METHOD FOR MANUFACTURING SPRING STEEL BILLET HAVING EXCELLENT HEAT-CRACK RESISTANCE

摘要

PURPOSE: A method for manufacturing a spring steel billet having an excellent thermal crack resistance is provided to restrain the generation of a thermal crack in a process for reheating and hot-rolling a spring steel bloom in order to manufacture the billet. CONSTITUTION: A method for manufacturing a spring steel billet having an excellent thermal crack resistance includes: a step of reheating a spring steel bloom in a reheating furnace having a preheating zone, a heating zone, and a soaking zone; and a step of rolling the bloom in order to manufacture the billet. At the end point of the preheating zone, a temperature difference between the surface and the center of the heated bloom is below 150C. In the step of reheating the bloom, a volume expansion difference (delta-V = (V (surface) - V (center)) / V (center)) between the surface and the center of the bloom is below 0.32%.