Welding A514 Grade Q to API 2H Grade 50

[Andyfoghorn]

We have to Weld A514 Grade Q to API 2H Grade 50 and the question is how to lower the hardness values down to 325HV without having to PWHT.because the overmatch as far as yeild and tensile strengths are considerable between the two materials we are not overly concerned with the loss of some of the mechanical properties of the A514 .

Consumable is lincoln ultracore 71A85,Trials so far have suggested a higher than normal preheat 400F with max interpass 500 and using slow higher heat input runs.

Given that the A514 material is already hitting over 300HV ,325HV is not a realistic target but we would like to find away of lowering the hardness as much as possible .Anyone have any ideas .

 

[metengr]

Ok. The ASTM A 514 is a quenched and tempered (Q&T) steel plate, with a min 100 Ksi YS and 110-130 Ksi UTS. The API 2H Grade 50 is the obvious lower strength steel, it looks to be supplied in a normalized (N) or normalized and tempered (N&T) condition because of required impact properties.

Knowing this information, I would keep the preheat at 400 deg F and increase the interpass to 600 deg F.
As far as welding technique to avoid PWHT, I would suggest using a temper bead method for these materials.

I would qualify a temper bead procedure and perform impacts for the API 2H steel. Do you know the temper bead weld technique? You did not mention plate thickness, what is the plate thickness at the weld joint?

 

[Andyfoghorn]

We have a 3" A514 tapered down to 2" API 2H On the coupons run so far we have run a temper bead cap with no real effect.Although we did run a coupon with 400preheat and a max interpass of 550 so maybe we,ll see some favourable results

Thanks for the input glad im not going down a blind alley,will keep you informed of results

 

[metengr]

Andyfoghorn;
What is a temper bead cap? The temper bead technique requires buttering the weld joint and filling the weld joint while remaining on top of the butter layer using higher heat input for the second and successive weld passes.

You should have no problems with using a gas shielded flux core process. What exactly did you do?