基于物理参数和响应面法的S280超高强度不锈钢本构模型

Constitutive model of S280 ultra-high strength stainless steel based on physical parameters and response surface method

采用Thermecmaster-Z型热模拟试验机在变形温度为800~1000℃、应变速率为0.001~10 s-1条件下对S280超高强度不锈钢进行了等温恒应变速率压缩实验,分析了S280超高强度不锈钢的热变形行为,计算了热变形激活能。考虑变形温度对自扩散系数和杨氏模量的影响,建立了S280超高强度不锈钢基于应变补偿的物理本构模型。以变形温度、应变速率和应变为输入变量,流动应力为响应目标,建立了S280超高强度不锈钢的响应面本构模型。结果表明,S280超高强度不锈钢为正应变速率负温度敏感型材料,其流动应力随应变速率的增加和变形温度的降低而增大。热变形激活能对变形条件敏感,其随变形温度、应变速率和应变的增加而减小。基于应变补偿的物理本构模型具有一定的物理意义和良好的预测精度,其相关系数R和平均相对误差eAARE分别为0.971和7.8%。响应面本构模型的响应曲面和等高线图能反映变形条件之间的相互作用对流动应力的影响。建立的两个本构模型都能够用于表征S280超高强度不锈钢在热变形过程中的流动应力行为。

The isothermal compression experiments with constant strain rate of S280 ultra-high strength stainless steel were carried out by Thermecmaster-Z thermal simulator under the conditions of deformation temperature of 800-1000℃and strain rate of 0.001-10 s-1.The hot deformation behaviors of S280 ultra-high strength stainless steel were analyzed,and the hot deformation activation energy was calculat-ed.Considering the influence of deformation temperature on self-diffusion coefficient and Young′s modulus,the physical constitutive mod-el of S280 ultra-high strength stainless steel based on strain compensation was established.Taking the deformation temperature,strain rate and strain as input variables and flow stress as response target,the response surface constitutive model of S280 ultra-high strength stainless steel was established.The results show that the S280 ultra-high strength stainless steel is a positive strain rate and negative temperature sensitive material,and its flow stress increases with the increase of strain rate and the decrease of deformation temperature.The hot de-formation activation energy is sensitive to the deformation conditions,and it decreases with the increase of deformation temperature,strain rate and strain.The physical constitutive model based on strain compensation has certain physical significance and good prediction accura-cy,and its correlation coefficient R and average relative error eAARE are 0.971 and 7.8%,respectively.The response surface and contour map of response surface constitutive model can reflect the influence of the interaction between deformation conditions on flow stress.Both the established constitutive models can be used to characterize the flow stress behaviors of S280 ultra-high strength stainless steel during hot deformation.