Austenization Temperature Research Articles

ПРИЧИНЫ СНИЖЕНИЯ КОРРОЗИОННОЙ СТОЙКОСТИ ДЕТАЛЕЙ МАШИН И ОБОРУДОВАНИЯ ПЕРЕРАБАТЫВАЮЩИХ ОТРАСЛЕЙ АПК

The fast-wearing parts of machinery and equipment of the processing branch of the agro-industrial complex are made of corrosion-resistant steels of various classes. There are many ways to restore them, but the most optimal way is electrocontact welding of corrosion-resistant steels of the appropriate class. This method has a number of advantages over other recovery methods, however, the effect of electrocontact welding of the tape on the corrosion resistance of the coating has not been practically studied. (Research purpose) The research purpose is theoretically substantiating the possible reasons for the decrease of corrosion resistance of coatings obtained by electrocontact welding of tape from corrosion-resistant steels, and experimentally proving the hypotheses presented. (Materials and methods) Were used as materials for the study of 0.5 mm thick tapes made of corrosion-resistant steels 12X18N10T, 20X13, 12X17, 15X28, 12X13. Tests were carried out for the formation of intercrystalline corrosion under various types of thermal influence according to the AM method (GOST 6032-2017). (Results and discussion) Laboratory tests have shown that welded tapes made of austenitic steels (12X18H10T) are not prone to the intercrystalline corrosion due to the presence of titanium in the tape and the austenization temperature of 1100-1200 degrees Celsius. In ferritic steels at a temperature of 1000 degrees Celsius in the welding zone, intercrystalline corrosion does not form according to the theory, but reheating (tempering zone) provokes its formation. The same pattern is observed with martensite steels (for example, 20X13). (Conclusions) The theory was confirmed that during electrocontact welding of tapes made of corrosion-resistant steels of martensit (20X13), martensit-ferritic (12X13), ferritic (12X17) steels are subjected to intercrystalline corrosion, with the exception of austenitic steels (type 18-10). It is recommended to take into account the results obtained to restore machine parts and equipment of the processing branches of the agro-industrial complex by electrocontact welding of the tape.

PENGARUH TEMPERATUR AUSTEMPERING TERHADAP SIFAT MEKANIK DAN STRUKTUR MIKRO BESI COR KELABU DENGAN NIKEL 10% UNTUK KOMPONEN BOILER PLTU

Effect of austempering temperature on microstructure and mechanical properties gray cast iron with 10%wt nickel for boiler combustion application has been studied. Cast iron with the JIS FCD 45 standard with a minimum tensile strength of 414 MPa and a hardness of 187 HB is commonly used for this application. To improve its mechanical properties such as strength and hardness, austempering heat treatment usually applied. Austempering was carried out at 250°C, 300°C, 350°C, 400°C, and 450°C for 1 hour, with the same austenization temperature of 850°C for 1 hour. The highest increase in hardness was found at the austempering temperature of 250°C. The hardness was 321.80 HB or 19.30% of the initial hardness of 259.70 HB. In terms of strength, the highest increase occurred at the austempering temperature of 250°C which was 257 MPa or 31.52% of the initial strength of 176 MPa.

Formation mechanisms of affected layers induced by grinding hardened AISI 52100 steel

To establish a systematic cognition of formation mechanisms of affected layers in hardened AISI 52100 steel, the experiments were conducted to measure and characterize the microstructure and properties of the affected layers subject to a varying grinding depth and thermal and mechanical effects at different-levels. It is found that the affected layers can be formed mechanically or thermally depending on whether the mechanically-induced effect predominates the thermally-induced effect, and the 25 μm is exactly the critical grinding depth of the above two effects. From the novel perspective of thermo-mechanical decoupling, when the grinding depth exceeds 25 μm, grinding temperature is higher than the nominal austenization temperature (Ac1) of the bulk material, the thermally-induced effect becomes dominate, the thickness of the white layer changes abruptly, and there is an obvious dark layer underneath. When the grinding depth is less than 25 μm, grinding temperature is lower than Ac1, the mechanically-induced effect becomes dominate, the white layer is extremely thin and no dark layer can be observed. The thermally-induced affected layers are formed mainly by a rapid austenite transformation, accompanied by the fragmentation and dissolution of carbide particles, and the white layer is formed on the ground surface. Meanwhile, the subsurface undergoes tempering subjected to high temperature; this leads to the decomposition of austenite and precipitation of a large amount of cementite. With a continuous dynamic recrystallization, a dark softening layer is formed under the white layer. The mechanical-induced affected layers are formed by fragment and refinement of nano- and micro-structures subject to severe plastic deformation and dynamic recovery.

