发动机气门导管的磨损失效原因分析

Causes Analysis of Wear and Failure of Engine Valve Guide

随着发动机性能的不断提升,气门导管的工作环境也变得更为恶劣,导致气门导管的失效问题频发,对发动机排气门导管的耐久件和失效件进行对比分析寻找材料失效的原因。对导管的耐磨性能、显微组织和孔隙进行分析,结果表明,2个工件的耐磨试验结果符合台架试验结果,失效件磨损严重;2个样品的显微组织一致,均为少量珠光体+大量不规则珠光体+合金相+孔隙;耐久件孔隙率占比高,储油多且密度符合标准,失效件内部存在直径100μm的大孔隙,降低耐磨性能。故导致磨损失效的原因为较低的孔隙率和存在较大的孔隙。

Currently,with the continuous improvement of engine performance,the working environment of the valve guide has become more harsh,so the failure problem of the valve guide has become more and more common.A comparative analysis of the durable and failed components of the engine exhaust valve guide is conducted to identify the causes of material failure.The wear resistance,microstructure,and porosity of the valve guide are studied.The results show that the wear test results of the 2 specimens are consistent with the bench test results,and the failed specimen experiences wear serious.The microstructure of both is consistent with a small amount of pearlite and a large amount of irregular pearlite and alloy phase and pores.The porosity results indicate that the durable specimen has a higher porosity ratio,storing more oil and with a density meeting the standard.However,the failed specimen has a large hole with a diameter of 100μm,which reduces its wear resistance.Therefore,the cause of wear failure is identified as lower porosity and the existence of larger pores.