If you've got enough forge up a small test piece and quench in water, if it breaks like glass and has a fine grain use the rest of the chain. Heat to non magnetic and quench, start out tempering at 350 deg.F. and edge test, keep raising the temp 15-25 deg. at a time till the edge quits chipping and comes back true.
If the test piece is a little low in carbon like some hay bailier chain I forged once, add some pieces of 1095-1084, some 15&20 or other high carbon steels to get the carbon content up to where it'll make a good knife.
Good luck, I've got some I'm working on that's the bigest I've ever seen, looks like it's all high carbon so we'll see how the test blade comes out. Chainsaw has some increadable paterns, and like cable you never know exactly what your gonna get.