Experimental and Numerical Process Design for Press Partitioning of the New Q&P Steel 37SiB6

Quenching and partitioning (Q&P) heat treatments of low-alloy steels with exceptional property combinations are particularly promising. In this study, we characterize for the first time a new low-alloy steel to be processed using Q&P heat treatments. In combined experimental and numerical studies, we design a novel approach that effectively combines the short cycle times of press hardening with the excellent property profiles of Q&P-treated steels. We identify an appropriate austenization temperature of 950 °C and a portioning temperature of 250 °C for Q&P heat treatments through dilatometric studies. We adjust a number of reference conditions with fractions of 2.1 to 6.3 wt.% of retained austenite, resulting in tensile strengths up to 1860 MPa and elongations to failure up to 7%. Initial numerical designs of the process can identify varying temperature profiles and cooling rates depending on the position in the die. The results show that the geometry of the part plays a minor role, but the die temperature of 200 °C is the dominant factor for successful partitioning directly in the press hardening process.

Effect of Austenization and Repeated Quenching on The Microstructures and Mechanical Properties of Wear-Resistant Steel

This study was focused on determining the effect of repeated austenitization and quenching on mechanical properties and microstructure. The experiment was carried out in a rolled quencher facility with a heat treatment process of one to two times, with parameters of an austenizing temperature of 9500C and quenching at a temperature of 8500C with pressurized water media. Testing of specimens, including microstructure observations and hardness testing. The repeated heat treatment process showed an increase in hardness of 0.79% on one-time repeated heat treatment and 1.65% on two repeated heat treatments. This occurs due to the presence accompanied by refinement of the prior austenite grains and the martensite structure. In addition, the hardness value decreases in the surface area 17.9 HV and 24.9 HV due to the deeper accumulation of decarburization 0.06-0.10 mm followed by thicker iron oxide growth 0.04-0.07mm.

Optimization of Heat Treatment Parameters to Improve Hardness of High Carbon Steel Using Taguchi’s Orthogonal Array Approach

EN31 is a high carbon steel, used in manufacturing bearings, punches and gauges because of its better hardness. Heat treatment is one of the major process adopted to improve microstructural and mechanical properties of high carbon steels. The present investigation aims to improve hardness of EN31 high carbon steel through heat treatment. Parameters considered during this investigation were austenization temperature, soaking time, temper temperature and temper time. Microstructure examination was carried out to confirm the phases of heat treated EN31. Taguchi’s orthogonal approach was adopted to minimize the number of experimental runs. Influence of each parameter on the hardness was analyzed. The levels of each parameter were identified that maximize the hardness through S/N ratio. Identified optimal levels of parameters are 900 °C austenization temperature, 30 min soaking time, 150 °C temper temperature and 10 min temper time. A regression model for hardness has been established. Analysis of variance test was used to identify the significant parameters. Finally, the results were validated through confirmation experiments.

Моделирование технологических параметров индукционной поверхностной закалки на основе обобщенных экспериментальных исследований

The article discusses the modeling of induction surface hardening technology of low-alloy carbon steels with a carbon content of 0.2 to 0. 8 %. To optimize technological parameters, such as heating power and time, current frequency and quenching depth, experimental data were generalized: dependences of austenization and homogenization temperatures heated steel on the heating rate, carbon content and grain size of the initial structure. Also, on the basis of experimental data, the dependences of austenite grain growth on the heating rate and temperature are obtained. A nonlinear coupled electrothermal numerical model was used in the work, in which the calculation of the nonlinear ferromagnetic problem was carried out in the time domain. To study the effect of phase transformations during induction heating on the choice of the optimal heating mode, an iterative algorithm was developed that controls the numerical electrothermal model. The article compares the results of simulation of induction surface hardening modes for cylindrical bodies made of St35 and St45 steels, and also provides the required surface heating temperature. The influence of the initial structure on the choice of heating mode is shown. In addition, the developed model makes it possible to predict the ultimate hardness on the surface of the hardened part for optimal cooling mode.

