Electrochemical Evaluation of Corrosion Property of Welding Zone of 304 Stainless Steel

J. Ocean Eng. Technol. 2009;23(4):58-63.

Moon Kyung-Man,Kim Yun-Hae,Kim Jong-Do,Lee Myung-Hoon,Kim Jin-Gyeong

Dept. of Marine Equipment Engineering Korea Maritime Univ,Dept. of Marine Equipment Engineering Korea Maritime Univ,Dept. of Marine System Engineering Korea Maritime Univ,Dept. of Marine System Engineering Korea Maritime Univ,Education and Research Di

304 스테인리스강의 용접부위의 부식특성에 관한 전기화학적 평가

문경만,김윤해,김종도,이명훈,김진경

한국해양대학교 공과대학 조선기자재 공학부,한국해양대학교 공과대학 조선기자재 공학부,한국해양대학교 해사대학 기관시스탬공학부,한국해양대학교 해사대학 기관시스탬공학부,한국해양수산연수원 교육연구처

Keywords: Laser welding, TIG welding, Corrosion potential, Weld metal, Heat affected zone, Polarization curves, Chromiun depletion

핵심용어: 레이저용접, 텅스텐 불활성가스 용접, 부식전위, 용접금속, 열영향부, 분극곡선, 크롬결핍

Abstract

Two kinds of welding methods are used for austenitic 304 stainless steel: laser welding and TIG welding. The difference in the corrosion characteristics of 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 of all the welded zones (WM: Weld Metal, HAZ: Heat Affected Zone, BM: Base Metal) showed relatively higher values in the case of laser welding than for TIG welding. Furthermore, the corrosion current densities of all the welding zones showed lower values compared to TIG welding. In particular, the corrosion current density of the HAZ with TIG welding had the highest value of all the welding zones, which suggests that chromium depletion due to the formation of 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 of all of the welding zones for austenitic 304 stainless steel could apparently be improved by using Laser welding.