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两种结构钢的热变形行为及其数学模型 总被引:1,自引:0,他引:1
采用热物理模拟的方法,对35CrMo和20CrMnTi结构钢热变形过程的动态再结晶行为进行了研究,获得了应力-应变曲线,并讨论了热变形参数对该曲线的影响,得出了两种钢发生动态再结晶的临界条件,得到了两种钢的变形参数与Z参数的关系,建立了两种钢的动态再结晶动力学、晶粒尺寸的数学模型. 相似文献
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Twinning induced plasticity (TWIP) steels, which rely on high Mn contents to promote twinning as the deformation mechanism, exhibit high ultimate strengths together with outstanding combinations of ultimate strength and ductility. In terms of mechanical properties, one of the most important microstructural features is grain size. The knowledge of the kinetics of recrystallization mechanisms, i.e., dynamic recrystallization (DRX) and static recrystallization (SRX), can be used in order to control the grain size of the final product by a proper rolling schedule design. The focus of this work is the characterization of the DRX kinetics of two TWIP steels. The basic composition of the steels is Fe–21Mn–0.4C–1.5Al–1.5Si, and one of them is further alloyed with 0.12% V. With this objective, compression tests were carried out at 900, 1000, and 1100°C and strain rates ranging from 1 × 10?1 s?1 to 1 × 10?4 s?1. Furthermore, metallographic observation by optical microscopy (OM) was done to assess the evolution of grain size for the different deformation conditions. According to the results, the existence of V in the composition does not affect the hot flow behavior of the steel, although recrystallization fraction and recrystallized grain size decrease for the V‐containing steel. 相似文献
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利用Gleeble-3800热模拟试验机在温度为1 040~1 120℃,应变速率为1~20s-1的条件下进行了高N马氏体不锈轴承钢的热压缩变形试验。结合真应力-真应变曲线和热变形组织研究了变形参数对高N马氏体不锈轴承钢的热变形行为和碳氮化物演变规律的影响。结果表明:在该变形条件下,试验钢的真应力-真应变曲线为动态再结晶型。随着应变量的增大,碳化物的平均尺寸呈减小趋势,但数量有所增多。基于热变形方程计算得到的应变量为0.6时的热变形激活能Q为410.7kJ/mol。构建了包含应变量在内的流变应力方程,同时建立了高N马氏体不锈轴承钢的Zener-Hollomon参数本构方程。 相似文献
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M. D. Richards M. E. Burnett J. G. Speer D. K. Matlock 《Metallurgical and Materials Transactions A》2013,44(1):270-285
The effects of processing temperature on the deep-rolling response of three medium carbon bar steels, a quenched and tempered 4140 alloy, a 0.34C, 1.21Mn, 0.66Si nontraditional bainitic alloy, and a 0.36C, 1.37Mn V-microalloyed ferrite plus pearlite steel, was assessed through bending fatigue. The significantly different deformation behaviors of the three alloys were characterized through standard and nonstandard quasi-static and cyclic uniaxial tension and compression tests at room temperature (RT) and in situ at temperatures up to 634?K. Deep rolling, performed at RT and at elevated temperature (HT) in the dynamic strain-aging (DSA) regime, increased measured endurance limits by 51-62?pct (RT) and 96-117?pct (HT) as compared with the baseline condition. The enhanced fatigue performance by RT deep rolling primarily reflected the effects of the introduction of favorable residual stresses. The improved fatigue performance from HT deep rolling was attributed to the enhanced resistance to strain reversal of the material deformed during deep rolling, due to a change in deformation mechanism from dislocation-interstitial interactions in the DSA regime during processing, which inhibited mechanically induced relaxation of residual stress during cyclic loading. 相似文献
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Grain refinement in a plain carbon steel under intercritical warm deformation was studied by torsion testing. Based on the experimental results, the warm flow behaviour and microstructural evolution of ferrite were researched with particular emphasis on the effect of the strain rate in controlling the grain refinement mechanism of ferrite. The deformed microstructures were investigated at various strain rates using optical microscopy and electron back-scattered diffraction (EBSD). The EBSD observations indicate that an increase in the strain rate leads to the development of new fine ferrite grains with high angle boundaries. Furthermore, it shows that the annihilation of dislocations occurs more readily at lower strain rate. The elongated ferrite grains continuously dynamically recrystallize to form the equiaxed fine ferrite grains. Thereby, the aspect ratio of elongated grains decreases with increasing the strain rate. Furthermore, the peak stress and steady state stress of ferrite both increase with increasing strain rate. Based on the study, the effect of strain rate on the development of fine ferrite grains during continuous dynamic recrystallization of ferrite was analyzed in detail. 相似文献
