回火温度对耐热钢组织和性能的影响

通过光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、布氏硬度计和拉伸试验研究了一种硼含量为0.01%的耐热钢经200~650 ℃回火后的碳化物形态和分布情况,以及其对力学性能的影响。结果表明:随回火温度的升高,碳化物的平均尺寸逐渐增加,形态由低温回火时的针状逐渐转变为高温回火时的块状;耐热钢的硬度、抗拉强度和屈服强度随回火温度的升高呈现先增加后下降的趋势,伸长率由6%提高到12%;随回火温度的升高,耐热钢由脆性断裂转变为韧性断裂,断口形貌由河流花样转变为韧窝。

Effect of tempering temperature on microstructure and properties of heat-resistant steel

Morphology and distribution of carbides in a heat-resistant steel with 0.01%boron after tempering at 200-650 ℃ and their effect on mechanical properties were studied by means of optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), Brinell hardness test and tensile test. The results show that as the tempering temperature increases, the average size of carbides gradually increases, and its shape gradually changes from flake at low tempering temperature to block at high tempering temperature. The hardness, tensile strength and yield strength of the heat-resistant steel increase first and then decrease with the increases of tempering temperature, and the elongation increases from 6% to 12%. With the increases of tempering temperature, the tensile fracture of the heat-resistant steel changes from brittle fracture to ductile fracture, and its morphology changes from river pattern to dimples.