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65 Si2MnWA钢860℃加热、290℃等温30分油冷得到以下贝氏体和低温上贝氏体(BⅡ)为主的复合組織。贝氏体铁素体有呈多向分布、也有县平行排列,贝氏体铁素体条内ε碳化物成一定方向析出,在贝氏体铁素体条内和条间有殘余奥氏体。经低温(230℃)回火,有较高強度和高的塑、韧性,尤其是冲击值为常规热处理工艺的三倍。随着回火溫度升高,強度降低、塑性δ_5升高,但ψ_K和a_K值降低。在～450℃回火时,韧性大大降低,出现贝氏体回火脆,这是与殘余奥氏体完全分解、碳化物类型转变及贝氏体铁素体条间和条内存在硬脆的θ相有关。对于形状复杂、要求韧性较高的弹性零件,宜采用下贝氏体等温淬火和低温回火,回火温度不能超过等温淬火的温度。
65Si2MnWA steel 860 ℃ heating, 290 ℃ isothermal 30 minutes oil cooling to obtain the following bainite and low temperature bainite (B Ⅱ) based composite structure. Bainitic ferrite has a multi-directional distribution, there are also counties arranged in parallel, bainite ferrite strip ε carbide precipitation in a certain direction, within the bainitic ferrite strip and residual austenite body. After low temperature (230 ℃) tempering, high strength and high plasticity, toughness, especially the impact value of the conventional heat treatment process three times. As the tempering temperature increases, the strength decreases, the plasticity δ_5 increases, but the values of ψ_K and a_K decrease. Tectonics at ~ 450 ℃ tempering, greatly reduced toughness, there bainite temper brittleness, which is completely decomposed with residual austenite, carbide type transition and bainitic ferrite bars and the existence of hard and brittle Theta phase related. For the complex shape, higher toughness of the elastic parts, lower bainite should be used isothermal quenching and tempering, tempering temperature can not exceed the temperature quenching.