welding stainless to mild steel

rubbersdown · 09-26-2008, 01:22 PM

How do I go about welding stainless to mild steel? I can just use a regular mild steel rod or wire right? I am not worried about rust because they are going to be coated. I need to weld a 2.5 stainless pipe to a mild steel t6 flange.

99345hp · 09-26-2008, 05:24 PM

I would use a ER309 stainless wire. That is what we use at work to weld stainless to mild steel pipe. It welds really nice. I imagine your are tig welding? if not they do have 309 mig wire i believe, but ive never used it. Just make sure you purge the inside of the pipe when welding it together to prevent sugar on the inside.

THROTTLEJUNKIES · 09-29-2008, 05:35 PM

Use the 309 wire for the stainless. The only problem will be that the stainless and the milled steel will expand and contract at different rates so eventually after so many heat cycle the two will start to crack and pull away from eachother.

acidrain088 · 10-02-2008, 01:30 AM

ive had decent luck welding in mild steel 02 bungs into stainless with standart mild steel mig wire. the only thing you really have to wath out for is that u dont use too much heat. with mild steel too much heat isnt that big of a problem but with stainless it causes the chromium to seperate out causing a crappy weld and will rust extremly easily.

XtraCajunSS · 10-02-2008, 06:54 PM

I've had the best luck welding stainless to mild steel using stainless filler rod. The stainless filler helps to build a buffer between the differing expansion rates of the two metals.

Shane

Derek @ EDO · 10-02-2008, 07:19 PM

You can use 309 304l 316, always go with or a step above your metal when choosing a filler metal. A higher grade will always be correct for filler use.
For example.. Any grade of stainless wire will be adequate for mild steel.

01ssreda4 · 10-06-2008, 09:34 PM

Quote:

Originally Posted by Derek @ EDO

You can use 309 304l 316, always go with or a step above your metal when choosing a filler metal. A higher grade will always be correct for filler use.
For example.. Any grade of stainless wire will be adequate for mild steel.

i have heard this as well.

jabberman · 10-07-2008, 09:32 PM

309 is Good.

99345hp · 10-08-2008, 06:15 AM

309 is the correct wire for this application. I am a pipe welder in a nuclear power plant and that is the wire that we use to weld 308 and 316 to carbon pipe. I dont believe that the weld will ever begin to crack if it is welded properly. There are stainless to carbon pipe welds in these plants that have been there for 30+ years being heated to hundreds of degrees to room temperature and back up again every year and are still in excellent shape. I know any kind of stainless wire will weld the two together, but 309 is the correct alloy.

RippinZ121 · 10-08-2008, 07:57 PM

Where I worked over the summer all of the boiler tubes they made were mild steel and stainless. It was all stick welded, with a welding rod called Inconel. Not sure of the exact number, I think it was a 9018? Welded up super nice and strong. The stainless needed to be preheated to 300F first.

99345hp · 10-09-2008, 05:43 AM

Quote:

Originally Posted by RippinZ121

Where I worked over the summer all of the boiler tubes they made were mild steel and stainless. It was all stick welded, with a welding rod called Inconel. Not sure of the exact number, I think it was a 9018? Welded up super nice and strong. The stainless needed to be preheated to 300F first.

I dont think anyone would weld up mild steel or stainless with inconel stick rod, but maybe. 9018 is a mild steel rod that is used for alloy steel with 4.5 percent chrome moly in it. 7018 is for strait carbon steel. 8018 for 1.5 percent chrome moly. the only difference is the tensile strength of the rod. 70 means 70,000 lbs psi. Ive never seen stainless preheated, because if you get it too hot while welding you will actually ruin the stainless. You do have to preheat the alloy steels with chrome moly in them though.

THROTTLEJUNKIES · 10-09-2008, 07:07 AM

Quote:

Originally Posted by RippinZ121

Where I worked over the summer all of the boiler tubes they made were mild steel and stainless. It was all stick welded, with a welding rod called Inconel. Not sure of the exact number, I think it was a 9018? Welded up super nice and strong. The stainless needed to be preheated to 300F first.

Im a boilermaker and none of what you just said made any sense.

RippinZ121 · 10-09-2008, 10:03 AM

They definatly use inconel. Like I said, I'm not sure of the exact rod. There are stainless slots in between the tubes of the steel boilers and those slots are able to move up and down, giving the boiler some room to move up and down while still being held together. I dont work there anymore but I can try and find out what the exact rod it. Inconel is hard to use though.

99345hp · 10-10-2008, 03:36 PM

Quote:

Originally Posted by THROTTLEJUNKIES

Im a boilermaker and none of what you just said made any sense.

im with you on that one. Hence my post above. I have never seen inconel rod used on anything but inconel. Im not a boilermaker, but I work with several of them. Arn't most if not all boiler tubes carbon steel? No reason to use inconel rod. A short 7018 boiler rod is what I have always heard they use.

RippinZ121 · 10-10-2008, 03:46 PM

Quote:

Originally Posted by 99345hp

im with you on that one. Hence my post above. I have never seen inconel rod used on anything but inconel. Im not a boilermaker, but I work with several of them. Arn't most if not all boiler tubes carbon steel? No reason to use inconel rod. A short 7018 boiler rod is what I have always heard they use.

I'm not saying that I'm right or you guys are wrong, I'm just telling you what they use. Everything is certified and leakdown tests are performed, its not some little company. Chicago Tube and Iron in Romeoville, Ill. The boilers were being made for the big powerplant in Joliet (for those of you familiar with the area) off of rt.80.

01ssreda4 · 10-12-2008, 12:15 AM

Quote:

Originally Posted by 99345hp

im with you on that one. Hence my post above. I have never seen inconel rod used on anything but inconel. Im not a boilermaker, but I work with several of them. Arn't most if not all boiler tubes carbon steel? No reason to use inconel rod. A short 7018 boiler rod is what I have always heard they use.

can you not read??? he said they weren't steel. i hate people that dont pay attention.

01ssreda4 · 10-12-2008, 12:20 AM

and code work at my job indicates that matching 316 grades of stainless to a non-stainless material requires preheat of the stainless to 400*. i know this for a fact bc i saw the code procedure and im the one that put the stainless in an oven. then im the one that welded it. it was tig and it was a filler rod that was used for that purpose only. no i dont remember the number and no i aint gonna look for you.

99345hp · 10-12-2008, 03:54 PM

No reason to be a dick, because obviously you didn't read. He said they were mild steel and stainless. Maybe you should read before starting to run your mouth. Where is it that you work? Because I have welded plenty of stainless pipe to carbon steel pipe and havn't ever preheated anything.

01ssreda4 · 10-17-2008, 11:24 PM

Quote:

Originally Posted by RippinZ121

They definatly use inconel. Like I said, I'm not sure of the exact rod. There are stainless slots in between the tubes of the steel boilers and those slots are able to move up and down, giving the boiler some room to move up and down while still being held together. I dont work there anymore but I can try and find out what the exact rod it. Inconel is hard to use though.

you said carbon steel, he says stainless steel more then once. who is misreading? im done with this thread.

99345hp · 10-18-2008, 05:55 AM

you have been nothing but a prick through the whole thread. Im glad that you have welded stainless to non stainless material, but you wont even look for the guy to see what to use? im glad you think you can weld being in a fab shop, why dont you get out there in the real world of welding and weld something 4 inches of the floor in a corner with a mirror and see how those fab shop skills do for you.