부산대학교 도서관

A top drive side cover joint is fractured after service for 5 h. In this paper, the failure causes were investigated by mechanical property tests, chemical composition analysis, metallographic analysis, and scanning electron microscopy analysis. The results showed that the failure mode of the top drive side cover joint was a brittle fracture. In addition, the failure cause is mainly attributed to the banded metallographic structure of martensite and bainite. This would result in a low Charpy-V impact toughness and high ductile-brittle transition temperature of the material. The low service temperature and complex load conditions during the drilling process would make the fracture failure easier to happen. [ABSTRACT FROM AUTHOR]