인코넬 FM52 및 308L 스테인리스강을 이용한 탄소강 이종 클래딩 및 공정변수에 따른 응고균열 발생 거동 변화: Transverse-Varestraint 시험을 이용한 응고취성 온도범위 평가

• Published in: 대한금속·재료학회지, 58(6) Vol. 58; no. 6; pp. 403 - 412
• Main Authors: 김유경, Yookyung Kim, 문병록, Byungrok Moon, 강남현, Namhyun Kang, 천은준, Eun-joon Chun
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.06.2020; 대한금속·재료학회
• Subjects: dissimilar cladding; impurity elements; solidification cracking susceptibility; solidification segregation; varestraint test; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2020.58.6.403

In this study, solidification cracking behavior and susceptibility in dissimilar cladding of Inconel alloy FM 52, 308L stainless steel to carbon steel, was investigated by submerged arc welding and transverse-Varestraint testing with gas tungsten arc welding. The effect of cladding conditions on cracking behavior and susceptibility was extensively evaluated, and metallurgical factors affecting susceptibility were clarified. Depending on the cladding sequence (cladding combination A: Inconel 52→308L, cladding combination B: 308L→Inconel 52), opposite types of solidification cracking behavior were observed. Specifically, solidification cracking was observed only for cladding combination A. Using transverse-Varestraint tests, the solidification brittle temperature range (BTR) was determined to be 298 K for cladding combination A and 200 K for cladding combination B. The reason for solidification cracking in cladding combination A could be its higher solidification susceptibility (i.e., a larger BTR (298 K)) compared with cladding combination B (BTR: 200 K). To elucidate differences in solidification cracking susceptibility, a numerical simulation of non-equilibrium solidification segregation for impurity elements (P, S) was performed, based on velocity dependent solidification theories and the finite differential method. Different segregation behaviors were calculated upon the cladding combinations. The severe segregation of P and S during solidification was found to be one of the important metallurgical factors for the large BTR of cladding combination A, compared with cladding combination B. (Received February 28, 2020; Accepted April 17, 2020)