Causes of Cracking of Flat Valve of a High-Pressure Inlet Device

Crack occurred on the surface of flat valve of a high-pressure inlet device. The causes of flat valve crack were analyzed through macroscopic observation, chemical composition analysis, tensile test, metallographic inspection and scanning electron microscopy analysis. The results showed that welding layer of flat valve had high hardness and poor toughness, and there were delamination and pores at interface between welding layer and substrate. The valve was subjected to vibration load during service, resulting in crack at the pores. After that, the crack propagated until it penetrated the entire welding layer and cracked.