Generation mechanism and distribution characteristics of residual stresses in wire-arc additively manufactured ultra-high strength steel components

The generated residual stresses (RS) in wire-arc additively manufactured components might harm their capability and lifetime. This work aims to systematically elucidate the generation and distribution mechanism of RS in wire-arc additively manufactured components made of the increasingly applied ultra-high strength steel (UHSS). Here, numerical sensitivity analyses as well as experimental measurements were executed for investigation. The results indicate that, apart from the thermal effect, austenite transformation (if present) is the other source of RS induced by wire-arc additive manufacturing, irrespective of the metallurgical phase temperature. The distribution of longitudinal residual stress (LRS) stabilizes first if the deposition height reaches a certain value, then its magnitude becomes stable as well with further increase in deposition height. Note that the maximum tensile LRS in the wall always approaches the yield strength at room temperature (σ y•RT ) of the used filler wire with or without metallurgical phase transformation. The metallurgical phase transformation temperature and the associated produced phase fractions mainly affect the magnitude and distribution patterns of LRS at the last layers in the wall. The transverse residual stress (TRS) in the wall is small and can be negligible, while that in the substrate is non-negligible. In the present work, the generation and distribution mechanism of RS in wire-arc additively manufactured UHSS components has been systematically illuminated.