root cause for failure of bend test

[vks1986]

Hello,

what is possible root cause for failure of bend test from haz(crack parallel to weld seam).

bend sample taken from tranverse to weld seam in api 5l x52 material..

 

[desertfox]

Hi

Please can you give a lot more information about the failure at present the failure could be a multitude of things of which the following list is not exhausted:-

Hydrogen embrittlement
weld porosity
lack of fusion
weld inclusions
incorrect post or pre heat treatment
incorrect filler material
incorrect settings of weld parameters

A picture of the failure also might help you get some proper answers

 

[stanweld]

What was the welding process and welding filler metal used? If E7010, most likely hydrogen embrittlement.

 

[metengr]

Not enough information to provide an opinion. Have the sample examined or have a competent met lab evaluate the bend test failure.

 

[redpicker]

Is this an ERW weld?

If so, you can rule out:
Hydrogen Embrittlement (if you have hydrogen problems, you have a base metal problem and the integrity of the weld isn't going to matter)
Weld Porosity (If there in porosity in an ERW weld, again, it's a base metal problem, not a welding problem)
Lack of Fusion (ERW is a non-fusion process; there is no fusion, so it can't be lacking)
Incorrect filler metal (as with the fusion; hard to have incorrect filler when there is no filler metal)

That leaves:
weld inclusions (could show up as hook-cracks; check silicon content and weld pressure)
incorrect pre/post heat (in particular normalizing of the weld seam and cooling afterward)
incorrect weld parameters
and, not mentioned
improperly prepared faying surfaces (dirty, contiminated, or unsuitable geometery).

rp

 

[vks1986]

thanks to all to give your presious openian..

we are using double side welding by tandam arc saw , woldwide used for manufacturing of line pipes as per api 5l LSAW PIPE.

before cut bend sample rt was clear,
pipe size: 18"X17.50mm
grade: api 5l x52mo

hardness come in haz area was max 200hv10

 

[metengr]

Thanks for the additional information. It could be lack of fusion from your original description. However, this is only a guess and you need to send it to a lab for root cause analysis.

 

[stanweld]

The process is not low hydrogen plus acid based fluxes are often used plus preheating normally not done; hydrogen embrittlement remains a suspect. Was there appreciable mismatch (skewing) of the two sides (ID & OD) of the weld or were they symetrical?