Hi all
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.

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Since I'm a blade smith upsetting stock isn't anything I normally do because it can be so upsetting.  lol.  Keep the stock rotating, move a little, twist.  That will help keep things even.  There's a few really good smiths on here, I'd like to hear what they have to say.

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Get it hot. When it's yellow it's mellow.

I use a hand hammer, not a press, so can't help with technique, altho it's most likely no different.

It sounds like you are upsetting this into a die to get your upset, meaning closed die forging.
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