Soldering on stainless steel - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: July 10, 2021, 03:39:30 am
content: I have small strips of stainless steel 202 grade (5cmx2cm) , thcinkess is 0.4mm of sheet.I tried to do direct tinning of it on small area so that i can direct solder wire on it for use. Tempearture of iron is 425C.Sometimes tinning happens and sometimes not? whats the right way to do it?

author: viperidae
author_rank: Frequent Contributor
timestamp: July 10, 2021, 03:44:17 am
content: At the very least you'll need an acid flux to get through the oxide layer.

author: Zoli
author_rank: Frequent Contributor
timestamp: July 10, 2021, 03:51:36 am
content: Kester 817is the answer; unfortunately, the smallest amount is one gallon.

author: Ian.M
author_rank: Super Contributor
timestamp: July 10, 2021, 04:13:02 am
content: Quote from: viperidae on July 10, 2021, 03:44:17 amMaybe not. Copper sulphate solution and a Q-tip may be sufficient to flash plate the area you want to solder to with enough copper for it to 'take' solder. See my comments here:https://www.eevblog.com/forum/beginners/soldering-to-strange-metal-contacts/msg3315024/#msg3315024+ later in the same topic.

author: Raj
author_rank: Frequent Contributor
timestamp: July 10, 2021, 05:03:09 am
content: Quote from: Vindhyachal.takniki on July 10, 2021, 03:39:30 amexperiment with braising some other metal onto it. Handling Oxy Acetylene or propane is easier than using chemicals.Get a brass brush and heat your steel part until rubbing that brush there, will turn it yellowish.btw. flux for stainless steel usually have HCL (very dangerous)

author: Raj
author_rank: Frequent Contributor
timestamp: July 10, 2021, 05:06:43 am
content: https://youtu.be/hz6wdvraC-g?t=68

author: gcewing
author_rank: Regular Contributor
timestamp: July 10, 2021, 05:50:30 am
content: Quote from: Raj on July 10, 2021, 05:03:09 amI think you mean brazing.You could try braising, but I don't think it would work very well on stainless steel...

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 10, 2021, 07:36:28 am
content: Since you're already getting intermittent results, maybe try adding some RA flux?

author: bobbydazzler
author_rank: Regular Contributor
timestamp: July 10, 2021, 07:41:12 am
content: sand the surface down a little?

author: RoV
author_rank: Regular Contributor
timestamp: July 10, 2021, 09:45:20 am
content: I confirm brazing with silver-loaded material (Castolin or similar) allows using tin over it, but requires a flame.Another technique that I found useful is attaching a small patch of Nickel with the spot welder (same material and technique used for connecting 18650 batteries). Nickel patches attach very strongly to stainless steel and then are easily tinnable.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 11, 2021, 08:45:05 pm
content: The problem with stainless steel is that it has a thin oxide skin (Just like Aluminimum) and the solder does not adhere to this oxide.There are fluxes specifically designed for use on stainless steel. These are usually quite agressive acids, that dissolve the oxide.It also helps if you use sandpaper just before soldering, and do this under an protective atmosphere.For example, fist use dry sand paper, then apply some "regular" flux just to form an air tight layer, and then scrub again with a glass fiber pencil through the flux.

author: wizard69
author_rank: Super Contributor
timestamp: July 12, 2021, 11:52:25 pm
content: It might help to say why you are doing this. Also what are you trying to solder to that stainless. There are a range of soldering and brazing solutions that might apply. Then there is welding.

author: Raj
author_rank: Frequent Contributor
timestamp: July 13, 2021, 04:07:02 am
content: Quote from: wizard69 on July 12, 2021, 11:52:25 pmHe's gonna need high temp gases or argon for welding such thin metal. But ones he has that, brazing with TIG is pretty easy.