Hello Gabriel,

the material is part of the model data, your load steps are part of the history data.

I think that you need a model for each Young Modulus you want to calculate with.

Greetings Tamlin

You could possibly prescribe different modulii in different steps by having temperature dependent values of Young's Modulus in the model data. In each step you would then need to assign a different uniform temperature to the structure (assuming no thermal loads are involved) corresponding to the value of Young's Modulus you required. Set the thermal expansion coefficient to zero though to prevent thermal stresses from restraints.

corus

You can supply Elastic properties (as well as other material properties) using dependencies on field variables.

You can prescribe values of field variable in each step for a custom defined set of nodes/elements or you can use UFIELD subroutine (at a nodal level during each increment). Such that your material property will locally change acording to the associated field variable during each increment.

Values of field variables can be adjusted also by using an associated amplitude curve.
 
->Field variables can be requested as output.

There's a useful example in Abaqus/St. User's Manual v6.3(or ABAQUS Analysis User's Manual v6.4) - Chapter:19.6.1.  "Predefined fields " -> Section "Field variables"