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Up Topic American Welding Society Services / Certifications / Test Coupons cracking in half during bending
- - By billk63 (*) Date 04-22-2014 19:33
we bent some D1.1 coupons  ,1" plate CJP  Lincoln NR 212 filler metal ,A36 duel grade plate / flat bar,during the bending process some, not all of the coupons cracked in half in the center of the weld metal ,there is no evidence of any discontinuities , base metal is all of same batch

my thoughts are this is caused by  lack of preheat and inter pass temp

we have used this base metal for other CJP test with  select arc 720 and have had no problem
Attachment: photo1.JPG (38k)
Attachment: photo2.JPG (37k)
Parent - By Blaster (***) Date 04-22-2014 19:40
NR 212 is not recommended for materials over 3/4":  http://www.lincolnelectric.com/en-us/Consumables/Pages/product.aspx?product=Products_Consumable_Flux-CoredWires-Self-Shielded-Innershield-InnershieldNR-212(LincolnElectric)

I have seen 1" plate samples of A36 snap through the weld with NR 211 (an E71T-11 v E71T-G for NR 212)... but only once, I have seen many that passed following the same procedures.  This was many years ago.  It is also not recommended for unlimited thickness (1/2" max w/ .068" wire).
Parent - - By aevald (*****) Date 04-22-2014 19:47
Hello billk63, look at the specifications on Lincoln's site for this wire, you'll notice that it is listed with a max. thickness of 3/4". Generally this is indicative of issues that come up from running pass after pass over the preceding filler metal without having the proper tempering elements/additives in the wire's core make-up. You should consider using a more suitable wire and make sure to stay within the operating parameters of that wire as well. NR 212 is considered a general purpose wire with limited thickness application and although it is likely wonderful to run, it doesn't have the necessary characteristics to qualify on the D1.1 structural test. NR 232, NR 233, Coreshield 8, and other such wires "will" make that test when properly set-up and run. Good luck and regards, Allan
Parent - By JTMcC (***) Date 04-22-2014 23:47
Of course 211/212 have thickness limitations, that's been common knowledge for over 2 decades.

Given that, 211 1" structural tests made the bends (by the hundreds of thousands) every year prior to that.

211 never had a problem making the run of the mill 1" plate structural test, I would look at other factors if it was me. Or you can blame the wire.
Why are you qualifying to 1" with that wire anyway since it's semi illegal???

J
Parent - By Len Andersen (***) Date 04-26-2014 19:09
Ladies and Gentlemen,
      Look at a lot of bend straps for A36. The failure mode is something I have not seen. You left out "Innershield® NR®-212 - Lincoln Electric www.lincolnelectric.com/.../product.aspx?...212(Lincoln... Lincoln Electric Innershield® NR®-212 from Lincoln Electric is recommended for single or multiple pass welding on up to 19 mm (3/4 in.) thicknesses" FCAW (G). Start point it is not for 1 inch plate. If you call Lincoln they would say more. The other aspects are numerous. The wire might have been from different batch or wax used to get it through the contact shoe. The "failure" looks near "brittle".  Been an engineer and into welding for plus 20 years / five patents.
    Sincerely
        Len Andersen     weld@spemail.org
          914-536-7101
        www.lenandersen.com
PS - I am looking for a job !
Parent - By 99205 (***) Date 04-28-2014 21:13
Just a thought here, but I'm wondering if the heat generated when the backing bar was cut off, has anything to do with this problem.  I noticed the heat bluing where the break is widest.
Parent - By Mwccwi (***) Date 04-28-2014 23:47
I've seen similar fracture on practice tests when the coupon was put in the bend jig still hot from grinding.
Up Topic American Welding Society Services / Certifications / Test Coupons cracking in half during bending

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