is stainless welding much harder?

[e9999]

I'm a beginner at welding. Not much experience yet but I do plan on learning more and doing some fabbing eventually. I'm doing both MIG and TIG now in a shop, but of course it may end up being MIG mostly if I get a home welder.
I have the opportunity to get quite a bit of stainless tubing from scrap which sounds good for subsequent fabbing plans, except that I don't know if SS welding is much harder than regular carbon steel. If it's not I may want to stock up on that SS, but if it is it may not be worth it. If it's just a matter of using the right wire, than no biggie, but if it's an order of magnitude more difficult than carbon and requiring much training, I may not get there during my lifetime...

 

[gtfour43]

For tig welding it welds basically the same as cs. I use the same amps on both as well.

 

[cruiser88]

No, not much diffrent.

 

[spressomon]

This may or may not matter to you: Most stainless is considerably harder to drill and cut...since you mentioned tube project

Haven't noticed a big difference with TIGing SS so far...albeit I'm a TIG newbie. MIG...again not much difference. Welding SS sounds a little different though...

 

[e9999]

yes, cutting and all may be an issue, but welding sounds good so far.
What about welding a SS piece to a CS one. Is that more problematic?

 

[Michael Hanson]

Why would you switch materials? Mike

 

[cruiser88]

I got some stainless rods from PPG, those welds have never gotten anything but surface rust, not treated. Thats why I prefer it.

 

[Mace]

Stainless is no harder than conventional (mild) steel. And combining it to mild steel is simple. That being said, if you do weld stainless to mild steel the weld will rust so you are painting it anyway.

Supressomon, stainless is about as resistant to drilling/cutting as mild steel is. Alloys of carbon steel are much more resistant (I'll use the garbage can term for chromo) to drilling/cutting.

I will also mention that there are some high tech alloys of stainless that are much stronger now tho.

 

[steffan]

The actual welding part is about the same but there are a lot of subtleties when welding stainless steel that you need to pay attention to. You should know what type of stainless you have so you know how to approach it. Supposed to use pure argon gas, shielding gas on both sides of the weld, if you get it to hot you get chromium precipitation and it will oxidize quickly and be very weak also stainless will tend to shrink and crack. There's a lot of good info out there on the web depending on how critical the part is

 

[fabriwelder]

Stainless Welding.

TIG welding stainless-

Much like TIG welding CS. You do need a purge on the back side of the weld, or it will sugar. You can use an argon purge, flux cored TIG wire, or Solar Flux.

Welding stainless to carbon is the same process and is not any more difficult. You will need to use the proper wire however. Like 309, Inconel, depends on the two metals. Still need a purge.

You can quench stainless between passes, use a squirt bottle with water.



Stick welding stainless-

Less difficult. Don't need the purge. Can do dissimilar weld.....

 

[brian]

Stick welding stainless-

Less difficult.....

have to disagree with you here.
for the average home garage guy, stick welding stainless will be a handful.


a back purge is not required to weld stainless. however you need to pay attention to your heat setting.

 

[TRAIL TAILOR]

have to disagree with you here.
for the average home garage guy, stick welding stainless will be a handful.


a back purge is not required to weld stainless. however you need to pay attention to your heat setting.

I can't help it.. I deleted my previous post but, I must comment on this one.

I have to disagree Brian...

If I'm looking at a GTAW/TIG weld that lost its purge on a SS weld or was welded without a purge... It's a reject, plain and simple, no questions asked. Purge on GTAW/TIG is an essential variable on 100% of any WPS/PQR I have ever reviewed. I’ve never seen a GTAW/TIG procedure that didn't require/call out an argon purge/cover on GTAW/TIG for SS.

Reason for rejection is that the "Sugar" / "Drywashing" effect is simply... S**T...and if a welder thinks it's OK, I'll jerk his certs and kick his A** down the road (It’s a quality and experience issue) and #2 is:

Two things happen when you overheat SS (THIS IS WHAT SUGARING AND DRYWASHING IS/CAUSES) by not using a purge/cover on SS:

1) The carbon combines with the chromium to make carbides.. This basically robs the surface of the chromium that forms the chromium oxide that creates the stainless' quality.

