using different strength filler

Date 09-22-2008 19:06

Hello Carl, I realize that SAW is quite different from SMAW, however some of the coupons that I have seen for joining A514 SMAW were in fact done with E7018. In this case the coupons were bent, but did not fracture, instead the weld area cross-section stretched to the point where it actually recessed into the crown of the bend and there were visible edges where the A514 ended and the weld metal began. These were side bends. I'm sorry I don't remember the exact application or code that these were done for, this was quite some time ago. Best regards, Allan

By ctacker (****)

Date 09-22-2008 19:26

Hi Allen,
Did you happen to do any or see any tensiles that were done using the E7018?
I was curious how they would accept a tensile with the mentioned base/fiiller metal combo!

Regards, Carl

By aevald

Date 09-22-2008 19:33

Hello again Carl, no I didn't and at that point in my career I hadn't ever even seen tensiles pulled. The particular set of coupons that I saw were clean other than the stretch issue so I really didn't have any criteria to even judge pass/fail limits. Best regards, Allan

By HgTX

Date 09-22-2008 19:33

D1.5 has some things to say about undermatching that may or may not be useful for your application. Among other things, they leave out the reduced section tensile and the bend tests, just doing an all-weld-metal test. Check out 5.15.1 and its commentary.

Hg

By 803056

Date 09-22-2008 20:46

You would fail the test requirements if the weld strength didn't match the base metal strength if you are welding to any of the welding standards I am familiar with.

The weld deposit, even when undermatch, will typically produce tensile results higher than the minimum specified for the electrode classification. However, when you are welding to a code, you have to produce a weld deposit that at least meets the tensile strength of the weaker base metal (if dissimilar B.M. are joined). A weld that is undermatched by too wide a margin will fail to meet that criteria.

Best regards - Al

By ctacker (****)

Date 09-22-2008 21:32

Al,
we are welding this particular job to D14.3, I have been told by the EOR that D1.1 would be an acceptable alternative for testing.

originally he said to send him a sample plate and they would do bends. But my QA manager said if we are gonna do testing, we should do it to D1.1 and ASME IX so we can use it in the future for other jobs as well!

I had looked in the code and couldn't find anything about undermatching filler. so I guess I would be wasting time and money to qualify a procedure! That is one thing I was hoping to get answered by my post. Thank you!

Regards, Carl

By 803056

Date 09-22-2008 23:43

Hello Carl;

This is extracted from Article 1 of Section IX.

QW-153 Acceptance Criteria -- Tension Tests
QW-153.1 Tensile Strength. Minimum values for
procedure qualification are provided under the column
heading "Minimum Specified Tensile, ksi" of table QW/
QB-422. In order to pass the tension test, the specimen
shall have a tensile strength that is not less than:
(a) the minimum specified tensile strength of the base
metal; or
(b) the minimum specified tensile strength of the
weaker of the two, if base metals of different minimum
tensile strengths are used; or
(c) the minimum specified tensile strength of the weld
metal when the applicable Section provides for the use
of weld metal having lower room temperature strength
than the base metal;
(d) if the specimen breaks in the base metal outside
of the weld or weld interface, the test shall be accepted
as meeting the requirements, provided the strength is
not more than 5% below the minimum specified tensile
strength of the base metal.
(e) the specified minimum tensile strength is for full
thickness specimens including cladding for Aluminum
Alclad materials (P-No. 21 through P-No. 23) less than
1⁄2 in. (13 mm). For Aluminum Alclad materials 1⁄2 in.
(13 mm) and greater, the specified minimum tensile
strength is for both full thickness specimens that include
cladding and specimens taken from the core.

The basis of my comments were conditions a, b, and c. Item c is conditional if the construction code, i.e., Section I, Section VIII, etc. permits the use of undermatched filler metals. I don't recollect too many construction codes that permit undermatching filler metals if the disparity is too large. Again, there may be special cases, but they are the exception rather than the rule.

If I may ask, why are you trying to undermatch the base metal to such a great extent? The disparity between 70ksi and 100 ksi is considerable to say the least.

Best regards - Al

By ctacker (****)

Date 09-23-2008 01:25

Al,
The only reason I know of for the stronger Base metal is for wearability on large earthmoving equipment. We have welded alot of dredgeheads and hoe buckets using A514 plate and E70T1 wire. Theres a team of engineers that have done nothing but design these things and tell us what to use for welding. From what I know its common practice to use A514 and weld with a LH 70K electrode. the spec they quote is for Visual Inspection and doesn't really apply to Testing of welds!

My QA manager and myself thought we could run a PQR and have a WPS to change to SAW and have it on file for future jobs. Even though we don't really need one as the engineers have told us what to use. and when I mentioned the tests that would be needed(visual,NDT,tensiles,bends,etc) they werent even aware of all the testing required for a PQR. all they do is bend tests.

This afternoon we decided to scrap the idea, we were gonna use a handheld SAW and the largest wire that one will accept is 3/32. same as what we use for FCAW. so the cost savings wouldn't be great enough to do all the R&D required for trying to weld inside and outside the radius of a cutterhead arm.

I will attach a couple pics of one, some of the grooves are 2.5 feet long and the way they are formed go from 3" on the ends to 8" thick in the center.

Regards,Carl

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By 803056

Date 09-24-2008 00:17

OK, now I have a better understanding of what you are doing. It isn't that you are trying to meet a code requirement, you are using the code as a rational means of establishing the mechanical properties of your weld.

That makes sense. The code or welding standard simply lays out a means of establishing the mechanical properties of the combination of filler metal and base metal used.

