含硅型高铬马氏体耐热钢的回火脆性研究  

Temper Embrittlement in Si-bearing High Chromium Martensitic Heat Resistant Steel

作　　者：周强国[1,2] 严伟[1] 王威[1] 单以银[1] 杨柯[1] 

机构地区：[1]中国科学院金属研究所,辽宁沈阳110016 [2]中国科学院大学,北京100049

出　　处：《原子能科学技术》2013年第B12期406-411,共6页Atomic Energy Science and Technology

基　　金：中国科学院战略先导科技专项子课题资助(XDA03010301;XDA03010302)

摘　　要：采用冲击试验、X射线衍射分析、断口和显微组织观察，研究了回火温度和冷却速度对含硅型高铬马氏体耐热钢冲击韧性的影响。研究结果表明，含硅型高铬马氏体耐热钢在400℃以下回火时组织中存在少量残余奥氏体，在450～600℃区间存在高温回火脆性，硬度达到峰值，产生沿晶和准解理混合断裂。分析认为，沿晶界生成的链状碳化D物降低晶界结合强度，以及基体组织中析出的大量细小弥散的碳化物产生二次硬化，两者是回火脆性产生的主要原因。冷却速度通过碳化物析出差异影响基体强度，进而影响钢的冲击韧性。The effects of temper temperature and cooling rate on the impact toughness of a silicon bearing high chromium martensitic heat resistant steel were studied by a series of Charpy impact test, X-ray diffraction and fracture morphology and mierostructure observations. The results show that the retained austenite exists in the mierostructure of the steel tempered below 400 ~C, the toughness of the steel decreases greatly when tempered at 450-600 ~C and the Vicker hardness reaches a maximum, where the steel exhibites a morphology of intergranular plus quasiclevage fractures. The grain boundary weakening caused by the precipitation of chain-like carbides along grain boundaries and the secondary hardening produced by fine dispersed carbides are considered to be the main causes for the temper embrittlement. The strength of the steel matrix decided by the difference in carbides precipitation due to the different cooling rates shows significant effect on the impact toughness of the steel.

关 键 词：马氏体耐热钢 冲击韧性 回火脆性 冷却速度 沿晶断裂 

分 类 号：TG142.1[一般工业技术—材料科学与工程]