SUPER304/T92异种钢焊接件热老化的涡流检测

The eddy current test of thermal aging of SUPER304/T92 dissimilar steel welded parts

异种钢焊接接头是超(超)临界发电机组管道的薄弱环节,在高温高压作用下易出现力学性能退化甚至失效现象。涡流检测是金属材料检测的一种重要方法,采用涡流法对SUPER304/T92异种钢焊接件的热老化进行检测。首先,研制涡流传感器并搭建了涡流扫查试验平台;其次,开展涡流扫频试验,分析不同激励频率对焊接试件涡流检测能力的影响,优选三种励磁频率下的涡流检测信号,并结合试件的金相显微组织进行分析;最后,研究SUPER304、焊缝和T92三种不同区域的涡流信号随热老化时间的变化关系,并与试件表面硬度进行相关性分析。试验结果为异种钢焊接件的热老化评估提供了一种有效的无损检测方法。

The dissimilar steel welded joint in the ultra-critical generator set pipeline is considered as a weak link,susceptible to mechanical property degradation or even failure under high temperature and pressure conditions.Eddy current testing(ECT)is an important method for evaluating metal material properties.In this study,ECT was employed to detect thermal aging in SUPER304/T92 dissimilar steel welded parts.Firstly,an eddy current sensor was developed and an experimental platform for eddy current scanning was constructed.Secondly,a frequency sweep experiment was conducted to analyze the influence of different excitation frequencies on the eddy current detection capability of the welded specimens.Eddy current detection signals were selected from three excitation frequencies and analyzed in conjunction with the metallographic microstructure of the specimens.Finally,the relationship between eddy current signals in three different areas(SUPER304,weld and T92)and thermal aging time was explored while correlating it with surface hardness measurements of the specimen.The research results provided an effective nondestructive testing method for evaluating thermal aging in dissimilar steel welds.