Influence Of Heat Treatment Process Research Articles

Prediction of rotational bending fatigue life of bearing steel based on damage mechanics

Based on the theory of continuous damage mechanics, this paper proposes a fatigue damage evolution model and numerical calculation method considering the influence of vacuum chemical heat treatment process, and studies the rotational bending fatigue damage analysis and life prediction method of M50NiL bearing steel. Firstly, the constitutive model, fatigue damage evolution equation and material parameter calibration method in the theoretical model are given. Secondly, based on the ABAQUS platform, the damage mechanics-finite element numerical calculation method of fatigue damage analysis considering the influence of hardened layer is realized by writing the UMAT subroutine; then, the rotational bending fatigue test of M50NiL bearing steel treated by vacuum chemical heat treatment of quenching and tempering, carburizing and carbonitriding is carried out, and the influence of heat treatment process on fatigue performance is analyzed; finally, based on the proposed fatigue damage model and numerical calculation method, the rotational bending fatigue life of M50NiL bearing steel is predicted, and the results are compared with the experimental results to verify the correctness of the proposed method.

Influence of layer thickness and heat treatment on microstructure and properties of selective laser melted maraging stainless steel

As one of the main parameters of selective laser melting (SLM) process, layer thickness has a significant impact on the forming performance and efficiency of printed parts. Based on microstructure analysis and properties testing, the metallurgical mechanism, phase composition and mechanical behavior of SLM-formed Corrax stainless steel with different layer thicknesses were discussed. The influence of heat treatment process on the properties was comparatively investigated. The results indicated that at smaller or larger layer thicknesses, the increase in melt dynamic instability and spheroidisation feature easily induced the formation of unfused pore defects, which in turn led to lower relative density and mechanical properties. At the appropriate layer thickness, the suitable melt flow behaviour promoted the formation of good metallurgical bonding between adjacent melt channels. The maximum tensile strength, yield strength and hardness of the samples prepared at a layer thickness of 60 μm were 1224 MPa, 948 MPa and 39.2 HRC, respectively. The microstructure of the as-built samples was martensite and a small amount of austenite. With increasing layer thickness, the cooling rate of the molten pool decreased and the austenite content increased. After solution treatment, the alloying elements dissolved in the martensitic matrix resulted in lower mechanical properties. After aging and solution aging treatment, the mechanical properties were significantly improved due to precipitation strengthening of NiAl nanoparticles and dislocation strengthening. The corresponding tensile strengths were 1655 MPa and 1796 MPa, the yield strengths were 1328 MPa and 1573 MPa, and the hardnesses were 45.7 HRC and 50.2 HRC, respectively.

Prediction of rotational bending fatigue life of bearing steel based on damage mechanics

Based on the theory of continuous damage mechanics, this paper proposes a fatigue damage evolution model and numerical calculation method considering the influence of vacuum chemical heat treatment process, and studies the rotational bending fatigue damage analysis and life prediction method of M50NiL bearing steel. Firstly, the constitutive model, fatigue damage evolution equation and material parameter calibration method in the theoretical model are given. Secondly, based on the ABAQUS platform, the damage mechanics-finite element numerical calculation method of fatigue damage analysis considering the influence of hardened layer is realized by writing the UMAT subroutine; then, the rotational bending fatigue test of M50NiL bearing steel treated by vacuum chemical heat treatment of quenching and tempering, carburizing and carbonitriding is carried out, and the influence of heat treatment process on fatigue performance is analyzed; finally, based on the proposed fatigue damage model and numerical calculation method, the rotational bending fatigue life of M50NiL bearing steel is predicted, and the results are compared with the experimental results to verify the correctness of the proposed method.

Study on the influence of heat treatment process on the microstructure and hardness of carburized layer of 20CrMoH steel

Abstract In this paper, the effects of different carburizing quenching processes and tempering processes on the depth of the hardened layer and microstructure of 20CrMoH were studied by means of hardness analysis and SEM microstructure analysis. The results show that: when the quenching temperatures in the range of 820-880 °C, it has little effect on the depth of the hardened layer. And the hardness value at the same depth is at a considerable level, which is not affected by the quenching temperature. When the tempering temperature range is 150-280 °C, the tempering temperature has a great influence on the depth of hardened layer. And with the gradual increase of tempering temperature, the depth of hardened layer decreases gradually. Also the hardness value at the same depth from the edge shows a monotonous decreasing trend with the gradual increase of tempering temperature.

