hot rolling but it is necessary to cool the rail by taking a lot more time than necessary to shorten the time and to make good use of sensible heat it is desirable to charge promptly the rail into a heating furnace the structure of the rail charged into the heating furnace is transformed again by heating into austenite structure at ac 3 transformation point the austenite structure produced by heating becomes very fine compared with austenite grains of the rail hot rolled at first in order to obtain this fine structure it is indispensable to cool the above mentioned rail to ar 3 transformation point or less after the hot rolling to complete perfectly the transformation since insoluble cementite structure remains in austenite structure immediately after the transformation hardenability of the rail becomes inhomogeneous and decreases to solve this insoluble cementite structure and secure a stable hardenability a heating temperature needs to be raised to a temperature higher than ac sub 3 transformation point the austenite having become fine grows into coarse grains with the grain growth caused by the rise of the heating temperature therefore it is necessary to heat the rail at a temperature of less than 950 u00b0 c when the heating temperature exceeds 950 u00b0 c the austenite.