합금강관의 Energy Resistance Welding 용접조건에 따른 미세조직 거동 및 기계적 특성 연구

서지정보

ㆍ발행기관 : 한국재료학회 ㆍ수록지정보 : 한국재료학회지 / 21권 / 1호
ㆍ저자명 : 이경민, 이동언, 김성웅, 윤병현, 강희재, 강남현, 조경목

영어 초록

Energy resistance welding (ERW) is a pipe-producing process that has high productivity and low manufacturing cost. However, the high heat input of ERW degrades the mechanical property of the pipe. This study investigates the effect of heat input and alloying elements on microstructure and mechanical properties of ERW pipes. As the heat input increased, the ferrite amount increased. The ferrite amount in the weld centerline was larger than t at in the weld boundary. Medium carbon steels (S45C and K55) having 0.3~0.4wt.% carbon yielded a significant difference of ferrite amount in the weld centerline and weld boundary. High alloyed steels (DP780 and K55) having 1.5~1.6wt.% Mn showed a ferrite rich zone in the weld centerline. These phenomena are probably due to decarburization and demanganisation in the weld centerline. As the ferrite fraction increased, the hardness decreased a little for the S45C steels. In addition, DP780 steels and K55 steels showed that the hardness drops when those steels have a ferrite rich zone. But we demonstrated the good tensile property of the DP780 steels and K55 steels in which Mn is included.

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