基于蠕变损伤的P91钢应力-应变本构关系

Stress-strain constitutive relation of P91 steel based on creep damage

高温下材料的本构关系和时间相关,可以由高温等时应力-应变曲线表示。对P91钢分别进行高温(600℃)短时拉伸实验,高温蠕变100、500和900 h实验之后的高温短时拉伸实验,以及完整的蠕变断裂实验。结果表明:用高温等时应力-应变曲线描述P91钢高温蠕变损伤后的本构关系极为保守。由此,引入寿命分数参数定义材料的高温蠕变损伤,获得了P91钢发生高温蠕变损伤后材料抗拉强度与蠕变损伤的关系,修正了高温等时应力-应变曲线,建立了基于蠕变损伤的P91钢应力-应变本构方程。

The material constitutive relation at high temperature was related to time and could be indicated by isochronous stress-strain curve. Experiments on P91 steel, such as instantaneous tensile tests at 600 ℃ , high-temperature instantaneous tensile tests after 100, 500 and 900 h creep tests, and creep rupture tests, were performed respectively. The results showed that the isochronous stress-strain curve was extremely conservative to describe the material constitutive relation of P91 steel after high-temperature creep damage. By defining creep damage under high temperature based on life fraction parameter, the relation of tensile strength of P91 steel with creep damage was obtained, and the isochronous stress-strain curve at high temperature was modified, therefore, the constitutive relation equation of P91 steel with creep damage at high temperature was established.