Method for recovering cooling characteristics of water-soluble quenching medium, and water-soluble quenching medium with recovered cooling characteristics

摘要

Disclosed are a method for restoring a water-soluble quenching medium being used, of which the cooling characteristics have been deteriorated during use, to its original condition to have nearly the original cooling characteristics which the fresh medium has before use, and a water- soluble quenching medium thus restored to its original condition to have nearly the original cooling characteristics thereof. The method comprises adding to a quenching bath being used an aqueous solution comprising a water-soluble polymer (B) that has a larger weight average molecular weight than that of the water-soluble polymer (A) existing in the fresh water-soluble quenching medium to be in the fresh bath.