Verification of Quantitative Evaluation Method for Ferritic Weld Metal Microstructure

Kim, Ka-Hee; Ki, Hee-Jin; Ryoo, Hoi-Soo

Journal of KWJS 2005;23(4):27-33.
Published online September 22, 2005.

[기술논문]철강 용착금속 미세조직의 정량화 기법 검증

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Verification of Quantitative Evaluation Method for Ferritic Weld Metal Microstructure

Ka-Hee Kim, Hee-Jin Ki, Hoi-Soo Ryoo

Abstract

Quantitative evaluation was performed on the microstructure of flux-cored arc(FCA) weld metal using a method known as IIW scheme. It was mainly intended to figure out any practical difficulties in applying this method and also to provide the consumable makers with basic guide line in developing FCA welding consumables for better properties. Assessment of the experimental results showed IIW scheme was quite reliable in the low heat input range where the acicular ferrite was a major constituent. However, in the high heat input range, some scatter was noticed as the other phases like grain boundary ferrite and Widmansttaten ferrite become dominant. It implies that the accuracy of IIW scheme depends on the fraction of microstructure constituents and it become worse as the fraction of latter t재 phases increases. This tendency was discussed in terms of the characteristics of those two phases. In addition, base line microstructure of rutile type FCA weld metal was addressed for developing new FCA welding consumables intended for higher heat input welding.