【摘要】 研究了不同工艺热处理后对440C钢轴向尺寸的变化规律,分析了尺寸变化机理,并提出了轴向尺寸变化率最小的热处理工艺参数。试验结果表明,退火和回火后试样轴向尺寸收缩,且随着退火和回火温度的升高,轴向尺寸的收缩量增大。淬火和冷处理后试样轴向尺寸增大,随着淬火温度的升高和冷处理前存放时间的延长,轴向尺寸伸长量减小。轴向尺寸伸长是马氏体相变引起的组织应力大于热应力所致;而热应力单独作用时导致轴向尺寸减小。推荐热处理工艺为163℃×2h去应力退火+850℃×1.5h退火+1050℃×15min淬火+16h后-75℃×2h冷处理+190℃×2h回火。更多还原

【Abstract】 The change of axial length of 440C steel tube after different heat treatment was studied,the distortion mechanism was analyzed and the optimum heat treatment parameters for getting the minimum change rate of axial length was proposed based on experiments.The results show that the axial length of 440C steel tube specimen decreases after annealing and tempering,and the higher the annealing and tempering temperature,the larger the contraction of axial length of the specimens.The axial length of the specimens increases after quenching and deep-cold treatment,and the higher the quenching temperature and the longer the remaining time before deep-cold treatment,the smaller the elongation of axial length of the specimens.The stress induced by martensite transformation is higher than the thermal stress and brings on the elongation of axial length of the specimens,and the thermal stress results the contraction axial length of specimens.The optimum heat treatment of the specimen for minimum distortion is recommended based on experiments.更多还原