Resistance microwelding of crossed Pt–10Ir and 316 LVM stainless steel wires

Resistance microwelding of dissimilar materials such as Pt–10Ir and 316 low carbon vacuum melted stainless steel is becoming increasingly important for making electrical connections in medical devices. The joining of dissimilar materials increases flexibility in design while providing economic advantages, where more cost effective materials can be substituted for traditional materials. In this work, the performance of joints made using different electrode forces was studied by examining the surface morphology, cross-sections, joint break force and dynamic resistance measurements from resistance microwelding joints. Electrode sticking and excessive expulsion were observed with low electrode forces, whereas joints with undesirable cracks and notches were produced at higher electrode forces. Based on the analysis of single pulse welds, a new process variation using multiple pulses was developed, which improved the weld surface quality while obtaining a joint strength near 90% of the Pt–10Ir wire tensile strength.