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研究了不同模拟焊后热处理(PWHT)工艺对15CrMoR钢板的组织和性能的影响。结果表明,采用正火+回火工艺和采用正火(加速冷却)+回火工艺生产的15CrMoR钢板均具有良好的强韧性匹配。在相同的模拟焊后热处理温度下,随模拟焊后热处理时间的延长,两种热处理状态下钢板的基体组织和晶粒度均未发生明显变化。钢板的强度在初期有一定程度的降低,其后趋于稳定,而延伸率和断面收缩率变化不大。采用正火+回火工艺生产的钢板,由于珠光体层片状结构的合并减少及新析出相析出的相互作用,使得其低温冲击韧性有较大程度地降低。采用正火(加速冷却)+回火工艺生产的钢板,新析出相的析出并逐步向晶界处聚集长大是导致其低温冲击韧性较大程度降低的主要原因。
The effects of different simulated PWHT processes on the microstructure and properties of 15CrMoR steel were investigated. The results show that 15CrMoR steel produced by normalizing and tempering process and normalizing (accelerated cooling) and tempering process all have good toughness matching. Under the same simulated post-weld heat treatment temperature, no significant change was observed in the microstructure and grain size of the steel under both heat treatments with the increase of the post-welding heat treatment time. The strength of the steel sheet decreased to a certain extent in the initial stage and then stabilized. However, the elongation and the reduction of the area of the sheet did not change much. The steel plate produced by normalizing and tempering process can reduce the low temperature impact toughness to a great extent due to the decrease of the combined pearlite layer structure and the precipitation of newly precipitated phase. The steel plate produced by normalizing (accelerated cooling) + tempering process is the main reason that the precipitation of newly precipitated phase and the gradual accumulation to the grain boundary are the main reasons for the low temperature impact toughness reduction.