Welding on B7 material 2

[atomicbob]

We recently discovered a supplier had substituted B7 studs in place of the SA36 we ordered. (a no charge "upgrade") Some of these B7 studs got welded to SA516-70 plate as a lifting device (GMAW ER70S-6). I know that ASME does not recognize B7 as a weldable material, but this is not an ASME Code weld. It just needs to work. I am not concerned with the diminished tensile strength of the stud materials as it is not under high load. Perhaps 500 pounds on a 1" stud.

The question I have is, are these welds mechanically sound? Or is the B7 so hard that it will simply crack at the heat affected zone under impact? Or...???

Many of them are in the field and replacement would be difficult to replace.

Thanks

 

[SnTMan]

atomicbob, I'd say the B7 has a good chance of cracking. People have gotten hurt doing this.

You said 1" stud, but how much weld?

Can you NDE 'em all?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[NBrink]

I wouldn't risk it for a lifting device. B7 is pretty dang hardenable.

 

[atomicbob]

It is welded with a simple 1/4-3/8" fillet. Going forward we won't be using it. We are trying to assess the viability/necessity of reworking scores of units scattered over the globe.

 

[SnTMan]

Understood. Should be enough weld for the load if its sound.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[atomicbob]

Thanks. We will do some tests in house...weld some on and bash them around, see if we have any failures. I was just curious if welding turns B7 to glass, etc.

 

[SnTMan]

atomicbob, let us know how it goes

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[metengr]

You should perform surface NDT (like wet fluorescent MT)to at least ensure no cracks from welding, this is a MINIMUM requirement.

 

[CoryPad]

Welding B7 won't turn it to glass, but it could produce cracks and a microstructure that is similar to glass (brittle, unstable crack propagation under stress). Extreme caution is warranted.

 

[weldstan]

Also perform your MT test after about 48 hours in case delayed cracking occurs. With GMAW, the weld metal and B7 HAZ will be quite hard. Assuming an Argon CO2 mix hydrogen embrittlement (cracking) is quite likely. We used to make this weld with nickel base filler metals and a 400F Preheat with great success.

 

[NBrink]

This is just a threaded stud fillet welded to whatever it is you're lifting?


Does anyone actually feel comfortable that WFMT will accurately be able to find an indication in a 1" thread root? I've never tried, but I can't imagine it not immediately lighting everything up...

 

[1gibson]

"Scattered over the globe..."

Be sure to "bash them around" at minimum ambient temperatures.