40CrNiMo鋼主軸斷裂原因分析

40CrNiMo鋼主軸斷裂原因分析Analysis on Fracture Reasons of the Main Shaft of 40CrNiMo Steel

40CrNiMo鋼主軸在使用過程中發(fā)生斷裂。采用宏觀觀察、化學(xué)成分分析、硬度測試及顯微組織分析等方法，分析了該40CrNiMo鋼主軸斷裂的原因。結(jié)果表明：主軸的倒角曲率半徑偏小且材料中存在氮化物，使應(yīng)力集中程度嚴(yán)重，導(dǎo)致裂紋源產(chǎn)生；粗大的晶粒降低了主軸的解理斷裂強(qiáng)度，使疲勞擴(kuò)展速率加大，最終導(dǎo)致主軸發(fā)生早期疲勞斷裂。最后根據(jù)主軸失效原因提出了改進(jìn)措施。

A main shaft of 40CrNiMo steel fractured during use. The fracture reasons of the main shaft of 40CrNiMo steel were analyzed by means of macroscopic observation, chemical composition analysis, hardness testing, and microstructure analysis. The results show that:the chamfer curvature radius of the main shaft was relatively small, and the nitrides existed in the material, which made the stress concentration more severe and caused the generation of the crack source; coarse grains decreased the cleavage fracture strength of the main shaft and increased the fatigue spreading rate, and finally the early fatigue fracture occurred to the main shaft. In the end, the improvement measures were put forward according to failure reasons of the main shaft.

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