Effect of Cr and C on microstructure evolution of medium carbon steels during friction stir welding process and their mechanical property

C. Cheng, K. Kadoi, S. Tokita, H. Fujii, K. Ushioda, H. Inoue

Research output: Contribution to journalConference articlepeer-review

Abstract

The aim of the present study was to investigate the effect of chromium and carbon in medium carbon steels on the microstructure evolution during FSW process and their mechanical property. The materials are dynamically recrystallized in austenite during FSW followed by phase transformation from austenite to ferrite, pearlite, bainite, and martensite. In the case of 0.2%C, the microstructure of the stir zone transited from pearlite and ferrite to bainite and martensite with the increase in chromium content. On the other hand, in the case of 0.4%C, the microstructure transited from pearlite to martensite with the increase in chromium content. The specimens of 0.2%C-4%Cr, 0.4%C-2%Cr and 0.4%C-4%Cr showed high tensile strength of over 1.5 GPa. In addition, even though the microstructures in the stir zones of the specimens are martensite, the elongation of 0.2%C-4%Cr was 31%while those of the others were less than 5%. TEM observation revealed that many tiny carbides precipitated in martensite of the stir zone of 0.2%C-4%Cr and micro twin formed in martensite in those of 0.4%C-2%Cr and 0.4%C-4%Cr. Thus, it was considered that auto-tempering occurred in the stir zone of 0.2%C-4%Cr during FSW process. The carbide precipitation in martensite is more effective to improve the tensile elongation compared with micro twin formation.

Original languageEnglish
Article number012032
JournalJournal of Physics: Conference Series
Volume1270
Issue number1
DOIs
Publication statusPublished - 2019 Aug 14
Externally publishedYes
Event7th International Conference on Recrystallization and Grain Growth, ReX and GG 2019 - Ghent, Belgium
Duration: 2019 Aug 42019 Aug 9

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'Effect of Cr and C on microstructure evolution of medium carbon steels during friction stir welding process and their mechanical property'. Together they form a unique fingerprint.

Cite this