Progress in Rolling Mill Technologies

The excessive residual stresses caused by heat treatment and grinding processes is one of the main challenges for Cam manufacturing, because they will lead to delayed cracks and reduce the fatigue life of Cam. Experimental studies are one of the essential ways to keep residual stresses at a reasonable value. Thus, orthogonal and single-factor experiments are carried out to explore the effect of heat treatment and grinding processes on the residual stresses of the Cam. The heat treatment processes include quenching temperature, tempering temperature, and tempering holding time. The grinding process includes grinding speed and feed speed. Besides, the superimposed residual stresses produced by heat treatment and grinding processes are analyzed. The results show that the heat treatment and grinding processes produce compressive residual stresses. The heat treatment process combined with the grinding process increases the superimposed residual stress. In addition, the critical factor for the distribution of the final stresses on the Cam surface is the grinding process, and the grinding speed plays the most important role. Therefore, in order to optimize the Cam machining processes to control the residual stresses, the optimization sequence is grinding speed, quenching power, and tempering temperature. The processes to obtain the least stress are as follows: 128 kW of quenching power, 200 °C of tempering temperature and 8 h of tempering time.

With the rapid development of China's economy and society, the application range of metal materials has gradually been widely used in all walks of life. Whether in industry, agriculture, medical industry, etc., they all play a very important role. China's demand for metal materials is increasing day by day, and there is an urgent need for more and better quality metal materials to be consumed in the market. However, China is very scarce in metal materials research teams, talents, complete preparation processes and excellent equipment. It is necessary to strengthen the introduction of talent teams and excellent technology and strengthen the country's team building and mature guidelines system. Among the processing technologies of metal heat treatment, the heat treatment of metal is a fundamental processing technology. China has thrived in recent years and has already possessed complete equipment and facilities, scientific and excellent processing technology, and sound processing technology. In this way, metal materials with excellent properties can be produced, and the heat treatment process can significantly improve the strength, corrosion resistance, and fatigue strength of the metal and reduce the cost of processing. The impact on the environment cannot be ignored in the development process of metal materials. The processing of metal materials should not damage the environment but lose more for less. Therefore, improving metal material processing technology has become an urgent matter. This article will deeply analyze the performance of metal materials after heat treatment, the method of heat treatment processing technology and the innovation of metal heat treatment, and put forward relevant opinions for the heat treatment process of metal materials.

Poly(o-methoxyaniline) emeraldine-salt form (ES-POMA) was chemically synthesized using hydrochloric acid and subjected to a heat treatment (HT) process for 1 h at 100 °C (TT100) and 200 °C (TT200). The HT process promoted a progressive decrease in crystallinity. The Le Bail method revealed a decomposition from tetrameric to trimeric-folded chains after the HT process. The unheated POMA-ES presented a globular vesicular morphology with varied micrometric sizes. The heat treatment promoted a reduction in these globular structures, increasing the non-crystalline phase. The boundary length (S) and connectivity/Euler feature (χ) parameters were calculated from the SEM images, revealing that ES-POMA presented a wide distribution of heights. The TT100 and TT200 presented a narrow boundary distribution, suggesting smoother surfaces with smaller height variations. The UV-VIS analysis revealed that the transition at 343 nm (nonlocal π → π*) was more intense in the TT200 due to the electronic delocalization, which resulted from the reduced polymer chain caused by the HT process. In addition to the loss of conjugation, counter ion withdrawal reduced the ion-chain interaction, decreasing the local electron density. This result shows the influence of the chlorine counter ions on the peaks position related to the HOMO → LUMO transition, since the π → polaron transition occurs due to the creation of the energy states due to the presence of counter ions. Finally, the electrical conductivity decreased after the HT process from 1.4 × 10−4 S.cm−1 to 2.4 × 10−6 S.cm−1 as result of the polymer deprotonation/degradation. Thus, this paper proposed a systematic evaluation of the POMA molecular structure and crystallite size and shape after heat treatment.

