Zhuang LI
,
Di WU
材料科学技术（英）
Influence of hot deformation and subsequent austempering on the mechanical properties of hot rolled multiphase steel was investigated. Thermo-mechanical control processing (TMCP) was conducted by using a laboratory hot rolling mill, where three different kinds of finishing rolling reduction, and austemperings with various isothermal holding duration were applied. The results have shown that a multiphase microstructure consisting of polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. Mechanical properties increase with increasing the amount of deformation because of the stabilization of retained austenite. Ultimate tensile strength (σb), total elongation (δ) and the product of ultimate tensile strength and total elongation (σb•δ) reach the maximum values (791 MPa, 36% and 28476 MPa%, respectively) at optimal processes.
关键词:
Hot deformation
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null
,
null
,
null
Ming GAO
,
Hongxing GU
,
Furen XIAO
,
Bo LIAO
,
Guiying QIAO
,
Ke YANG
,
Yiyin SHAN
材料科学技术（英）
The continuous cooling transformation (CCT) diagrams of 86CrMoV7 steel samples including hot deformed and not hot deformed were constructed by dilatometry, metallography and transmission electron microscopy (TEM). The results showed that hot deformation accelerated pearlite transformation and fine pearlite microstructure. Moreover, the undissolved carbides became the nucleating sites of pearlite, accelerated pearlite formation and fine pearlite if the steel had been deformed at high temperature. In contrast, undissolved carbides did not make any influence on pearlite transformation if the steel had not been deformed at high temperature.
关键词:
Hot deformation
,
null
,
null
Pingli MAO
,
Ke YANG
,
Guoyue SU
材料科学技术（英）
The hot deformation behavior of an as-cast 0Cr17Mn14Mo2N duplex stainless steel has been studied by hot compression test at the temperature range from 1000℃ to 1200℃, and the strain rates are 0.1 s-1, 1 s-1 and 5 s-1, respectively. It was found that during hot deformation there is only dynamic recovery taking place within the δ-ferrite phase, but the γ-austenite phase undergoes dynamic recrystallization. The activation energy of the steel for hot compression is estimated to be 480 kJ/mol.
关键词:
Hot deformation
,
null
,
null
Yong WANG
金属学报(英文版)
The processing maps were used to identify the optimal forging parameters of Ti-24Al-17Nb-0.5Mo alloy by evaluating the flow data according to the DMM model. The actual local strain rate and strain distribution in the samples were obtained by finite element calculations. The local microstructures of the deformed samples were related to the local deformation parameters and correlated with the processing maps at 0.3, 0.4, 0.5 and 0.6 of logarithmic strain. Flow regimes predicted by DMM analysis were then correlated with the local microstructural observations. Five domains of efficient coefficient could be distinguished. Unstable regions were microstructurally related to shear band formation within the α2+B2 phase deformation field, and to flow localization at grain boundaries of B2 phase in the near B2 phase deformation field. Stable flow regimes were shown to be associated with dynamic globularization of the plate-like α2 in the α2+B2 phase deformation zone, and with dynamic recrystallization of B2 in the near B2 phase deformation zone.
关键词:
Processing map
Pengfa FENG
材料科学技术（英）
The influences of preparation conditions of Al-5Ti-B (as-cast and hot-rolled) and Al-10Sr (as-cast and hot-extruded) and melt treatment procedures on the grain refinement and modification performance of A356 alloy are experimentally studied. For the two master alloys, the 50% reduction is sufficient to meet the demands of the efficient grain refinement and modification of A356 alloy. When Al-5Ti-B is introduced into the melt prior to degassing, the grain refinement efficiency of Al-5Ti-B will be greatly increased due to the better dispersity of TiB2 particles. Al-5Ti-B master alloy is less prone to affect the modification effect of Al-10Sr when they are used together.
关键词:
Grain refinement
,
中间合金
,
热变形
,
晶粒细化
,
A356合金
Ping LI
,
Qing ZHANG
,
Kemin XUE
材料科学技术（英）
Grain shape of the hot deforming alloy is an important index to character the microstructure and performance of material. The fractal theory was applied to analyze the recrystallized microstructure of Ti-15-3 alloy after hot deformation and solution treatment. The fractal dimensions of recrystallized grains were calculated by slit island method. The influence of processing parameters on fractal dimension and grain size was studied. It has been shown that the shapes of recrystallized grain boundaries are self-similar, and the fractal dimension varies from 1 to 2. With increasing deformation degree and strain rate or decreasing deformation temperature, the fractal dimension of grain boundaries increased and the grain size decreased. So the fractal dimension could characterize the grain shape and size. A neural network model was trained to predict the fractal dimension of recrystallized microstructure and the result is in excellent agreement with the experimental data.
关键词:
Ti-15-3 alloy
,
null
,
null
,
null
,
null
G.Y. Lin
,
Z.F. Zhang
,
H. Zhang
,
null
,
null
金属学报(英文版)
The hot deformation behaviors and microstructures of Al-Zn-Mg-Cu-Cr aluminum alloy during hot deformation have been studied using thermal stimulation test, optical microscopy and transmission electron microscopy. As a result, the true stress vs. true strain cures and the microstructures of various deformation conditions are obtained; the microstructures gradually incline to dynamic-recrystallization with the deformation temperature rising and the recrystallization grains refine with the decrease of deformation temperature or with raising the strain rates; the quantitative relationship between the Zener-Hollomon parameter (Z) and average recrystallization grain size in the subsequent heat treatment is set up.
关键词:
Al-Zn-Mg-Cu-Cr aluminum alloy
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aluminum
,
alloy
,
Hot
,
deform
