The Effects of Heat Treatment on Mechanical Properties and Microstructure of Wire-arc Additive Remanufacturing of AISI 4130 Steel Components

Abstract

This study focused on the remanufacturing of industrial components using wire-arc additive manufacturing (WAAM) and the influence of heat treatment on the mechanical properties and microstructure evolution of printed parts. The study analyzed the microstructure and mechanical properties in as-built and heat-treated conditions of the 3D printed parts. The results show that the deposited AISI 4130 steel had ferrite-pearlite phases. Microstructural analysis indicated distinct characteristics in the substrate, interface, and deposited regions. Austenitisation and tempering heat treatment caused microstructure homogenization, revealing the predominant ferrite-pearlite phase. The interface had the highest microhardness value of 180.3±6.9 HV0.3 in as-built condition. After heat treatment, the hardness improved by an average of 50.2%. The deposited region recorded a density of 7.695 g/cm3 in an as-built state. In the as-built condition, the test samples exhibited a yield strength of 172.9±2.1 MPa, but the interface sample had 162.1±5.3 MPa. The printed parts had an ultimate tensile stress of ~539.6±68.9 MPa compared to 493.3±21.8 MPa of the substrate. After heat treatment, yield strength improved by 8.9% for the printed part and decreased by 12.1% at the interface region. The ultimate strength for the samples section parallel and perpendicular to the deposition directions increased by 8.0±40.5% and the interface by 36.1%. Fractography analysis indicated that failure changed from brittle to ductile fracture after heat treatment. The findings of this study contribute to designing heat treatment schedules for industrial remanufacturing of structural and functional components using WAAM.