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采用金相观察、硬度测试、冲击和拉伸试验,研究了Q235钢60℃控时水浴淬火并低温回火对强韧化的影响。结果表明,完全淬火、180~300℃回火比控时水浴淬火、同样条件回火的硬度及强度高,这归因于完全淬火过程中马氏体的自回火程度低及残留奥氏体量少。但进行控时水浴淬火、300℃回火则强度升高,增大的强度与水浴淬火增加的残留奥氏体及其转变有关。与完全淬火、回火相比,水浴亚温淬火、回火的冲击性能较高,这主要是未溶铁素体及水浴淬火时增加的残留奥氏体对韧性的贡献。而水浴完全淬火、300℃回火则表现出更好的韧性。对于Q235钢,采用890℃加热、60℃水浴13 s控时淬火并300℃回火,能够获得良好的强韧化效果。
The metallographic observation, hardness test, impact test and tensile test were carried out to study the effect of quenching and low temperature tempering on the toughening of Q235 steel at 60 ℃. The results show that the complete quenching, 180 ~ 300 ℃ tempering water bath quenching than control, the same conditions tempering hardness and high strength, due to the complete quenching martensite low degree of self-tempering and retained austenite Less amount. However, when controlled water bath quenching, 300 ℃ tempering the strength increases, the increased strength and water quenching the residual austenite and its transformation. Compared with the complete quenching and tempering, the impact performance of the tempering bath in the water bath is higher than that in the quenching and tempering. This is mainly due to the contribution of retained austenite to the toughness in the undrifer ferrite and water bath quenching. The complete quenching water bath, 300 ℃ temper is shown to be a better toughness. For Q235 steel, the use of 890 ℃ heating, 60 ℃ water bath 13 s control quenching and tempering at 300 ℃, can get a good toughening effect.