Weldability of Galvannealed Interstitial Free Steel

Abstract

A series of interstitial free steel strips were subjected to different annealing treatments after being galvanized by immersion. Samples from these strips were cut and various tests were carried out on them. The coating was studied by optical and scanning electron microscopy, analysis of the X-ray spectra was conducted on the samples while being observed in the latter equipment. Resistance to powdering of the coating was studied by means of V-bend testing. Spot resistance welding tests were conducted by varying the current supplied by the machine, different geometrical parameters and the resistance of the welded joint were evaluated. It was found that the amount of powdering of the coating increased as the amount of Γ phase augmented, as well as with the increment in coating thickness. The mechanical strength of welded strips was found to improve with the increment in welding current, up to the point where expulsion of material was occurred.