Fracture of Poppet-Valve Stems Due to Incorrect Material Selection
A series of poppet-valve stems fabricated from 17-4 PH (AISI type 630) stainless steel failed prematurely in service during the development of a large combustion assembly. The poppet valves were part of a scavenging system that evacuated the assembly after each combustion cycle. The function of the valve is to open and close a port; thus, the valve is subjected to both impact and tensile loading. Analysis (visual inspection, hardness testing, and stress analysis) supported the conclusions that the valve stems were impact loaded to stresses in excess of their yield strength. That they failed in the threaded portion...
Fracture of Poppet-Valve Stems Due to Incorrect Material Selection, ASM Failure Analysis Case Histories: Design Flaws, ASM International, 2019, https://doi.org/10.31399/asm.fach.design.c0047109
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