Revealing the microstructural evolution and mechanical response of repaired Fe–Cr–Si based alloy by directed energy deposition

Abstract

This study investigates the microstructure and mechanical properties of wear-resistant hardfacing structures fabricated on an AISI 1045 carbon steel substrate using a specially designed Fe–Cr based powder for directed energy deposition (DED). Electron backscatter diffraction (EBSD) analysis reveals that the texture predominantly consists of cube rotated {001} and cube {001} textures, in addition to weaker Brass {112} texture components. These textures contribute to the random orientations of martensitic grains and facilitate the tracing of austenite reconstruction. Notably, the as-printed samples exhibited superior yield strength (999.4 ± 86.3 MPa) and ductility (9.6 ± 2.6%) along the build direction (BD), compared to conventional samples, which demonstrated a tensile strength of 790 MPa and ductility of 2%. This improvement is primarily attributed to the hardening effects associated with a low volume fraction of retained austenite and the precipitation of Cr carbides. Comprehensive mechanical response, nanoindentation hardness profile across the interface, and microstructural analyses were conducted to confirm the feasibility of using a Fe-based hardfacing alloy for DED. The findings underscore the outstanding balance of strength and ductility exhibited by as-printed hardfacing alloy, further enhanced by its high printability, highlighting its potential in producing wear-resistant structures for repair applications.

Keywords

• Additive manufacturing (AM)
• Directed energy deposition (DED)
• Hardfacing flux-cored wire
• Nanoindentation
• Electron backscatter diffraction (EBSD)