This is a follow-on question to Is it reasonable to use full word and abbreviation in parenthesis in a chapter title?
One answer to that question indicates that in some cases, using an abbreviation in a chapter/section title is acceptable, other times not.
In the cases when it is acceptable, should you redefine the abbreviation before its first use in the chapter/section? Here is an example:
Chapter 4 - Results of Differential Scanning Calorimetry (DSC)
The apparent crystallographic phase transition of the sample material suggested that Differential Scanning Calorimetry (DSC) was warranted to determine the phase transition temperature and heat capacity. The results of the DSC measurements follow.