某远洋轮主柴油机排气门发生漏气。采用扫描电镜对排气门基体、堆焊层的显微组织和裂纹形态进行了观察,同时检测了气门材料和腐蚀产物的化学成分。结果表明,排气门的材质合格,主要由于燃烧产物中硫和钒的氧化物等粘附在气门受热面上,在组织应力和热应力作用下产生了应力腐蚀,同时在高温燃气冲刷及冲击载荷的作用下加速了该气门的失效。

The microstructure and crack forms of the exhaust valve of the diesel engine were observed,and the chemical compositions of the valve material and corrosive products in the cracks were examined. The results indicated that material of exhaust valve have not defect. It is pointed out that stress corrosion action of S and V oxidation on the seal surface of the exhaust valve was main reason that resulted in cracks in exhaust valve. The brush of high temperature gases and the effect of impact load accelerated the exhaust valve failure.