P1 to P8 carbon side cracking 1

[InspCool]

Hello,
We have been attempting to perform a WPQ for P1 to P8 using ER 309 (GTAW)process. Twice now we have experienced cracking on the carbon steel side of the face bends.
Is this an issue with pre-heat? Currently we do not pre-heat and I have seen qualified procedures that do not cite this as necessary.

Filler and cap welded at 155 amps, DCEN.

Thanks all in advance.

InspCool

 

[weldstan]

Was there a minor discontinuity associated with the fractures?

 

[InspCool]

No sir, the weld on the carbon side when sectioned shows a visible line along the HAZ and when a face end is performed it splits at the toe as if it had not properly bonded into the carbon side.

I presume this is a heat problem.

 

[Duwe6]

Exactly - that 'line' you are seeing is a 'braze'. The filler lapped up onto the c/s and froze without 'breaking down' the metal. To have a weld, both sides have to melt, and then mix with the filler. Make a fresh coupon, cut it across the weld 2 to 4 places, then polish and etch them. This will tell you if your settings are now working, without the wait and expense of making bends.

Most expensive thing in the Weld Shop is cheap welding 'talent'. Sorry, but your welder needs more training and experience. Also, check to see if the welder got lazy and did not grind the weld prep area to bright, shiny metal.

 

[gtaw]

If the weld on the CS side of the joint is too shallow, it can tear out of the CS at the toe. This can be a problem when the welder tries to "wash" (weave) the weld beyond the edge of the groove to eliminate undercut at the weld toe.


Best regards - Al

 

[weld7777]

InspCool , it is not mentioned which P-8 material you are attempting to qualify, may I advise you to refer to Sec IX table 466.1, and verify the jig dimensions to the material's elongation requirements. There are quite some differences.

 

[InspCool]

Thank you all.

The material is SA-516-70 to SA-240-304

Welding in the flat position.

InspCool