Experimental investigation of residual stresses after heat treatment and grinding processes in the production of ball bearing rings has been carried out. The residual stresses were measured by X-ray diffraction method utilizing chromium radiation, which has an average penetration depth of 5 μm incident on 100Cr6 (AISI-E52100) ball bearing steel. The process parameters of heat treatment and grinding processes were varied so as to represent the extreme values that can be applied in the respective processes. Hardness and percent retained austenite limit the heat treatment process parameters; while roundness, surface roughness and form the grinding process. Tensile surface residual stresses on the raceway of ball bearing rings changes to compression after grinding in both circumferential and axial directions. In grinding relatively higher compressive stresses were measured in axial direction compared to the circumferential direction. This experimental investigation also showed that the influence of heat treatment process parameters on the magnitude and distribution of residual stresses survived even after grinding process; i.e. heat treatment and grinding processes cannot be evaluated independently in process design for favourable residual stresses.

This paper presents the results of experimental and theoretical studies regarding the behavior of AlCu4Mg1 aluminum alloy after a heat treatment. The methodology has been proposed to study improvements in AlCu4Mg1 aluminum alloy in the process of heat treatment, which included the following steps: (1) adopting the heat treatment technology for the specified alloy, (2) choosing the necessary heat treatment installations to perform the heat treatment of the specified alloy, (3) choosing tools and machines used to study the mechanical characteristics, and (4) planning the experiment and analytical interpretation of the results. On the basis of these experiments and the obtained regression equation, we performed a theoretical study with the aim to determine the heating parameters for quenching and aging in order to obtain a specified stress needed for application of this alloy. We considered two cases for this theoretical study: (1) the stress and quenching temperatures were fixed and we determined the aging temperature; (2) the stress and aging temperatures were fixed and we determined the quenching temperature. Using the determined equations, we assumed the definite characteristics needed for the working part after treatment and calculated the parameters for quenching and artificial aging in the process of the heat treatment. Note that the calculated temperatures should be in the standard limits for the studied alloy. In conclusion, an algorithm was proposed for the process of the optimum heat treatment in order to obtain the necessary properties of the working parts.

To evaluate the effect of rolling process on microstructures and textures development, this work was carried out using pure Ta sheets. For this work, conventional rolling (CR) and cross roll rolling (CRR) as a deformation process were introduced, pure Ta sheets were cold rolled to 90% in thickness reduction. After this, to obtain the recrystallized microstructure on cold rolled materials, the recrystallization heat-treatment was performed at 1200°C for 60 min under the high vacuum state. Also, to analyse the grain boundary character distributions of the annealed sheets, electron back-scattered diffraction method was introduced. As an experimental result, increase in strain rate led to the development of texture with its texture component of <111> at conventional rolling and cross roll rolling, in common. Therefore, in this study, we systematically discussed the texture development due to increase in effective strain.

The effect of heterogeneous precipitation behavior on the mechanical properties of IN718 superalloy after laser shock peening and heat treatment processes

The effect of heat treatment and thermal spray processes on the grain growth of nanostructured composite CoNiCrAlY/YSZ powders

Intermetallic alloy is a combination consists of two metal compounds or more. One of intermetallic alloy that can be used is nickel. Nickel is a corrosion resistant metal and withstands high temperature. Intermetallic alloy can be used for application on aircraft components such as turbin gas engine that operate in high temperature and extreme environment. This study is conducted to find out the changes of micro structure and hardness in NiAlTi material added by germanium of 1,5% as doping. In this study, heat treatment process was carried out with variation of temperature and aging time. The heat treatment included solution treatment and aging process. Solution treatment process was carried out at 1000 o C using tube furnace with holding temperature time for 2 hours. Aging process was carried out at 700 o C, 800 o C, 870 o C for 1, 2 and 3 hours for each temperature. Based on the hardness result, solution treatment heat treatment increase the grain size and also hardness of NiAlTi+1,5%Ge due to intermetallic compound formed in the alloy. Aging treatment increase the grain size and also hardness value. Maximum hardness take place at 870 o C for 3 hours with hardness of 45 HRc. Characterization by optical microscope and SEM showed that the alloy contain dendritic and interdendritic microstructure. Examination by XRD and EDS shows that intermetallic compound formed in all NiAlTi+1,5%Ge specimens are dominated by intermetallic of Ni 3 Al (Ɣ’).

