Welding Filler material help needed

[fredieusa]

I am trying to match the Nickel content of the filler so the finish is consistent after Hot-Blue/Rust-blue. This thread discusses it a bit.

Nickel content varies from 0.15% and less in cheap rods, that give a very dark finish compared to the rest of the receiver, as the weld is highly reactive and therefor soaks up the color. Additional drawback is that it does not flow as smooth resulting in microscopic pits, which i s not as clean.

The other option is getting what we call quality rods which are expensive as sold by Brownell's here.. These have high Ni content, flows beautifully for making beautiful welds. However it takes no reaction for the finish. Rest of the receiver gets dark and this weld with high nickel content, stays bare.

I am not able to find a filler rod with nickel content in the range of 0.25 to .05%. I know, original material works best but there is not enough of it. Do we have any pro welding stores here in the Bay Area that carry other than standard ER70S(x) and the types? Thanks for your help.

[69powerwagon]

I'm a little confused how much nickel you want in your weld. do you want in the range of 0.25-0.05%?(that's not specific enough of a criteria their) In which case 0.15% in cheap rods(what is a cheap rod? er70xx perhaps?) sounds like what you want as it's in the middle. Once you tell us how much nickel you want, I can probably find the filler.

[kcstott]

I've used ER70 S2 with great results. after bluing can't see the weld. Problem is I have no clue what that top cover is made of. If it is anything near mild or 4140 ER70S2 would work just fine.

Now knowing the AK and being stamped out of just about anything Id give it a go with ER70S2 and if that didn't work I'd use a metal coat hanger as that recycled crap the use for steel to make them out of is most likely pretty close to the top cover.

That said You may be getting the metal to hot. or leaving it to hard. Either will not allow it to take a rust blue with ease. I'd try warming the metal up to a dull red and hold it there for a few minutes then let it cool very slowly like say an hour or two to go from 1200 degrees to room temp that would anneal the area and possibly allow it to take a better blue

[kcstott]

You don't have to heat treat the top cover. But it won't hurt.
As for shielding gas yeah it will have an effect.... ALL BAD!!

100% Argon on steel for Tig welding. Tri mix for Stainless, Argon/Helium for aluminum for added heat but makes striking an arc harder.

The problem is most likely due to too much heat input on the part and to fast cool down hardening the weld preventing the rust bluing from taking.