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 采用扫描电镜、低倍检验、金相检验、力学试验和化学分析等方法，分析了人字齿轮轴发生劈裂的原因。结果表明，齿轮轴劈裂是由心部的氢逐渐聚集形成白点，以白点为断裂源向外对称扩展致断的；用不同条件测得的断面收缩率和延伸率评价了齿轮轴的氢脆效应；较多的砷、锡等残余元素增加了氢脆敏感性。

Failure Analysis of Gear Shaft

The failure of a gear shaft was analyzed by SEM analysis, macrograph, metallographical examination, mechanical test, chemical analysis and etc. The results showed that the flaking was formed by the accumulation of the hydrogen near the center of the gear shaft, and that the flaking were expanded symmetrically to the split. The effect of hydrogen of the gear shaft was comparatively evaluated by reduction in area and elongation values in different condition. The remainder of arsenic and tin in large amount have increased the sensitivity to the. embrittlement.