亚温淬火对低合金耐磨钢增韧及性能的影响

Effect of intercritical quenching on toughening and properties of low alloy wear-resistant steel

采用亚温淬火对NM500级耐磨钢进行增韧处理。结果表明,试验钢经790℃亚温淬火和170℃回火后,其组织中含体积分数7.3%的铁素体,冲击吸收能量由完全淬火的40 J提高到58 J,磨损性能最好;完全奥氏体化冷却到Ac3以下再进行亚温淬火,因铁素体分布使冲击吸收能量提升不明显,磨损性能降低。亚温淬火使马氏体中碳含量增加,组织中少量针状铁素体不仅能明显提高韧性,耐磨性也较完全淬火优良。

NM500 wear-resistant steel was toughed by intercritical quenching. The results show that after intercritical quenching at 790 ℃ and tempering at 170 ℃, the microstructure of the tested steel contains 7.3% volume fraction of ferrite, and the impact absorbed energy is increased from 40 J after complete quenching to 58 J, with the best wear resistance. Complete austenitization cooling to below Ac_3 followed by intercritical quenching reduces wear properties of the steel due to the distribution of ferrite, while impact absorbed energy does not change a lot. Intercritical quenching increases the carbon content of martensite, a small amount of needle-like ferrite in the structure can improve the toughness of the steel, and wear resistance is better than that of the complete quenched.