Local approach applied to the fracture toughness of resistance spot welds

Florent Krajcarz (1, 2) , Anne-Françoise Gourgues-Lorenzon (1) , Emmanuel Lucas (2) , Matthieu Mazière (1) , André Pineau (1)

1 MAT - Centre des Matériaux
2 ArcelorMittal

A recently developed methodology for measuring the nugget fracture toughness in mode I was applied to three high-strength steel resistance spot welds, exhibiting either mixed cleavage/ductile or ductile fracture at room temperature. Fracture toughness tests revealed a difference in ductile-to-brittle transition temperature between the welds. Constitutive equations of weld nuggets were determined and implemented in a finite element model of the fracture toughness test, revealing both in-plane bending and in-plane stretching in front of the crack tip. Brittle cleavage fracture of the nuggets is not conveniently described using a simple Ritchie-Knott-Rice approach but the Rice-Tracey model allowed quantitatively relating the high number density of small particles to the nugget fracture toughness in the ductile regime.

Mots clés: Local approach; Brittle to ductile transition; High strength steels; Resistance spot welds

Domaines: Sciences de l'ingénieur [physics]; Matériaux

Florent Krajcarz, Anne-Françoise Gourgues-Lorenzon, Emmanuel Lucas, Matthieu Mazière, André Pineau. Local approach applied to the fracture toughness of resistance spot welds. 13th international conference on fracture, Jun 2013, Beijing, China. 10 p. ⟨hal-00853411⟩