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通过高温压缩试验研究齿轮钢SAE8620H在950~1100℃、应变速率0.01~10 s-1条件下的高温变形行为.该合金钢的流动应力符合稳态流变特征,流变应力随变形温度升高以及应变速率降低而减小,其本构方程可以采用双曲正弦方程来描述.基于峰值应力、应变速率和温度相关数据推导出SAE8620H高温变形激活能Q=280359.9 J·mol-1.根据变形量40%和60%下应力构建该齿轮钢的热加工图,通过热加工图中耗散值及流变失稳区确定其热变形工艺参数范围.SAE8620H钢在在变形程度较小时宜选取低的应变速率进行成形,而在变形程度大时则要选取低温低应变速率或者高温高应变速率.
The high temperature deformation test of gear steel SAE8620H at 950 ~ 1100 ℃ and strain rate of 0.01 ~ 10 s-1 was carried out by high temperature compression test.The flow stress of this alloyed steel accorded with the steady state rheological characteristics and the flow stress increased with the deformation temperature And constitutive equation can be described by the hyperbolic sine equation based on the peak stress, strain rate and temperature-related data. The activation energy of high temperature deformation of SAE8620H is Q = 280359.9 J · mol-1. According to the deformation 40% and 60% of the stress under the stress of the gear steel to build the map, through the thermal processing diagram of the dissipation value and rheological instability zone to determine the thermal deformation process parameters.SAE8620H steel should be selected in the smaller degree of deformation is low Strain rate for forming, and in a large degree of deformation will have to select the low temperature and low strain rate or high temperature and high strain rate.