Any experience with 409 Stainless?

Date 09-12-2009 13:20 Edited 09-12-2009 14:34

I am interested in hearing opinions on AK Steel 409 stainless.

Their publication claims few worries about sensitization or 885 embrittlement.

Given a choice between 410, 430, and 409 I am curious if it might be the silver bullet.

I have my back against the wall because I am forced into a 400 series weld that can not be post weld heat treated.

The bad thing too is it is a manual weld on a thin wall tube without cooling or heat sink fixturing.

I am also having trouble finding a domestic supplier since this part must begin its life as bar stock before it becomes a tube with a threaded hex nut. It looks like AK steel only makes it in tube form. The other issue is rust. It forms a protective layer that has poor appearance but it won't corrode supposedly.

By jarcher (**)

Date 09-12-2009 17:07

FWIW, we just did a 410 to 316L with 316L filler on 1/2" material with no PWHT, 300F preheat and had no embrittlement problems. It is key that the 410 be in the annealed condition, ~ 65Ksi UTS. I didn't have the time or money to try other HT conditions, and I really doubt very much whether we would have successful with hardened or quenced and tempered conditions.

By OBEWAN

Date 09-12-2009 17:29

We weld a lot of 410 too with no heat treat. The issue is this is a 430ti to 430 weld currently. I want to kill any possiblity of a problem since we have cracks in the field. I am even willing to consider using a stabilized austenitic filler, but the joint is not designed for filler. 410 might give us better results, but also could bring the same problems. A lot of variability seems to exist between suppliers too. I am afraid it could become quite a science fair project if we have to generate a custom material spec of our own. There is some possibility of finding a smoking gun tramp element, but there may be more practical and easier fixes to implement like using 410. The effort to switch and requalify is a bit of work too.

By Lawrence (*****)

Date 09-12-2009 21:28

Consumable insert?

By OBEWAN

Date 09-12-2009 23:02

That is a pretty good idea, but I don't know if it would be any better than a fillet weld. The current joint is an edge flange weld made by a connector nut that pilots over a tube. The resultant weld resembles a fillet weld. That is what I hate about it. The weld symbol calls a butt for a flange that ends up a fillet. It is a constant source of confusion and debates for design reviews and shop inspections. If we could add filler and make it a fillet weld I would be happier, but not all others. The concern would be getting pen on the edge flange, but is pen really an issue on a fillet if the edges are fused? I have only seen fillet weld specs for root pen in the vertex - ie a throat dimension. The problem is the weld is a stack and not a T though.

By OBEWAN

Date 09-13-2009 17:15

That gives me the idea of welding a 430Ti to a 321. 321 is available in bar and could be made into our connector nut.

By OBEWAN

Date 09-14-2009 14:29

There are still more claims on 409 made by ATI Allegheny Ludlum. They claim straight 409 still may have problems with sensitization and/or 885 embrittlement and they make a 409 HP that is not supposed to have these problems. The only problem is they do not make it in bar stock form. I suppose this is now one of these can't get there from here problems unless anyone else knows of other suppliers. I am headed towards a 321 now perhaps.

By DaveBoyer (*****)

Date 09-15-2009 02:36

I have no idea what they are like any more, but Carpenter Technology [CarTech] used to be a good company to work with, and they did a lot with stainless & other specialty steels. Everybody I knew who worked there has retired.

By Ke1thk

Date 10-01-2009 13:43

I recently have 409 experiences. One job is a 3" x .065 tube (409) to a 308 flange. I used Arcos 409 filler wire (GMAW-Robotic). I also had .065 to .065 joints.

I had great fear because of tight holes on the flange and burn-through because we're not purging. The welds look great. The burn-through is like a bead...it's perfect.

Also, another new part was a 409 tube to a carbon steel flange. It didn't look as good as the above, but it wasn't bad.

I was surprised at the burn through. There's on sugaring. It's nice and smooth.

Good Luck,

Keith