Method and apparatus for heat treating steel

Abstract

A method for heat-treating steel, which method uses a coolant having a large coefficient of heat transfer and which method treats the steel at low cost and in an environment-friendly manner (no pollution), and an apparatus for the method. The heat-treatment method cools austenitized steel in a coolant, which is a mixture of solid particles and water. It is desirable to cool the steel by passing it through a deposited layer of the solid particles in the water. It is desirable that the solid particles be oxides or graphite powders. It is also desirable to fluidize the solid particles. One type of the heat-treatment apparatus submerges steel in a coolant bath described below. The coolant bath comprises (a) a liquid bath that contains water and (b) a solid-particle bath that is partitioned in the liquid bath by a mesh and that contains solid particles. The mesh has openings smaller than the particle diameter of the solid particles. Another type of the heat-treatment apparatus treats steel by using a loaded coolant comprising water and solid particles and a means for forcibly supplying water between the solid particles. It is desirable that this type be provided with a means for fluidizing the solid particles.

Dependencies are inferred from the claim text.