The Effect of Austenization Temperature in Surface Hardening Process on Steel Plate as Ballistic Plate

Ballistic resistant plate is a plate that is able to withstand the rate of projectiles. Ballistic resistant plates or armor plates are applied to military vehicles. It requires a combination of hardness, strength and toughness. Surface hardening with heat treatment is carried out to obtain ballistic resistant properties. The article is aimed at increasing the hardness of one of the surface in commercial medium carbon steel. The variation of austenization is done at the temperatures of 700, 800 and 900 °C with induction heating and holding time for 3 seconds. The quenching media used 15 litters of oil. Several tests are conducted: The results of surface hardening are observed in microstructure, distribution of hardness is tested by micro vickers, tensile testing and impact testing. Tensile testing in accordance with ASTM E8 standards and impact testing with E 23 standards. The transformation of ferrite and perlite to marten site is obtained on the surface of the plate in the temperature of 900 °C. At that temperature, hardness increases on the surface and tenacity can be maintained. In addition, the value of hardness, tensile strength and impact energy were significantly increased. Impact energy as a material requirement for ballistic resistance had been achieved, but hardness and tensile strength still need to be increased.

Modern methods for studying of phase transformations in high-carbon wire rod to ensure quality of high-strength reinforcement

The structural transformations (formation and decay of austenite) in high-carbon boron microalloyed 80R steel are studied by the differential scanning calorimetry method. The temperatures of the beginning and end of the formation of homogeneous austenite during heating and its decay during cooling, proceeding according to the type of ferritic-carbide mixture with the release of the α-phase of one morphological type, are determined. The obtained results can be used to select one of the main technological parameters of the deformation and heat treatment mode of rolled products — the rational austenization temperature, which ensures the formation of structure and properties in high-carbon wire rod intended for the manufacture of high-strength stabilized reinforcement for iron-concrete structures.

Thermomechanical Treatment of Martensitic Stainless Steels Sheets and Its Effects on Their Deep Drawability and Resulting Hardness in Press Hardening

The deep drawability of three Martensitic Stainless Steels (MSS) alloys under conventional press hardening thermomechanical process conditions was investigated. The three alloys differ in the content of the main elements C and Cr. Firstly, the metallurgical properties of the alloys were determined, i.e., the phase mass fraction diagrams and the concentration of alloying elements in solid solution at the austenitic temperatures with help of the JMatPro® software version 7.0. Derived from this analysis, specific thermomechanical process parameters were defined to evaluate experimentally and numerically the hot sheet formability of the alloys during the deep drawing process. The hot deep drawability of the MSS alloys was experimentally assessed. The hot deep drawability was evaluated with the resulting maximum drawing depth values. In general, all three alloys developed very good formability at forming temperatures between 700 and 900 °C. However, they are susceptible to chemical composition, austenization temperature, dwell time, and flange gap. The hot formability behavior of the alloys as well as the resulting hardness showed very good concordance with the calculated metallurgical values. Finally, a numerical analysis was conducted using Simufact Forming® 15.0 software. The interval time during hot blank transfer to the tool determines the initial and final forming temperature. The effect of the time interval on the forming temperature was analyzed numerically and validated experimentally. It was also possible to determine the maximum level of plastic strain in the deep drawn cup.

The Effect of Austenization and Isothermal Soaking Temperatures on the Wear of Perlite Steel

The authors have studied grade R260 rail steel after austenization in the temperature range from 800 to 930°C and isothermal soaking at 500, 550, and 600°C followed by quenching in water. The steel structure and abrasive wear resistance were characterized. Recommendations concerning an increase in steel wear resistance were provided.

Hydrogen trapping and desorption of dual precipitates in tempered low-carbon martensitic steel

The hydrogen trapping behaviors of dual nanometer-sized ε-copper and TiC carbide precipitates have been investigated in a low-carbon steel. The precipitation fashions were controlled by quenching and tempering at different austenization temperatures. The nanostructures of the dual precipitates were characterized by high-resolution transmission electron microscopy and atom probe tomography. Hydrogen desorption was studied through thermal desorption analysis of steels electrochemically charged with hydrogen. The hydrogen trapping capability of the precipitates was investigated through the release process. The precipitation routes of TiC carbides influenced the behavior of hydrogen trapping and the co-precipitation of copper and TiC carbides significantly increased the hydrogen trapping capability of the steels. These heat treatments can therefore be used to tailor the resistance to hydrogen embrittlement in tempered martensitic steels. Importantly, co-precipitated TiC and ε-copper particles in tempered martensitic steels show an enhanced capacity for hydrogen trapping and provide a range of trapping strengths. Co-precipitation is therefore proposed as a new prospect for designing steels with the capacity for substantial hydrogen trapping.

