A bit more information would be helpful. For example, what type of stainless? Austenitic? What temperature/color did the steel reach? However, you are most likely dealing with a transformational effect in the carbon steel.
You have to go a bit further. It is not sufficient that the scientific method be used to test any hypothesis. The hypothesis must be falsifiable. How many angels can dance on the head of a pin? Since there is no way to count the number of angels no hypothesis can be formulated that can be...