摘要
使用热处理风冷炉模拟研究了大型汽轮机转子内外径处的冷却速率对转子材料30CrMoNiV511钢的组织转变及强韧性的影响。结果表明,淬火冷却速率对转子材料的强度影响不明显,而对冲击韧性的影响显著。随着淬火冷却速率从50℃/min逐渐降低至7℃/min,淬火组织由下贝氏体逐渐向上贝氏体、粒状贝氏体及其混合组织转变,冲击韧性由66 J急剧降低到16 J;当冷却速率降低到5℃/min以下时,组织中出现先共析铁素体,且上贝氏体铁素体粗大,碳化物分布极不均匀,冲击韧性极差。不同冷却速率转子钢的微观组织及碳化物析出形态和分布是决定其冲击韧性的主要原因之一。
Quenching cooling at different radius positions of large-scale steam turbine rotor were simu- lated by air-cooling heat treatment furnace. The effects of quenching cooling rate on microstructure, strength and toughness of 30CrMoNiV511 rotor steel were investigated. The results show that the cooling rate has a little influence on the strength, while the toughness evidently depends on it. As the cooling rate decrease gradually from 50 ℃/min to 7 ℃/min, and the transformed microstructure changes from low bainite to upper bainite, granular bainite and their mixture. Meanwhile, impact toughness decreases sharply from 66 J to 16 J. When the cooling rate is below 5 ℃/min, proeutectoid ferrite is formed. The sub-unit of ferrite in upper bainite is coarse with uneven distribution of carbides, which results in extreme- ly low toughness. The microstructure and carbides shape and distribution depending on the quenching cooling rate is one of the main reasons determining the impact toughness of rotor steel.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2013年第3期331-336,共6页
Chinese Journal of Materials Research
