Recommendations on welding process

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My company is new to welding and would like recommendations on which process would be best.We are trying to weld a piece of 1" wide by 0.05" think 304 or 316 stainless steel to a piece of 1.5" wide by 0.04" (or thinner) 430 stainless steel. We are trying to make a heater coil ourselves. The company that used to make these used two spot welds from a resistance spot welder, but under the high heat and poor weld, these heaters were failing at or next to the weld. They suggested using a silver braze. We have seen other companies use a line of what looks to be MIG welding.Which process, brazing or MIG, would be better in terms of up front cost, consumables cost, ease of use, and production volume (at least 40 welds per day)?I've at least deduced that MIG has an easier learning curve and is better for production than TIG or stick. We know how to solder, so I figured brazing wouldn't be too hard to learn either.Any information would be helpful.Thanks!
Reply:Personally I'd Tig weld that, very easy... Do you have any pictures of a broken piece? Silver Soildering may be an option depending on the stress.The issue with 430 is it needs a preheat before welding or it would need to be annealed after the process. If not it becomes brittle which is what I am suspecting is your current issueLast edited by Rick_H; 08-18-2014 at 11:35 AM.AWS 17.1, D1.1 and ASME IX (GTAW)Miller Syncrowave 350LX, Maxstar 150sth, Maxstar 200DX and  Millermatic 252 w/ Spoolmatic 30aMiller buzz box with Lincolin TombstoneThermal Dynamics Cutmaster 38
Reply:Yes tig. You could do a search to find out if you can do an autogenous weld(fuse without filler). You may also want to make a fixture that will contain some gas so as not to foul the weld on the backside. Let us know if you need further advise. This should be an easy job.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:I'd have to say TIG welding would be the best process also.  All though I'd probably opt for adding some filler rod and not just fusing it.   Another thing I would look at closely is if you really needed to be using 430 ss for that one part.   If 304 or 316 is working for the one piece why wouldn't it work for the other one?  Looks to me like they'd both probably be subjected to the same temperature conditions when in service.   If you could get rid of the dissimilar alloy situation (and the problems associated with welding 430) that might go a long way to eliminating potential problems and insuring a good service life for the part.   If I had all the parts and a simple fixture to hold them I'd guess I could put 40 of those assemblies together in under 2 hrs.
Reply:Originally Posted by HT2-4956 Another thing I would look at closely is if you really needed to be using 430 ss for that one part.   If 304 or 316 is working for the one piece why wouldn't it work for the other one?
Reply:On other resistance values they use a thinner coil and are able to use their resistance spot welder to weld it twice on each side of the tab (a total of 4 spot welds).
Reply:Here's what they're proposing, but we think we can do it ourselves to save money, control supply, and save time.BrazeMIG
Reply:Originally Posted by Rick_HPersonally I'd Tig weld that, very easy... Do you have any pictures of a broken piece? Silver Soildering may be an option depending on the stress.The issue with 430 is it needs a preheat before welding or it would need to be annealed after the process. If not it becomes brittle which is what I am suspecting is your current issue
Reply:Wow! That is a tiny ss mig weld. I would not trust it. Tig would be better IMO, and weld the full length of the joint to take advantage of the arc in the coil for resistance to deflection. If you are bent on filler, 316L would be the recommended filler. Torch silver braze is a time consuming process, but the initial outlay of capital is low. A tig machine will be capable of many repairs. One thing you can think of is using tig and  silicon bronze for filler, as that is called tig-brazing.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by DoctorWhat430 is the only material I actually care about. This is actually a brake resister for a pump jack (oil pumping grashopper-looking things). When the motor is shut off, the counterweights have a lot of momentum left and need to burn off the energy somewhere so it doesn't damage the motor. The coil is a fixed resistance to match how much current is going through it. It gets slammed with about 16,000W for a little less than 5sec, and these things get red hot. One theory is that the failure is being caused by the expansion of the 430 and the feet of the tab is holding it in place. It should be noted that these failures take a couple of years in the field to develop.Here's some pictures of some of the failures:
Reply:Originally Posted by DoctorWhat It gets slammed with about 16,000W for a little less than 5sec, and these things get red hot.
Reply:http://cdn.bleacherreport.com/images...ek_feature.gifTo help clarify what I'm talking about the piece that's bolted between those two tabs would look similar to the Greek symbol for Omega.  It would be made from the same width and thickness of material you're using for the straight pieces you're currently bolting between them.Also, not sure exactly how it might effect the resistance in your electrical circuit but maybe that connecting piece between those tabs could be made from electrical grade copper strip.  Being softer than 430 ss it might be better able to absorb the thermal expansion and result in less stress going to where it's been breaking.  Any way something for you to consider.Last edited by HT2-4956; 08-18-2014 at 01:44 PM.
Reply:Originally Posted by shovelonWell rule out braze then. It will fall apart in short order.
Reply:Originally Posted by shovelonI don't think it needs preheat or annealing for welding seeing as resistance welding was used in the past. I don't think 430 is a hardening 400 series alloy. 316 is a good choice for the mating part, and should weld ok without filler.
Reply:Originally Posted by DoctorWhatThat is a very good point. I hadn't thought about that before. I'm not sure exactly how hot it gets but they've said, "glowing red hot."
Reply:Originally Posted by Rick_HCorrect it is a non hardenable stainless, but since I was not 100% but this is what I found when I looked this morning http://www.azom.com/article.aspx?ArticleID=996"Welding- To perform any welding, stainless steel grade 430 has to be pre-heated at 150-200°C (302-392°F). In case of embrittlement in the welded metal, the particular area can be post-weld annealed at 790-815°C (1454-1499°F); however grain refinement will not happen. It is recommended that grade 430, 308L, 309 or 310 filler rod should be used based on the application."
Reply:Originally Posted by Rick_HCorrect it is a non hardenable stainless, but since I was not 100% but this is what I found when I looked this morning http://www.azom.com/article.aspx?ArticleID=996"Welding- To perform any welding, stainless steel grade 430 has to be pre-heated at 150-200°C (302-392°F). In case of embrittlement in the welded metal, the particular area can be post-weld annealed at 790-815°C (1454-1499°F); however grain refinement will not happen. It is recommended that grade 430, 308L, 309 or 310 filler rod should be used based on the application."