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用扫描电镜和拉伸试验研究了铅浴淬火对72钢显微组织和力学性能的影响。结果表明:加热温度为990℃→960℃→930℃→900℃,铅浴淬火温度从500℃升至530℃时,72钢组织由珠光体+贝氏体+索氏体+铁素体变为索氏体+珠光体+少量铁素体,其抗拉强度和断后伸长率均呈降低趋势。当加热温度为1010℃→970℃→930℃→900℃,铅浴淬火温度从530℃升高至550℃时,组织中索氏体含量增多,抗拉强度和断后伸长率均逐渐升高,铅浴温度为540℃时,强度为1228 MPa,伸长率为7.2%,断面收缩率均值为45%,具有良好的强韧性,可作为3.0 mm钢丝热处理的定型工艺。
The effect of lead-bath quenching on the microstructure and mechanical properties of 72 steel was studied by scanning electron microscopy and tensile test. The results showed that the microstructure of 72 steel changed from pearlite + bainite + sorbite + ferrite when the heating temperature was 990 ℃ → 960 ℃ → 930 ℃ → 900 ℃ and the temperature of lead bath was increased from 500 ℃ to 530 ℃. Sorbite + pearlite + a small amount of ferrite, the tensile strength and elongation after fracture showed a downward trend. When the heating temperature is 1010 ℃ → 970 ℃ → 930 ℃ → 900 ℃, the temperature of lead bath is increased from 530 ℃ to 550 ℃, the content of sorbite increases and the tensile strength and elongation at break increase gradually . When the lead bath temperature is 540 ℃, the strength is 1228 MPa, the elongation is 7.2% and the average value of the section shrinkage is 45%. It has good toughness and can be used as the shaping process for the 3.0 mm steel wire heat treatment.