Improvements relating to processes for the heat treatment of rails or other massive steel bodies

摘要

A rail or other massive steel body which has already been rapidly cooled below the critical range so that substantial temperature differences exist therein, is immersed in a highly heat-conductive medium, such as a molten lead bath, at a temperature above the "blue heat" zone (ordinarily between 200 DEG and 300 DEG C.) and below the critical range to reduce the temperature differences quickly. A good proportion of the interior of the rail, particularly the head, will still be above the blue heat zone so that the reduction of the temperature differences diminishes the chances of permanent defects from strains produced by the differences. The rail may be taken from the bath and then tempered in a furnace at 1000 DEG F. or the tempering may be effected in the lead bath by prolonging the immersion therein. An example of the range of composition of steel for the rail is given. Reference has been directed by the Comptroller to Specifications 1842/04 and 12098/04, [both in Class 72, Iron &c.].