On Corrosion Behaviors in Welded Zone of API 5L-X65 Steel for Natural Gas Transmission

J. Ocean Eng. Technol. 2004;18(5):50-56.

JO SANG-KEUN,SONG HAN-SEOP,KONG Yu-SIK,KIM YOUNG-DAI

천연가스 수송용 API 5L-X65강 용접부의 부식거동에 관한 연구

조상근,송한섭,공유식,김영대

부경대학교 대학원 기계공학과,서부산공업고등학교,부경대학교 기계공학부,부경대학교 기계공학부

Keywords: Constant-Current Corrosion Test, Corrosion Rate, Relative Electrode Potential, Relative Corrosion Current, Surface Corrosion Pattern, Stress Corrosion Cracking

핵심용어: 정전류부식실험, 부식속도, 상대적극전위, 상대부식전류, 표면부식양식, 응력부식균열

Abstract

This study is on the constant-current stress corrosion test, related to the load stress, in both the welded and non-welded zones of high tensile strength steel that is used for natural gas transmission. The surface corrosion pattern of the welded zone of API 5L-X65 specimens for natural gas transmission showed general corrosion and narrow pitting, and the pitting was increased with load stress. Initially, the average relative electrode potential and the average relative current of the high tensile strength steel, used for natural gas transmission specimens, were decreased rapidly, and the average relative electrode potential was higher and the average relative current was lower in welded zone, compared to base metal. The average relative electrode potential was decreased with load stress, and the average relative current was somewhat increased by increasing the load stress. The corrosion rate was less in welded zone, compared to base metal, and the corrosion rate was decreased by increasing the load stress.