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在变形温度800~1200℃和应变速率0.01~50s-1下,利用Gleeble-3800热模拟试验机对Aermet100钢的高温变形本构关系与微观组织演变进行了研究。结果表明,增加应变速率和降低变形温度都能提高材料的流动应力,延迟动态再结晶发生,使变形材料表现出加工硬化和动态回复。运用位错理论研究了微观组织和流动应力曲线的变化规律并做出了合理的解释。在压缩实验的变形条件下变形激活能为489.10kJ/mol。确定了峰值应力、变形温度和应变速率之间的双曲正弦模型的本构关系。 相似文献
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通过热压缩试验,研究了SiC颗粒增强铝基复合材料在应变速率为0.001~1s-1,变形温度为713~773K的热成形性能。结果表明:所研究复合材料的真应力随变形温度的升高、应变速率的降低而降低,同时采用Zener-Hollomon参数对其热变形方程进行了研究,建立了铝基复合材料的热变形方程,并综合考虑应变速率与温度的影响,采用动态材料模型建立了所研究复合材料的热加工图,同时根据Malas’s稳定性准则确定了其非稳定变形区的范围。 相似文献
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剧烈塑性变形制备超细晶金属材料是当前的研究热点。基于机制和微观组织变化综述了剧烈塑性变形制备块状超细晶材料的一些方法,特别是给出了两种新型成形技术-等截面椭圆变通道扭挤和等截面椭圆转变通道扭拉,此外还阐述了剧烈塑性变形存在的问题及未来的研究方向。 相似文献
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The macro-plasticity power function constitutive model (MPFCM), the modified macro- plasticity power function constitutive model (MMPFCM) and the micro-plasticity constitutive model (MCM) taking the material intrinsic length were established to characterize the microindentation size effects of pure aluminum, respectively. The experimental results indicated MPFCM only determined precisely in the great indentation load. While a modified one named MMPFCM was subsequently established taking account of the parameters variation with the increase of indentation depth. The conventional dimensional analysis method was employed to determine the strength coefficient K and the strain hardening exponent n of this modified model. And then MCM taking account of size effects was proposed based on the Taylor dislocation model. The first- order steepest gradient descent method was adopted to obtain the material intrinsic length for the geometrically necessary dislocations. The parameters of MCM were identified by using the UMAT subroutine of ABAQUS software. The average absolute relative error of MCM is relatively lower than that of the macro-one. Although the precision of the modified one is also high, the applied scope is limited, only for the microindentation material. In addition, the intrinsic length 5.09 bun of pure aluminum is also obtained based on the strain gradient theory. 相似文献