Effect Of Heat Treatment Process Research Articles

Effects of Heat Treatment Process on Microstructure and Mechanical Properties of 31Mn2SiREB Cast Steel

The heat treatment process of 31Mn2SiREB cast steel used in crawler shoes is directly lifted from the heat treatment process of Mn13 high-manganese cast steel, i. e., quenching at 1050 oC after casting. The reasonableness of the process needs to be surveyed. In this paper, the effects of quenching temperature and diffusion annealing pre-treatment on mechanical properties, micro-area composition uniformity and micro-hardness uniformity were investigated. For quenching after casting, the tensile strength and impact energy increase observably with the elevation of quenching temperature, but the impact energy at higher quenching temperature is still very small. The fluctuation of micro-hardness and chemical composition at different micro-areas becomes obviously small with the increase of quenching temperature. For quenching after a diffusion annealing pre-treatment, the impact energy is very high and up to 36.3 J.

Effect of heat treatment process on tensile properties of 2A97 Al-Li alloy: Experiment and BP neural network simulation

Effects of heat treatment processes on tensile properties of 2A97 Al-Li alloy were investigated. The results show that one new heat treatment process which was developed from traditional T8 temper can effectively improve the tensile properties of Al-Li alloy. In the peak-aged condition, a large quantity of fine T1 dispersedly precipitated in the matrix. At the same time, few secondary phases precipitated at the grain boundaries, and precipitation-free zone was unobvious. The corresponding tensile strength, yield strength and elongation of alloy were 597 MPa, 549 MPa and 7.4%, respectively. In addition, BP neural network model was developed for prediction of the tensile properties of alloy subjected to different heat treatment processes. A very good correlation between experimental and predicted results was obtained, which indicates that the BP neural network can be used for the prediction of tensile properties of 2A97 Al-Li alloy.

Prediction of mechanical properties of A357 alloy using artificial neural network

The workpieces of A357 alloy were routinely heat treated to the T6 state in order to gain an adequate mechanical property. The mechanical properties of these workpieces depend mainly on solid-solution temperature, solid-solution time, artificial aging temperature and artificial aging time. An artificial neural network (ANN) model with a back-propagation (BP) algorithm was used to predict mechanical properties of A357 alloy, and the effects of heat treatment processes on mechanical behavior of this alloy were studied. The results show that this BP model is able to predict the mechanical properties with a high accuracy. This model was used to reflect the influence of heat treatments on the mechanical properties of A357 alloy. Isograms of ultimate tensile strength and elongation were drawn in the same picture, which are very helpful to understand the relationship among aging parameters, ultimate tensile strength and elongation.

Investigation of the effect of heat treat-ment process on characteristics and photocatalytic activity of TiO2-UV100 nanoparticles

Investigation of the effect of heat treat-ment process on characteristics and photocatalytic activity of TiO2-UV100 nanoparticles

Effect of Heat Treatment Process on Microstructure and Properties of High Strength Heavy Plate for Ship Hull

The variation of microstructure and their effect on the mechanical properties of heavy plate for ship hull treated by quenching in full austenite region at 910°C once or twice and tempering, or quenching in full austenite region and quenching in intercritical austenite region at 840°C again and tempering were studied with SEM and TEM. It was found that the strength and low temperature toughness of the steel were higher after double quenching in full austenite region and tempering than the steel which was quenched once and tempering, because smaller bainite inter-lath spacing, finer grains were obtained. The steel treated by intercritical quenching at 840°C after quenching in full austenite region and tempering showed the best combination of mechanical properties. This can be attributed to comprehensive effect of the uniform distribution of ferrite and bainite, stronger grain refining effect caused by formation of ferrite.

Influence of Heat Treatment Processing on the Magnetic Properties of Fe-3.5Si Soft Magnetic Composites in Material Application

In this paper, the effect of heat treatment processing on magnetic properties of Fe-3.5Si soft magnetic composite has been investigated. The thermal treatment improved the magnetic properties of Fe-3.5Si SMC materials. With the treatment temperature increasing, the permeability and eddy loss of the composites increase and the core loss and hysteresis loss decrease. The magnetic properties would be deteriorated at too high temperature. Annealed temperature at 750°C for 60min, the Fe-3.5Si soft magnetic composite has the optimum overall magnetic properties.

