4用持久强度公式计算剩余寿命不可靠性的原因如前所述，采用持久强度式（3）～（6）计算高温部件的剩余寿命时，首先必须确定和持久强度值。目前，国内确定这些持久强度值系由几千小时的持久强度曲线外推所得，现国外许多实验已证明，用直线外推10万或20万h的持久强度值与试验 4 Reasons for Calculating the Unreliability of Remaining Life with the Long-Lasting Strength Formula As mentioned above, when using the long-lasting strength formulas (3) to (6) to calculate the remaining life of a high-temperature part, it is first necessary to determine and maintain the long-lasting strength value. At present, these long-term strength values ​​are determined by the extrapolation of long-term strength curves over thousands of hours. Many experiments in foreign countries have proved that using the linear extrapolation of long-term strength values ​​of 100,000 or 200,000 h to test