Effects of fusion zone size and failure mode on peak load and energy absorption of advanced high strength steel spot welds under lap shear loading conditions

Xin Sun, Elizabeth V. Stephens, Mohammad A. Khaleel

Research output: Contribution to journalArticle

143 Citations (Scopus)


This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of 4 sqrt(t) cannot produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

Original languageEnglish
Pages (from-to)356-367
Number of pages12
JournalEngineering Failure Analysis
Issue number4
Publication statusPublished - 1 Jun 2008
Externally publishedYes



  • Advanced high strength steels
  • Energy absorption
  • Failure load
  • Failure mode
  • Resistance spot welds

ASJC Scopus subject areas

  • Engineering(all)
  • Mechanical Engineering

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