Welding 17-4PH ( double aged H1150)

[HF2085]

Dear experts,

We had qualification with GTAW and SMAW (manual process) on 1.5” thick test coupon . to prepare build up welding procedure . our test coupon got Post weld heat treatment at 1150°F for 4 hours ( without solution annealing ) .
Test got failed at the first step for side bend ( see attached picture ).

I`m looking for a reason or reasons of this failure .
Do you think the reason should came from , not perform solution annealing on the test coupon ? or something else should be reason !

 

[metengr]

The failures all look to be in the weld metal itself. I would remove several samples for metallographic examination and hardness testing.

What was the filler metal, and did you confirm the chemistry?
What was the bend radius used for side bend testing?

 

[HF2085]

metenger: the Filler metal for GTAW was ER630 and for SMAW was E630-16 (Both Lincoln product) hardness test is in progress and I asked Laboratory for side bend radius .

 

[metengr]

I would also macroetch to determine if the failure was in all weld metal or the heat affected zone.

1. 17- 4 PH initial heat treatment condition?
2. Did you apply a second 1150 deg F PWHT?

 

[metengr]

HF2085;
The attached AWS paper will be of interest to you. If you look at the tensile properties you really don't gain much with a second 1150 deg F PWHT. My point is look at the elongation values - less than 20%. Bend testing in accordance with ASME Section IX might be too aggressive for this material, and may require a larger radius to result in tensile fiber elongation values closer to 12%.

What were the tensile properties?

http://files.aws.org/wj/supplement/WJ_1995_05_s153.pdf

 

[EdStainless]

What NDT was done after welding?
We were doing some welding on heavy sections of 15-5PH we found that we needed to over age the material (H1150M) prior to welding.
Then following welding we solution annealed and aged.
We never go acceptable impact toughness or elong with any other process route.

I have seen (ISIJ International, Vol. 38 (1998), No. 8, pp. 866-874) work where 15-5PH was welded, annealed at 1400F for 4hrs, and then aged at 1050F.
This material developed good strength and toughness. I have never tried to replicate this work.

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P.E. Metallurgy, Plymouth Tube

 

[HF2085]

metengr:
I have had review this article which was interesting . the case is our side bends snapped almost as soon as they started bending it . and the fracture was right in weld metal .I`m still working with laboratory to get results of hardness and tensile.

 

[HF2085]

EdStainless:
we had UT and PT for NDE and condition of heat treatment on BM is H1150D per SA-564 Type 630 H1150D (double aged ) . the case is we had fracture right in middle of the weldmetal.

 

[metengr]

Having fractured in a brittle manner in the weld metal seems to indicate perhaps hydrogen embrittlement or some type of elevated temperature embrittlement. You should have been able to bend them to at least 45 degrees without snapping.

Look at the weld metal microstructure carefully. Also, double check the PWHT temperature and time.

 

[HF2085]

metengr: good point . thanks

 

[dhengr]

HF2085:
Well, of course, the failure is happening at the middle of the weld. In good part, becuase your test set-up is inducing the max. elongation and stress in that region. It also seems to have some fairly consistent anomaly a short distance below the tension surface. Is there some sort of bead over bead annealing, or the opposite, a hardening of the previous bead, from the last bead or beads, immediately below the surface? In highly alloyed steels and filler metals, I’ve also seen the situation where, with progressive weld beads, you tend to boil-up and concentrate manganese or some other such alloy. Thus, with each layer of weld beads that concentration grew, and the outer weld beads were much harder and more brittle than the deeper beads. Our solution to this problem was to use a lower alloy filler metal, so as to reduce the alloy content in the remelt and weld puddle as the layers progressed.

 

[EdStainless]

Did you double age after welding? Twice at 1150F x 4 hrs at temp with air cool in between?
The hardness survey should tell you a lot.


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P.E. Metallurgy, Plymouth Tube

 

There are basically two possibilities:

(i) Weld discontinuity. From the picture the root appears to be implicated - that is where defects are most likely.
(ii) Metallurgical issue(s). The root has the highest base metal dilution so that could be a factor.

With case (i) you should be able to see it visually or with the help of a stereoscope. If it's not obvious, then as metengr advises, section it and see.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[metengr]

Also, I would have a complete chemical analysis of the weld deposit. You need to rule out possibilities related to wrong wire and weld rod.

 

[HF2085]

Thank you All for tips. I`m still waiting to getting result of hardness from Lab

 

[pradipgoswami]

HF2085,
You may read through Sec-II, Pt-C, SFA 5.4 on the usability recommendations for E-630 electrodes. The recommendations are:-
-these electrodes may be used in as welded condition
-or with welding +ageing heat treatment, what was done here
-or welding +solution annealing +aging HT, which is most desirable.
Option 1, as welded condition results weld which is half of the mechanical properties of the base metal(which is usually supplied as solution annealed & aged). That's why vendors push for aging for the welds.

However for base metal the %EL seldom exceeds 15% for this alloy. Hence one may achieve tensile strength for the weldments , but passing bends are always problematic due to such low elongation values. I had come across many such issues related to welding of this steel. Welding of this steel is a real challenge and many vendors prefers finished products rather than resorting to fabrication.

The best advice for 1.5 inch coupon to pass in qualification test would be to resort to solution anneal followed by aging. You may adopt the cycle proposed in SA 564. as there are very little referenced for this alloy, in BPV codes.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299