Welding Tips and Tricks

Do TIG welds in stainless exhibit hardening or other annoyances for later machining work, such as drilling and tapping? I received some 304 cable-style handrail posts with oversized nuts already welded into them, so I'm wondering if I can weld 'em up and then drill and tap to the correct smaller size.

I have not had any adverse effects from machining stainless after welding. Use a good cutting fluid, and you should be fine.

Stainless is "gummy" and difficult to machine regardless of the condition it's in, but after welding it's even worse to tap. Harder is actually better, not worse. It's the gummy nature of it that makes tapping difficult.

I might opt to even try never-seize as a tap "fluid" if the stuff has been welded. It LOVES to gall and bind on things, even threading a part together by hand often results in them seizing to where it's not possible to ever get them apart. I'd use some black molybdenum based lube as a tap lube, but that's just me.

Yup.. Austenitic stainless steels like 304, 316 and the like are by default more tricky to machine as it won't make a good chip and tends to gall quickly.

The advantage of these in fabrication though is that 304 and 316 and the like do not harden with heat, but can only be (cold) work hardened, so the material stays basically the same wether it's welded or not. Still machines just as bad

LIke mentioned above, don't spare the cutting fluid and go slow and steady in stainless and it will work. For drilling stainless I personally like to use cobalt drills, but again with plenty of cutting fluid and fairly low speeds.

There are many stainless types and some that can be easier to machine (eg. 303), but that usually comes with other tradeoffs like reduced corrosion resistance or less visual appeal, which is often the reason stainless is used to start with. If you want to go down the rabbit-hole of stainless steels, start searching for 'duplex stainless' and 'precipitation hardened stainless' for the more esoteric ones

Bye, Arno.

Very belated thanks to all. (This isn't the only forum I've had trouble with getting set up to notify me of new replies...says it is, then...doesn't...)

Pants wrote: ↑Mon Mar 21, 2022 8:15 pm Very belated thanks to all. (This isn't the only forum I've had trouble with getting set up to notify me of new replies...says it is, then...doesn't...)

You cheating on us? lol JK

My first job. Drill dept. at Leeds & Northrup.
1 thing I learned, dull your drill bit slightly. It will last much longer.
302 and 304 are bitches to tap. Do it by hand. Thick lube of course.
316 we did a lot. Much easier tapping. Seems more ductile than 302/304.
Weld 300 series. Never fear, it does not harden.
Weld 400...not so forgiving.