Welding Tips and Tricks

Noob Question: I scuba dive. The metal hardware for scuba diving is often made from 316 stainless steel. Regardless of the years of use, these factory-manufactured parts never show corrosion. On occasion, I attempt to modify a 316 SS part with TIG welding. After my TIG work, I often observe what looks like brown rust around my work. After I wire brush the corrosion off it reappears on the next dive. What have I done wrong? Thanks

I believe you need to passivate the weld. There is a citric-acid based spray that is easily accessible.

To weld 316 and avoid corrosion, you need to use 316 or better filler, purge the backside of the weld, and passivate it. Then it will not corrode.

And as much as possible keep the heat input low, so if you had several inches to weld you could do a 1/2" length, let the part cool and repeat.

Also make sure any wire brush/wheel or abrasive you use on the part or weld has not been in contact with low carbon steel or cast iron as you will contaminate your part with it and it will rust. "Never the twain shall meet."

Thanks everyone. Very good information.

Yup.. LIke mentioned above you need to use at least 316 filler and usually pickle/passivate afterwards to get a 'pure' stainless surface again that can form it's protective oxide layer.

But the issue with welding stainless is also in how hot you get the area around the weld.

If you overheat the base material then then the nickel in the alloy comes out of the steel solution, depletes it, and you get an area next to the weld that's lost a lot of it's corrosion protection in the base material itself.

While passivating this may show up as an area that gets deeply etched by the acids as it has turned more into a plain steel.

On stainless things to keep in mind are:

• ONLY use stainless steel brushes and use these dedicated for stainless work
• Do not use any of your abrasives on other materials or steels as it will contaminate the stainless with bits of metal/steel from other sources
• Use the correct filler for the stainless type. Often using a higher grade filler compared to a base is OK. Don't use a lower grade. Using low-carbon (eg. 316L ) also helps.
• Get good gas coverage and seal/purge any areas on the back that may get exposed to air while welding.
• Keep your heat input in check (304 and 316 are austenitic, so you can cool them with damp rags without hardening) to prevent changing the base material composition
• Use a passivating solution/gel to treat the surface and get the full corrosion protection after welding

Bye, Arno.

Coldman wrote:Also make sure any wire brush/wheel or abrasive you use on the part or weld has not been in contact with low carbon steel or cast iron as you will contaminate your part with it and it will rust. "Never the twain shall meet."

Yup make sure the wire brush is SS as well. I label my brushes and grinder wheels that are SS only.

robertaustin wrote:Hi,

TIG Welding 316 Stainless Steel is a good choice but my favorite is Miller Maxstar 150 STL which I found on Welding Judge.

It has DC inverter with lift arc features.

You can read more details about it here: xxxx

That's an odd post. Curious if it is just a bot ad for that website, or if the link is a virus. Either way, I won't click it to find out.

Spartan wrote:
That's an odd post. Curious if it is just a bot ad for that website, or if the link is a virus. Either way, I won't click it to find out.

its spam.
reported, mods should clean it up soon.

tweake wrote:

Spartan wrote:
That's an odd post. Curious if it is just a bot ad for that website, or if the link is a virus. Either way, I won't click it to find out.

its spam.
reported, mods should clean it up soon.

Gotcha. Seemed like something fishy was going on there. Those people would probably find a lot more success in life if they spent their time trying to build legitimate business instead of spending their time trying to spam/scam/trick people.

Kind of sad when you think about it.

Spartan wrote:

tweake wrote:

Spartan wrote:
That's an odd post. Curious if it is just a bot ad for that website, or if the link is a virus. Either way, I won't click it to find out.

its spam.
reported, mods should clean it up soon.

Gotcha. Seemed like something fishy was going on there. Those people would probably find a lot more success in life if they spent their time trying to build legitimate business instead of spending their time trying to spam/scam/trick people.

Kind of sad when you think about it.

i suspect its a fake review site. which is all to common these days. not sure if its ad driven or sponsored. sometimes they trick a company into sponsoring them. spam the crap out of everyone to generate traffic, show traffic report to sponsors to get them to pay for reviews.

i've dealt with small successful companies that have spent the time on forums etc. they will post products but also answer questions, show how to do things. get involved with their customer base. of course most of that has moved to FB and IG.