열분석 방법을 이용한 AISI 5160스프링강의 용접시 Heat Affected Zone에서의 결합규명과 수소취성에 관한 연구

A study on the identification of the weld defects and hydrogen embrittlement in heat affected zone of AISI 5160 spring steel using thermal analysis technique

To explore the possible application of thermal analysis technique as a probe for finding weld defects, Hydrogen trapping phenomena in Heat Affected Zone (HAZ) of the AISI 5160 spring steel were investigated. HAZ was divided into five parts, which were used as thermal analysis specimens. Two types of trap sites were found in HAZ, ferrite/cementin interface and microvoid. The thermal analysis peak due to the ferrite/cementite interface increased its height toward the weld deposit. The thermal analysis peak due to the microvoid was the highest where the grain size was the smallest. The correspondence between the cold cracking and hydrogen trap nature is also discussed.