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Up Topic Welding Industry / Technical Discussions / 17-7 PH Filler Metals
- - By js55 (*****) Date 06-06-2008 15:12 Edited 06-06-2008 16:22
Whats the recent state of the art on these alloys (semi austenitic PH's)?
I've read some older material that reports two seperate filler alloys for 17-7 PH depending upon the expected dilution. The point being to ensure delta ferrite control.
Some more recent stuff mentions AMS 5824 only.
Any comments?
Anybody varying fillers based upon ferrite control, or for other reasons?

To ammend the question, if SMAW is being used, what filler is the choice and what sort of mechanicals are you getting?
Parent - - By Stephan (***) Date 06-07-2008 13:08 Edited 06-07-2008 15:52
Jeff,

by God, how do I miss the great Chuck Meadows!

Most likely it had needed less than a 1/2 of an hour and there would have been the most interesting discussion between you and Chuck on this topic.

I have often thought by myself since he has unfortunately so early passed away, it's almost like "Yin" without "Yang"...

Unfortunately I am not blessed enough to reply your question neither in an appropriate nor in an approximate way.

But please Jeff, let me ask one or two questions, since I have never particularly heard of welding these austenitic-martensitic materials.

What kind of primary structure has the weld metal deposit in general? Is it solidifying similarly to a 304 grade, i.e. delta ferrite transforming secondarily to austenite?

And if so, how does the share of martensite emerge afterwards? Is it by a controlled heat treatment from the interpass temperature?

And finally, so if you may allow, which role does the remaining amount of delta ferrite even play when transforming a large share of austenite into martensite.

Does it - if too high - deteriorate the mechanical or chemical (corrosion) properties of the base material, or weld deposit?

Edit: I have found somewhat by using the SANDVIK material's brand:

http://www2.sandvik.com/sandvik/0140/SM/se01240.nsf/f9aff13490287b65ea2564f50042c670/49040ce20e5ced08412568290044e2f1!OpenDocument

Please forgive me that I have asked, but I couldn't resist (by knowing you as one of the most outstanding experts in stainless steel welding)! :-)

Thanks a lot in advance for enlightening me and my best regards,
Stephan
Parent - By js55 (*****) Date 06-08-2008 19:56
17-7 PH is a semi austenitic PH stainless. It solidifies as ferrite and then transforms fully to austenite. Or at least in my understanding it is expected or desired to transform fully to austenite. I suspect there is always a little sneaky delta hangin around. I've never done any testing on it myself and I've read conflicting reports.
The martensitic PH's always have a little delta ferrite in them. My understanding of the semi austenitic PH's is that the very reason for their existence was to result in a fully austenitic microstrucure at room temp and result ultimately in differing properties offered by the martensitic PH's.
The martensite is achieved by preparatory heat treats, one at high temp ~1700F to 1750F and one at lower temps 1350F to 1400F, depending on the final properties desired. The higher HT results in higher strength but who wants to, or has the facilities to refrigerate the stuff. This prep HT raises the MsMf temps by percipitating carbon out of solution. The high temp version must be refrigerated to get transformation, the low temp version has Mf just above room temp. Then you perform the PH heat treat.
Parent - - By js55 (*****) Date 06-08-2008 19:59
"experts in stainless steel welding)!"
That was Chuck and we miss him.
Parent - - By js55 (*****) Date 06-09-2008 01:27
OK, what I posted about delta ferrite content is not correct according to a different source. Its just the opposite. 17-7 PH will contain about 15% delta ferrite in the BM, and an auteogneous weld metal will contain about 25% delta. Thats a lot. Heat treat will reduce considerably.
Parent - - By Stephan (***) Date 06-09-2008 10:52
Dear Jeff,

a heartfelt "Thanks" for taking your precious time and explaining the background of these materials and their behavior - as always - so excellently.

I appreciate this outstandingly and have learned a lot from you again!!

Very interesting group of materials as it seems to me and understandable to questioning the "filler issue".

Best regards,
Stephan

P.S. Future I will open my eyes to perhaps find some information on these steels.
P.P.S. Who knows, perhaps Hank (ssbn727) has somewhat additional in his treasure chest :-)
Parent - - By js55 (*****) Date 06-09-2008 13:26
Stephen,
ASM Handbook Volume 6 and WRC Bulletin 103 are two of the best. Yes 103 is 1965. That stuff has been around awhile. Actually since 46.
Not to change the subject  but, the 40's and the 50's are truly the golden age of fusion welding. Few of us will come close to understanding welding the way those old boys did. And there's not many of em still around. A great loss. You will need a library to capture what they had in their heads.
Parent - - By Stephan (***) Date 06-09-2008 14:31
Jeff,

a wise saying!

Please allow that I agree Sir!

WRC Bulletin 103*..? 1965..?

Good heavens, at that time I haven't thought about welding yet, but who knows... perhaps the seed was already sown that time. :-)

To be serious. I truly haven't heard of these particular grades until you have initiated this interesting topic.

13-4? Yes. 13-6? Yes...

17-7?

Honestly... No.

As you say that these steels have been around awhile.

Is it eventually possible that they were basically the predecessors of the (soft) martensitic grades as stated above? 

