Corrosion Behavior Evaluation of TIG Welding Joint of Low Carbon Steel

Abstract

The current research studies the corrosion behavior of Low Carbon Steel 1020 AISI welded joint by means of TIG welding method using mutable DC current and constant voltage. Before the welding process, shot peening by steel balls for certain welded joints is applied to the sheet metal, and then welding under the same welding conditions without shot peening. A number of corrosion inspection samples have been prepared with the measurements of (15 * 15 * 3 mm), according to ASTM (G71-31). Microstructure, residual stress has been tested and the corrosion test has been conducted electrochemically in 3.5 per cent NaCl solution for all samples. Corrosion rate was computed by means of the Tafel equation. The results show a rise in corrosion rate in some welded joints compared with other welded joints and base metal due to the variation in heat input from the input current for each weld passes. Shot peening process contributed to lower corrosion rate compared to welded joints without shot peening, due to the residual compression stresses produced by shot peening process. The best results obtained when number of welds passes and welding current are decreased to get suitable heat input.