Forming galvanized parts.

[Hercules28]

Dear all,

I am stamping some galvanized carbon steel plates. Usually the galvanizing was after the stamping but I got a batch to try out. Do you expect any problems with forming or a deterioration of the coating?

I have heard that hot dip galvanizing is a metallic coating so it shouldn't chip off.

Any comments?

 

[metengr]

Do you expect any problems with forming or a deterioration of the coating?

Yes, cut edges are exposed (unprotected) if you are stamping parts and possible delamination in heavily formed parts.

If you are concerned why ask here, why not subject them to corrosion testing?

 

[swall]

Hercules28, galvanized steel comes in a wide variety of forms. There is hot dipped galvanized and electro galvanized and these can be applied in different coating thicknesses. The steel supplier would have to work with you to find the best combination of formability and corrosion resistance for your application.

 

[Hercules28]

I am not conserned as much for corrosion, but for embritlement.

 

[TomDOT]

The problem with corrosion testing galvanized products is that the conditions usually used to "accelerate" corrosion (salt fog) are disproportionately aggressive to metallic zinc. A lot of the corrosion resistance of the zinc is due to the (eventual) zinc carbonate patina which forms from the initial zinc oxides and hydroxides. In a continuous-wet or mostly wet (intermittent) salt fog, the zinc never has a chance to form the protective patina, and corrodes much faster and with a different mechanism than it would in most real-world (onshore anyway) conditions.