An Investigation into the Fatigue Crack Growth Rate of Electron Beam-Welded H13 Tool Steel: Effect of Welding and Post-Weld Heat Treatment

摘要

Fatigue crack growth rate (FCGR) behavior of 3-point bend specimen of electron beam-welded AISI H13 tool steel is studied. Three types of specimens were studied here; specifically: the base metal, as-welded, and post-heat-treated welded samples. The crack length is measured visually as well as calculated using crack mouth opening displacement (CMOD) gage. The FCGR curves of different specimens are compared. The validity of using CMOD as a tool for indirect crack length measurement as per ASTM E399 is explored. Additionally, the possibility of using CMOD as a crack driving force parameter instead of stress intensity range (AK) is explored. It is shown that the CMOD is a better crack driving force parameter and the indirect crack length measurement is not a reliable tool, especially for welded specimens. In the end, CMOD versus crack length is numerically simulated by finite element analysis to give us a base line CMOD versus crack length without microstructural or plasticity effects.