The influence of heat treatment process on the dynamic recrystallization evolution mechanism of Inconel 718 during high-speed machining

This study aims to investigate the cutting mechanisms of Inconel 718 alloy under different heat treatment processes and the grain refinement patterns of the transformed layer. By establishing a constitutive model suitable for cutting and importing it into DEFORM-3D for heat treatment processing and single-factor cutting experiment simulation, the effects of heat treatment processes and cutting parameters on cutting force, cutting temperature, and surface grain refinement were studied. The results indicate that the increase in cutting force is maximum, approximately 12 %, after the aging temperature is raised from 668 °C to 718 °C. The cutting force generated after aging heat treatment shows a negative correlation with cutting speed, whereas the cutting force after solution heat treatment rises significantly between 1400 and 1600 mm/s. The maximum cutting temperature occurs in workpieces after solution heat treatment, about 112 % of that of workpieces treated at 718 °C aging heat treatment. At the onset of cutting, the size relationship of the original grain volume is as follows: untreated < solution heat treatment < aging heat treatment; the number of nucleation points for dynamic recrystallization at grain boundaries is as follows: aging heat treatment < solution heat treatment < untreated. The most significant increase in the number of dynamic recrystallizations is observed after aging heat treatment at 621 °C, with the relationship of the number of recrystallizations in different cutting deformation zones being: secondary deformation zone < primary deformation zone < tertiary deformation zone. With the increase in cutting depth, the grain size of the workpiece after solution heat treatment first increases then decreases during the cutting process; the grain size of the workpiece after aging heat treatment first decreases then increases. The grain size of the workpiece during the cutting process after heat treatment is negatively correlated with cutting speed. Specifically, when the cutting speed is 600 mm/s, the grain size after solution heat treatment is the largest, about 1.1 times that of the 718 °C aging heat-treated workpiece.

Influence of heat treatment processes on microstructure evolution, tensile and tribological properties of Ti6Al4V alloy

The influence of heat treatment processes on microstructure, tensile and tribological properties of Ti6Al4V alloy was investigated. The specimens were heated for 30 min at 925 °C and then cooled at various rates by water quenching, air cooling, and furnace cooling. After that, the samples were aged for four hours at 600 °C. Three phases make up the microstructure: primary α-phase (αp), secondary α-phase (αs), and retained β-phase (βr). Cooling in the air and water followed by aging (AC + Aging and WQ + Aging) resulted, αs-phase precipitating inside βr-phase. The highest hardness of 35 HRC was recorded for WQ + Aging specimen due to existence of a high amount of βr-phase and precipitation of αs-phase. On the other hand, the lowest hardness of 26 HRC was obtained for the FC specimen. AC specimen achieved the highest elongation value of 14%. However, WQ + Aging specimen exhibited the highest ultimate tensile strength of 1028 MPa. For WQ + Aging and AC + Aging specimens, the ideal balance of strength and elongation was discovered. The wear resistance of solution-treated specimens was significantly improved by the aging process and 125% improvement could be achieved in WQ compared to WQ + Aging specimens.

Influence of heat treatment process on leakage current of anodic aluminum oxide films

Influence of heat treatment process on leakage current of anodic aluminum oxide films

Influence of heat treatment process on the hardness and material structure of SKD61 tool steel

This study investigates the influence of heat treatment on the hardness and material structure of SKD61 steel. The study focused on the influence of quenching temperature and tempering temperature on the hardness distribution of SKD61 steel. The equations representing the relationship between hardness and tempering temperature were derived based on the results. By the results of the analysis of the material structure, the appropriate process conditions for machining molds at high temperature were determined. We concluded that the steel should be heated to 1050[Formula: see text]C. The heat was maintained for 2 h and the steel then quenched in oil media. It was further annealed at 580[Formula: see text]C, with the heat maintained for 2 h and then cooled in the same furnace. With the above heat treatment process, an average hardness of 52HRC was obtained and the structure of the steel was sufficiently stable to ensure the success of subsequent heat treatment processes.

