Weldability and Electrode Wear Characteristics of Hot-Dip Galvanized Steel With and Without a Ferrophos Containing Primer

This study examined the effect of primers containing a conductive pigment on the resistance spot weldability of hot-dip galvanized steel. The pigment used was ferrophos, essentially Di-iron phosphide. Basically, two types of tests were used in this work. Current range tests were used to establish the effect these primers have on the effective ranges of weldability. Limited electrode life tests were used to infer the long term performance of the hot-dip galvanized steels with and without this paint.

It was found that the addition of the Ferrophos bearing paints had pronounced effects on weldability. Typically, required current levels were reduced by several thousand amps, and effective current ranges were increased by 50 to 100 percent.

During electrode life testing significant reductions were also noted both in the rates of electrode face diameter increase, and the degree of electrode pitting. In addition, improvements were noted in the degree of current range shifts for a given level of electrode wear.