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Effects of post-weld heat treatment on mechanical properties and microstructure of resistance spot–welded lightweight steel

  • Insung Hwang
  • Heewon Cho
  • Sangwoo Nam
  • Munjin Kang
  • Min-Seo Koo
  • Young-Min KimEmail author
ORIGINAL ARTICLE
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Abstract

To improve the mechanical properties of resistance spot–welded 780-MPa-grade lightweight steel, post-weld heat treatment (PWHT) through the application of a second welding current and using a furnace was performed after resistance spot welding. It was not possible to obtain satisfactory mechanical properties of the weld through the application of a second welding current. In the case of the PWHT by a furnace, the required loads were satisfied when PWHT was applied at temperatures of less than 300 °C for more than 30 min, and at more than 300 °C for 15 min or more. Due to the softening of martensite by PWHT, the resistance to fracture progression during tensile test was increased, and mechanical properties could be improved.

Keywords

Resistance spot welding Lightweight steel Post-weld heat treatment Tempered martensite Second welding current Furnace 

Notes

Acknowledgments

This research was funded by the Technology Innovation Industrial Program funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea) (Development of Car Body Modularization Technology using Advanced Cold Forming and Welding Technologies of Low Density GIGA Grade Light Steel Sheets).

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Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2019

Authors and Affiliations

  • Insung Hwang
    • 1
  • Heewon Cho
    • 1
    • 2
  • Sangwoo Nam
    • 1
    • 3
  • Munjin Kang
    • 1
  • Min-Seo Koo
    • 4
  • Young-Min Kim
    • 1
    Email author
  1. 1.Joining R&D GroupKorea Institute of Industrial TechnologyIncheonRepublic of Korea
  2. 2.School of Mechanical Design EngineeringHanyang UniversitySeoulRepublic of Korea
  3. 3.Department of Materials Science & EngineeringSeoul National UniversitySeoulRepublic of Korea
  4. 4.Technical Research Laboratories Gwangyang Research Lab.Sheet Products & Process Research Group, POSCOGwangyangRepublic of Korea

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