Higher water splitting hydrogen generation rate for single crystalline anatase phase of TiO2nanotube arrays

This paper presents a detailed investigation on the effect of heat-treatment process on the highly ordered titanium dioxide (TiO 2 ) nanotube arrays in connection with the photoelectrochemical (PEC) response and hydrogen evolution rate. TiO 2 nanotube arrays have been systematically heat-treated to control the transformation of as-anodized TiO 2 amorphous structure to crystalline anatase and rutile phases. In this study, single crystalline TiO 2 anatase phase exhibited a higher PEC response and hydrogen evolution rate at 400 °C heat treatment. The photocurrent density increase was mainly attributed to the effective transport of photo-induced electrons within the single crystal anatase phase. However, polycrystalline anatase and rutile phases showed the fluctuation in lower photocurrent density upon heat treatment above 500 °C. The mobility of photo-induced electrons was obviously hindered due to the recombination losses in defect sites between the anatase and rutile phase.

Selection of Heat Treatment Process and Wear Mechanism of High Wear Resistant Cast Hot-Forging Die Steel

AbstractDry sliding wear tests of a Cr-Mo-V cast hot-forging die steel was carried out within a load range of 50–300 N at 400 °C by a pin-on-disc high-temperature wear machine. The effect of heat treatment process on wear resistance was systematically studied in order to select heat treatment processes of the steel with high wear resistance. The morphology, structure and composition were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS); wear mechanism was also discussed. Tribo-oxide layer was found to form on worn surfaces to reduce wear under low loads, but appear inside the matrix to increase wear under high loads. The tribo-oxides were mainly consisted of Fe3O4 and Fe2O3, FeO only appeared under a high load. Oxidative mild wear, transition of mild-severe wear in oxidative wear and extrusive wear took turns to operate with increasing the load. The wear resistance strongly depended on the selection of heat treatment processes or microstructures. It was found that bainite presented a better wear resistance than martensite plus bainite duplex structure, martensite structure was of the poorest wear resistance. The wear resistance increased with increasing austenizing temperature in the range of 920 to 1120 °C, then decreased at up to 1220 °C. As for tempering temperature and microstructure, the wear resistance increased in following order: 700 °C (tempered sorbite), 200 °C (tempered martensite), 440 to 650 °C (tempered troostite). An appropriate combination of hardness, toughness, microstructural thermal stability was required for a good wear resistance in high-temperature wear. The optimized heat treatment process was suggested for the cast hot-forging steel to be austenized at 1020 to 1120 °C, quenched in oil, then tempered at 440 to 650 °C for 2 h.

Microstructure and mechanical properties of low frequency electromagnetic casting 7075 aluminum alloy

This work explores the microstructure of low frequency electromagnetic casting (LFEC) 7075 aluminum alloys and investigates the effect of heat treatment process on its mechanical properties via the mechanical properties test, X-ray diffraction and transmission electron microscopy. It was found that the grains of LFEC ingot were finer and more evenly distributed than that of the conventional direct chill cast (DC) ingots. The microstructure of LFEC ingot extruded kept their original as-cast structure with small and fine grains. With the same extrusion ratio, the average grain diameters of LFEC and conventional DC extruded were about 10 and 20 μm, respectively. LFEC extruded also had a better aging property, since the regime of T6 treatment peak value aging was at 120 ◦C for 24 h, the tensile strength and hardness (HV) of the LFEC extruded were 673.50 MPa and 194.62, respectively, which were all higher than those of the conventional DC extruded, indicating that the process regime can be applied in the industrial production.

Heat Treatment of AlZn10Si7MgCu Alloy and its Effect on Change of Mechanical Properties

Heat Treatment of AlZn10Si7MgCu Alloy and its Effect on Change of Mechanical Properties The most important parameters which predetermine mechanical properties of a material in aspects of suitability for castings to machinery components are: tensile strength (Rm), elongation (A5, hardness (HB) and impact strength (KCV). Heat treatment of aluminum alloys is performed to increase mechanical properties of the alloys mainly. The paper comprises a testing work concerning effect of heat treatment process consisting of solution heat treatment and natural ageing on mechanical properties and structure of AlZn10Si7MgCu alloy moulded in metal moulds. Investigated alloy was melted in an electric resistance furnace. Run of crystallization was presented with use of thermal-derivative method (ATD). This method was also implemented to determination of heat treatment temperature ranges of the alloy. Performed investigations have enabled determination of heat treatment parameters' range, which conditions suitable mechanical properties of the investigated alloy. Further investigations will be connected with determination of optimal parameters of T6 heat treatment of the investigated alloy and their effect on change of structure and mechanical/technological properties of the investigated alloy.

