Destructive testing and hardness measurement of resistance stud welded joints of ASTM A36 steel

Abstract

Resistance stud welding process is mostly used in several industries for manufacturing and joining of structural parts and components. During this process, the stud is stably welded on a base plate or component before bringing the other part or component to join them together by means of mechanical fastening. Resistance stud welding is a fast process with high energy density and low heat input that minimize the amount of residual stress and is suitably used for welding and joining of sheet metals that have a risk of distortion which can cause problems during assembly steps. In this study, we investigated the optimum resistance stud welding process parameters for stud welding on 3 mm thick ASTM A36 steel. The variable process parameters include main current time (MC time) from 5 to 50 ms, and pre-current time (PC time) of 20, 40, and 60 ms. After stud welding is complete, destructive testing was performed on stud welds by visual inspection and bend test to primarily check which parameter combinations are suitable for stud welding of ASTM A36 steel. Then, the specimens were macro-tested and hardness test to check the soundness and changes in mechanical properties in the stud heat affected zone regions. It was found that for stud welding of ASTM A36 steel, the suitable parameter is MC time between 25 and 35 ms and PC time between 20 and 60 ms.