调质工艺对低碳贝氏体型高强钢屈强比的影响规律研究

Study on Effect Rule of Q&T Process on Yield Ratio of Low Carbon Bainitic High Strength Steel

研究了调质工艺对低碳贝氏体型高强钢屈强比的影响。结果显示:当淬火温度进入两相区时,钢的屈强比显著降低,但强度指标也相应较低;完全奥氏体区淬火时,钢的抗拉强度和屈服强度均显著上升,且升高淬火温度虽能使屈强比有所降低,但始终处于较高的水平;在试验温度范围内,回火温度上升钢的屈服强度上升,抗拉强度连续降低,导致屈强比总体呈上升趋势,但回火温度较低时,碳化物的析出不明显,屈服强度的增加较少,故屈强比缓慢上升,升高回火温度,碳化物大量弥散析出,屈服强度显著增加,导致屈强比快速上升。

The effects of quenching and tempering on the yield ratio of high strength steel were studied. The results show that the yield ratio decreases substantially if quenched at two-phase region, but the strength is lower than the one quenched at full austenite region. Quenched at full austenite region, the strength increases greatly and the yield ratio decreases slightly with the increase of quenching temperature, but the yield ratio is always more than 0.9. Tempered at the temperature adopted in this, the yield strength increases and tensile strength reduces with the increase of tempering temperature, which results the increase of yield ratio. The microstructures show that the precipitation of carbide is not strong when tempered at lower temperature, which results the yield strength and yield ratio increase slowly. Tempering at a higher temperature, carbide precipitates strongly, so yield strength and yield ratio rise greatly.