中文摘要：

对45钢在Gleeble3500热模拟实验机上进行多道次拉伸实验,利用Lemaitre提出的弹性模量法,并结合Zener-Hollomon参数,建立损伤阈值与Z参数的关系;根据实验处理后的数据,分析变形温度、应变速率与损伤阈值之间的变化规律。结果表明,损伤阈值随着温度的升高而增大,随着应变速率的增大而减小,得到了损伤阈值与Z参数之间的关系。当应变速率较小（0.1s-1和1s-1）时,应变速率增大,断裂应变减小;当应变速率较大（5s-1）时,其应变速率与断裂应变的关系则无此变化规律。

英文摘要：

Relationship between critical damage value and Z parameter has been established based on elastic modulus method proposed by Lemaitre and the experiment data acquired from multi-step tensile test with 45 steel on Gleeble3500,According to the experiment data,variation regularity between critical damage value and process condition（deformation temperature and strain rate）had been analyzed.Results suggest that critical damage value increases with the increase of deformation temperature and decrease of strain rate.The relationship between critical damage value and Zener-Hollomon parameter has been established.When the strain rate is rather small（〈1s-1）,strain limit decreases as the strain rate increases.When the strain rate is bigger（approximately 5s-1）,there is no such variation law between strain limit and strain rate.