Characterization of wire arc additive manufactured products: A comparison between as-deposited and inter-layer cold worked specimens

The presence of large dendrites and alloy segregation in as-deposited wire arc additive manufacturing (WAAM) products results in a wide range of mechanical properties that are often inferior to wrought ones. In this study, the effect of inter-layer cold working on the microstructure and mechanical properties of AISI 347 samples manufactured by WAAM has been investigated. The average hardness of single-pass welding, as-deposited, and cold worked WAAM samples were 190 HV, 249 HV, and 323 HV, respectively. Inter-layer cold working has led to an increase in ultimate tensile strength from 576 MPa to 803 MPa and yield strength from 395 MPa to 697 MPa. Also, Inter-layer cold working and thermal energy due to the deposition of subsequent layers have resulted in microstructural evolution and grain refinement through recrystallization. Besides, a semi-quantitative analysis has shown that increasing the amount of cold working by four times resulted in 64 % decrease in average recrystallized grain size.