Effect of heat treatment on the microstructure and properties of CoCrFeNiMo0.2 particles reinforced titanium matrix composites

In this paper, the influence of heat treatment process on the microstructure and properties of CoCrFeNiMo0.2/Ti composites was studied by heat treatment of the composites. The structure and composition of CoCrFeNiMo0.2/Ti composites were characterized by X-ray diffraction and optical microscope. The distribution of elements of the interface layer was explored by electron probe. The mechanical properties of the composites were analyzed by nano indentation experiment and hardness tester. The relationship between irregular particles and the thickness of the interface layer was studied. The results are as follows: when the heat treatment temperature is 770 °C, the morphology of the high entropy alloy does not change significantly. As the temperature rises to 830 °C, the shape of the particles deforms and the thickness of the diffusion layer increases significantly. With the increase of the heat treatment temperature, the Young’s modulus and hardness of the interface layer have increased. When the heat treatment temperature rises to 890 °C, the particles completely diffuse into the matrix. Overall, the distance of the particles from the inscribed circle and the thickness of the interface layer are positively correlated.

Effect of heat treatment on nano-mechanical behaviour of matrix and carbide phases of Fe–13Cr–1C hardfaced alloy coating

Fe–Cr–C hardfaced coatings are applied over components used in mining, earth moving, ash and coal handling systems. The performance of these coatings depend on microstructural phases present in the deposit post-solidification and/or heat treatment. To prevent the failure of a coating, understanding the mechanical behaviour of the existing phases is one of the key areas of focus. In the current investigation, the study was limited to understand the influence of heat treatment process on nano-scale hardness and reduced modulus properties of phases of Fe–13%Cr–1%C hardfaced alloy coating by accelerated property mapping (XPM) technique. Colour variation in the property maps showed the relative deformation nature of the material. The hardness and reduced modulus values for carbide phases were found to be higher in all conditions. From Weibull statistical analysis, the Weibull modulus values reduced drastically for the carbide phase after heat treatment, revealing higher variability of mechanical properties. The above trends were observed mainly due to %C and %Cr difference across phases and carbide phase morphology transformation happened due to heat treatment.

Study on the influence of heat treatment process on machinability behaviour of aluminium alloy 6060

In this work, the impact of full annealing heat treatment process on the machinability behaviour of Aluminium alloy 6060 has been studied elaborately. The samples were kept at 300 degree celsius (6 h) and subsequent cooling process was done at room temperature. Three levels in three input parameters (Spindle speed 300, 600, 900 rpm, Feed rate 0.05, 0.10, 0.15 mm/rev and Depth of Cut 0.50, 1.00, 1.50 mm) and two output parameters (Material Removal Rate and Surface Roughness) were selected for this study. 17 experimental runs were used in this study for optimization process. The experiments were conducted at CNC lathe using HSS tool and the results were compared between the heat treated and non - heat treated samples. The heat treated samples showed 34.67% better MRR and 11% reduction in surface roughness than non - heat treated samples. The optimal results in heat treated workpiece was achieved at 893 rpm spindle speed, 0.15 mm/rev feed rate, 1.5 mm depth of cut. The confirmatory test was conducted and the results obtained shows negligible error percentage which further extends the scope of this study in real applications like railings, motor housings, and heat sinks.

Study on Kinetics of Transformation in Medium Carbon Steel Bainite at Different Isothermal Temperatures.

Ultra-fine carbide-free bainitic (UCFB) steel, also known as nano-bainite (NB) steel, is composed of bainitic ferrite laths with nanoscale thickness and carbon-rich film-like retained austenite located between laths. The bainite transformation kinetic model can accurately describe the bainite transformation kinetics in conventional austempering (CA) processes based on the shear mechanism combined with the dilatometer test. UCFB steels with medium and high carbon composition are designed in this work to systematically study the transformation kinetics of bainite, and the evolution of its microstructure and properties, and reveal the influence of heat treatment processes on the microstructure and properties the UCFB steels. The results show that the activation energy for BF nucleation decreases during the CA process and isothermal transformation temperature decreases. The bainite transformation is first nucleated at the grain boundaries, and then nucleated at the newly formed bainitic ferrite/austenite interface.