Microstructure and Mechanical Properties of Martensitic Stainless Steel 6Cr15MoVn

Martensitic stainless steel containing Cr of 12% to 18% (mass percent) are common utilized in quenching and tempering processes for knife and cutlery steel. The properties obtained in these materials are significantly influenced by matrix composition after heat treatment, especially as Cr and C content. Comprehensive considered the hardness and corrosion resistance, a new type martensitic stainless steel 6Cr15MoV has been developed. The effect of heat treatment processes on microstructure and mechanical properties of 6Cr15MoV martensitic stainless steel is emphatically researched. Thermo-Calc software has been carried out to thermodynamic calculation; OM, SEM and TEM have been carried out to microstructure observation; hardness and impact toughness test have been carried out to evaluate the mechanical properties. Results show that the equilibrium carbide in 6Cr15MoV steel is M23 C6 carbide, and the M23C6 carbides finely distributed in annealed microstructure. 6Cr15MoV martensitic stainless steel has a wider quenching temperature range, the hardness value of steel 6Cr15MoV can reach to HRC 60.8 to HRC 61. 6 when quenched at 1060 to 1100 °C. Finely distributed carbides will exist in quenched microstructure, and effectively inhabit the growth of austenite grain. With the increasing of quenching temperature, the volume fraction of undis-solved carbides will decrease. The excellent comprehensive mechanical properties can be obtained by quenched at 1060 to 1100 °C with tempered at 100 to 150 °C, and it is mainly due to the high carbon martensite and fine grain size. At these temperature ranges, the hardness will retain about HRC 59. 2 to HRC 61. 6 and the Charpy U-notch impact toughness will retain about 17. 3 to 20 J. A lot of M23C6 carbides precipitated from martensite matrix, at the same time along the boundaries of martensite lathes which leading to the decrease of impact toughness when tempered at 500 to 540 °C. The M3C precipitants also existed in the martensite matrix of test steel after tempered at 500 °C, and the mean size of M3C precipitates is bigger than that of M23C6 precipitates.

EFFECTS OF HEAT TREATMENT PROCESS ON THE MICROSTRUCTURE AND PROPERTIES OF A NEW CAST NICKEL-BASED SUPERALLOY

A new casting Ni-based superalloy is used in industrial and aircraft turbine because of its high strength and excellent hot corrosion resistance at high temperatures(about 900℃).The effect of heat treatment process on its microstructure and mechanical properties of the experimental casting Ni-based superalloy was studied in the present investigation in order to improve its application level.The results showed that the stress-rupture lives were changed with the increase of heat treatment temperatures.After solution treated for 2 h,then cooling by air cooling,the stress-rupture life under the conditions of 760℃and 660 MPa was the highest in the case of heat treatment temperature at 1220℃,while under the testing conditions of 980℃and 180 MPa the stress-rupture life was the highest in the case of heat treatment temperature at 1180℃.The stress-rupture life decreased when being heat-treated at temperatures above 1220 or 1180℃.The tensile strength of the alloy was improved with the increase of heat treatment temperatures from 1120 to 1220℃,and was decreased in the case of heat treatment temperature at 1240℃.The experimental results also showed that with the increment of holding time from 2 to 8 h at 1120℃the stress-rupture life increased under the conditions of 760℃and 660 MPa,while it was decreased under the conditions of 980℃and 180 MPa. It was found that the tensile strength was higher for the alloy being held for 2 and 4 h than that for the alloy being held for 6 and 8 h,and the stress-rupture lives changed with the different cooling ways. The mechanical properties of the alloy may be determined by the size,shape,distribution and volume fractions ofγ' phase andγ/γ' eutectic.

