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通过控制热处理参数在G55SiMoV钢中获得了不同贝氏体含量的马氏体/贝氏体复相组织,研究了贝氏体含量对其韧性和回火脆性的影响。结果表明:随等温时间延长贝氏体含量增加,等温淬火5 min、15 min、30 min、60 min可分别获得17%、27%、29%、31%的贝氏体。当贝氏体量较多(大于27%)时,马氏体对贝氏体的应变强化效果降低,韧性提高更加显著。300℃以下回火时组织和硬度基本不变;300℃回火时存在回火脆性,该马氏体/贝氏体复合组织钢的回火脆性温度区间几乎不受贝氏体量的影响,但增加贝氏体量可以提高残留奥氏体稳定性,使韧性降幅减小。
The martensite / bainite complex with different bainite content was obtained by controlling the heat treatment parameters in G55SiMoV steel. The effect of bainite content on the toughness and temper brittleness was studied. The results show that the bainite content increases by 17%, 27%, 29% and 31% after isothermal quenching for 5 min, 15 min, 30 min and 60 min, respectively. When the amount of bainite is more (greater than 27%), martensite strain hardening effect of bainite decreases, the toughness increased more pronounced. The microstructure and hardness of the martensite / bainitic composite microstructure are almost not affected by the amount of bainite when tempered at 300 ℃, but the temper brittleness exists at 300 ℃. However, increasing the amount of bainite can improve the stability of retained austenite, the decrease of toughness decreased.