Weldable high density and good machinability

[mi99kaan]

I have trouble finding a material that fulfills my requirements list.

Density >8,8 g/cm³
Relative magnetic pearmability <1,02
Weldable to soft iron, using laser spot welding.
Machinability >70% compared to UNS C36000 (free-cutting brass)
Availible on rod Ø20 or bar 15x15 [mm]

Thankful for any help!

BR
Anders

 

[btrueblood]

Um. Pure nickel, or nickel 200 alloy, I think has the density you want; it should weld ok to iron...though what strength and reliability you get from the joint may vary.

 

[mi99kaan]

Yes, nickel would work if we didn't have to consider the manufacturing. Monel and inconell alloys welds have been satisfying. Although mMachining of nickel and alloys with high nickel content is difficult because of the fact that is hardens a lot by deformation.

 

[GRoberts]

Have you tried copper?

 

[btrueblood]

Well, red brass would work too, but getting a copper alloy to "weld" to iron might be difficult.

 

[GRoberts]

It would all depend on what properties are wanted from the weld joint. However, using laser could only help with the differences in thermal conductivity that can give you fits with regular arc welding.

 

[mi99kaan]

We will use maximum 8 spots on a Ø11 cylinder in a hole with H9 fitting.

We have not tried pure copper because it is difficult. The laser pulse can be shaped to penetrate and give a proper melt of the copper but it's a too unsure solution to go through with.

The materials we've tried so far are:

Monel K500 - Ok welding but not machining

Inconell 600 - Ok welding but not machining

Brass - Not ok welding....

Beryllium copper, 0,5Be/1Ni/1Co/Cu bal. - The toxic issues are not fully investigated. Machining is pretty good, welding is a bit unsure.

85 Cu / 15 Ni - Ok for welding but machining is slightly too bad for us.

Too much zinc will make it impossible to weld with laser. It will more or less explode...

Thank you for all the answeres so far. I hope someon knows a solution that is usable.

BR
Anders

 

[mi99kaan]

The components we will weld are pretty small. The final product is 14x15x5 mm so we need small weld spots and minimal thermal inpact. We don't think there is another welding solution than laser, not for an automated process. Adding material is a big no no for this component. Keeping the mass properties at the same level is critical.

The thing with brass is that the zink transforms to gas very fast because of the high energy pulse, it's like a small explosion.

 

[btrueblood]

Are you trying to machine the welded area? If not, is there any way to strain harden the material first (nickel, copper/nickel alloy) to hopefully improve machining properties.

Yes, welding brass is pretty much impossible, was thinking you would solder it instead, but that "adds material". Welding copper is possible, but you really need to use OFHC copper; standard electrical-grade (electrolytic tough-pitch) copper has too much residual oxygen, and will result in very porous welds.

Would a composite construction work, e.g. having a tungsten core brazed into a machinable+weldable steel part, or pouring lead into a machinable+weldable part?