Comparison of cooling methods for medium frequency induction quenching of rails

Name

Principle

Features

Wrong process used

Quality issues

Spray cooling

Direct cooling of heated rail treads using spray (a mixture of water and air)

(1) The cooling is uneven and the nozzles are easily blocked, causing local cooling to be too fast, leading to the production of structures such as martensite.

(2) It is sensitive to surface conditions. If there is rust, oil, etc. on the surface, the cooling rate will be very different, resulting in low hardness or the emergence of martensitic structure.

(3) The hardness decreases from the upper fillet of the rail to the lower jaw. Resulting in reduced wear resistance.

(1) Reduce the medium frequency induction heating temperature

（2) Poor wear resistance and short life.

(1) Uneven hardness and shallow hardened layer

(2) Poor wear resistance and short service life

Jet cooling

Using high-efficiency nozzles, a single compressed air is used to spray and cool the three sides of the heated rail, with an outlet pressure of 0.2-0.3MPa.

(1) Uniform cooling, stable pressure, and good surface hardness uniformity after cooling.

(2) It can avoid the generation of martensite and obtain pearlite structure. It will never peel off, fall off or be damaged during use.

(3) There is almost no change in the fillet and jaw hardness of the rail, it is not sensitive to the performance state, the process is reliable, and the design is safe.