Thanks for the links Salvatio, i found one stress-strain graphic on the net. It´s not a very good one, but I think it´ll do it.
Yes, I do intend to deform it plastically... and a lot. It´s not very usual to do it with this kind of material, but I´m simulating the forging process of a cylinder that´ll be used in steel plates rolling. So it´s very difficult to find all the data I need.
Thanks again
Guilherme