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通过Gleeble-3800热模拟和热处理试验研究了热处理工艺对1.25Cr0.5Mo Si钢组织和性能的影响。结果表明:钢在950℃保温140 min后淬火水冷(冷却速率3~20℃/s),然后710℃保温245 min回火,空冷可获得回火贝氏体组织和优良的综合力学性能。钢板试样经模拟焊后热处理组织为回火贝氏体,钢板在690℃模拟焊后热处理0~32 h后,屈服强度达到400~470 MPa,抗拉强度560~600 MPa。当冲击温度低于-20℃时,冲击功急剧下降。随着模拟焊后热处理时间的延长,碳化物逐渐变粗大并沿晶界分布,导致钢板强度和低温冲击韧性大幅下降。
The effects of heat treatment on microstructure and properties of 1.25Cr0.5Mo Si steel were studied by Gleeble-3800 thermal simulation and heat treatment. The results show that the steel is tempered at 950 ℃ for 140 min and then quenched by water cooling (cooling rate 3 ~ 20 ℃ / s), and then tempered at 710 ℃ for 245 min. The tempered bainite microstructure and excellent mechanical properties are obtained by air cooling. After simulated post-weld heat treatment, the steel samples were tempered bainite. After simulated post-weld heat treatment at 690 ℃ for 0 ~ 32 h, the yield strength reached 400 ~ 470 MPa and the tensile strength was 560 ~ 600 MPa. When the impact temperature is below -20 ℃, the impact of work fell sharply. With the simulation of post-weld heat treatment time extension, carbide gradually become coarse and distributed along the grain boundary, resulting in a sharp decline in plate strength and low temperature impact toughness.