某油田在钻井完成后,发现13Cr钢防砂工具转换接头开裂导致接头不能继续再使用.通过对发生开裂失效的13Cr钢防砂工具转换接头进行宏观分析、外形尺寸测量、磁粉探伤检测、化学成分分析、金相检验、力学性能试验、电子显微镜分析以及能谱分析等,查明了其开裂原因.结果表明:13Cr钢转换接头材料冲击韧度低,硬度较高,材料表现出明显的硬脆性,接头开裂为典型的沿晶脆性开裂,接头近表面大量孔洞和夹杂物的存在导致其受到周向应力时,裂纹沿粗大的马氏体晶界快速沿晶扩展形成开裂.

After drilling an oilfield,the 13Cr steel sand control crossover joint cracked and could not continue service.The cracking reasons of the crossover joint were analyzed by means of macroscopic analysis,nondestructive inspection,chemical compositions analysis,metallographic examination,mechanical properties test and SEM analysis.The results indicate that the material of the crossover joint showed obvious brittleness with lower impact toughness and higher hardness.The cracking of the crossover joint was typical intergranular brittle cracking.There were a lot of holes and inclusions at sub-surface of the crossover joint,so when the crossover joint subjected to circumferential stress,intergranular cracks grew rapidly along the grain boundaries of coarse martensite and led to cracking failure.