Evaluation of Fracture Toughness and Microstructure on FCA Weldment According to Heat Input

Shin, Yong-Taek; Kang, Sung-Won; Kim, Myung-Hyun

Journal of KWJS 2008;26(3):51-60.
Published online July 31, 2008.

입열량에 따른 FCAW용접부 파괴인성에 미치는 미세조직의 영향

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Evaluation of Fracture Toughness and Microstructure on FCA Weldment According to Heat Input

Yong-Taek Shin, Sung-Won Kang, Myung-Hyun Kim

Abstract

This paper is to evaluate fracture characteristics of API 2W Gr.50 TMCP steel weldment typically applied for offshore structures, with the focus on the influence of heat input arising from flux cored arc welding. Based on the results and insights developed from this study, it is found that the toughness for both CTOD and impact exhibits a tendency to decrease as the weld heat input increases. The reheated zone of weldmetal exhibit lower hardness than solidified zone and microstructure that are liable to affect the toughness are acicular ferrite and martensite-austenite constituents (M-A). In particular, M-A is a more effective micro-phase for CTOD toughness than impact toughness.

Key Words: Fracture Toughness, Crack Tip Opening Displacement(CTOD), Thermo Mechanical Controlled Process Steel(TMCP), Heat Input, Acicular Ferrite, Martensite-Austenite Constituents(M-A), Impact Toughness