Stress relief simulation for post-weld heat treatment process of pressure equipment: Creep constitutive equation considering temperature and stress variations

The research on the simulation for the through process of low-pressure casting and heat treatment is conducive to combine information technology and advanced casting technology, which will help to predict the defects and mechanical properties of the castings in the through process. In this paper, we focus on the simulation for through process of low-pressure casting and heat treatment of ZL114A Bending beam. Firstly, we analyzethe distribution of the shrinkage and porosities in filling and solidification process, and simulate the distribution of stress and strain in the late solidification of casting. Then, the numerical simulation of heat treatment process for ZL114A Bending beam is realized according to the heat treatment parameters and the corresponding simulation results of temperature field, stress, strain, and aging performance are given. Finally, we verify that simulation platform for the through process of low-pressure casting and heat treatment can serve the production practice perfectly and provide technical guidance and process optimization for the through process of low-pressure casting and heat treatment.

Phase separation and crystallization processes in heat treatment of Mn4 +-doped 90GeO2–10BaO glass and fluorescence properties

To evaluate the effect of heat treatment and porcelain-fused-to-metal (PFM) processing on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys. Samples of CoCr-NiCr dissimilar alloys with 0.5 mm thickness were laser-welded single-side under the setting parameters of 280 V, 10 ms pulse duration. After being welded, samples were randomly assigned to three groups, 10 each. Group1 and 2 received heat treatment and PFM processing, respectively. Group 3 was control group without any treatment. Tensile strength, microstructure and element distribution of samples in the three groups were tested and observed using tensile test, metallographic examinations, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) analysis. After heat treatment and PFM processing, tensile strength of the samples were (537.15 +/- 43.91) MPa and (534.58 +/- 48.47) MPa respectively, and elongation rates in Group 1 and 2 were (7.65 +/- 0.73)% and (7.40 +/- 0.45)%. Ductile structure can be found on tensile fracture surface of samples and it was more obvious in heat treatment group than in PFM group. The results of EDS analysis indicated that certain CoCr alloy diffused towards fusion zone and NiCr side after heat treatment and PFM processing. Compared with PFM processing group, the diffusion in the heat treatment group was more obvious. Heat treatment and PFM processing can improve the mechanical properties and microstructure of welded CoCr-NiCr dissimilar alloy to a certain degree. The improvements are more obvious with heat treatment than with porcelain treatment.

The high-purity ethylene dichloride (EDC) head tower is an important pressure vessel in the vinyl chloride production process. During the manufacturing process, the bending test of 2 product specimens broke. In this paper, the failure analysis of the bending test fracture of the welding test plate was carried out, and a systematic analysis, including chemical composition, mechanical properties, and microstructure, was carried out. The causes of fracture of welded test plates during the manufacturing process of the head tower were studied. The results show that the incorrect heat treatment process leads to the extension strength, hardness, and impact performance, being lower than the standard requirements. The combined fracture analysis shows that the material is brittle, which makes the welding test board brittle fracture. At the same time, metallographic analysis shows that the steel is tempered. The comprehensive performance of duplex stainless steel in the tempered state is significantly lower than the original solid solution heat treatment performance. Thus, the bending test fracture of the welding test board of the equipment is caused by the improper heat treatment process, resulting in the microstructure and performance of the material not meeting the relevant requirements. According to the cause of the fracture, the heat treatment and welding process are improved. The heat treatment was carried out first, and then the duplex steel was welded to prevent the heat treatment state of the duplex steel supply from changing. Finally, a qualified specimen was obtained.

Mechanical and microstructure properties of weld joint between mild steel plates before and after heat treatment process have been studied. In this study, electric arc welding was used as a welding method as it is the most common welding method. Then heat treatment of the samples were done in the furnace. Firstly, in the heat treatment process, stress annealing was done as stress generated at different places in the welding zone and after that full annealing was done using furnace cooling for cooling purpose. Tensile strength was measured using ASTM A370 standard specimen and Brinell hardness test was done at different surfaces of the welding zone. The microstructures were observed by cutting the specimen in a certain shape, and mirror surfaces were generated to observe in electron microscope. From the results, it was observed that PWHT causes a 4.1 % increase in tensile strength, a 13.84 % gain in yield strength, and a 4.96 % rise in percentage elongation. However, the value of hardness decreased 19.19 % after heat treatment as heat treatment increased the ductility of the specimen. At the place of the Electric Arc Welding joint, a smaller grain size, a lower gap between the grains, and comparatively few voids were identified.