Thanks again and best regards,
Stephan

* Will try to get the WRC Bulletin 103!
Parent - - By js55 (*****) Date 06-09-2008 15:27
Not that I'm an alloy historian or anything, far from it, but from what I understand PH SS's were developed to capture the corrosion properties of CrNi (which by this time we had austenitics) alloys only make them stronger.
The soft martensitics were generated from a desire to capture the properties of already existing martensitic SS's while making them more weldable by reducing carbon and adding other alloys, generally Ni.
The first group works by precipitation hardening in a martensitic matrix, sometimes with sophisticated heat treat regimes (including refrigeration), the other is predominantly solid solution strengthening in a martensitic matrix, sometimes without heat treat at all, depending upon the particular alloy and carbon content.
Martensitic SS's go way way back because when CrNi SS's were first developed they couldn't get the carbon very low.
Parent - - By Stephan (***) Date 06-09-2008 17:41
Jeff!

Is there actually anything in this world you do not know on Stainless Steels and their Welding???

What you have posted is most excellent and reasonable!

Once again thanks for widen my tiny horizon and best regards,
Stephan
Parent - By js55 (*****) Date 06-09-2008 18:08
Stephen,
LOL!!!
I appreciate your confidence. And I'm glad you enjoy the posts. But trust me, even though I yap a lot, that isn't how I see it. I do however know a few fellas of which I believe the statement may be much closer to the truth.
Parent - - By GRoberts (***) Date 06-10-2008 19:25
I can tell you what little I know about 17-7.  It bends easier than 17-4.  I got 4T transverse side bends to pass (dissimilar weld to 316L) with 17-7, but side bends wouldn't pass on 17-4 (longitudinal test passed though) at >4T.  Both without PWHT.  However, the 17-4 was in the 1150 condition.  If I remember correctly, the 17-7 was in the annealed condition.

Allegheny has a data sheet on 17-7 that has a little bit of info.  The new stainless book by Kotecki & Lippold has a bit of information as well.

It ain't much, but I hope it helps.
Parent - - By js55 (*****) Date 06-10-2008 20:30
Every little bit helps Greg, thanks.
I haven't bought the Kotecki/Lippold book yet. I suppose I should.
Now there's a couple stainless steel fellas.
Well, if I may be allowed to brainstorm, the 17-7 annealed is almost like a 300 alloy. And the HAZ without HT would be in the austenitic condition as well, similar with higher delta ferrite.
The 1150 HT for the 17-4 HAZ, though a more ductility oriented HT, is still martensite. And the BM would be tempered martensite.
Though I would still have thought it would pass a 4T.
I'm guessin the 17-4 tranverses busted in, or around, the HAZ?
Part of it is often overaged without solution annealing.
Maybe it took the brunt of deformation, which may not have been true in the longitudinals.
What filler did you use?
Its hard to find info on this stuff I think because the traditional markets have been so limited. But whatever discussion comes out of this thread is going in my file.
Thanks for the info.
Parent - - By aevald (*****) Date 06-10-2008 22:17
Hello js55, do you have a copy of "The Avesta Welding Manual"? I attended one of Chuck Meadows seminars in Spokane, Wa. and got a copy when I was there. I'm wondering if it might contain some information that might be relative to what you're looking for. I noticed that my copy has an ISBN #91-631-5713-6, otherwise it lists an email adress: info@avestawelding.com, maybe they might come up with a reply of some sort for you. Best of luck and regards, Allan
Parent - - By js55 (*****) Date 06-11-2008 13:25
Allan,
I found the Avesta manual as a pdf. thanks
That fricken thing is 300 pages long! I'm printing it out as I write these words. What a monster of a volume. I haven't seen one this big since Henry turned me on to Bhadeshia's Bainite book. Haven't finished that one yet either.

Again thanks
Parent - By js55 (*****) Date 06-11-2008 14:10
Ok. The majority of the Avesta book is product data sheets (not wholly unexpected) which I would only read if I had a need for that product or a severe case of insomnia, but there is still over 100 pages of welding type info.
Parent - - By GRoberts (***) Date 06-11-2008 00:03
It was definately a case of strain concentration in the HAZ of the 17-4 PH that caused the failure.  It was what I was hoping wouldn't happen, but thought might with the transverse bend tests.  We were using plain old 309L filler, FCAW process.

In answer to Stephen's question, we are bulding some gates for hydroelectric dams, and the 17-4PH is used as a sealing surface. 

The 17-7PH was used as a threaded rod, but I'm not aware of the application.  In our case, we only had to meet the strength of the dissimilar metal, so the high strength of the 17-7 wasn't a concern.  In this application, we were using GTAW.
Parent - By Stephan (***) Date 06-11-2008 06:33
Very interesting!

Thanks a lot Greg!

Best regards,
Stephan
Parent - - By js55 (*****) Date 06-11-2008 13:21
Greg,
You mean I guessed right???
Hah!!!
Even a blind squirrel finds nuts occasionally.
Parent - By Stephan (***) Date 06-11-2008 17:41
Jeff,

"Even a blind squirrel finds nuts occasionally"???

Huuh..!

Understatement par excellence! :-)

All the best to you and once again thanks for the great thread,
Stephan
Parent - By Stephan (***) Date 06-10-2008 22:47
Greg,

please allow that I ask.

Besides the question of Jeff in terms of what filler you have used it would be very interesting to know the welding process used.

I would be very interested as well in the kinds of components being manufactured from these steel grades. It appears that these materials are truly somewhat very special and must have very particular beneficial properties when they are used for dissimilar joints with 316L.

Are they used for pressure vessels..?

Thanks in advance for a short response and best regards,
Stephan
Up Topic Welding Industry / Technical Discussions / 17-7 PH Filler Metals

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