Characterization of bond line discontinuities in a high-Mn TWIP steel pipe welded by HF-ERW

Journal Article · Mon Aug 15 04:00:00 EDT 2016 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2016.05.005· OSTI ID:22689565

Park, Gitae; Kim, Bongyoon; Kang, Yongjoon ^[1]; Kang, Heewoong ^[2]; Lee, Changhee ^[1]

---

1. Division of Materials Science and Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763 (Korea, Republic of)
2. RD Team, Husteel, 131 Bugokgongdan-ro, Songak-eup, Dangjin-si, Chungnam 31721 (Korea, Republic of)

In this work, the microstructure and defects in a high-frequency electrical resistance welded (HF-ERW) pipe of high-Mn twinning-induced plasticity (TWIP) steel were characterized. The microstructure of the base metal and the bond line were examined using both optical microscopy and scanning electron microscopy. The features of the bond line were similar to those of conventional steel. Simultaneously, the circumferential ductility was evaluated via a flaring test. It was concluded that the deterioration of the circumferential ductility in a high-Mn TWIP steel pipe was caused by irregular shaped oxide defects and a penetrator that had been formed during welding. Specifically, the penetrator, which is composed of MnO and Mn{sub 2}SiO{sub 4}, was found to be the most influential on the circumferential ductility of the welded pipe. The penetrator was analyzed using both an electron probe micro analyzer and transmission electron microscopy, and the formation sequence of the penetrator was evaluated. - Highlights: •This study focused on applying the HF-ERW process to the seam welding of expandable pipe using TWIP steels. •For improvement of the circumferential ductility, deterioration factors were characterized. •Penetrator which would mainly deteriorate the circumferential ductility consisted of round MnO and Mn{sub 2}SiO{sub 4}. •Metallurgical evidence of existing theory regarding the mechanism of defect formation during the HF-ERW was characterized.

• OSTI ID: 22689565
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 118; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DEFECTS
DUCTILITY
ELECTRIC CONDUCTIVITY
ELECTRON PROBES
FLARING
MANGANESE OXIDES
MANGANESE SILICATES
MICROSTRUCTURE
OPTICAL MICROSCOPY
PENETRATORS
PIPES
PLASTICITY
SCANNING ELECTRON MICROSCOPY
STEELS
TRANSMISSION ELECTRON MICROSCOPY
WELDED JOINTS
WELDING