Your question about what the laboratory looks for threw me and sent me in the direction that you were trying to qualify the welding procedure to meet some code requirements.

If you send a test plate out to a lab for testing, you need tell them what tests you want them to perform. In this case, a radiograph to verify the weld is free of cracks, incomplete fusion, slag, etc. Then require a series of bend tests, either 2 face bends and 2 root bends or 4 side bends. The results of the bend test should be free of any open defects larger than some specified size. A common requirement would be no open defects larger than 1/8 inch or sum of defects more than 3/8 inch. Then a set of transverse reduced section tensile tests to establish the actual tensile strength of the combination of base metal and filler metal. The results of the testing then provides a rational means or foundation for your design assumptions.

A word of caution, where as you are using a filler metal that is so much "weaker" that the base metal, a wrap around bend testing machine is required to obtain a uniform bend and valid test results.

Again, the testing would not "meet" the requirements of a code or standard, but it would provide a rational means of determining the mechanical properties of the combination you have elected to use.

Good luck and I believe this is something worth while doing.

Best regards - Al

By js55

Date 09-24-2008 17:43

You may even consider longitudinal bends with that big of a strength differential. I can pertneer garantee that at the fusion line you will be seeing greater than 20% elongation.

By HgTX

Date 09-24-2008 18:45

In D1.5, the reduced section tensile (which has a requirement for the filler metal to meet minimum specified base metal strength) doesn't apply to undermatch situations (see 5.15.1). All you have is the all-weld-metal tension test, which probably wouldn't reflect any aspect of the base metal.

Hg

By 803056

Date 09-24-2008 21:40

Fine if the requirements of D1.5 were applicable.

Best regards - Al

By HgTX

Date 09-25-2008 15:20

Just sayin' there are codes, AWS codes even, where not meeting the higher base metal strength would be okay. A claim was made otherwise.

I've talked to people who think that in an undermatching situation, even in D1.1 the requirements of 4.8.3.5 wouldn't apply, at least not to the higher base metal. Because then an E60 used to weld Gr. 50 would need to have a minimum strength of 65 ksi, rather than 60 ksi, and since the electrodes are manufactured to 60 ksi, if you get lucky and pass the test once, how would you know you'd get the same strength with the next box of electrodes you open? The test can't be meaningful unless you special-order electrodes, and that doesn't seem to be the intent of the code.

Undermatched welds should be sized by the designer for that lower strength. They're undermatched. So why would an undermatched electrode need to match the base metal strength? That's a matching requirement.

All that said, though, there's nothing in D1.1 right now that says you *don't* have to meet 4.8.3.5 for undermatching. In my opinion, legally speaking, the requirement still stands. Commonsensically, maybe not.

Hg

By 803056

Date 09-25-2008 23:46

I understand what you're saying, but it appears Carl dosn't have to meet a specific code requirement. I didn't make that connection when I initially responded to his inquiry.

Best regards - Al

By ctacker (****)

Date 09-26-2008 02:17

your right Al, I don't have to meet any code requirement, I wanted to, but as I mentioned earlier we are going to scrap the Idea, for many reasons.

1st reason, the flux the engineer said we have to use (Lincoln 880M) is too course for the handheld SAW unless we special order it(added cost)

2nd reason, The wire the EOR said we must use(EM12K) has a silicon content of .10/.35 and for that flux if Si is less than .20 you have a better chance of porosity among other things(I'm not at work with all the info so if I'm wrong on any of this I'll edit tomorrow)

Another reason as mentioned before is the wire size, we were hoping to increase from 3/32" wire, and thats not possible with the handheld SAW.
we are now working on an automated FCAW system to weld the grooves, which,by the way, has to be welded 3 layers then move to the next for 3 layers and so on. That is the hard part, getting set up with a man-lift and preheating each arm to only put 3 layers of weld before moving to the next! (thats where our 120k lb positioner comes in handy, these weigh upwards of 40k lbs)

Initially, I talked to our company engineer and he said he has done it before using ASME, so I was wanting to do it to a code just for the sake of having a WPS on hand for future jobs. according to our customers engineers, they would OK the procedure using the filler and flux mentioned if we sent them a sample plate for them to bend. so your right, no code requirement.
My company wanted to do it to a code, but I see now thats not feasible and would actually end up being more costly without shaving much time.

Hg, I don't have D1.5, we don't do any bridge work. but I appreciate the input, as I do from everyone.

Beware of chinese chains also, our new purchasing guy bought some chains(found out they were from china after the fact) rated at 48K lbs at 60 degrees. we started picking up a 38k LB cutter at about 5 degrees(hooks almost straight below block) and the 5/8" chains snapped causing a slight earthquake in the shop.

By 803056

Date 09-26-2008 02:25

You're lucky the chain didn't induce a "spin" on the cutter head when it broke. From the looks of the photos of the cutter heads, you would have had a hole half way down to China. Since a portion of the chain was still attached, you could have asked the Chinaman that made the chain for your money back!

Best regards - Al

By 522029

Date 09-26-2008 14:07

I do not know about your purchasing people, but at my workplace, the only thing the purchasing agents know is cheap, cheaper, or even cheaper.

Griff

By HgTX

Date 09-26-2008 15:45

Why is your EOR dictating which consumables to use?

Hg

By ctacker (****)

Date 09-26-2008 15:58

We have a spec book we have to follow, listing the consumables that we are allowed to use! there are a team of engineers that design these things including what consumables to use, after talking with them, they don't want to budge. thats the only reason I can give.
follow the rules or find new work! I think its much easier to follow the rules. :)