Steel wire for low-temperature annealing and method for producing same

Abstract

Provided is a steel wire for low-temperature annealing which comprises, by mass%, C: 0.10% to 0.60%, Si: 0.01% to 0.40%, Mn: 0.20% to 1.50%, P: 0% to 0.040%, S: 0% to 0.050%, and N: 0.0005% to 0.0300%, and further comprises one or more selected from Cr: 0.03% to 0.4%, V: 0.03% to 0.2%, and Mo: 0.03% to 0.2%, with Fe and inevitable impurities as the remainder. The volume percent of pearlite structure is between 1.40*(C%)*100% and 100%, the volume percent of proeutectoid ferrite is between 0% and (1 - 1.25*(C%))*50%, and the volume percent of bainite structure is between 0% and 40%. The tensile strength is between 480 + 850*Ceq. MPa and 580 + 1130 Ceq. MPa.

Description

technical field [0001] The present invention relates to a steel wire for low-temperature annealing used as a raw material for machine parts such as bolts, screws, and nuts formed by cold forging, and a method for producing the same. In particular, it relates to a steel wire for low-temperature annealing which is excellent in softening properties and ductility by annealing, and which can be annealed at a lower temperature, and a manufacturing method thereof. [0002] This application is based on and claims priority to Japanese Patent Application No. 2009-262158 filed on November 17, 2009, and the content thereof is incorporated herein. Background technique [0003] In cold forging, the dimensional accuracy and productivity of finished products are excellent, so when forming mechanical parts such as steel bolts, screws, and nuts, the conversion from conventional hot forging to cold forging is expanding. On the other hand, in cold forging, compared with hot forging, the deform...

AI Technical Summary

Problems solved by technology

In this method, it is sometimes necessary to contain more than 10% of pseudo-pearlite in the structure of the steel material. Therefore, in the case of steel grades with low content of alloy elements and low hardenability or wire rods with large wire diameters, it is necessary to The cooling rate is increased, so there is a problem of increasing the manufacturing cost

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