Microstructure and Properties of the 308LSi Austenitic Steel Produced by Plasma-MIG Deposition Welding with Layer-by-Layer Peening

Abstract

This paper investigates the effect of cold working via layer-by-layer peening on the microstructure and properties of a 308LSi steel workpiece produced by the wire deposition welding with a consumable electrode following the principle of 3D printing. The microstructure, phase composition and mechanical properties of the metal are studied before and after the workpiece synthesis. In the microstructure of the workpieces produced by peening, there is, in addition to austenite, a small quantity of fine-dispersed carbides and residual δ-ferrite in the interdendritic spaces. It is demonstrated that the use of layer-by-layer cold working in the process of deposition welding enables eliminating transcrystallization of the deposited metal, promotes an increase in the microstructure’s degree of dispersion and a more uniform distribution of fine-dispersed carbides in the volume of the dendrites. It is found that these structural features of the deposited metal in the additive manufacturing of a workpiece with layer-by-layer peening lead to an enhancement of the strength characteristics as compared to the material produced by the conventional wire deposition welding. Meanwhile, the level of the ductility characteristics remains high.

Keywords

• austenitic steel
• additive manufacturing
• Plasma-MIG
• layer-by-layer peening
• microstructure
• mechanical properties