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Welding in the World

, Volume 55, Issue 11–12, pp 99–106 | Cite as

Methods to Obtain Weld Discontinuities in Spot-Welded Joints Made of Advanced High-Strength Steels

  • Holger Gaul
  • Stephan Brauser
  • Gert Weber
  • Michael Rethmeier
Peer-Reviewed Section

Abstract

Resistance spot welding is the major joining technique in mass car production. This applies in particular to high-strength steel and advanced high-strength steel (AHSS) joining of thin sheet steel components for lightweight body shell structures. Joining of AHSS in mass production might lead to weld discontinuities under certain circumstances. Those discontinuities in form of cracks might be an initial start of cracking in the spot-welded joints regarding fatigue loads. It is of great interest to figure out, if, in comparison to specimens without weld discontinuities, the crack initiating point changes and if the fatigue resistance might be reduced by the discontinuities. In this contribution, an overview of potential discontinuities is given. Their possible causes are discussed and means for their detection are highlighted. Among the possible causes of weld discontinuities, two major groups are distinguished: the welding parameters as primary influences in the welding process, and the production-specific influences as secondary ones. With emphasis on major cracks penetrating the weld nugget, these influences are analysed. Finally, a combination of extreme welding parameters with production-specific influences is chosen in order to establish a method which enables the preparation of fatigue test specimens with reproducible major cracks in different locations of the spot-welded joints. This method is then applied in order to prepare spot weld specimens for fatigue tests.

IIW-Thesaurus keywords

Cracking Defects Fatigue loading High strength steels Resistance spot welding 

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Copyright information

© International Institute of Welding 2011

Authors and Affiliations

  • Holger Gaul
    • 1
  • Stephan Brauser
    • 2
  • Gert Weber
    • 1
  • Michael Rethmeier
    • 2
  1. 1.BAM Federal Institute for Materials Research and TestingBerlinGermany
  2. 2.BAM Federal Institute for Materials Research and Testing and Fraunhofer IPKBerlinGermany

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