Research on the influence of heat treatment on residual stress of TC4 alloy produced by laser additive manufacturing based on laser ultrasonic technique

During the laser additive manufacturing (LAM) process large temperature gradients can lead to high level of residual stress. The residual stress can have irreversible effects such as warping and cracking of parts during and post manufacturing. Heat treatment is an effective method to control and eliminate residual stress. In this paper, the TC4 parts are prepared by laser additive manufacturing, and the influence of heat treatment process on residual stress is researched. Laser ultrasonic technology, as an advanced nondestructive testing method, is applied to measure the residual stress under different heat treatment processes for the first time. The surface wave generated by laser is used to evaluate the residual stress. The results show that laser ultrasonic method can complete the in-situ evaluation of residual stress in additive manufacturing components. The residual stress in TC4 deposited specimen is large, the longitudinal stress is obviously greater than the transverse stress, and the maximum residual stress is about half of the yield strength. The residual stress increases gradually from the upper surface to the bottom layer near the substrate before heat treatment. After heat treatment, the residual stress is reduced to low stress level and a small compressive stress appears. The cooling rate and solution temperature are the main factors affecting the residual stress, and the residual stress increases with the increase of cooling rate and solution temperature. The effect of aging temperature and aging time on residual stress is not obvious. The study serves as useful guidelines for engineers to assessment and regulation of residual stress reasonably in LAM.

Influence of Heat Treatment Process on Microstructure and Corrosion Resistance of Ultrafine Bainite Steel

Influence of Heat Treatment Process on Microstructure and Corrosion Resistance of Ultrafine Bainite Steel

Effects of Heat Treatment on the Corrosion and Mechanical Properties of Stainless Steel 316L as Used in Biomedical Applications

This work examines the influence of heat treatment processes, using oil and water at various temperatures as quenching media, on the mechanical, corrosion, and microstructural properties of 316L austenitic stainless steel as used as a biomaterial for temporary and permanent bone repairs or grafts and as a plate bone fixation during periods of treatment. The results show that the highest microhardness rate is obtained using normal water as a cooling media; this sample reached 157.7 Hv, a 9.97% higher value than that obtained using oil media and an 18.66% higher value than that obtained using one-hour heating. The microstructure images for the quenched samples in oil displayed more evenly and uniformly distributed carbon particles, suggesting the formation of a more pearlite structure as compared with the water-quenched samples, however. The highest polarization resistance value was obtained when using water cooling media with two hours heating time; this reached 2.849 V/μA. Dec., while the minimum value, reached 0.185 V/μA. Dec., was obtained using the hot water cooling medium. The minimum corrosion rate value was obtained using the oil cooling media; this was 0.34 × 10-5 milli-in./year, while the maximum value reached 0.86x10-5 milli-in./year for the water cooling medium with a three-hour heating duration. The resulting equivalent von-Mises stress reached its maximum value at 285.24 MPa at 150 Kg patient weight and 5 mm plate thickness. The total deformation reached a minimum value of 0.0723 mm, while the stress safety factor reached a maximum value of 2.7 for a patient weight of 60 Kg when using 10 mm plate thickness. The equivalent elastic strain and the strain energy reached minimum values of 4.7 × 10-4 mm and 0.021 mJ for a patient weight of 60 Kg when using 5 mm plate thickness, respectively.

Effect of heat treatment processes on hydrogen embrittlement in hot-rolled medium Mn steels

The influence of heat treatment processes, which consist of a quenching partitioning (QP) process, intercritical annealing (IA) process and warm rolling (WR) process, on the hydrogen embrittlement (HE) of medium Mn steels is investigated. The corresponding experimental specimens are labeled QP160, IA810 and WR760, respectively. WR760 reveals the best mechanical properties, and the corresponding product strength and elongation (PSE) is 42.9 GPa•%; nevertheless, HE susceptibility is the lowest due to fine grains and microcrack propagation paths, which are parallel to rolling direction (RD), and they relax the triaxial stress conditions ahead of the main transverse crack's tip. IA810 (PSE = 29.1 GPa•%) shows the highest HE susceptibility due to the extremely unstable γ, which makes the microcrack propagation along the interface of γ(α′)/α-ferrite occur more easily when there is hydrogen. Compared to IA810, QP160 (PSE = 17.6 GPa•%) reveals a lower HE susceptibility due to the higher γ stability.

