EB Welding Nickel Alloy 718

[acspain]

Good Morning All,

Do you know of a resource that connects EB Welding parameters such as focus, milliAmps, speed, etc. with weld shape and size?

I understand that the above is likely to be machine dependent and have reached out to the manufacturer as well.

We have significant experience EB Welding assemblies of stainless steels, nickels, and titanium.

But we have found ourselves in a unique situation (to us anyway) with welding a variant of the Nickel Alloy 718 and finding liquation cracks.

Our customer has experience with this and has shared the strategy for resolving but that puts us in the position of trying to determine a suitable weld schedule with limited amount of time and material and I am trying to reduce the amount of experimentation.

Thank you for your help.

 

[MG1983]

Greetings ;

what kind of strategy your customer has shared ?
You are having liqcracks probably due to nickel has FCC structure. Using a filler metal that would generate some BCC in the weld metal would solve the liqcracks.


for speed amperage you can check example WPS s from the standards however i am not certain you will be able to find one for Ni 718

Best regards.

IWE EWE certificate holder.

 

[acspain]

Hello MG1983,

Thank you for your reply.

We ended up conducting a series of experiments that could be characterized as an fast informal DOE which in turn provided us with relationships between the various inputs.

The solution ended up being a series of steps including preheat, root weld, deep cover pass (re-melt top of root weld), then a cosmetic cover pass to smooth out any surface irregularities.

Have a good day!

 

[kingnero]

@acspain, out of curiosity, do you have an installation that allows feeding a wire into the weld? The (very few) EB machines I'm familiar with are purely autogenous ...

@ MG1983, as liquation cracking typically happens in the HAZ (and not in the weld pool), how would a different filler metal help against this?

 

[acspain]

Good Afternoon Kingnero,

All of our welding with the EB Machines is autogenous - no filler added.

To follow up on MG1983's comment, the concept was broached of adding another alloy (a thin 625 washer) into the weld to aid with liquation cracks. Apparently this has worked in other assemblies. This was not a desired approach as it would have added another component to the assembly along with associated costs, potential errors, and lead-time.

Have a good day!