Investigating Isotropy of Mechanical and Wear Properties in As-Deposited and Inter-Layer Cold Worked Specimens Manufactured by Wire Arc Additive Manufacturing

Wire arc additive manufacturing (WAAM) has several industrial applications because of its advantages over other additive manufacturing methods. In this study, two stainless steel 347 walls, namely as-deposited (AD) wall, and inter-layer cold worked (CW) wall, were prepared using the WAAM method to investigate the isotropy of their mechanical properties and wear properties in vertical and horizontal directions. For the AD wall, the mean yield strength, ultimate strength, and elongation of horizontal samples were 410 MPa, 620 MPa, and 47%, respectively. In comparison, these values for the vertical (V) samples were 402 MPa, 590 MPa, and 49%, respectively. For the CW wall, the mean yield strength, ultimate strength, and elongation of horizontal samples were 815 MPa, 876 MPa, and 26%, respectively, while those of vertical samples were 722 MPa, 824 MPa, and 25%, respectively. The CW wall's tensile test results indicated that inter-layer cold working intensified the anisotropy of tensile properties in both vertical and horizontal directions. Microstructural investigation revealed that inter-layer cold working and the heat resulted from subsequent layers deposition in the CW wall recrystallized the layers and reduced the grain size. Additionally, wear test results demonstrated that inter-layer cold working increased hardness and thus wear-resistance of the samples and reduced their friction. The results showed that the coefficient of friction (COF) and wear rates of the samples are not highly dependent on their direction.