柴油机曲轴断裂原因分析  

Fracture cause analysis of diesel engine crankshaft

作　　者：焦丽[1] 王国亮[1] 徐向阳[1] 葛保红 孙思东[1] 张燕明[1] 

机构地区：[1]河北华北柴油机有限责任公司,河北石家庄050081

出　　处：《金属热处理》2015年第8期195-198,共4页Heat Treatment of Metals

摘　　要：针对曲轴早期断裂失效的问题,通过宏观检验、化学成分分析、力学性能测试、金相检验、断口微观结构分析等手段对其断裂原因进行了分析。结果表明,轴颈油孔内壁异常粗糙的加工刀痕,因应力集中而诱发了材料的最初损伤;感应淬火过渡区低硬度铁素体与刀痕的叠加,明显加速了裂纹的萌生与扩展,是此次曲轴断裂的主要原因;心部上贝氏体的存在一定程度上弱化了材料的力学性能,最终曲轴在复杂交变应力作用下,发生高周疲劳而断裂。Fracture cause of the crankshaft was analyzed by means of macroscopic examination, chemical compositions analysis, mechanical property test, metallographic examination and fracture analysis. The results show that the rough cutting marks led to the original damage of the material because of the stress concentration. The combination of cutting marks and ferrite with low hardness in transition region of induction hardening makes the cracks initiate and propagate and to be the main reasons of the fracture. Upper bainite existing in the matrix reduces the mechanical properties to some extent. Finally, the crankshaft occurs high cycle fatigue fracture under alternating stress.

关 键 词：曲轴 疲劳断裂 加工刀痕 应力集中 

分 类 号：TK426[动力工程及工程热物理—动力机械及工程] TG157[金属学及工艺—热处理]