Grey cast iron

Hello.all!

Is anyone doing the work on the modeling of  constitutive equation of Grey cast iron in large deformation?

Recently i read  Holm Altonbach's paper "on the Elastoplastic deformation of Grey cast iron" ,  i wonder how to convert the relation (stress-strain) into (stress-hardening parameter). I'm also not sure if the constitutive model can be used in large defomation simulation. 

 thanks in advance!

Y.T.