大块含铌MC碳化物对LF2合金高温性能的影响

摘要

对700℃长时时效态LF2合金在700℃进行高温拉伸试验,并对固溶时效态LF2合金在725℃进行拉伸持久试验,主要分析了含铌MC碳化物对其断裂机理的影响。结果表明：在高温拉伸状态下,裂纹在大块含铌MC碳化物周围萌生,然后扩展,最终断裂;高温持久状态时,裂纹起源于大块一次含铌MC碳化物周围,然后沿晶扩展直至断裂,表现为沿晶断裂特征;大块含铌MC碳化物是影响LF2合金高温性能的最主要因素。%The high-temperature tensile test of LF2 alloy at 700 ℃ after long-time aging at 700 ℃ and the tensile creep test of LF2 alloy at 725 ℃ after solid solution and aging were carried out,and the effect of MC carbide with niobium on fracture mechanism of LF2 alloy was mainly analyzed.The results show that cracks initiated around massive carbide with niobium at high-temperature tensile state,and then propagated and fractured at last.Cracks initiated around massive carbide with niobium at high-temperature creep state,and then propagated along grain boundaries until fractured,and it exhibited the characteristic of intergranular fracture.Massive carbide with niobium was the main factor of affecting high-temperature properties of LF2 alloy.