Effect of latter feeding wire on double-wire GTA-AM stainless steel

ABSTRACT

A novel double-wire gas tungsten arc additive manufacturing (DE-GTA-AM) approach in which a former wire is fed into the arc and a latter wire is melted by the molten pool is developed to regulate the microstructure features and tensile performances of austenitic stainless steel. Attempting to achieve this aim, thin walls were fabricated via regulating the latter wire feed speed (LWFS). The results show that the microstructure in the as-built 308 L walls consists of δ and γ phases, and the residual ferrite content presents an increasing trend with the increase in LWFS. As the LWFS reaches 0.2, 0.5, and 0.8 m/min, the microstructures exhibit the coarse dendrite, fine dendrite, and columnar dendrite morphologies, respectively. The microhardness and tensile strength of the tensile specimens increase with the LWFS. As the LWFS is 0.8 m/min, the tensile strength in the horizontal direction can reach 570.71 MPa, increasing by 7.55% in comparison to the LWFS of 0.2 m/min and enhancing by 50.71 MPa than the wrought 308 L stainless steel.

KEYWORDS:

• Additive
• manufacturing
• double
• wire
• GTA
• latter
• feeding
• stainless
• steel
• microstructure
• mechanical
• strength

Highlights

1. A novel double-wire metal additive manufacturing is proposed.

2. Latter wire feed speed is employed to regulate the microstructure of stainless steel.

3. Tensile properties increase along with the latter wire feed speed.

Additional information

Funding

This work was funded by National Natural Science Foundation of China, no. 51975491 and no. 61573293, Sichuan Science and Technology Program, no. 2020JDRC0059 and no. 2020YFG0197..