Lamellar structure formation of hot-stamped galvannealed coating during tempering

Akihiro Sengoku, Hiroshi Takebayashi, Norihiko Okamoto, Haruyuki Inui

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A significant amount of research and development on partial softening techniques, including tempering, is being conducted. Coated steel sheets, including galvannealed (GA) steel sheets, have been applied to automobile components. It is thought that tempering has a great influence on the coating structure in heating treatment after the hot-stamping process. In this study, a change of hot-stamped GA coating during tempering was investigated. By analyzing hot-stamped GA coating tempered at different temperatures, it was elucidated that the coating structure of hot-stamped GA may change during tempering. Tempering at more than 500°C separates the Fe-Zn solid solution, which is the hot-stamped GA coating, into two phases, a r phase and an Fe-Zn solid solution, which contain less Zn than the original. This coating structure change results in lamellar structure formation. Lamellar structure formation is thought to be caused by discontinuous precipitation from the Fe-Zn supersaturated solid solution. The main factor of generating lamellar structure formation is the diffusion velocity of Fe and Zn, determined by the tempering temperature. In addition, the driving force of the phase separation has an effect on this reaction.

Original languageEnglish
Title of host publication6th International Conference Hot Steel Metal Forming of High-Performance Steel, CHS2 2017- Proceedings
EditorsMats Oldenburg, Braham Prakash, Kurt Steinhoff
PublisherAssociation for Iron and Steel Technology, AISTECH
Pages121-129
Number of pages9
ISBN (Electronic)9781935117667
Publication statusPublished - 2017 Jan 1
Externally publishedYes
Event6th International Conference on Hot Steel Metal Forming of High-Performance Steel, CHS2 2017 - Atlanta, United States
Duration: 2017 Jun 42017 Jun 7

Publication series

Name6th International Conference Hot Steel Metal Forming of High-Performance Steel, CHS2 2017- Proceedings

Other

Other6th International Conference on Hot Steel Metal Forming of High-Performance Steel, CHS2 2017
CountryUnited States
CityAtlanta
Period17/6/417/6/7

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Metals and Alloys

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