anneal
verb (specialist)- anneal something
to heat metal or glass and allow it to cool slowly, in order to make it softer and easier to shape (= more ductile) 给（金属或玻璃）退火 Word OriginOld English onǣlan, from on + ǣlan ‘burn, bake’ from āl ‘fire, burning’. The original sense was ‘set on fire’, hence (in late Middle English) ‘subject to fire, alter by heating’.