Residual velocity and kinetic energy of the ballistic simulations test on hardened medium carbon steel plate

Ballistics testing is the study of collision phenomena between projectiles and target material. Simulation with finite element is one alternative to ballistic testing that can provide detailed numerical data and specific. Validated simulations can be used as a reference for improving projectile resistant material in addition to the results of experiments test. These papers presents the effect of austenization temperature and quench media in the S45C steel plate on the residual velocity of the projectile and kinetic energy after being fired blunt projectile at a speed of 303.5 m/s with simulation base on finite element. Material data was obtained from the results of an experimental test of S45C steel plate thickness 8 mm which was austenization at 700, 800, 900°C which was quenched in water and oil media. Validation of simulations is carried out with past research. The simulation results show that the steel plate is austenization 900°C with treatment on the quench oil media can withstand the projectile better, with a projectile residual velocity of 234.46 m/s, with projectile kinetic energy of 1346.8 Joule.

Effect of Austenization Temperature on the Microstructure in Cr-Mn-Si Steel

This work is a part of research on the microstructure and mechanical properties of Cr-Mn-Si steels after various thermal treatments. In order to increase the resistance of the materials against failure it is necessary to possess simultaneously high strength and plasticity at the same time. Normally, in conventional metals, this is impossible. The purpose of the present study is to trace the polymorphic transformation of the microstructure and the redistribution of the trace elements in the corresponding microstructural transformations of the steel at each stage of applied heat treatment - austenization, quenching, austempering, tempering. The chosen sequence of applied heat treatments is to obtain a bainite structure of up to 50% in order to achieve high strength and toughness of the material.

Computational modeling of the effect of B and W in the phase transformation of M23C6 carbides in 9 to 12 pct Cr martensitic/ferritic steels

The effect of B and W in the precipitation kinetic of M23C6 carbides in martensitic/ferritic steels were studied assisted by ThermoCalc and TC-PRISMA. The simulation predicts that B has low solubility in the austenitic and ferritic matrix, thus promoting the formation of M2B borides and (Cr, Fe)23(C, B)6 carbides. Furthermore, calculation carried out in ThermoCalc shown that M2B borides are stable even at austenization temperature (1100 °C). This suggests that in martensitic/ferritic steels M2B precipitates first, hence consuming most of available B. Additionally, the precipitation kinetics of (Cr, Fe)23C6, (Cr, Fe, W)23C6 and (Cr, Fe)23(C, B)6 were simulated in TC-PRISMA, results obtained predict a higher steady nucleation rate for the latter. When B atoms incorporate to (Cr, Fe)23C6 reduces the interfacial energy from 0.26 J/m2 to 0.17 J m−2, which indicates a smaller misfit between (Cr, Fe)23(C, B)6 carbides and matrix. On the other hand, B and W reduce the coarsening rate of M23C6 carbides by decreasing the interfacial energy and reducing diffusivities, respectively. Theoretical results compared with experimental data of the coarsening rate of (Cr, Fe, W)23(C, B)6 shown that it is one order of magnitude lower than the predicted by TC-PRISMA. This suggests that B can be the rate-controlling element of the coarsening of (Cr, Fe, W)23(C, B)6 carbides instead of W.

Effect of Al, Ni, Mo, Ti, Nb and temperature on grain size number in low carbon high alloyed steel

Usually steels for manufacturing are purchased on the basis of chemical composition. This can affect its properties. In this study chemical composition and temperature effect on grain size number has been observed carefully. Three steels with different chemical composition as well as heat treatment temperatures at 920°C and 1100°C respectively with holding time of 30 minutes in the oxidization atmospheric laboratory based furnace, to know the influence of both factors composition and temperature, microstructures of these three different steels have been obtained by conventional metallography methods. Grain size of each steel sample has been calculated as indicated by Higginson, R.L. and Sellars C.M. The ASTM grain size number. The data has been plotted at both observing temperatures. In the light of above experiments and observations it was concluded that chemical composition and temperature has definitely effect on ASTM grain size number. Al, Ni, Mo, Ti, Nb has significant effect on forming the microstructure and grain size can be affected by the presence of these elements in the steel composition. Also as the austenizing temperature is increased the grain size number is decreased. Aluminum can hinder the grain growth and nickel is austenite stabilizing element which can affect the grain size number.

