【摘要】 12%Cr耐热钢的脆化一直是材料研究的热点问题,借助于力学性能测试、金相分析、断口扫描分析以及TEM微观结构分析,研究了1Cr12Ni3Mo2VN(M152)耐热钢在淬火、回火以及时效过程中产生的脆性,结果表明:淬火时的冷却速度对冲击韧性有显著的影响,冷却速度过慢将导致不可逆脆性,其脆化机制是由于缓冷时M23C6碳化物沿原奥氏体晶界连续析出,以及回火时残余奥氏体发生分解导致M2C碳化物沿奥氏体薄膜连续析出,杂质元素的原奥氏体晶界偏聚不是产生脆化的原因,导致不可逆脆化的淬火缓冷通过的温度区间为820℃～660℃;与回火温度有关的脆性有二类:450℃～500℃回火产生的(475脆性),脆化严重,其脆化机制是杂质元素的原奥氏体晶界偏聚和脆性相的析出,去脆化处理可以恢复其韧性;另一类是在约625℃回火产生的,脆化程度较轻;高温回火后缓冷引起的脆化很复杂,杂质元素的晶界偏聚、粗碳化物的析出以及二次淬火均导致回火脆性,通过去脆化处理均可以恢复其韧性。杂质元素的晶界偏聚是脆化的主导机制,二次淬火引起的脆化受环境影响非常大,引起的脆化也非常严重,是产品质量不稳定的主要原因。595℃长期时效脆化主要是由碳化物的析出以及杂质元素的非平衡晶界偏聚引起的,临界时间约为100h,通过去脆化处理可以恢复其部分韧性。更多还原

【Abstract】 The brittleness of steel 12%Cr has always been a hot issue in material research work. In this paper, the brittleness of steel 1Cr12Ni3Mo2VN(M152)in the process of quenching, tempering and aging was researched by means of mechanical property test, metallographic analysis, fracture scanning analysis and TEM. The results showed that the cooling speed during quenching had a remarkable effect on the impact toughness, excessive low cooling speed resulted in irreversible brittleness. The brittleness was caused by continuous precipitation of MC carbides along prior austenite grains boundary and that of MC carbides along prior austenite films resulted from decomposition of the retained austenite. The segregation of impurity elements at prior austenite grain boundary was not the reason for brittleness and the temperature range of quenching and slow cooling resulting irreversible brittleness was 820-660℃; brittleness related to tempering temperature was divided into the following two types: the first type of brittleness was caused by tempering at 450-550℃, this brittleness was serious and caused by segregation of impurity elements at prior austenite boundary and the precipitation of the brittle phases. This kind of brittleness could be eliminated to recover its toughness; the second type of brittleness was caused by tempering at 625℃ and was not serious; the brittleness caused by cooling after tempering at elevated temperature was complicated, segregation of impurity elements at grain boundary, precipitation of coarse carbide and secondary quenching could result in tempering brittleness, which could also be eliminated for recovering its toughness. impurity elements at prior austenite boundary was the main reason for brittleness. Atmosphere had a great influence on brittleness caused by secondary quenching, this kind of brittleness was very serious and was the main reason for unstable product quality. Long-term aging brittleness at 595℃ was mainly caused by the precipitation of carbides and unbalanced segregation of impurity elements at grain boundary, the critical time was 100h, and the toughness could be partly recovered after eliminating the brittleness.更多还原