针对电厂再热器开裂的薄壁不锈钢小径管割管取样进行了失效分析，发现其材料为10Cr18Ni9NbCu3BN，焊缝焊材为YT-304H，渗透分析发现开裂处为母材侧热影响区，显微组织分析发现焊缝熔合区存在晶间腐蚀；制定了相控阵检测方案，制作了相控阵检测对比试块，对现场割管取样的56个试样进行相控阵检测，共发现6个试样有缺陷，对有缺陷管子进行渗透检测发现缺陷全部为裂纹，对相控阵未发现缺陷的管子进行渗透检测则未发现有裂纹缺陷。试验结果表明，相控阵检测的结果与渗透检测结果是相符的。

The failure analysis of thin-walled stainless steel small diameter tube was carried out on the sample tube cut from the cracked reheater tube of a power plant. Material analysis showed that the material mark of reheater tube is 10Cr18Ni9NbCu3BN and weld material is YT-304H. Penetration testing found that cracks were produced and expanded on heat affected zone close to one side of the parent metal. Microstructure analysis found that there existed intergranular corrosion in the weld fusion zone. To prevent tube-burst accident happening again in the short term,the test scheme by phased array ultrasonic testing and the reference blocks for the test of reheater tube were performed. Six defective tubes were found within the scope of 56 samples cut from the power plant. All cracks of the defective pipes were verified by penetration testing,and there was no trace of the crack being found among the rest of the tubes by penetration testing method. The results tested by phased array ultrasonic testing and penetration testing were validated with each other.