Abstract: A method and apparatus are provided for producing rods having a desired tensile strength from a rod manufacturing process set to an optimal operating condition. Initially, the rod manufacturing process is set in an optimal condition to produce rods at a maximum rate, while optimizing the mechanical properties therein. Raw materials are melted and a "heat of steel" representing one lot is poured into a ladle which is sampled to determine its chemical composition. The percentage content of each element is utilized within an empirical model modeling the rod manufacturing process to predict the tensile strength of rods. The empirical model is again utilized to determine the amount by which a control element must be varied to adjust the predicted tensile strength to the desired tensile strength. The control element represents an element, such as, carbon which significantly impacts the tensile strength of the rod.

Abstract: A rod having end portions of a hardness characteristic of a pearlitic microstructure, the remainder comprising an annular outer region and a core region, at least the outer region having a surface hardness greater than Rockwell C 50. A method of producing heat treated rods involves passing a heated rod through at least one quench zone, initiating a liquid quench after the leading end of the rod has emerged from the quench zone and turning off the liquid quench before the trailing end of the rod enters the quench zone.