中文摘要：

对锁紧轴渗氮后断裂的原因进行了分析,检测了渗氮前后的硬度、断裂韧性及金相组织。研究结果表明,锁紧轴调质后的不良组织导致整个轴韧性下降,硬度升高,对裂纹敏感。氮化并未引起调质后氮化层以外的其它部位组织和性能发生明显变化。退刀槽根部圆弧过渡不完全,尖角易产生应力集中,断裂易产生在应力集中处。针对以上问题提出改进措施。

英文摘要：

The reason for the fracture of clamp axis after nitridation was analyzed, and the hardness, breaking tenacity and microstructure before and after nitridation were also investigated. The results indicate that the unfavorable histology of clamp axis after quenching and tempering treatment results in the decline of toughness, the rise of hardness and the sensitivity to fissures of the whole axis. Nitridation does not bring obvious changes to other organizations and properties except nitration case after quenching and tempering treatment. The bottom circular arcs of relief groove can not transit completely so sharp comers easily contribute to stress concentration, where fractures are easily produced. Improvement measures are put forward to solve these problems above.