Actually, the pure austenitic fillers are regarded as appropriate for "high" and "low" (cryogenic applications) due to the lack of ferrites. In the application you are describing, 1000F range, the ENiCrFe-3 should be a good choice. Remember, ferrites are detrimental to weld metal integrity at elevated and very low temperatures. For information on cryogenic welding and the criteria it must meet, you can refer to Section VIII of the ASME Boiler and Pressure Vessel Code that requires the weldment to be qualified by a Charpy V-notch testing, and the ability to attain a later expansion opposite the notch of 15 mils, minimum. Pure austenitic fillers can achieve this requirement much easier than a ferrite containing filler metal. There are numerous publications that state that the ferrite containing fillers will experience sigma embrittlement quicker at elevated temperatures than the pure austenitic fillers. In essence, your choice of filler metals for your particular application is a good choice.
Chuck
Hi Chuck
Just a question, Is the ENiCrFe-3 better than ENiCrMo-3 (112).
Leroy,
That's sort of a hard question to answer. Which is better...It really depends on the application. The ENiCrFe-3 is a 65 Ni, 15 Cr nickel alloy with application temperatures from cryogenic up to 900F. The ENiCrMo-3 is a 60 Ni, 22 Cr, 9 Mo with application temperatures from cryogenic up to 1000F. Both can be used to weld steel to other nickel-based alloys. The ENiCrFe-3 is usually used to weld and clad other nickel-chrome-iron alloys. The ENiCrMo-3 is used to weld and clad other nickel-chrome-moly alloys. Strictly from my personal perspective, and if I had to choose one or the other, it would be the ENiCrMo-3. The 9% Moly will give you better resistance to pitting corrosion and has a slight upper temperature application range. Hope this answers your question.
Chuck
Chuck,
Recently, I have found some interesting information on this topic. I have always heard that we should go low ferrite for high temp and cryogenic applications. For obvious reasons with sigma concerns, we should use a low ferrite filler on the high temp applications. With cryogenic applications, I have found several overseas projects where filler materials with over 12 ferrite have been used for -320F. After more investigation, the impact curve comes back to where you can get even better impact and lateral expansion results than you can with the low ferrite materials. My guess is that American fabricators do not want to use two different wires for High temp and Cryogenic??? After seeing some of the results, I think we are cheating ourselves out of some great cryogenic wires. I have just started looking at the board and thought it might be of interest to you.
Zeke
Zeke,
Your response is quite interesting about high ferrites being acceptable for cryogenic temperatures. We know that higher ferrites mean lower austenites. Austenitic structure is critical to achieving the 15 mils (minimum) lateral expansion when adhering to the Code requirements. We also know that the more austenitic structure, the better in trying to achieve these requirements. With ferrite numbers above 3 FN, there should be careful consideration pertaining to cryogenic applications. In essence, it is not the ferrites that should be the driving force in cryogenic applications, but the austenite content. The more austenite, the better. With all due respect, I cannot agree with using FN of 12 or greater for cryogenic applications. Ferrites are definitely detrimental to the success of achieving all the requirements specified in the Code for this application.
Chuck,
I fully understand Austenite and Ferrite. I may be a newby to the board, but am not a newby to the welding industry. I won't argue the fact that what you have said is all we have ever been taught. I also won't argue with test results that I have observed. I am talking about a 308L FCAW electrode which had about 14 ferrite which achieved 36 ft-lb and 19 mils lateral expansion @ -320F. When I inquired how this could be possible, I was told of how the impact curve worked with Stainless electrodes. This is a very popular electrode in the asian market and has been used as a cryogenic wire for years. They have also told me that there are a couple of manufacturers in the asian market who do the same thing. "Definitely" is a strong word in this ever changing industry. But, take it for what it is worth to you. I thought it would have been of some interest?
Zeke
If it worked for you, use it, but as a Welding Engineer, I will not recommend using a 14FN for cryogenic applications. Also, 14FN seems quite high for a 308L FCAW. I use the word "definitely" is the sense it is meant to be taken. Ferrites are definitely detrimental to the success of cryogenic applications. I have documents to back up what I'm trying to relay to you. Thank you for your input, but in my position I must stay with what is recommended, and has been proven to work. Also, we use only AWS speccified electrodes.
Chuck,
I seemed to have hit a nerve somehow. For that reason, I will not bother you with the subject anymore. I was trying to contribute an interesting find, but hit a wall. I do have to say you assume too much. This electrode does meet AWS specs. Is there a requirement in the spec for ferrite levels I am not aware of? I also previously said that I have documentation stating the test results of a cryogenic test that passed wonderfully. Do you actually have documentation of cryogenic tests of a 14 Ferrite 308L material? I have no doubt you have documentation of materials with low ferrite. Also, instead of using the word definitely, you might want to phrase it like the AWS specification does. It says that ferrite is "Generally regarded as detrimental to toughness in cryogenic service". They are open minded as I am, and as a Welding Engineer, I will leave my mind open to new possibilities.
Zeke
Interesting conversation. Zeke, could I get accesst to the information that you talk about? This would be for my personal interest only. My email is consult-leroy@shawbiz.ca.
Thanks
Leroy
Leroy,
I am interested in your opinion. It is not even available in the states that I am aware of. It just happened to be a formulation I stumbled across. I was amazed, because I have always been told that ferrite was terrible for impacts and lateral expansion. I probably will never use it but thought it would be interesting to discuss. I always like to try and think outside the box we have been put in. I had two reports from different manufacturers. The one that I have located is from Kobelco. The other one I thought was from Nippon. This probably is not the case, because if anyone should know the Nippon line it is Chuck. It might be Hyundai or Taseto? I will keep looking. I do beleive that impact values are not linear. What I have learned from asking a Kobe R&D engineer is that the curve works its way down at about 4 or 5 and comes back up starting at 12 or 13. Apparently, in the range above this, the impacts are very easy to achieve. I think the only downfall would be if someone used it by mistake on a high temp job. But that's what 308H is for right? Anyway, I will keep looking. I have the Kobe report and can send it to you, but my scanner is down. Do you have a fax number?
Zeke
By -
Date 11-17-2005 19:35
ANSI/AWS A5.4-92, A9.10.3 states, "Delta ferrite is harmful (sounds pretty definite to me), therefore minimizing the ferrite in weld metal (3 FN max) is recommended. Weld metal free of ferrite (fully austenitic) is preferred; the more austenite, the better."
