Laser Welding Hastelloy and the problems associated with it

[AWOC]

Hello. I am am trying to find out why Hastelloy cracks during laser welding. What techniques are used to lessen the cracks etc. The main focus is to learn as much as I can about laser welding this material and what laser setting to start with . A simple google search has gotten me no where and seems that laser welding companies are very discreet about their processes. Any info or articles that you can point me towards would be great. Thank you!

 

[MagnetDave]

There is little information out there, but I have had to pry into this before.

What are you welding to, what is the weld geometry?

 

[AWOC]

I am welding a stainless round 304 barrel to a hastelloy round tube using a rotary fixture.

 

[MagnetDave]

Ugh.

I've seen this before welding a round 316 to a 316 barrel - so it's pretty similar, only your problem is a lot more complicated because you are welding dissimilar materials, usually a big no-no.

Cracking is usually caused by thermal expansion during the welding process - the sleeve expands, welds, the melt solidifies, and the sleeve thermally contracts, stressing the weld bead and leaving cracks.

The best solution is to make the sleeve an interference fit. The tension should dominate the expansion forces as minimize the problem. I would also try to match the materials, if possible - this will also help with corrosion in the future.

 

[AWOC]

I am trying to weld 5mm wide barrel to 1.7mm tube. These are small scale parts that the material choice is not decided by me, but rather the costumer.

I have sent these parts out to other laser companies and when the parts come back I have noticed:
1) very smooth almost mirror finish weld joint
2) No roll of dimes look

I am assuming the welds were done at super high frequency rates or a continuous beam weld. I don't know how this was achieved.