二次回火对23MnNiCrMo54钢矿用接链环疲劳循环次数的影响

Influence of second tempering on fatigue cycle number of mining link made of 23MnNiCrMo54 steel

因设备技术改造更换了矿用接链环的淬火介质,23MnNiCrMo54钢矿用接链环按原工艺淬火、回火后的疲劳寿命达不到图纸标准技术要求。通过二次回火试验发现,矿用接链环疲劳循环次数明显提高,达到了图纸标准技术要求。对经二次回火提高矿用接链环零件疲劳寿命的现象进行了验证确认,对不同回火状态下矿用接链环的显微组织、夹杂物进行了观察分析,未发现异常。在使用扫描电镜对回火试样的碳化物分布、合金元素分布和碳化物形态进行观察发现,分别经420℃一次回火和380℃+420℃二次回火后钢中碳化物具有不同的形态结构。一次回火后的碳化物边界较清晰,碳化物数量少,而经二次回火后碳化物的边界较模糊,碳化物数量多,二次回火状态下的碳化物形态对应有较高的疲劳寿命。

Due to technical transformation of the equipment,the quenching medium of the the 23MnNiCrMo54 steel mining link was replaced,and the fatigue life of the mining link after quenching and tempering according to the original process could not meet the technical requirements of the drawing standards.Through adding a second second tempering after the first,it is found that the fatigue cycle number of the mining link significantly increases and reaches the technical requirements of the drawing standard.The phenomenon that second tempering improves the fatigue life of the mining link parts is verified and confirmed,and no abnormality is found in observation of microstructure and inclusions of the mining link under different tempering conditions.When using the scanning electron microscope to observe and analyze the carbide distribution,alloy element distribution and carbide morphology of the tempered specimen,the results show that the carbides after the the first tempering at 420℃and double tempering at 380℃+420℃have different morphologies and structures.The carbide boundary after the first tempering is clear,and the number of carbides is small.The carbide boundary after the second tempering is fuzzy,and the amount of carbides is large.The carbide morphology under the second tempering state corresponds to a higher fatigue life.