摘要
通过化学成分分析、断口分析、金相分析、电子显微分析和能谱分析,确定了某300 MW汽轮机1号高压主汽阀阀杆断裂的原因,为错用了25Cr2MoVCu钢,而非设计的2Cr12N iMoWV钢所致。过高的淬火温度造成组织粗大,晶粒度达到4级,且存在富铜相、带状组织和大量夹杂物,使钢产生较大脆性。在淬火过程中,组织应力和热应力使弹簧内孔根部产生应力集中,致使形成淬火裂纹,阀杆启闭产生的应力使裂纹扩展,最终引起阀杆断裂。
The fracture reason of No.1 high pressure main steam valve stem of a 300 MW steam turbine was determined by chemical composition analysis,metallographic analysis,fracture analysis,electron microscopic analysis and energy spectrum analysis.The results show that the fracture is caused by the misuse of the 25Cr2MoVCu steel,rather than the designed 2Cr12NiMoWV steel.Because quenched at overheating temperature,the microstructure is coarse and the grain sizes reach 4 grade.Also there are a rich copper phase,banded structure and a large number of inclusion,these cause the steel brittle further.In the quenching process,the transformation stresses and thermal stresses concentrating on the root of spring inner hole cause the quenching crack,and the stress caused by opening and closing of the valve stem results in crack propagation,and lead the stem fracture eventually.
出处
《金属热处理》
CAS
CSCD
北大核心
2011年第8期21-24,共4页
Heat Treatment of Metals
关键词
汽轮机
阀杆
断裂
错用钢材
steam turbine
valve stem
fracture
misuse steel
