대입열용접 열영향부 인성에 미치는 Al의 영향

Abstract

The present work investigated the effects of Al and Si content on the HAZ toughness of high heat input welds. Steels having different Al and Si contents were given a weld thermal cycle to simulate HAZ using Gleeble, and then Charpy impact toughness of simulated HAZ was determined. The results of this work were interpreted in terms of microstructure, especially martensite-austenite constituent (M-A). Al showed beneficial effect on simulated HAZ toughness by increasing the amount of ferrite and inhibiting grain growth. Al also showed detrimental effect by increasing the amount of M-A. These complex effects of Al was influenced by Si content in the steel. As Si increases the amount of M-A, when both Si and Al contents were large, simulated HAZ showed low toughness because of large amount of M-A. However, when Si content was small, high Al content was beneficial on HAZ toughness because of large amount of ferrite and small grain size even if HAZ has relatively small amount of M-A.