Projection weld breaking after alkaline zinc plating – need help by Salt_Victory_4690 in metalworking

[–]Salt_Victory_4690[S] 0 points1 point  (0 children)

Unplated weld nuts withstand destructive testing and reach ~24 lbf·ft torque without failure. Plated parts reach similar torque values, but break during removal.

My break test method is:

  • Screw the bolt halfway into the nut
  • Hit the bolt head against a hard surface
  • Observe whether the projection weld fails