Microstructures and mechanical properties of stainless steel component deposited with 308L wire by hot wire plasma arc additive manufacturing process

Shapes of deposited components are more complicated and their weights are obviously heavier than before, therefore the ratio of deposited time cost in sum production cost increases dramatically. Hot wire plasma arc additive manufacturing process is proposed to reduce deposited time cost, by increasing deposition rate while keeping welding torch reaches more deposition positions as much as possible. Both CW-PAM process and HW-PAM process were used to manufacture 50 layers walls with 308L filler wire, and the investigation of fundamental characterization of HW-PAM process was implemented, then under different torch speeds, microstructures and mechanical properties of deposited sample by two processes were compared in details. Experiment results show that the deposition rate of HW-PAM process increased by 105% on an average. Its maximum wire lose rate reduced to 1.42%, which is lower 6.18% than the CW-PAM process at the torch speed of 20 cm/min. In addition, when the travel speed is 50 cm/min, lots of non-equiaxed ferrites exist in the samples deposited by HW-PAM process, the mean grain diameter refined to 7.62 μm from 8.37 μm of CW-PAM process. The ultimate tensile strengths of the HW-PAM samples are all above 700 MPa, and the maximum elongation reaches 53%, which raised by 6.25% in contrast to the CW-PAM process.