The Effects of Microstructure on Cold Crack in High-Strength Weld Metals

Lee, Myung-Jin; Kang, Nam-Hyun

doi:2014.32.1.22

J Weld Join > Volume 32(1); 2014 > Article

Special Issue

Journal of Welding and Joining 2014;32(1):22-27.
DOI: https://doi.org/10.5781/JWJ.2014.32.1.22 Published online February 27, 2014.

The Effects of Microstructure on Cold Crack in High-Strength Weld Metals

Myung-Jin Lee^*, Nam-Hyun Kang^*

Correspondence: Nam-Hyun Kang,
Email: nhkang@pusan.ac.kr

Abstract

In the past, cold crack was commonly observed in the HAZ(heat affected zone) of high-strength steels. Applying to TMCP(thermo-mechanical controlled process) and HSLA(high strength low alloy) steels, cold crack tends to increase the occurrence in the weld metal. It is generally understood that cold crack occurs when the following factors are present simultaneously : diffusible hydrogen in the weld metal, a susceptible microstructure and residual stress. In particular, many studies investigated the microstructural effect on the cold crack in HAZ and the cold crack in weld metals starts to receive the special attendance in modern times. The purpose of the study is to review the effect of weld microstructures (grain boundary ferrite, Widm?nstatten ferrite, acicular ferrite, bainite and martensite) on cold crack in the weld metals. Among various microstructures of weld metals, acicular ferrite produced the greatest resistance to the cold crack due to the fine interlocking nature and high-angle grain boundary of the microstructure.

Key Words: Cold crack, Weld metal, Grain boundary ferrite, Widm?nstatten ferrite, Acicular ferrite, Bainite, Martensite