M3, M4, M5, M6, M8, M10, Stainless Steel (A2), Weld Studs.

M3, M4, M5, M6, M8, M10, Stainless Steel (A2), Weld Studs.
 
CD (Capacitor Discharge) Fasteners have a small pip under the weld end which melts during the arc and welds the end of the fastener to the material, this is assisted by spring pressure from the welding gun.
 
The process is completed from one side only and leaves a smooth and usually unmarked reverse side due to the extremely low weld penetration depth.