某600 MW亚临界机组2Cr13钢螺栓的断裂失效分析

通过对一起2Cr13钢循环水泵地脚螺栓失效断裂事件进行失效分析,开展了包括化学成分、力学性能、微观组织等方面的系统分析,对螺栓断裂原因进行了研究。结果表明:该批次螺栓C含量较低,室温抗拉强度、规定塑性延伸强度、硬度、冲击性能均低于标准要求,结合断口分析表明材料脆性较大。同时,显微组织分析表明该2Cr13耐热钢热处理工艺为退火处理,退火处理状态的2Cr13耐热钢综合性能均明显低于调质处理后材料综合性能,故该批次螺栓热处理工艺不当导致螺栓微观组织和性能不符合相关要求是引起螺栓运行时疲劳断裂的主要原因。

Fracture failure analysis of 2 Cr13 steel bolt in a 600 MW subcritical unit

Fracture causes of ground bolts made of 2Cr13 steel for circulating water pump, were studied by the systematic failure analyzing including chemical composition, mechanical properties, microstructure and so on. The results indicate that not only the C content of the batch bolts is lower, but also the tensile strength, yield strength, hardness and impact property at room temperature are lower than the standard requirements. The fracture analysis shows that the material is very brittle. At the same time, the microstructure analysis shows that the heat treatment process of the 2Cr13 heat-resistant steel is as-annealed, and the comprehensive properties of the as-annealed 2Cr13 heat-resistant steel are obviously lower than those of the quenched and tempered steel. Therefore, the main cause of the bolt fatigue fracture is that the microstructure and properties do not meet the relevant requirements due to the improper heat treatment.