2) The other thing is that the iron, chromium, and everything else gets badly oxidized and forms scale and there will be a loss of corrosion resistance due to the chromium carbide you have created.

You may think that if you watch your heat you can do without a purge/cover (For a newb... IMPOSSIBLE) however, argon is a "Cold Gas" and therefore that is why it is the most common cover/shield/purge gas used and for a very good reason... I don't care if you talk to a metallurgist, welding engineer, CWI, SCWI, etc.. etc... we will all agree on this. Argon shields/protects the weldment and keeps the chromium safe/cool in its composition to maintain its integrity and corrosion resistance. Heat treated SS (which is basically what has been created without the purge/cover) will crack within days once introduced to an adverse ambient condition/sour gas/extreme cold and/or fluctuating pressures... list can go on for sometime...........

You can "back yard' a SS GTAW/TIG weld all day long.. this is true.. But, with the deletion of the purge/cover gas on SS... you are certainly going to have rust issues (due to #1 and #2 above) within a week and over time the weldment will become brittle/crack and lead to failure.

As far as stick welding SS.. I agree with you.... an average guy in the garage will have to spend some serious time practicing with this or it will be an absolute nightmare.

Boilermakers/etc.. use this everyday to weld CS/SS or SS/SS on SCR's, catalyst bays, etc.. You need to burn this hot, fast and pay attention to create a good quality weld. I've inspected 1000's of them inside power houses over the years. I've seen all qualities of SS stick welds...... I'll leave SS stick welding at that...

As with any welding... practice makes perfect..period...

J

 

[TRAIL TAILOR]

TIG welding stainless-

Much like TIG welding CS. You do need a purge on the back side of the weld, or it will sugar. You can use an argon purge, flux cored TIG wire, or Solar Flux.

Welding stainless to carbon is the same process and is not any more difficult. You will need to use the proper wire however. Like 309, Inconel, depends on the two metals. Still need a purge.

You can quench stainless between passes, use a squirt bottle with water.



Stick welding stainless-

Less difficult. Don't need the purge. Can do dissimilar weld.....

Agree with everything except the squirt bottle theory/recommendation.... Watering down a weld reduces ductility, strength, and eventually leads to embrittlement......

Most of the time a welder uses a squirt bottle or the " wet rag " trick to pull a weld.... reduce a dog leg... etc... I don't allow it on any of the projects I oversee. If you need to squirt/wet rag a SS weld... the welder needs to learn a better technique to reduce distortion... "quarter" welding, less heat input, get a more proficient travel speed...

J

 

[brian]

I can't help it.. I deleted my previous post but, I must comment on this one.

I have to disagree Brian...

If I'm looking at a GTAW/TIG weld that lost its purge on a SS weld or was welded without a purge... It's a reject, plain and simple, no questions asked. Purge on GTAW/TIG is an essential variable on 100% of any WPS/PQR I have ever reviewed. I’ve never seen a GTAW/TIG procedure that didn't require/call out an argon purge/cover on GTAW/TIG for SS.

Reason for rejection is that the "Sugar" / "Drywashing" effect is simply... S**T...and if a welder thinks it's OK, I'll jerk his certs and kick his A** down the road (It’s a quality and experience issue) and #2 is:

Two things happen when you overheat SS (THIS IS WHAT SUGARING AND DRYWASHING IS/CAUSES) by not using a purge/cover on SS:

1) The carbon combines with the chromium to make carbides.. This basically robs the surface of the chromium that forms the chromium oxide that creates the stainless' quality.

2) The other thing is that the iron, chromium, and everything else gets badly oxidized and forms scale and there will be a loss of corrosion resistance due to the chromium carbide you have created.

