I haven't seen anthing like your alloy in US specification either. The closest I have seen is .2 C, 25 Ni, 21 Cr, 2 Nb, which was mentioned in an earlier thread about superplastic forming die block repairs. It is not in an ASTM specification though. If you look at ASTM A297, which is for heat resistant Fe-Cr and Fe-Cr-Ni castings, many of the alloys have low elongation requirements. Most are between 4% and 10% elongation. If you can find out the required ductility of the alloy and are supposed to qualify in accordance with ASME IX, you can use QW-466.1 to reduce the thickness of the bends to a more fitting outer fiber elongation. Also, to weld the above alloy without cracking, we preheat to 600F as the ductility of the alloy increases substantially when heated.

Is this a Niobium alloy?
If so, there is a good article in this month's Welding Journal about Niobium welding process controls.

Tim

First of all, this material is not steel. To be classified as steel, a material must contain at least 50,1% of iron, which is not the case here. This material is a high chromium - high nickel alloy. Of course, it's not easy to weld, and the fruitless trials Niekie has made confirm this.
Second, it's an austenitic alloy, as the Schaffler diagram shows.
My advice to you, Niekie, is the following. No one knows better a material than its manufacturer. Who's the manufacturer in this case? If you know, then get in touch with him and explain him your problem. No one will be in a better position to help you.
If you don't know who the manufacturer is, then I've got a different advice. Looking at the designation, it would appear that the material has been made in Europe rather than in the USA. So, I suggest you to get in touch with one of the best (if not THE best) alloy specialist in Europe (if not in the world), which is the firm of Sandvik from Sweden.
In South Africa they have the following offices:
Johannesburg. Telephone 11-570-9602. Mr. Chris Brindley
Boksburg. Telephone 11-929-5300. Mr. Glendon Menteath.
Sandvik people are very kind and willing to be of service. I know it because they have an office in Brazil too, I've been in contact with them countless times and they've always helped me, regardless of commercial considerations.
I don't know whether the material has been made by Sandvik, possibly not, but in any case they must have a similar one and know how to treat it.
If you follow my advice, let me know the end of the story.
Giovanni S. Crisi
Sao Paulo - Brazil

Hi
This material is a high temperature austenitic material. With 0.45C it is never going to be ductile. Room temperature elongation has little significance for weld metal designed for high temperature service and creep resistance. ASTM HP40 castings allow elongation figures down to 4.5% (4d). The ductility of multipass welds will approach this due to carbide precipitation in successive runs. In short, this material will not bend without failure. For more info regarding the material and weldability try www.metrode.com

Niekie,

Interesting. My first guess is that there is an awful lot of carbon and not enough niobium to take care of it all. That leads to the formation of other less favorable precipitates (CrC and FeC.) There should be enough chromium for the remaining carbon, but I'm not so sure there is.

Next, what are the sulfur and phosphorus contents, too high = embrittlement, too low, weld solidification problems.

What are the heat inputs, preheat may be critical to have a quench effect and prevent precipitation at grain boundaries.

Finally, did anyone run the zero ductility transition (ZDT) temperature tests (gleeble) to see if this stuff recovers enough ductility on cooling without microcracking that then leads to failure on the bend test.

Bill Spataro