Study of the influence of heat treatment process on the mechanical performance of wedge shaped components

Mine Splitter is widely used in mining machinery, and wedge assembly components are very important parts of it. In this work, we studied wedge assembly’s element content by EDS, and through different heat treatments to improve the performance of wedge assembly components of Mine splitter. The heat treatment process of wedge assembly components is divided into quenching, quenching and tempering to find the changes on microstructure and mechanical properties. It is found that after quenching at 840°C and tempering at 450°C, the structure is tempered Sorbite with the highest strength and wear resistance and the best comprehensive mechanical properties.

Optimization of Microstructure and Mechanical Properties of Hipped Inconel 718 by Various Heat Treatment Processes

The influence of heat treatment processes on hardening and harmful phases in microstructure and mechanical properties of hipped Inconel 718 (IN718) alloy was investigated. In comparison with conventional solid solution treatment, modified solid solution one entirely eradicates δ phase from the microstructure of hipped IN718 alloy. However, a thin film of δ phase precipitates at the grain boundaries of γ matrix. Aging at 750 °C for 4 h, another morphology of needle-like δ phase appeared as small colonies in the microstructure of IN718 alloy. Prolonging the aging duration time to 50 h, these colonies enlarge in size and spread in the whole matrix. X-ray diffraction and transmission electron microscope observations were used to identify different phases such as γ, γ′, γ″, and δ in the microstructure of IN718. Hardness property was measured representing the mechanical properties of investigated heat-treated IN718 alloy. Conventional solutionized specimens have higher rate in hardness increasing with aging time compared to modified solutionized ones. The latter specimens need an incubation period of about 24 h to ascent suddenly achieving the same hardness level of the other corresponding specimens. These heat treatment conditions are considered as the best compromise to achieve the optimum mechanical properties.

Investigation of Heat Treatment Processes Effects on Erosion Behavior of BOHLAR Steel K720

This study aim to investigate from influence of heat treatment processes on erosion resistance of high carbon steel Bohler K720, where we got untreated plate of this steel with dimensions (500x60x10 mm), then cut it to specimens with dimensions (60x15x10 mm), and every group of these specimens was undergone to different heat treatment, heating to 810ºC, holding 10 min, then cooling in different mediums (water, oil, air), other groups of specimens that cooled in oil were tempered at temperatures (100,200,300,400 ºC) for 30 min, and by that we got eight groups including the as received specimen that differ on each other in heat treatments conditions. The microstructure was examined for each sample, and the hardness was measured, and erosion test was applied by use rubber wheel machine with preload and sand current. The results of tests showed that the water quenched specimens have the highest hardness 70HRC and the highest erosion resistance 0.14%, but the quenching in water caused cracks in specimens, while the cooling in air gave the lower hardness 59HRC and erosion rate 0.306%. For the specimens that quenched in oil and tempered, the results showed that with increasing the temperature of tempering from 100ºC to 400ºC the hardness decreasing from 64HRC to 50HRC and the erosion rate increased from 0.201% to 0.451. The summery that the quenching process which aim to obtain martensitic structure and cause internal stresses within structure because of cooling speed was by oil and gave high hardness and erosion values without cracks and fractures, and by tempering process which consider important to make the specimens more stable can re-control by these two values to suit the practical application by changing temperature.

Microstructure and crystallographic properties of Cu77Zn21 alloy under the effect of heat treatment

ABSTRACTThe influence of heat treatment process on microstructure and physiochemical properties of Cu77Zn21 alloy was studied. Samples were heated from 300 to 700°C for 15 minutes and gradually cooled to room temperature. Samples were characterized using mechanical testing and surface analysis techniques. It was observed that the grain size increases with the increasing temperature. The decrease in hardness is due to composition change of the Cu-Zn alloy attributed to zinc diffusion.XRD shows the presence of only α brass with a preferential orientation along the (111) plane. The analyses show that temperature affects the crystalline parameters. The rms microstrain was reduced mainly by thermal activation. The heat treatment promotes atomic diffusion and leads to a better crystallinity of the particles. The results of Raman investigations confirmed the changes in the Cu-Zn alloy surface composition with a clear enrichment in CuO. This behavior correlates with the results obtained by mechanical testing.