerning this interesting subject.

    Este trabajo se basa en los resultados y conclusiones básicas de la tesis doctoral del autor, dirigida por el Profesor D. José Calavera. Se propone, por un lado, una forma de medir mediante un único parámetro la ductilidad de los aceros utilizados como armaduras para hormigón armado, de forma que se puedan comparar y clasificar con arreglo al mismo. Por otro, se estudian los resultados de los ensayos sobre 12 losas continuas de dos vanos, de sección maciza, armadas con cuatro cuantías diferentes elegidas de forma que, en la sección más solicitada, sea el acero el que alcance, en primer lugar, su agotamiento (situación en el dominio 2, pivote A . El armado para conseguir las citadas cuantías se realiza con aceros de la misma resistencia nominal y del mismo diámetro, pero con distinta ductilidad. Los resultados de este estudio experimental, ponen de manifiesto la importancia de la ductilidad del acero en relación con el comportamiento, as

  8. Simulación de la precipitación de inclusiones en diferentes etapas del procesamiento del acero líquido

    Carreño, V.

    1998-05-01

    Full Text Available Steelmaking processes are continuously improved in order to attend the increasing requirements of the cleanness of the liquid metal. At the refining stages, as deoxidation and desulphuration, the formation of inclusions of oxides and sulphides is promoted, which on the other hand, are the most frequent inclusions. In this work a mathematical simulator of the precipitation and chemical composition of non-metallic inclusions at different steps of the steelmaking process is presented. To this purpose, it is assumed that inclusions formed by reoxidation can be simulated by increasing arbitrarily the oxygen levels consumed by the residual elements (aluminium, calcium, etc. and starting the chemical reaction with less powerful deoxidants (silicium and manganese. Accordingly, different operative conditions can be simulated. Numerical predictions are compared with experimental results of industrial trials, as well as results included in the bibliography.

    Los procesos de fabricación de acero se mejoran constantemente en respuesta a las demandas del consumidor que exige un mayor control de limpieza del metal líquido en las diversas etapas de su elaboración. En las etapas de refinación, como son desoxidación y desulfuración, se promueve la formación de inclusiones de óxidos y sulfuros, que por otra parte son las más frecuentes en el acero líquido. En este trabajo se presenta un simulador matemático que predice la precipitación y composición de las inclusiones no metálicas que se encuentran en el acero líquido en diferentes etapas de su procesamiento, asumiendo que las inclusiones formadas por reoxidación también se pueden simular al incrementar arbitrariamente los niveles de oxígeno que deberán consumir los elementos residuales altamente oxidables (Al, Ca, y empezar la reacción con los desoxidantes menores (Si y Mn. De esta manera se simulan diferentes condiciones de operación. Las predicciones numéricas se comparan con los

  9. Influencia de la cantidad de O2 adicionado al CO2 en el gas de protección sobre la microestructura del metal depositado en uniones soldadas de bordes rectos en aceros de bajo contenido de carbono con el proceso GMAW Influence of O2 content, added to CO2 in the shielding gas, on the microstructure of deposited metal in butt welded joint with straight edges, in low carbon steels using GMAW process

    Eduardo Díaz-Cedré; Amado Cruz-Crespo; Félix Ramos Morales; Mauricio Tello Rico; Joel Chaparro Gonzáles; Manuel Rodríguez Pérez; Juan A. Pozo Morejón; Nancy M. Pérez Pino

    2010-01-01

    La presencia de ferrita acicular (FA) en la microestructura del cordón de soldadura, dentro de determinado rango de valores, eleva considerablemente la tenacidad de las uniones soldadas. Es por ello, que el presente trabajo trata sobre un estudio que relaciona la cantidad de ferrita acicular en el cordón en función del contenido de oxígeno presente en la mezcla activa CO2+O2, durante la realización de uniones soldadas de bordes rectos en aceros de bajo carbono con el proceso con electrodo fus...

  10. Diseño de redes neuronales con aprendizaje combinado de retropropagación y búsqueda aleatoria progresiva aplicado a la determinación de austenita retenida en aceros TRIP

    Capdevila, C.

    2010-12-01

    Full Text Available At the beginning of the decade of the nineties, the industrial interest for TRIP steels leads to a significant increase of the investigation and application in this field. In this work, the flexibility of neural networks for the modelling of complex properties is used to tackle the problem of determining the retained austenite content in TRIP-steel. Applying a combination of two learning algorithms (backpropagation and creeping-random-search for the neural network, a model has been created that enables the prediction of retained austenite in low-Si / low-Al multiphase steels as a function of processing parameters.

    A partir de los años noventa, el interés que los aceros TRIP despiertan en la industria ha producido un incremento considerable de su estudio y aplicación. En este trabajo, aprovechando la flexibilidad que las redes neuronales proporcionan para la modelización de propiedades complejas, se ha abordado el problema de la determinación de la austenita retenida en los aceros TRIP. Una combinación de dos algoritmos de aprendizaje (retropropagación y búsqueda aleatoria progresiva de la red neuronal ha permitido crear un modelo que predice la cantidad de austenita retenida en aceros multifase con bajo contenido en aluminio y silicio en función de los parámetros de procesado.