Development of microstructure features and mechanical properties of AISI 317L stainless steel produced by wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) process has been considered the most promising technology for fabricating metallic structures at high deposition rate, cost-effective, and near net shape. This research influence the wire feed speed (WFS) effect on the 317L fabricated using cold metal transfer WAAM process, the microstructure characteristics and mechanical behavior of deposited parts were investigated. Microstructure studies indicate columnar grains structure with small amount of equiaxed grains in various regions and epitaxial growth of dendrites were formed. Electron back scattered diffraction results indicate the well-aligned austenite (γ) columnar crystals with strong crystallographic orientation (001) texture in the deposition direction. X-ray diffraction analysis displays the formation (111), (200) and (220) of austenite phase and (110) of ferrite phase formed in various samples. Micro-hardness results indicate the hardness value was not uniform from bottom to top region of deposit wall, the average micro-hardness values ranging from 200 to 215 HV. Tensile test results reveal the horizontal direction samples secure the higher ultimate tensile strength, yield strength values of 530 and 340 MPa than the vertical direction samples of 485 and 310 MPa, which feature the anisotropic material properties. The fracture surface indicates the uniform distribution of dimples with enough plastic deformation, which is characterized by ductile fracture. The results found that WFS 1 exhibits higher mechanical properties when compared to WFS 2. This study demonstrates the mechanical integrity of WAAM stainless steel is primarily influenced by the essential process parameters offering significant potential for tunable performance.