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<p>The failure behavior of resistance spot welds in advanced high-strength steels (AHSS) is traditionally attributed to nugget size and hardness characteristics; however, the influence of weld notch geometry has received limited attention. In this study, the effect of notch morphology on mode-I pullout failure was investigated in 1200&#xa0;MPa martensitic AHSS under cross-tension loading. Two distinct notch shapes-sharp V-shaped and tongue-shaped-were produced through low-heat (LH) and high-heat (HH) welding schedules, respectively. Interrupted cross-tension tests revealed that notch geometry fundamentally controls the failure mechanism by dictating stress concentration, local constraint, and the effectiveness of the solid-state corona bond. LH welds, which develop a sharp notch and a weak corona bond, exhibit brittle cleavage initiated at the fusion boundary/upper-critical HAZ. Conversely, HH welds form a tongue-shaped notch with a continuous and strong corona bond, allowing strain localization in the softened subcritical HAZ (SCHAZ) and leading to ductile micro-void coalescence. These findings demonstrate that pullout failure is governed by the <i>combined</i> effect of notch geometry, corona bond integrity, and SCHAZ softening. The results highlight weld notch morphology as a critical geometric parameter that must be incorporated into predictive models and finite-element simulations for crashworthiness assessments of AHSS structures.</p>

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Effect of Notch Geometry on Opening-Mode Pullout Failure of AHSS Resistance Spot Welds

  • 期刊论文

  • 发表日期：

    2026年4月19日

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  • Nima Nadimi,
  • Majid Pouranvari

摘要

The failure behavior of resistance spot welds in advanced high-strength steels (AHSS) is traditionally attributed to nugget size and hardness characteristics; however, the influence of weld notch geometry has received limited attention. In this study, the effect of notch morphology on mode-I pullout failure was investigated in 1200 MPa martensitic AHSS under cross-tension loading. Two distinct notch shapes-sharp V-shaped and tongue-shaped-were produced through low-heat (LH) and high-heat (HH) welding schedules, respectively. Interrupted cross-tension tests revealed that notch geometry fundamentally controls the failure mechanism by dictating stress concentration, local constraint, and the effectiveness of the solid-state corona bond. LH welds, which develop a sharp notch and a weak corona bond, exhibit brittle cleavage initiated at the fusion boundary/upper-critical HAZ. Conversely, HH welds form a tongue-shaped notch with a continuous and strong corona bond, allowing strain localization in the softened subcritical HAZ (SCHAZ) and leading to ductile micro-void coalescence. These findings demonstrate that pullout failure is governed by the combined effect of notch geometry, corona bond integrity, and SCHAZ softening. The results highlight weld notch morphology as a critical geometric parameter that must be incorporated into predictive models and finite-element simulations for crashworthiness assessments of AHSS structures.