PTA Tungsten Carbide overlay on 27%Cr Steel

[dieselofdog]

Does anybody see an issues with welding a Tungsten Carbide (40/60 Ni based) overlay onto an a Ferritic steel 27%Cr? I am looking to start up some trials to achieve 3mm overlay height in one pass. The base metal will be > 50mm thick.

I am thinking of starting with the following:

PTA process 100% Ar gas
Pre heat 250 deg C
Slow cooled in vermiculite

Does anybody have any experience with this combination.

 

[Duwe6]

No experience it this combo.
However, once the welding starts, do not stop for anything. The heat will need to be maintained to keep from having 'hot cracks' under the beads. Use a 50% overlap, similar to 'Temper Bead' weld repairs; making each weld bead stress relieve at least 50% of the one next to it. Might work.

Probably should run a mock-up coupon, with 30% or less overlap [worst case] and check for cracks 48-hours after the mock-up has cooled to room temperature.

 

[Guest102023]

Google and call a few fabricators or powder suuppliers.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[EdStainless]

How thick is the base material?
You actually have it in hand and know its properties?
Most 27% Cr grades are made over 0.083" thick, it isn't possible to suppress the formation of secondary phases in thicker material. These phases result in very poor corrosion resistance and no ductility (and a DBT above room temp).

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P.E. Metallurgy, Plymouth Tube

 

[dieselofdog]

EdStainless, base material thickness will be greater than 2 inches. The overlay will cover the entire surface area of base material exposed to the working media in service, therefore negating the loss of corrosion resistance. Can you explain more on suppressing the formation of the secondary phases? What is 'DBT'?

Duwe6 - Thanks for the tips, I am defiantly conducting trials prior to production.