Effect of Heat-Affected Zone on Spot Weldability in Automotive Ultra High Strength Steel Sheet

Akihiko Nagasaka, Junya Naito, Shota Chinzei, Tomohiko Hojo, Katsumi Horiguchi, Yuki Shimizu, Takuro Furusawa, Yu Kitahara

研究成果: Chapter

抜粋

Effect of heat-affected zone (HAZ) on spot weldability in automotive hot stamping (HS) steel sheet was investigated for automotive applications. Tensile test was performed on a tensile testing machine at a crosshead speed of 3 mm/min, using spot welded test specimen (Parallel length: 60 mm, Width: 20 mm, Thickness: 1.4 mm, Tab: 20×20 mm). The spot welding test was carried out using spot welded test specimen with welding current (I) of 6.3 kA to 9.5 kA. Hardness was measured with the dynamic ultra micro Vickers hardness tester. In HS steel, has very high strength of 1 500 MPa, tensile strength (TS) and total elongation (TEl) of the spot welded test specimen of HS steel were lower than those of base metal test specimen. The spot welded test specimen broke in the weld. The Vickers hardnesses (HVs) of base metal and fusion zone of hot stamping steel were around HV500. In addition, the hardness of HAZ was under HV300. The difference of hardness between fusion zone and HAZ was around HV200. The hardness distribution acted as a notch. On the other hand, in dual phase (DP) steel, has low strength of 590 MPa, the TS of spot welded test specimen of DP steel was the same as the base metal test specimen because of the breaking of base metal. The TEl of the spot welded test specimen of DP steel was smaller than that of base metal test specimen. In the spot welded test specimen of DP steel, the hardness of base metal was around HV200 and the fusion zone was around HV500. The hardness distribution did not act as a notch. The difference in hardness between base metal and HAZ acted on a crack initiation at HAZ softening.

元の言語English
ホスト出版物のタイトルHSLA Steels 2015, Microalloying 2015 and Offshore Engineering Steels 2015 Conference Proceedings
出版者wiley
ページ489-494
ページ数6
ISBN(電子版)9781119223399
ISBN(印刷物)9781119223306
DOI
出版物ステータスPublished - 2015 11 6

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)

フィンガープリント Effect of Heat-Affected Zone on Spot Weldability in Automotive Ultra High Strength Steel Sheet' の研究トピックを掘り下げます。これらはともに一意のフィンガープリントを構成します。

  • これを引用

    Nagasaka, A., Naito, J., Chinzei, S., Hojo, T., Horiguchi, K., Shimizu, Y., Furusawa, T., & Kitahara, Y. (2015). Effect of Heat-Affected Zone on Spot Weldability in Automotive Ultra High Strength Steel Sheet. : HSLA Steels 2015, Microalloying 2015 and Offshore Engineering Steels 2015 Conference Proceedings (pp. 489-494). wiley. https://doi.org/10.1002/9781119223399.ch58