I'm not sure I understand your question properly, but here's an example assuming metal plasticity :
*MATERIAL
*PLASTIC
stress_1,strain_1
stress_2,strain_2
...
where the pairs (stress_i,strain_i) define the material's curve.
As corus said, why don't you split your step ?
Another solution would be to modify the default Dm factor under the *CONTROLS,PARAMETERS=TIME INCREMENTATION card (see Keywords Ref Manual) :
- specify an adequate initial increment
- set Dm to 1.0
But it is imho far more complicated ...
Eric