Question

A resistance seam-welding operation is performed on two pieces of 3-mm-thick austenitic stainless steel to fabricate a container. The weld current in the operation is 12,000 amps, the weld duration = 0.25 sec and the resistance at the interface is 90 micro‑ohms. Continuous motion welding is used, with 250-mm-diameter electrode wheels. The individual weld nuggets formed in this RSEW operation have diameter = 8 mm and thickness = 4 mm (assume the weld nuggets are disc‑shaped). These weld nuggets must be contiguous to form a sealed seam. The power unit driving the process requires an off‑time between spot welds of 1.5 sec. Given these conditions, determine:

i)     The unit melting energy of stainless steel; (I got 16.114 J/mm^3, not sure if it's correct)

ii)    The proportion of energy generated that goes into the formation of each weld nugget, (I got 16.67%, not sure if it's correct) and

iii) The rotational speed of the electrode wheels. (not sure how to do this part)

Answer 1