Welding dissimilar stainless

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Hi guys, Happy Father's Day!I have to tig weld some 17-4 PH stainless to 304 stainless this week. What would be the preferred rod to use?Thanks!Dynasty 300DX TIG RunnerMillermatic 210Spectrum 375Smith O/A Metal working tools out the ears, Yada Yada Yada....I can still walk in my shop......That means I need more equipment, right?
Reply:Originally Posted by 1320RaceFabHi guys, Happy Father's Day!I have to tig weld some 17-4 PH stainless to 304 stainless this week. What would be the preferred rod to use?Thanks!
Reply:I use 347 for everything stainless.        Sincerely,             William McCormick
Reply:309 +1Damn, I'm agreeing with Zappy.
Reply:I would think 308 would also work for that??MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:They used to say for 316-L to use 308-L filler wire. Now I see they say to use 316-L.I just use 347 though. It is great stuff, but expensive and a lot of places do not stock it as much as they did.        Sincerely,             William McCormick
Reply:http://weldingweb.com/vbb/showthread.php?t=36686
Reply:347 filler wire is niobium stabilized wire.        Sincerely,             William McCormick
Reply:It is the best stuff I have ever used on stainless steel.        Sincerely,             William McCormick
Reply:Originally Posted by Old Fart309 +1Damn, I'm agreeing with Zappy.
Reply:Thanks guys!Dynasty 300DX TIG RunnerMillermatic 210Spectrum 375Smith O/A Metal working tools out the ears, Yada Yada Yada....I can still walk in my shop......That means I need more equipment, right?
Reply:Somehow I breezed past this post?The above advice is OK to put them together, 308L, 309 and 347 will all give a ductile weld that is not crack sensitive.For some reason AWS data gives ER630 for 17-4 to 17-4 and doesn't seem to consider welding a semiaustenitic(17-4 duplex type) material to austenitic (304etc type).Lincoln data seems to suggest 309 for welding to a dissimilar PH duplex stainless and 308 for welding to an austenitic (18-8 type) stainless.I can't for the life of me reason why ER312 is not considered for PH to 18-8 as it would have a duplex (two phase structure) giving it a strength closer to 17-4 and would be far more crack resistant than either 308 or 309 when joining dissimilar structures?Perhaps someone recently in school has more on this?Matt
Reply:Isn't 309 actually recommended for joining steel and stainless?308L was recommended at one time for 316-L, but now they say 316-L wire for 316-L material. 347 used to be the only wire recommended for metals like 304, 316 and 321 material. As of late they seem to have changed up a bit.        Sincerely,             William McCormick
Reply:You need 347 for sure if you hit a piece of 321 or titanium steel.        Sincerely,             William McCormick
Reply:Originally Posted by William McCormick JrIsn't 309 actually recommended for joining steel and stainless?308L was recommended at one time for 316-L, but now they say 316-L wire for 316-L material. 347 used to be the only wire recommended for metals like 304, 316 and 321 material. As of late they seem to have changed up a bit.        Sincerely,             William McCormick
Reply:Oh I forgot to add to the above that 18-8 and 17-4PH have different stuctures and are dissimilar steels. And the big price differences that used to be there re: fillers seems to have vanished (checked Stoody).Matt
Reply:I forgot about posting back here... Most of my work with 17-4 was part machining (some weldments after heat treat). Usually when welding materials you consult the maker first and the filler supplier second. The first question I was usually asked by both was "what are you trying to do with it KID".From a design viewpoint welding 304 to 17-4PH I can find almost nothing in my ASM materials selection. It's no better from my AWS filler selection?Without posting anything with DRM problems I've attached some data from Alcan Metels Goods (a supplier) showing properties of 302 (18-8 type SS), 309/310 and 17-4PH. I also found a couple of neat links for welding stainless via Google.From AISI in pdf good enough to read (not sure about printout though);http://www.ssina.com/download_a_file/weldingbook.pdfand from Stoody;http://www.stoodyind.com/Catalogs/FISC/05catpg382.pdfFrom what I can gather from properties, these are not often weld joined by designers due to thermal expansion differences. They are very similar in corrosion properties but differ a lot in strength, further 17-4 is no good above 600°F.I wondered out loud about 312 (typ 110-120,000psi) but it would result in too much ferrite so scratch that thought! The only filler I could find advised via Google for this was 308L but I imagine 309 would work just as well for a little more money. You're just not going to get anything near the strength of 17-4PH, which depending on condition can be as strong as a med carbon low alloy steel (heat treated to Whup-A$$).Matt (attachments below) Attached Images
Reply:309 is the correct electrode
Reply:I used to go by a defense plants in house, recommendations for stainless steel welding. That were tested, in house, destructively tested in house, and were X-rayed in house to very high standards. Often you could not see the weld on their test pieces in the X-ray. And I knew the guys that setup, tested and did the welding. Ha-ha. There was only one rod that cross referenced to every other stainless. And that was 347. Then one day 347 was a bad word in the welding supply house. No failed TIG welds, no reason for it really, it was just taboo. But I know I have welded 321 to plow blade material with 347. And it held like mad. I have welded 321 to 316, to 304 to 301, and even some nickle alloys, all with incredible holding power. It may be that for TIG welding it is just amazingly awesome, because you are combing the two base metals and then adding in a niobium stabilized material. So you get an amazing weld. But at the welding house you have guys doing stick and MIG, where not a lot of mixing of base metals takes place. That might be a problem. Because 347 is soft as butter. Very much like 40-43 aluminum filler wire is soft as butter. So because no one knew how to pick a filler wire, they just black balled 347 because a Guy MIG-ing with it to cold, was not really blending the base materials. And ended up with pure 347 stuck to two different surfaces. Both harder then the filler wire. I do all my stainless rails with 347 and the welds are invisible after grinding or polishing. Over time with natural corrosion you can just barely see the weld, I can anyway.  But I don't know any material that will not do that. Even a fusion weld will cause that, after chemical etching takes place. But the 347 gives you a minimum of corrosion. And crazy strong TIG welds. I mean crazy strong. It leaves no pits or grains. It blends totally with the base material. Making polishing it a dream. This is solid 304 stainless bar welded to itself with 347 filler material.       Sincerely,             William McCormick
Reply:Nice polish job on the table Will. I think most welding gets done with the usual culprits; ie 308, 309, 316 because many shops don't carry as many fillers as possible, and also, there are a few that work well, so people go to the most common allowable filler available.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by RojodiabloNice polish job on the table Will. I think most welding gets done with the usual culprits; ie 308, 309, 316 because many shops don't carry as many fillers as possible, and also, there are a few that work well, so people go to the most common allowable filler available.