The Welding Residual Stress and Fracture Toughness Characteristics of HT50 Laser Welded Joint

J. Ocean Eng. Technol. 2007;21(3):71-76.

Ro, Chan-Seung;Bang, Hee-Seon;Bang, Han-Sur;Oh, Chong-In;

Graduate School, Dept. of Naval Architecture & Ocean Eng., Chosun Univ.;Division of Aerospace and Naval Architecture Eng., Chosun Univ.;Division of Aerospace and Naval Architecture Eng., Chosun Univ.;Graduate School, Dept. of Naval Architecture & Ocean En

고장력강(HT50) 레이저용접부의 용접잔류응력 및 파괴인성 특성

노찬승;방희선;방한서;오종인;

조선대학교 선박해양공학과 대학원;조선대학교 항공.조선공학부;조선대학교 항공.조선공학부;조선대학교 선박해양공학과 대학원;

Keywords: Laser beam welding, Crack tip opening displacement(CTOD), Charpy absorbed energy, Fracture toughness, Fracture pass deviation(FPD)

핵심용어: 레이저빔용접, 균열선단개구변위, 샤르피 흡수에너지, 파괴인성, 파괴경로변경

Abstract

Recently, many industries have been employing the application of laser beam welding, due to the resulting high welding quality, such as smaller width of melting and heat affective zone, smaller welding deformation, and fine grains of weldment, compared to arc welding. However, in order to appropriately utilize this welding process with steel structure, the characteristics of welding residual stresses and fracture toughness in welded joints are to be investigated for reliability. Therefore, in this study, the mechanical properties of weldments by arc and laser welding are investigated using FEM to confirm the weldability of laser welding to the general structural steel (HT50). The Charpy impact test and 3-points bending CTOD test are carried out in the range of temperatures between $-60^{circ}C;and;20^{circ}C$, in order to understand the effect on the fracture toughness of weldments. From the research results, it has been found that the maximum residual stress appears at the center of plate thickness, and that the fracture toughness is influenced by strength mis-match.