First of all, in FCAW wires, consumable manufacturer control the weld chemistry by the core filling formulation which control the toughness. So the results varies with manufacturers. You didnt specify the brand name.
As per my experience, go with Kiswel brand manufactured in Korea (1st solution).
Further, as you specified that the lower heat input also didn't help you to achieve the toughness, the failures can be attributed to coarse grain ferrite/ pearlite in your weld micro structure presents in root and cap. You are able to achieve the toughness in center which is highly possible due to grain refinement by successive weld beads. For a improved microstructure you can go with argon mix as advised by Mr. Goswami as using poor CO2 will give high arc efficiency with increased heat input in the weldment and this will not reflect by general heat input equation.
Follow as stated above along with stringer beads, weld with maximum weld passes so you will have a better grain refinement. You can use controlled weld deposition for the capping pass.
regards
Sandeep Kumar
Sandeep Kumar
Welding Specialist
MSc.welding Engg, IWE, IWT
On Monday, August 19, 2019 at 7:47:47 AM UTC+3, chakote...@gmail.com wrote:
Dear experts,
We have carried out FCAW WPQR with PWHT. Welding consumable is E71 T12 CJ. Below are the conditions
Test coupon thk- 70 mm
Parent material- S355 G8+N
Process- FcAW
Welding consumable- E71T-12CJ
PWHT Temp- 580 deg C
Soaking time - 280 minutes
Impact test temp- minus 40 deg C
Heat input range (root)- 1.0-1.6 KJ/mm
Heat input range (cap)- 1.0-1.4 KJ/mm
Thermal efficiency- 0.8
Welding position-3G
The above welding consumable is recommended for PWHT.
The impact values are too low at root as well as cap.
Energy values- 16,15,25 J (root)
Energy values- 30,30,31 J (cap)
Can you please focus on impact values failure reasons?
Even if keeping low heat inputs the test has failed.
What could be the possible reasons of failure?
And with the same conditions WPQR passed with 2G position.
Please focus on possible reasons.
Regards,
Vishal
https://materials-welding.blogspot.com/
https://www.linkedin.com/groups/122787
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