Stainless Steel or Zinc plated Screw
Stainless Steel or Zinc plated Screw
(OP)
Situation #1: I have two powder coated steel plates that will be attached with #8-32 screws. There are clearance holes in one plate and threads in the other plate. They will be installed indoors at room temperature in Florida. I am concerned with the high concentration of salt in the moist humid air so I want the correct screw material to reduce the possibility of galvanic corrosion between the screws and the steel plates. Cost and strength are not a consideration. Would electrodeposited zinc plated steel screws or 316 passivated stainless steel screws be a better choice to avoid galvanic corrosion?
Situation #2: I am attaching a zinc plated steel DIN rail to one of the painted steel plates. What would be the correct choice screw material to best prevent corrosion between the screw and the DIN rail, an electrodeposited zinc plated screw or a stainless steel 316 screw?
Situation #3: If you specify a zinc plated screw for either of the above situations, is there a possibility that the zinc plating itself may eventually disappear and then the steel screw would start to rust?
Situation #2: I am attaching a zinc plated steel DIN rail to one of the painted steel plates. What would be the correct choice screw material to best prevent corrosion between the screw and the DIN rail, an electrodeposited zinc plated screw or a stainless steel 316 screw?
Situation #3: If you specify a zinc plated screw for either of the above situations, is there a possibility that the zinc plating itself may eventually disappear and then the steel screw would start to rust?





RE: Stainless Steel or Zinc plated Screw
How long do you want it to last?
Are there actual electrical requirements involved, e.g. do the plates have to bonded to each other electrically, independent of attaching means?
I think the tapped hole in the mild steel plate will disappear first.
Mike Halloran
Pembroke Pines, FL, USA
RE: Stainless Steel or Zinc plated Screw
RE: Stainless Steel or Zinc plated Screw
If you're really worried about corrosion, and bonding is not required, nylon screws in tapped metal holes might be better, and ty-raps threaded through adjacent holes punched before powdercoating would be even better than that.
Mike Halloran
Pembroke Pines, FL, USA
RE: Stainless Steel or Zinc plated Screw
RE: Stainless Steel or Zinc plated Screw
Stainless steel fasteners are not suitable for these parts, they will make galvanic corrosion worse.
A better option for these conditions is a steel fastener with a zinc-rich coating like Magni 565 or Dorken Delta-Protekt or Atotech Zintek.