Effect of Heat Treatment Processes on the Mechanical Properties of Medium Carbon Steel

The importance of various form of heat treatment operations on medium carbon steel in order to forester the problem that may arise in making a wrong choice of these steel materials or faulty heat treatment operations which may give rise to serious disruption in terms of human safety, higher cost and untimely failure of the machine components is of great concern. The mechanical properties such as ductility, toughness, strength, hardness and tensile strength can easily be modified by heat treating the medium carbon steel to suit a particular design purpose. Tensile specimens were produced from medium carbon steel and were subjected to various forms of heat treatment processes like annealing, normalizing, hardening and tempering. The stiffness, ductility, ultimate tensile strength, yield strength and hardness of the heat treated samples were observed from their stress-strain curve. The value of the yield strength (σy) was observed to be higher for the tempered specimen possibly as a result of the grain re-arrangement, followed by the hardened, normalized and annealed specimens. The value of the ultimate tensile strength (σu) were also observed to be in the order; hardened> tempered>normalized>annealed.

Effect of Heat-treatment Process on the Structure and Photoelectric Performance of TiO<SUB>2</SUB> Nanotube Arrays

通过阳极氧化法在钛箔上制备了TiO 2 纳米管阵列, 在不同热处理工艺下使其晶化. 利用扫描电子显微镜(SEM)和X射线衍射(XRD)对TiO 2 纳米管阵列的形貌和结构进行了表征. 结果表明, 阳极氧化法制备的TiO 2 纳米管经450~750℃热处理后为纳米晶结构, 平均晶粒尺寸随退火温度升高而增大, 相同温度下氮气气氛中热处理的TiO 2 平均晶粒尺寸小于空气气氛中热处理的TiO 2 . 氮气气氛下退火可拓宽TiO 2 由锐钛矿型(Anatase)向金红石型(Rutile)结构转变的热处理温度范围, 650℃以上退火处理后, TiO 2 纳米管中掺杂有少量的氮. 光照开路电位测试和稳态极化曲线测试结果表明, 在氮气气氛中、经650℃退火处理2 h制备的TiO 2 纳米管阵列电极光电响应性能最佳, 此时TiO 2 为锐钛矿型和金红石型的混晶结构.

Effect of Heat Treatment Process on Mechanical Properties and Microstructure of Modified CNS-II F/M Steel

Ferritic/martensitic (F/M) steels have been recommended as one of the candidate materials for supercritical water cooled reactor (SCWR) in-core components use for its high thermal conductivity, low thermal expansion coefficient and inherently good dimensional stability under irradiation condition in comparison to austenitic steel. CNS-II F/M steel which has good mechanical properties was one of the 9-12Cr F/M steels designed for SCWR in the previous work. In this study a modified CNS-II F/M steel was used and it's ultimate tensile strength was 925 MPa at room temperature and 483 MPa at 600 °C after optimizing heat treatment parameter. The ductile to brittle transition temperature of modified CNS-II F/M steel is −55 °C. Those are at the same level or even higher than that of CNS-II and some commercial F/M steels nominated for SCWR in-core component use. The transmission electron microscope (TEM) results showed that the mechanical properties of the tempered martensite was closely related to the decomposition stage of the martensite.

Effects of heat treatment processes on microstructure and creep properties of a high nitrogen 15Cr–15Ni austenitic heat resistant stainless steel

Abstract Conventional thermo-mechanical treatment (CTMT) and modified thermo-mechanical treatment (MTMT) process were applied for manufacturing a high nitrogen niobium-stabilized 15Cr–15Ni austenitic alloy. CTMT process consists of 5 h of solution treatment at 1270 °C followed by water quenching and subsequent aging at 820 °C for 50 h. MTMT process differs from CTMT process in hot plastic deformation performed immediately after the solution treatment at 1270 °C and longer aging time. Microstructure and creep properties of the steel obtained by both processing routes were investigated. Creep rupture tests at 750 °C showed double increase in rupture time brought about by MTMT process. Examination of crept microstructure by transmission electron microscopy revealed that the improved creep properties in MTMT process were mainly due to improved distribution uniformity of fine nano-sized carbonitride precipitates in the austenitic matrix and that MTMT process has no effects on the number density and distribution of copper precipitates present in the steel. However, the creep ductility in MTMT process drastically reduced comparing to CTMT process. The higher density of grain boundaries due to finer grain recrystallized microstructures and the formation of higher volume fraction of coarser M23C6 precipitates at the boundaries are believed to be the main reason for the lower creep ductility in MTMT process.

