MANUFACTURING METHOD OF HYPER-EUTECTOID STEEL WIRE

摘要

PROBLEM TO BE SOLVED: To provide a manufacturing method of a hyper-eutectoid steel wire which is efficiently softened and excellent in cold workability even when conducting spheroidizing with shortened time of a heating treatment.;SOLUTION: There is provided a manufacturing method of a hyper-eutectoid steel wire having C content of 0.8 to 1.3 mass%,, including a rolling process to obtain a rolling wire and a heat treatment process for spheroidizing, the rolling process includes a process for finish rolling a steel material at a finish rolling temperature of 750 to 800°C, a process for cooling the same from the finish rolling temperature to 650°C at average cooling rate of les than 1°C/sec., the heat treatment process includes a process for heating the rolled wire from room temperature to a heating temperature T₁ of 800 to 880°C at average heating temperature of 10°C/sec. or more, a process for holding at the heating temperature T₁ for 0 to 30 sec., a process for cooling from the heating temperature T₁ to a slow cooling initiation temperature T₂ (=880-0.2×T₁) at average cooling rate of 10°C/sec. or more and a process for cooling the slow cooling initiation temperature T₂ to a slow cooling finish temperature T₃ (=T₂-40) at average cooling rate of 0.03 to 1°C/sec.;SELECTED DRAWING: None;COPYRIGHT: (C)2018,JPO&INPIT