Investigation on high-strength low alloy 0.35Cr-1.9Ni-0.55Mo steel deposited on 20Cr substrate by wire and arc-based directed energy deposition

Abstract

This article aims to observe the microstructure, mechanical properties, and interface bonding of a 0.35Cr-1.9Ni-0.55Mo alloy deposited on 20Cr steel by wire and arc-based directed energy deposition (WA-DED). For this purpose, different characterization techniques such as optical microscope, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and high-resolution X-ray diffractometer were used to analyze microstructure, chemical composition, and phases of the deposited material. Microhardness and tensile tests were also carried out. The results show that the microstructure of the deposited material is relatively homogeneous with a slight increase in grain size from the bottom to the top of the deposited part, thus resulting in a gradually decreasing trend in microhardness, from 288±16.78 HV0.1 (in the bottom) to 256±17.04 HV0.1 (in the top). The heat-affected zone (HAZ) is the hardest (301±2.70 HV0.1), while the substrate has the lowest microhardness (203±17.64 HV0.1). The tensile strengths of deposited materials are relatively isotropic in both the horizontal direction (HD) and vertical (VD) direction: UTSVD = 1013±9.29 MPa, USTHD = 985±24.58 MPa, YS(0.2%)VD = 570±4.51 MPa, and YS(0.2%)HD = 614±19.66 MPa. The tensile strengths of interface specimens are also comparable to those of the substrate materials (e.g., 951 vs. 972 MPa in UTS), indicating an excellent metallurgical bonding between the deposited and substrate materials. The results of this work confirm the efficiency of WA-DED technique to produce high-quality components in industry