Influences of heat treatments on crystallization in SiO2-Al2O3-MgO-K2O-F glass-ceramics

Five kinds of heating treatment processing were chosen according to the experiment result of differential scanning calorimeter to prepare SiO2-Al2O3-MgO-K2O-F glass ceramics samples. The effects of heat treatment processing on the crystallization of these samples were explored by X-ray diffraction and scanning electron microscopy techniques. The results indicate that phase separations can occur in the bulk regions of the glass sample when holding at 670 °C for 3 h. The phase separation can accelerate the precipitation of the crystallization phase: when the temperature directly rises to 950 °C after the phase separation, there are mainly interlocked plate-shapes mica phases; If holding at 860 °C for 3 h first after the phase separation, the star-shape cordierite phases form; Thereby, elevating temperature to 950 °C and holding for 1 h will bring plate-shapes mica phases growing at inter-phases of the star-shape cordierite and finally the homogeneously distributed micacordierite composites form. However, if heating at 950 °C directly without holding at 670 °C, there is a small quantity of phase separation appearing at 670 °C and a little crystallization phases precipitating at last.

Crack‐Tip Stress Field and Fatigue Crack Growth Monitoring Using Infrared Lock‐In Thermography in A359/SiCp Composites

Abstract: This paper deals with the study of fracture behaviour of silicon carbide particle‐ reinforced aluminium alloy matrix composites (A359/SiCp) using an innovative non‐destructive method based on lock‐in thermography. The heat wave, generated by the thermo‐mechanical coupling and the intrinsic energy dissipated during mechanical cyclic loading of the sample, was detected by an infrared camera. The coefficient of thermo‐elasticity allows for the transformation of the temperature profiles into stresses. A new procedure was developed to determine the crack growth rate using thermographic mapping of the material undergoing fatigue. The thermographic results on the crack growth rate of A359/SiCp composite samples with three different heat treatments were correlated with measurements obtained by the conventional compliance method. The results obtained by the two methods were found to be in agreement, demonstrating that lock‐in thermography is a powerful tool for fracture mechanics studies. The paper also investigates the effect of heat treatment processing of metal matrix composites on their fracture properties.

Effect of Heat Treatment Process on Microstructure and Properties in Low Carbon Si-Mn Q&P Steel

The mechanical properties of Low Carbon Si-Mn Q&P steel are strongly affected by the conditions of heat treatment. Microstructures and mechanical properties of Low Carbon Si-Mn Q&P steel at different partitioning temperature and holding time was investigated. The microstructure was analysed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is shown that the microstructure of Q&P steel is carbon-depleted lath martensite and carbon enriched retained austenite. The retained austenite appear film-type between the laths. Higher partitioning temperature and longer partitioning time can obtain more retained austenite. It is shown that with increasing partitioning time ultimate tensile strength decreases, while elongation increases obviously. Carbon-enriched metastable retained austenite is considered beneficial because the TRIP phenomenon during deformation can contribute to formability and energy absorption.

Heat-Treated Microstructure and Mechanical Properties of TC4 Alloy

The effects of heat treatment process on the microstructure and mechanical properties of TC4 alloy were investigated. The double shear and tensile tests were carried out by using the 12mm diameter standard specimens after solution treatment at 520°С for 1.5h and water quenching, followed by aging at 480-540°С for 8h. The microstructure and facture surface were analyzed using the equipment of metallurgical microscope and scanning electron microscopy. The results show that TC4 alloy show the best comprehensive performances after solution treatment at 940°С for 1.5h, aging at 520°С for 8h; the tensile specimens display a typical ductile fracture with oval dimples of various sizes; the microstructures with clear grain boundary and obvious lamellar structure are observed at room temperature. It indicates that the excellent comprehensive properties can be obtained by controlling the grain size of primary α phase and the morphology structure and amount of the secondary α phase at optimized aging temperature.