You may think that if you watch your heat you can do without a purge/cover (For a newb... IMPOSSIBLE) however, argon is a "Cold Gas" and therefore that is why it is the most common cover/shield/purge gas used and for a very good reason... I don't care if you talk to a metallurgist, welding engineer, CWI, SCWI, etc.. etc... we will all agree on this. Argon shields/protects the weldment and keeps the chromium safe/cool in its composition to maintain its integrity and corrosion resistance. Heat treated SS (which is basically what has been created without the purge/cover) will crack within days once introduced to an adverse ambient condition/sour gas/extreme cold and/or fluctuating pressures... list can go on for sometime...........

You can "back yard' a SS GTAW/TIG weld all day long.. this is true.. But, with the deletion of the purge/cover gas on SS... you are certainly going to have rust issues (due to #1 and #2 above) within a week and over time the weldment will become brittle/crack and lead to failure.

As far as stick welding SS.. I agree with you.... an average guy in the garage will have to spend some serious time practicing with this or it will be an absolute nightmare.

Boilermakers/etc.. use this everyday to weld CS/SS or SS/SS on SCR's, catalyst bays, etc.. You need to burn this hot, fast and pay attention to create a good quality weld. I've inspected 1000's of them inside power houses over the years. I've seen all qualities of SS stick welds...... I'll leave SS stick welding at that...

As with any welding... practice makes perfect..period...

J

You realize ss comes in shapes other than pipe right?

 

[TRAIL TAILOR]

You realize ss comes in shapes other than pipe right?

Fabriwelders post was based on purge that you disagreed with... therefore pipe.

Yes, SS along with all other metals can be any shape or size... No matter what the shape of any SS material.. What I posted still stands. SS degrades when a cover or purge is not applied.

BAD things are eventually going to occur.

J

 

[brian]

He may have been referring to pipe, however the post does not mention it. Just a blanket statement saying stainless needs back purged.... Which it does not need.
Shield gas around the puddle obviously.
The op is not doing code work and I doubt he is doing sanitary work either.

 

[cody c]

With a MIG, I found it not really harder than steel, but...

It seems there is a sweet spot with the amount of heat you put into it. You need to put heat into the metals, but just a pinch too much heat and your burning through much easier than steel.

Well, this is what I found with burning 304 for my exhaust anyway.

 

[LAMBCRUSHER]

been a while since I got to do any kind of volume with stainless, but I seem to feel like the stainless was cleaner overall and was IMO easier to weld than carbon. Tri mix gas in a mig rig and let er rip. it's just steel

 

[TRAIL TAILOR]

He may have been referring to pipe, however the post does not mention it. Just a blanket statement saying stainless needs back purged.... Which it does not need.
Shield gas around the puddle obviously.
The op is not doing code work and I doubt he is doing sanitary work either.

No, he doesn't post this is about pipe. Agreed. However, purge.. sugaring.. is indicitive of pipe and/or full penetration SS welds. So, yes if that is the case (pipe/full penetratiion) you would want the purge for a quality weld. Or I guess IF you can get to the backside (which is not always accessible) you can do without the purge, then grind and backweld, if not I hold strong to my previous statements. Code work on this varies.. some procedures/companies won't allow back gouge/back welding, just saying....

I understand this is not code work but, a good sound weld is probably what he is wanting to know how to produce. A sugared up, brittle weld is not and I think you would agree with that.

I personally think GTAW/TIG SS is easier than CS TIG once you do it enough. Some agree with me on this and others call BS. Different strokes for different folks.

Brian, I'm not trying to bust your chops on the purge. I just want guys to be as informed about welding as possible.Your statement was vague, "a back purge is not required to weld stainless." Sometimes its mandatory and sometimes not.

An inexperienced welder can take this statement many ways. If he takes it as he doesn't have to back purge ever when he needs to ... It's a bad weld and a frustrated welder. If he's doing a fillet weld on a lap joint... as long as he's got a good shield it's probably gonna be alright.

J

 

[gtfour43]

Purging or not will solely depend on joint design and material thickness no matter the metal being welded.