Steel rail head surface hardening - by uniform preheating, rapid heating and rapid air cooling (ZA 8.7.81)

摘要

The head of a steel rail is heat treated by (a) uniformly preheating to a predetermined temp. in the range 300-650 deg.C; (b) rapidly heating with a heat input of at least 2100 MJ/sq.m.-hrsuchthatatemp.gradientofatleast15deg.C/mm is produced in the rail head and that a predetermined depth of surface of the rail head is heated into the austenitisation temp. range. Then (c) quenching so that the predetermined depth of rail head surface is transformed to a uniform fine pearlitic structure Pref. step (c) comprises forced air cooling at a rate corresp. to 300l/min.-sq.m. of cooling water. The process gives a good depth of quench, is easy to control and produces a rail head surface having excellent abrasion resistance.