I'm not a welder so go easy on me. Been reading around the forum and figure if I am going to get an educated answer this is the place. Lots of great info.
Working on a project that has a requirement to weld an .040 thk inconel 625, 16 inch diameter coupling flange to a duct made of 17-7ph .040 thk. Can these two materials be welded together and if so, is there a spec for the process? Filler material?
The materials cannot change so I’m thinking we may be doing some redesign on this one to some sort of bolt on joint.
The short answer is that these materials can be welded together. Exactly how you will go about it depends largely on how strong you need the weld to be, and the condition in which you receive the 17-7ph. The 17-7ph is a precipitation hardening stainless steel, and in the highest strength condition is substantially stronger than the Inconel 625. In the weakest condition, the 17-7ph has a similar yield strength to the Inconel 625 in the annealed condition, so it is possible that no heat treatment following welding is required. At any rate, if you need to strengthen the 17-7ph, then the best approach is to butter the 17-7ph with an inconel filler, then doing the heat treatment and welding the Inconel to the buttered 17-7ph. If no strengthening is required, then just weld them together with an Inconel filler, and away you go.
I will attach the data sheets for the two alloys so that you can have a look at them.
That was the answer that I was hoping for. Problem I have is our materials and process engineer can’t find any documentation on the process of welding these dissimilar metals or a documented filler material. He will need something documented to prove to our customer that it is valid without doing a lot of testing. Can anyone point me in the direction of a process specification that would have any information on joining these two dissimilar metals and recommended filler materials. I can’t seem to find anything that even puts these two materials in the same paragraph when it comes to welding.
You might try looking to Pratt Whitney and General Electric standard practice manuals for aerospace turbine engines for data on dissimilar metal filler choices. They have filler selection charts and heat treat data for a great number of combinations.
The charts often list several possible fillers, dependent on operating conditions and whether its a fabrication, depot level repair or line repair.
In the old days it was just "welded up" with Hastelloy W.... Thankfully these decisions are generally made by experienced engineers now.
Edit:
Another thought (I'm not at my desk) would be to check the ASM metals handbook Vol 6
Sometimes one just has to do the calcs and go through the process of working it out yourself, because the information is not readily available. I am sure it has been done often enough in the past, but it is specialised enough that it will not be listed in the common references for dissimmilar metal welding. This sounds critical enough that I would recommend that you pay a welding engineer to give you a way forward.
For stainless and nickel questions, I've always found Techalloy or Special Metals to have some valuable resources. I think you might weld that combination with an Alloy 82 or 625, but don't quote me on that.
Now all they need to do is to get my kidneys under control, and I'll be headed to a skilled nursing facility for some short term physical rehab from being in bed for over three weeks straight. Btw, I'm getting better with walking today as I made around 75 feet with a walker
So , I'll be popping in and out until I finally get home in maybe another three weeks or so... We'll see. Anywho, it's good to be back online once again!!!
With respect to the OP's query... Got to the home page for Special metals who are knowledgeable with both metals to get a well informed recommendation... Here's the link:
You missed our Birthday greetings while you were gone. And a thread started by Joe Kane updating us on your condition and everyone sending their 'Get Well Wishes'. You have been the subject of many prayers.
Look here on page 30 of the attached .pdf...
