Fatigue crack propagation in functionally graded bi-material steel obtained through wire-arc additive manufacturing

Journal article (2025)

Authors

J. L. Galán Argumedo Team Vera Popovich - Mechanical, Maritime and Materials Engineering
A. Suresh Team Vera Popovich - Mechanical, Maritime and Materials Engineering
Zhaoying Ding Team Marcel Hermans - Mechanical, Maritime and Materials Engineering
Virgínia M. Morete Barbosa Bertolo Team Vera Popovich - Mechanical, Maritime and Materials Engineering
E. Reinton Team Vera Popovich - Mechanical, Maritime and Materials Engineering
AC Riemslag Team Vera Popovich - Mechanical, Maritime and Materials Engineering
Marcel Hermans Team Marcel Hermans - Mechanical, Maritime and Materials Engineering
Vera Vera Team Vera Popovich - Mechanical, Maritime and Materials Engineering
Research Group
Team Vera Popovich (Mechanical, Maritime and Materials Engineering) (TU Delft)
More Info
expand_more

Published Date

2025

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Materials Science and Engineering

Research Group

Team Vera Popovich

Abstract

This study concentrates on the fatigue crack propagation behaviour of a high-strength low-alloy (HSLA) steel and austenitic stainless (AS) steel bi-material part, as obtained by wire arc additive manufacturing (WAAM). Due to partial mixing in the weld pool, the first layer of AS steel laid onto the previously deposited HSLA steel results in a diluted interface layer of distinct chemical and microstructural characteristics. Average Paris parameters are obtained for the interface layer along transverse and longitudinal planes to the deposition direction (BD-LD plane: m = 2.79, log10(C) = –7.83 log10(da/dN)) (BD-TD plane: m = 3.47, log10(C) = –8.39 log10(da/dN)). However, it is observed that this interface layer manifests an intriguing crack propagation behaviour. FCGR consistently drop as the crack front transitions from undiluted AS steel to the interface. At ΔK = 20 MPa⋅m0.5, the greatest Δ is −0.77 log10 steps (R = 0.1). As cracks near the HSLA fusion line, rates re-accelerate up to + 0.75 log10 steps (R = 0.5). The phenomenon is attributed to the interplay between deformation-induced martensitic transformation and pre-existing allotropic martensite. Our findings, derived from a series of fatigue tests in correlation with multiscale microstructural and fracture characterization, offer insights into the damage-tolerant behaviour of these bi-material structures.