Integral Coach Factory (ICF) is the nation’s first and largest passenger coach manufacturing unit, producing over 3000 coaches annually. Resistance spot welding is a primary welding technique deployed in fabrication of railway coach shells.

Passenger coach shell side walls and end walls are made of SS 409M of 3mm thickness. To obtain the required rigidity and structural strength for the side walls and end walls, they are welded to horizontal and vertical stiffeners by means of resistance spot welding.

In a single side wall of a LHB coach, over 3000 spot welds are carried out. In the current paper, the change in mechanical properties and mode of failure during application of shear loads is discussed for 3 different Welding Procedure Specification (WPS) used in the 3 different Robotic resistant spot welding machines that are deployed in ICF for side wall fabrication.

In addition, the paper also discusses the lack of specific acceptance criteria in standards that govern quality control and WPS of spot welds, which leads to non-uniformity in properties of spot welds.

This article is shared by R. Niranjan, A. Ganesh and V. Gnanamoorthy.