M. Safari, H. Mostaan,
Volume 2, Issue 2 (11-2016)
Abstract
In this paper, resistance spot welding process of AISI 201 stainless steel is studied experimentally. For this purpose, effect of welding current on quality of weld is investigated and relationships between welding current and fusion zone characteristics are examined. For determining mechanical properties such as maximum load and fracture mode, tensile - shear test of spot welds is performed. Hardness and microstructural examinations are performed for study the influence of welding current on characteristics of welded joints. The results show that strength of resistance spot welds of AISI 201 stainless steel is increased with increase in welding current. Transition of fracture mode from interfacial to pullout and then pullout with tearing of sheet mode during tensile-shear tests of AISI 201 spot welds is investigated through experimental and theoretical approaches. It is concluded from results that increasing in welding current leads to change in fracture mode from interfacial to pullout mode due to increase in fusion zone size (weld nugget size). Also, it is observed that increasing in fusion zone size is accompanied by an increase in load carrying capacity of resistance spot welds. The minimum required fusion zone size to ensure pullout fracture mode is estimated using an analytical model.
H. Mostaan, M. Safari, A. Sonboli, M. Haddadi, A. Taherkhani,
Volume 4, Issue 1 (8-2018)
Abstract
In this paper, numerical and empirical investigations of the effect of AISI 347 stainless steel interlayer on the microstructure, mechanical properties and fracture mode of AISI 321 stainless steel resistance spot welds have been conducted. For this purpose, two types of joints, the first free from inter layer and the second contains interlayer with 0.05 mm thickness as well as difference currents and times,were evaluated. In order to examine the mechanical properties including maximum force and tensile mode, tensile – shear test of the spot welds was done. The obtained results indicated that an increase in the welding time and current resulted in a change in fracture mode from interfacial to peripheral owing to an increase in fusion zone volume. The change in the chemical composition because of the presence of interlayer and an increase in cooling rate caused the formation of different phases as well as observation of the dispersed Martensite phase in fusion zone.
