柴油机缸盖示功阀孔裂纹的形成原因分析  

Cause analysis of cracks in indicator valve hole of diesel engine cylinder head

作　　者：杨庆芬 周根树[1] 张曼茹 王建国 于彦峰 YANG Qing-fen;ZHOU Gen-shu;ZHANG Man-ru;WANG Jian-guo;YU Yan-feng(State Key Laboratory for Mechanical Behavior of Materials,Xi􀆳an Jiaotong University,Xi􀆳an 710049,China;Shaanxi Diesel Engine Heavy Industry Co Ltd,Xianyang 713105,China)

机构地区：[1]西安交通大学金属材料强度国家重点实验室,陕西西安710049 [2]陕西柴油机重工有限公司,陕西咸阳713105

出　　处：《材料热处理学报》2022年第5期151-157,共7页Transactions of Materials and Heat Treatment

基　　金：西安市轻合金重点实验室(201805064ZD15CG48)。

摘　　要：针对某QT500-7柴油机缸盖示功阀孔过渡圆角处出现裂纹,通过化学成分、组织、力学性能检测以及断口观察,分析其开裂原因。结果表明:缸盖本体的化学成分及组织均符合技术要求,力学性能部分略低于技术要求。缸盖示功阀孔本体内部的铁素体含量未超过70%,符合技术要求,随着接近受热面外表面,铁素体含量逐渐升高,这是由于在使用过程中珠光体受热分解所致。导致缸盖示功阀孔裂纹形成的主要原因是热疲劳,疲劳裂纹起源于示功阀孔的孔沿,这主要由于该处存在应力集中。In view of the crack at the transition round corner of indicator valve hole of a QT500-7 diesel engine cylinder head, the cause of the crack was analyzed through the detection of chemical composition, microstructure, mechanical properties and the fracture observation. The results show that the chemical composition and microstructure of the cylinder head body meet the technical requirements, and the mechanical properties are slightly lower than the technical requirements. The ferrite content inside the indicator valve hole body of the cylinder head does not exceed 70%, which meets the technical requirements. As it approaches the outer surface of the heating surface, the ferrite content gradually increases, which is due to the thermal decomposition of pearlite during the service. The main reason for the crack formation of the indicator valve hole in the cylinder head is thermal fatigue. The fatigue crack originates from the hole edge of the indicator valve hole, which is mainly due to the stress concentration there.

关 键 词：QT500-7 柴油机缸盖 示功阀 裂纹 热疲劳 

分 类 号：TG143.5[一般工业技术—材料科学与工程]