反射式非线性超声评估P91钢蠕变状态的试验探究

Experimental study on creep performance evaluation of P91 steel by reflective nonlinear ultrasonic measurement

超声非线性参量作为一种表征金属材料蠕变状态的参数,通常采用透射法进行检测时需要发射换能器和接收换能器分置于工件两侧,很难用于在役大型工件蠕变状态检测。针对透射法存在的问题设计了反射式非线性超声检测试验系统(只需一个超声换能器),通过分析一次底波的反射信号获得材料蠕变状态的信息。对带有焊缝的P91钢试块且蠕变时间分别为0 h、120 h、250 h,进行非线性超声检测。实验结果表明,对于蠕变时间120 h和250 h的试块母材区,二次谐波非线性参量相对无蠕变时增加量为2.9%、17.4%,试块焊缝区相对增加量为2%,23.6%,试块热影响区相对增加量为5.6%、34%。

As a parameter to characterize the creep state of metal materials,it usually requires the emission ultrasonic probe and the receiving probe to be in coaxial position in penetration detecting.It is difficult to align the position of the emission probe and the receiving probe accurately when the penetration method is used for detecting and acquisition.A set of reflective nonlinear ultrasonic experiment system is designed to solve the problem.The detection information is extracted by analyzing the reflection signal of a bottom wave.The creep properties of P91 specimen with weld structure and creep time of 0 h,120 h and 250 h were detected by the experiment system.The results show that the ultrasonic second harmonic nonlinear parameters after the 120 h and 250 h creep time of the P91 steel test block,the relative change of the base metal area is 2.9%,17.4%,the weld zone is 2%,23.6%,the heat zone is 5.6%,34%.