Hardness and Microstructural Behavior of Normalized Steel-Welded Joint under Varying Temperature

The effect of normalizing on a weld joint and heat affected zone of various grades of steel with known composition were estimated. Microexamination of samples was also done on the steel containing 0.22 wt % C to 0.36 weight percent of carbon. after normalizing at 7000C, 8000C and 9000C respectively. From the results, significant microstructural modifications due to heat treatment were noticed. The as- rolled 0.22 %C and 0.24 %C respectively consist of little pearlite regions in ferrite matrix. While the 0.36 %C consist of uniformly distributed pearlite regions (dark) in ferrite matrix (white) especially at austenization temperature of 8000C and 9000C above the upper critical temperature for all the steel grades. While those normalized at 7000C were fine pearlites, with varying amounts of spheroids of ferrite nucleated within the matrix.

Effect of austenitization temperature on microstructure and mechanical properties of low-carbon-equivalent carbidic austempered ductile iron

The wear resistances of austempered ductile iron (ADI) were improved through introduction of a new phase (carbide) into the matrix by addition of chromium. In the present investigation, low-carbon-equivalent ductile iron (LCEDI) (CE = 3.06%, and CE represents carbon- equivalent) with 2.42% chromium was selected. LCEDI was austenitized at two different temperatures (900 and 975°C) and soaked for 1 h and then quenched in a salt bath at 325°C for 0 to 10 h. Samples were analyzed using optical microscopy and X-ray diffraction. Wear tests were carried out on a pin-on-disk-type machine. The effect of austenization temperature on the wear resistance, impact strength, and the microstructure was evaluated. A structure–property correlation based on the observations is established.

Coupled Effects of Heating Method and Rate on the Measured Nonisothermal Austenization Temperature of Steel SUS420J1 in Heat Treatment

Steel SUS420J1, which is the key material of turbine blade, is generally treated by heat to improve the strength prior to use. And the austenization process at different heating rates would determine the depth and width of heat treatment. In this paper, the austenization temperatures in heat treatment with the heat from induction wire, infrared lamp, and laser are measured, respectively. The effect of heating rate on the austenization temperature has been investigated. The research results show that the measured austenization temperature increases with the heating rate. And this trend is specially enlarged in the heat treatment method with larger gradient of temperature distribution, e.g., laser. The calculated phase transformation threshold shows that negative linear relationship exists between the logarithmic heating rate and the logarithmic austenization threshold for both induction heating and infrared heating, while abnormal relationship exists for laser heating. Thermal finite element analysis (FEA) models are then developed to calculate the temperature distributions in these three heating methods, and the calculated results show that the nonuniform temperature distribution leads to the gap between the measured austenization temperature and that of the material, which also leads to the abnormal variation law of austenization threshold in laser heating. The measured austenization temperature in induction heating method is thought to be the closest to the actual austenization temperature of the material among these three methods. This paper provides a guide for choosing the proper parameters to heat the steel SUS420J1 in hardening.

Surface hardening and finishing of metallic products by hybrid laser­ultrasonic treatment

Theoretical and experimental study of the possibilities of using laser heat treatment (LHT) combined with ultrasonic impact treatment (UIT) for surface hardening and finishing of metallic products was carried out. The austenization temperature range (1,050...1,350 °C) at different speeds (50...150 mm/min) of LHT without surface melting by the scanning laser beam, as well as the beginning (~360 °C) and end (~245 °C) temperatures of the martensitic transformation during the specimen cooling were determined. As a result, it allows narrowing the range of optimum LHT regimes, providing the surface hardness of 800...1,000 HV and the hardening depth of 200...400 μm of the surface layer. Experimental studies have confirmed that the determined magnitude of temperature on the specimen surface of AISI 1045 steel correlates well with the heating temperature measured by the laser pyrometer. As a consequence, this provides the ability to determine the application distance of the ultrasonic tool during cooling in the laser surface hardening of metallic surfaces. The comparative analysis of the microhardness of the surface layer and the surface roughness of the samples treated by LHT, UIT, combined and hybrid laser-ultrasonic treatment was carried out. It was found that the hybrid laser-ultrasonic treatment allowed increasing the microhardness of surface layers more than 3 times and reducing the roughness parameter Ra approximately 3 times compared to the initial state, provided favorable conditions to trap oil on the product surface. Thus, there are reasons to assert the possibility of using the hybrid LHT+UIT for surface hardening and finishing of the large-sized products that work in extreme conditions