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In this work, a hot compression test was carried out at 1173 K to 1473 K (900°C to 1200 °C), with a strain rate of 0.01 to
1 s−1 up to ~50 pct height reduction on functionally graded steel (FGS) specimens comprised of ferritic, bainitic, austenitic,
and martensitic layers (αβγMγ). The stress-strain curves are strongly dependent on temperature and strain rate. Compressive flow stress varied from 40
to 105 MPa depending on the applied temperature and strain rates. Variation in steady-state flow stress with temperature and
strain rates was studied. The strain-rate-sensitivity exponent (m) and deformation activation energy (Q) for the αβγMγ composite under studied condition were 0.106 and 354.8 KJ mol−1, respectively, which are within the values of boundary layers of ferrite (304.9 KJ mol−1) and austenite (454.8 KJ mol−1) layers. Given the alternative microstructure of the αβγMγ FGS, a range of deformation mechanisms from dynamic recovery to dynamic recrystallization maybe prevails, where the intensity
of each mechanism depends on temperature and strain rates. In accordance with the experimental results, an empirical power-law
equation was developed over the range of temperatures and strain rates investigated. The equation accurately describes temperature
and strain-rate dependence of the flow stress. 相似文献
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Isothermal Grain Growth of Austenite in Hypoeutectoid and Hypereutectoid Plain Carbon Steels 总被引:4,自引:0,他引:4
Grain growth kinetics of austenite in a hypoeutectoid steel(containing carbon of 0.35%)at 920 ℃ and in a hypereutectoid steel(containing carbon of 1%)at 980 ℃ for holding time ranging from 1 h to 6 h was investigated.The hypoeutectoid steel exhibited normal grain growth without solute drag hindrance with a time exponent(0.51)close to the theoretical value(0.5).However,the grain growth of austenite in the hypereutectoid steel held up to 3 h was extremely slow,characterizing by a low value of time exponent(0.08).Thereafter,a breakaway occurred and the grain growth in the hypereutectoid steel held from 3 h to 6 h progressed normally with a time exponent(0.52)close to the theoretical value(0.5). 相似文献
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Recrystallisation kinetics of two low‐carbon steels, of which one with Ti and the other with Al as precipitate‐forming elements was studied by means of hot torsion tests. The mean size of TiN and AlN particles that precipitate during hot deformation was analysed by transmission electron microscopy (TEM). These results, along with the determination of the activation energy, the precipitated volume fraction and the diffusion coefficients of Ti, Al and N in austenite explain the ineffectiveness of these particles to inhibit the static recrystallisation. 相似文献
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The hot deformation behaviors and the microstructural evolution of plain C-Mn steels with similar contents of C and Si but different contents of Mn have been investigated by compressive processing using Gleeble-1500 mechanical simulator.Influence of Mn and hot deformation on continuous cooling transformation of steels has been studied.The experimental results showed that deformation in austenite region accelerated transformation process,and the extent is dependent on the hot deformation and cooling conditions.The hot deformation would promote transformation process,but the increase of transformation temperature is dependent on Mn contents.The results have also shown that the effect of deformation on ferrite transformation becomes more obvious with the increase of Mn content at relatively low cooling rate. 相似文献
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低合金钢在中国的发展现状与趋势 总被引:7,自引:0,他引:7
在过去的几十年里,品种结构调整一直是中国钢铁工业的重要任务。伴随中国钢铁产量的快速增长,在高强度低合金钢(HSLA)技术领域取得了一系列研究成果,并在实际品种开发中获得了成功的应用,如细晶/超细晶粒钢技术、微合金钢的析出相控制技术等。“十二五”期间国内外装备制造业的发展为中国钢铁工业产品结构调整带来了机遇和挑战。通过使用性能更优、用量更少的HSLA钢,可大量节约钢材消耗,减轻对资源、能源、环境的压力。毫无疑问,积极推进HSLA钢的应用是实现中国钢铁工业可持续发展的必由之路。 相似文献
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An empirical martensite kinetics model is proposed that both captures the sigmodial transformation behavior for alloy steels and remains computationally efficient. The model improves on the Koistinen and Marburger model and the van Bohemen and Sietsma model with a function that better represents the transformation rate, especially during the early stages. When compared with existing models, the proposed model exhibits better predictions of volume fraction of martensite. The proposed model also predicts various other transformation properties accurately, such as M90 temperatures and retained austenite. 相似文献