共查询到20条相似文献,搜索用时 31 毫秒
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应力与相变相互作用对马氏体淬火残余应力的影响 总被引:4,自引:0,他引:4
本文进行了有关钢在马氏体淬火过程中应力与相变相互作用的实验研究,在此基础上提出了一种预测钢的马氏体淬火残余应力的较完整的数学模型。根据实测的材料参数用有限元方法对26Cr2Ni4MoV钢圆筒形试件的淬火过程进行了计算分析,着重考察了相变塑性和应力诱导相变对残余应力形成的影响。结果表明,由本模型给出的残余应力预测值与实测值吻合较好,而不考虑相变塑性的模型实际上是不适用的,忽略应力诱导相变则倾向于在较大程度上低估淬火后的残余应力 相似文献
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A novel analytical method, which predicts the extent of the stress-induced martensitic transformation (SIM) in the crack tip vicinity of nickel–titanium (NiTi)-based shape memory alloys, as well as describing the stress distribution in both transformed and untransformed regions, is presented. The method has been validated by comparisons with results from finite-element simulations with good agreement. Furthermore, the method has been used to analyze the effects of various thermomechanical parameters on the extent of the transformation region near the crack tip. Finally, the effects of several thermomechanical loading conditions, in terms of both applied stress and temperature, on the crack tip transformation behavior have been analyzed. The results highlight a marked effect of temperature on the extent of the transformation region and, consequently, on the crack tip stress distribution. As a consequence, temperature plays a role in the fracture process of NiTi alloys. 相似文献
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自然对流条件下非稳态相变过程数值模拟 总被引:5,自引:0,他引:5
利用PHOENICS软件计算流场与温度场的功能,针对金属熔化与凝固过程的特点,依据单相统一控制方程,采用焓孔隙度方法,模拟了自然对流条件下相变的过程;并用经典的金属镓熔化过程基准实验进行了验证,良好的一致性表明,该程序能可靠地用于模拟金属相变过程的温度场、流场及确定相变前沿的位置。 相似文献
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ORIENTATIONVARIANTSELECTIONANDITSEFFECTINGFACTORSINTITANIUMSHEETZ.S.Zhu;N.P.Chen;J.L.GuandM.G.Yan(1)InstituteofAeronauticalMa... 相似文献
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Takuya Nagai Ryu Kasai Reiichi Suzuki Masahito Mochizuki Tetsuo Suga 《Welding International》2017,31(12):920-928
The residual stress behaviours in fillet welded lap joints of sheet metal have been researched in a systematic testing procedure with varied steel types, steel thicknesses and welding wires having different transformation points. Consequently, under the simulated fabrication welding conditions (with a constant amount of deposited metal), the transverse residual stress at the weld toe, which is deemed critical in fatigue strength, has been found almost invariable to a change in steel type and thickness, but it has been clarified to become compressive to a greater extent as the wire’s transformation point is lower. Moreover, as for the residual stress inside the weld metal, the compressive residual stress area has been found to expand as the welding wire’s transformation point reduces, from the results of the thermo-elastic-plastic analysis. 相似文献
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S. Serajzadeh S. M. H. Mirbagheri A. Karimi Taheri S. M. Zebarjad 《International Journal of Machine Tools and Manufacture》2004,44(14):1537-1545
A mathematical model has been proposed for evaluation of velocity and temperature fields in hot forging operations for axisymmetric parts. The model can be applied to determine forging load, strain rate, strain and temperature distributions. In addition, the effects of temperature and strain rate on metal flow have been considered through simultaneous modelling of dynamic phase transformation within the deforming metal. Hot forging experiments have been carried out under different working conditions and the results have been compared with the predictions. A good agreement between the simulated and experimental results was found. 相似文献
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1.IntroductionCementiteprecipitatesiniron-carbonalloyduringtempering,andtwoorientationrelationships(ORs)betweenitandferritehavebeenfound:BagaryatskiiORandIsaichevOR.Althoughtheirangulardifferenceisverysmall,muchattentionispaidtothembecausetheyinvolve... 相似文献
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低碳钢低温变形γ→α相变行为的预测模型 总被引:1,自引:0,他引:1
从变形使孕育期缩短的角度,讨论了形变诱导相变的发生条件,计算了不同变形条件下几种成分的低碳钢变形过程析出铁素体的开始温度Ar3d,发现同样变形条件下,碳含量越低的钢种,其Ar3d越高;同一成分钢种,随着变形量增加或变形速率减小,Ar3d提高,基于相变动力学理论,在形核速率计算中充分考虑变形和过冷的双重作用,探索了低温变形诱导铁素体相变的动力学模型,用该模型进行的计算机模拟结果和实验结果吻合良好,表明这种理论处理方法可用来模拟这种相变过程。 相似文献
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借助于X射线衍射,研究了C、Mn、Cr和Ni 含量对304奥氏体不锈钢拉伸力学性能和应变诱发 马氏体相变倾向的影响。结果表明:C、Mn、Cr和Ni在允许的成分范围内变化,应变诱发α′马氏体相变倾向差异很大,这导致屈服强度和抗拉强度复杂的变化,尽管应变诱发α′马氏体相变使加工硬化速率提高,相变可以诱发塑性,但相变速率较快,相变倾向较大的钢塑性反而下降,此外,由于室温变形还增大热诱发马氏体相变倾向,从而限制了C、Mn、Cr和Ni下限钢在高精度和低温环境下构件的应用。 相似文献
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邓克 《锻压装备与制造技术》2007,42(3):43-44
为解决故障率高、控制精度低的缺点,利用插装阀和PLC技术对锻造自动线机械手液压系统进行了改造,设计了插装阀式液压系统,分析了系统工作原理和改造的技术、经济可行性,取得良好的使用效果. 相似文献