| 摘要 |
<p>PURPOSE: A hot-rolled steel plate and a manufacturing method thereof are provided to enable the hardness of the steel plate to be lowered by converting a structure including pearlite into a mixed structure including proeutectoid ferrite and pearlite by spherodisation. CONSTITUTION: A method for manufacturing a hot-rolled steel plate includes the following steps of: reheating a slab plate comprising 0.40-0.50 wt% of carbon, 0.15-0.30 wt% of silicon, 0.6-1.0 wt% of manganese, 0.015 wt% or less of phosphorus, 0.005 wt% or less of sulfur, one or more kinds among 0.5 wt% or less of chrome, 0.2 wt% or less of nickel, and 0.03 wt% or less of soluble aluminum, and the rest of Fe and unavoidable impurities; hot-rolling the reheated slab plate and cooling; and spheroidizing and annealing the cooled slab plate at a temperature of 670-730°C. [Reference numerals] (AA) Start; (BB) End; (S110) Reheat a slab (SRT: 1150-1250°C); (S120) Hot rolling (FDT: 840-880°C); (S130) Cooling/winding (CT: 600-660°C); (S140) Spherodisation annealing (670-730°C)</p> |
