newbie here with perhaps not a newbie task.
i want to upset some 28mm ansi4340 round bar to a 40mm diameter for a length of 22mm. I have a 15 tonne press, an induction heater (takes 2mins to get the 28mm to orange hot over a 50mm length), and I have a die that I have machined up to give the final shape.
I had a play with some mild steel today, and beside being a bit off centre, it was ok’ish. Just using a flat SS plate ram face to reduce the heat leakage to the ram.
Google was not my friend just now in looking for some tip. My gut feeling is that a spherical (think big ball bearing ball) would be better than a flat plate for the initial pressing. That way it should spread into the die a bit easier, but I am doing nothing but guessing.
Comments from any one with experience here would be really appreciated.