Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Can stainless steel be hot dip galvanized?
Q. I have a piece of stainless steel which has some mild steel screws broken off inside and are difficult to remove.
This item is exposed to the outside weather and so we believe it will generate rust due to the reaction of the two metals.
We had a thought to seal the mild steel screws in side the stainless steel by welding them closed.
Any comments or suggestions.
The next question is it possible to galvanise the item which should encase the two metals and should prevent rust or is not a good idea to attempt to galvanise stainless steel.
Jeffrey Schachat
Construction - South Africa
2006
A. Stainless does not galvanize, but this depends a little on the grade of SS. 316: not, 304: a little. Both: a mess. A. Yes, it will lead to rust in those spots. welding over the spot will work, but you will have a bit of an alloy from the melted screw. You will also have some heat discoloration in that area unless you do a very slow or cold weld or with several starts and stops and cooling the parent metal with dry ice. Do you think that you can use a stainless steel filled epoxy? several Mfgr's sell it. |
A. For mild steel parts imbedded within stainless steel, and of course depending on size, weight and shape, and elements of mechanical stress, a stainless steel part can be coated, galvanized with special surface anchor pattern, pickling, double dip required.
However, it would be faster, easier, more cost effective, and reliable for these areas of mild steel within stainless to be encapsulated with stainless via welding or flat iron soft soldering. I toured a factory in Texas that produced stainless steel extractor drums approximately 20' x 7' for spinning 3000 lbs. of materials to 1500 rpm. To my surprise, the ends of these units were 2" thick cold rolled 4140 mild steel plate covered (fully encapsulated) with 10 gauge (1/8 inch) 316 stainless steel sheet, welded with 304 stainless filler all done hot & tight so the finished huge heavy disk looked like and acted like a solid stainless steel disk.
You can also soft solder stainless steel & mild steel with standard plumbing 95/5 or 50/50 solder if you use the correct flux and heating method (flat iron soldering). I've done both of these processes on small projects with relative ease and good long term reliability.
- Houston Texas
January 9, 2023
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