PROCESS FOR MANUFACTURE OF COLD-ROLLED HIGH-CARBON STEEL PLATE

摘要

A process for manufacture of a cold-rolled high-carbon steel plate comprising the steps of: hot-rolling a steel containing 0.2 to 0.7% by mass of C at a finishing temperature lower by 20°C than a Ar<SUB>3</SUB> transformation point or higher to produce a heat-rolled plate; cooling the heat-rolled plate to a temperature of 650°C or lower at a cooling rate of 60°C/sec or higher and lower than 120°C/sec; taking-up the cooled hot-rolled plate at a take-up temperature of 600°C or lower; cold-rolling the resulting hot-rolled plate at a pressure reduction rate of 30% or more to produce a cold-rolled plate; and annealing the cold-rolled plate at an annealing temperature ranging from 600°C and an A<SUB>c1</SUB> transformation point inclusive. The process can produce a cold-rolled high-carbon steel plate which is excellent in stretch-flange formalibity and evenness in hardness in the thickness-wise direction.