MONEL BODY X MONEL DISK X MONEL BODY - DIFFICULT TO GET GOOD WELD PENETRATION DEPTH

[65CCJ]

I'm trying to find out why an all-monel butt weld joint with no filler, just fused, is so much harder to get penetration depth than other CRA materials welded to Monel. We are fusing a .85 OD x.010 thick solid monel disk between two.850 OD x 1/2" ID monel tubes. We just fuse the parts together and require >.015" weld penetration. We section the welded assembly after welding to inspect the weld penetration. Unlike other nickel-based alloys, it is challenging to achieve the same penetration depths. The weld will not get much deeper than .015" despite trying different weld settings. It gets wider but not deeper. Many times .015 depth cant be achieved. I wanted to know why we have such trouble getting penetration with all monel joints vs others like Inc. 625 to Monel, or 316 to Monel. I attached a couple of images showing the weld pen depth for all monel joints. The materials are fused, with no filler. It's very wide and shallow unlike most that have .025 to .040 depth x .020 wide for a disk that's .01" thick.

Does anyone know why all Monel welded/fused joint is so difficult to achieve good penetration relative to other materials with the same Monel disk? I'm new to welding and hope my explanation makes sense.

 

[btrueblood]

Copper/nickel alloys are generally tricky to weld, I've tried it and had pretty crappy results (but I'm a novice welder even after 20 years, I just don't get enough practice). The nickel content in Monel makes the molten alloy not "wet" or flow into the weld joint very nicely, and you end up building up a lot of heat trying to get penetration, and then get blowouts. Welding without a filler is even trickier, and a lot of welding advice available on the interwebz says not to try it.

see

https://resources.arcmachines.com/what-is-the-best-way-to-weld-monel-ami/

If you use filler, make sure it's the one recommended for the particular monel alloy you are using.

 

[bobjustbob]

What grade of monel are you talking about. We made quite a bit of M35-1. Each heat required a weldability test per the supplementary requirement S-22 in A-494.

Bob

 

[weldstan]

Monel has a vey large liguidus to solidus temp range. Too great a fusion zone would lead to cracking when fusing as you did.

 

[Dhurjati Sen]

This document might help. Check the last section which talks about "Joining".



DHURJATI SEN
Kolkata, India