Welding jig

[Ovec]

I want to build a jig for silver soldering brass valves.
What type of steel should I use to limit dimensional changes caused by the heat?

 

[metengr]

Since the jig would be exposed to brazing temperatures ~ 1000 deg F, even Invar (which has a low coefficient of expansion) will grow at this temperature. I would build the jig out of low alloy steel (AISI Type 4140) to provide some strength at elevated temperature.