Query regarding use of block thermal substep in UDEC

I want to apply a thermo-coupled step on a block on which after heating the joints are broken(Thermal effects). I think block thermal substep is the way to achieve it. But I couldn’t understand how to go ahead with it. Can somebody please explain how to use this thermal substep.(As in does the thermal substep is written before or after/Do we need to write step or not)?

Thanking You