E9018-B3 repair is cracking

[Guest102023]

We are attempting a crack repair on a large F22 forging (several tons I estimate), where the joint restraint is extremely high. The first attempt with TIG & SMAW has failed, with at least one of the SMAW passes showing centreline cracking.
My question is this: is the B3L filler any less prone to cracking than B3?

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[weldstan]

The B3L would be less prone to cracking. What is the preheat temperature and how is it maintained. What is your joint design and if it is too narrow, why can you not increase the bevel included angle and the root radius?

d

 

[Guest102023]

I was only called in after the first attempt at repair failed.
The excavation was at a 90° internal corner where fatigue cracking had initiated, and I suspect the first excavation was too narrow.
I want to implement every technique possible to prevent a repeat of the cracking, including B3L if that helps. Block welds and root layers will all be done using GTAW.
Preheat will be 350°F min.



"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[dik]

If a large thermal mass, then pre-heat and maintaining it for a while may be in order. If mass cools too quickly, this may cause thermal cracks.

Dik

 

[metengr]

You will need to use an intermediate stress relief (PWHT) to reduce joint restraint based on your stated thickness.

 

[Guest102023]

metengr,

Do you mean after partial repair?

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[metengr]

Yes. I have used this technique before for heavy wall turbine casings and cast valve bodies. You still perform a final PWHT. The intermediate PWHT does two things - it reduces residual stresses and tempers any harmful transformation products (martensite), which can be crack sensitive.

 

[Ron]

How were the electrodes stored? These are sensitive to ambient moisture/humidity.

 

[weldstan]

What is the repair depth vs total thickness? I would advise a root radius of 1t least 1/4" and an included angle of 60 degrees. Preheat of 400F min and maintained by heating pads.

 

[Guest102023]

weldstan,
Your recommendations for the weld prep are similar to what I have advised them. Electric resistance pads are being used. They were worried about too much preheat, but I told them more is better, and with the mass involved there is no possibility of it running away.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[Guest102023]

Repair is nearly complete with no further cracking - thanks to all.
I had to put the brakes on the contractor's PWHT procedure, which permits a too high heating and cooling rate.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"