METHOD FOR HEAT-TREATING MAGNET WEB REGIONS OF A ROTOR

A method for constructing a rotor assembly for use with a rotary electric machine includes forming annular rotor laminations from metal blanks. Each lamination has a radial axis and an outer diameter surface. Multiple magnet web regions are defined in proximity to the outer diameter surface. Each web regions includes asymmetrical openings defined by a radially-extending strut and arcuate peripheral bridges. The method includes coaxially stacking the laminations into a rotor stack, including positioning every other lamination a predetermined angular distance with to unmask the bridges and/or struts and mask remaining surface area of the laminations. The rotor stack is subjected to a heat-treating process to harden only the unmasked bridges and/or struts. The method includes connecting a rotor shaft to the stack to construct the rotor assembly, with the web regions corresponding to a respective rotor magnetic pole.