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17:31 Jul-02-2016
Cracking In Carbon Steel

Hello everyone,

All fabrication and inspection is to AWS D1.1. Fabricating utility poles that are tapered with 12 or 18 flats. 1/4-5/8 shaft and 2 1/2 to 4in. flange is the range of raw material as of now. Finding many cracks in weld. Specifically inspecting today a 7/16 in. shaft welded to 3 in. flange. Mig welding a single groove, 45 degree bevel. Welding inner pass first then coming outside and back gouging and laying multiple passes to obtain CJP. Welding parameters are: Wire- Hobart .052 and Lincoln .052, Wire speed- 330, Volts- 26.5, Gas- 90AR 10Co2. Pre-heat- 300 F of flange and shaft"at least 3in. from direct area being welded." Everyone has gotten involved including engineering and owners. Material certs have been checked as well as WPS's verified as ok for our application. Cannot find solution. Found multiple defects with height reading as 1/4 to 7/16. Welder arc gouged and did find cracks. Then ground to specified height reading and re-welded. No verification that defect was gone with any other NDT method. When I checked with UT same indication and identical characteristics on A-scan as first inspection but now 000"- 5/16. Welder arc-gouged in and indeed found cracks again even though welder claimed that all defects were gone when he began welding for the repair. I'm being questioned as the UT tech of whether or not I'm giving accurate measurements. Is it possible for cracks to propagate height wise through the volume of the weld and why are we having so much cracking in the first place?

07:54 Jul-03-2016
Re: Cracking In Carbon Steel

John,
Can you upload any sketch of bevel configuration or WPS?

01:52 Jul-05-2016
Re: Cracking In Carbon Steel

John,
I recommend to verify metal soundness after air gouging by using MT. Very often visually it looks like crack removed but when you apply MT you see reminded crack which expanded during rewelding.

17:32 Jul-05-2016
Re: Cracking In Carbon Steel

Hi John,

Can you sketch exactly where the cracks are showing up? It's too bad you are being questioned as to your accuracy when upon excavation the cracks are visible. I've seen this happen alot and it's very frustrating... we're always the bearer of bad news!

-Paul

18:04 Jul-05-2016
Re: Cracking In Carbon Steel

Hi Paul,

I would say 90% of the time it's between the inner pass and root pass. A lot of times I also find cracking on the knuckles where the weld profile is concave, in the scenario it's almost always center line cracking.

17:25 Jul-06-2016
Re: Cracking In Carbon Steel

Hi Paul,

I would say 90% of the time it's between the inner pass and root pass. A lot of times I also find cracking on the knuckles where the weld profile is concave, in the scenario it's almost always center line cracking.