基于Larson-Miller参数的蠕变持久强度数学模型

MATHEMATICAL MODEL FOR CREEP-RUPTURE STRENGTH BASED ON LARSON-MILLER PARAMETER

根据持久强度的状态函数属性和Larson Miller参数的一般表达式 ,通过微分和积分运算得到高温材料持久强度的数学模型 ,即持久强度与瞬时抗拉强度之间的关系式。运用该式从理论上证明高温持久应力与持久断裂时间的半对数关系 ,并将高温材料长时持久强度预测问题转换为更高温度下瞬时抗拉强度的测量和计算。对Mod .9Cr 1Mo耐热钢 5 0 0℃～ 5 5 0℃下 10 5小时持久强度的预测结果表明 ,该方法与实际测量结果一致。

Though the differentiating and integrating process a mathematical model for creep-rupture was derived based on the attribute of state function and the general formula of Larson-Miller parameter, which correlates the creep-rupture strength with the short time tensile strength of materials at elevated temperature. Using the established model, the linear relationships between the creep-rupture stresses and the times to rupture in logarithm was proved theoretically, and reduced a long-term creep-rupture procedure of materials at elevated temperature to the measure and calculation of a short time tensile experiments at higher temperatures. Moreover, the 10 5 hours creep-rupture strength of steel Mod.9Cr-1Mo at 500℃～550℃ were calculated by this method. The predicting results show that it is consistent with actually tested values.