Purpose: it is mainly used for steel parts to be quenched, isothermal quenched, tempering, aluminum alloy quenched and annealed in nitrate or alkali solution, low-temperature oil bath furnace for heat treatment such as nitrocarburizing in salt bath and oxidation tank treated by QPQ, etc. It can also be used for metal parts to be quenched, high-temperature cooled, low-temperature tempering and aging treatment.