深冷处理对45钢力学性能和尺寸稳定性的影响研究

Effects of Cryogenic Treatment on Mechanical Properties and Dimensional Stability of 45 steel

本文研究了深冷处理与传统热处理相结合对45钢力学性能、尺寸稳定性和微观组织的影响。结果表明,淬火+深冷处理+回火工艺能够提高45钢的抗拉强度和屈服强度,而对延伸率和冲击韧性影响不明显。淬火+回火+深冷处理后45钢屈服强度略有降低。通过圆环三角法能够有效评价不同工艺处理后试样的尺寸稳定性,淬火后试样残余应力较高,圆环三角试样开口角度变化最大,增加深冷处理改变了角度变化方向,且变化量也较大,高温回火显著降低了材料的残余应力,从而减小了角度变化。淬火后增加深冷处理提高了试样表面压应力,促进了残余奥氏体转变为马氏并使得马氏体基体上析出的碳化物颗粒增加。

The effects of cryogenic treatment combined with traditional heat treatment on the mechanical properties,dimensional stability and microstructure of 45 steel were studied.The results showed that the process of quenching+cryogenic treatment+tempering improved the tensile strength and yield strength of 45 steel,but had no obvious effect on the elongation and impact toughness.The process of quenching+tempering+cryogenic treatment reduced the yield strength.The dimensional stability of the samples treated by different processes was effectively evaluated by the ring triangle method.The residual stress of the samples after quenching was high,and the opening angle of the ring triangle sample changed the most.Cryogenic treatment changed the direction of the angle variation,and the amount of change was also large.High temperature tempering significantly reduced the residual stress of the material,thus reduced the angle change.The addition of cryogenic treatment after quenching improved the surface compressive stress of the sample,promoted the transformation of residual austenite into martensite,and increased the carbide particles precipitated on the martensite matrix.