304 스테인리스강의 용접부위의 부식특성에 관한 전기화학적 평가

Two kinds of welding methods are used for austenitic 304 stainless steel: laser welding and TIG welding. The difference in the corrosion characteristics if the welded zone between these two welding methods was investigated using electrochemical methods, such as corrosion potential measurements, polarization curves, cyclic voltammograms, etc. The Vickers hardnesses if all the welded zones (WM: Weld Metal, HAZ: Heat Affected Zone, BM: Base Metal) showed relatively higher values in the case if laser welding than for TIG welding. Furthermore, the corrosion current densities if all the welding zones showed lower values compared to TIG welding. In particular, the corrosion current density if the HAZ with TIG welding had the highest value if all the welding zones, which suggests that chromium depletion due to the formation if chromium carbide appears in the HAZ, which is in the range of the sensitization temperature. Thus, it can easily be corroded with a more active anode. Consequently, we found that the corrosion resistance if all of the welding zones for austenitic 304 stainless steel could apparently be improved by using Loser welding.