JP2000063987A - High carbon steel wire with excellent drawability - Google Patents

Abstract

(57) [Problem] To provide a high carbon steel wire excellent in drawability suitable for applications such as wire ropes, springs, PC steel wires, bead wires, and steel cords. SOLUTION: In weight%, C: 0.5 to 1.3%, Si:
0.1-1.7%, Mn: 0.3-0.9%, P: 0.
02% or less, S: 0.02% or less, the balance being Fe
90% or more of the structure is a pearlite structure, and the average lamella spacing of the pearlite is 0.1%.
A high-carbon steel wire excellent in wire drawing workability having an average colony diameter of 150 μm or less at 0.4 μm or less.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high carbon steel wire excellent in wire drawing workability. More specifically, the present invention relates to a high carbon steel wire excellent in drawability suitable for applications such as wire ropes, springs, PC steel wires, bead wires, and steel cords. [0002] Wire ropes, springs, and PC steel wires are generally drawn by hot-rolling steel wires (hereinafter referred to simply as "wires"). Further, it is manufactured by subjecting it to a quenching and tempering refining process or a bluing process. In addition, ultra-fine steel wire for steel cord used as a reinforcing material for radial tires of automobiles is prepared by primary drawing into a wire rod with a diameter of about 5.5 mm adjusted and cooled after hot rolling.
It is manufactured by performing a patenting process, a secondary drawing process, a final patenting process, then performing a brass plating, and further performing a final wet drawing process. A steel cord is manufactured by twisting a plurality of the extra-fine steel wires obtained in this manner by twisting to obtain a twisted steel wire. In general, when a wire is broken into a steel wire, breakage occurs, and productivity and yield are greatly reduced. Therefore, the wire rod belonging to the above technical field, at the time of wire drawing,
Particularly, in the case of manufacturing a steel cord, it is strongly required not to break the wire at the time of wet drawing in which strong cold working is performed. In recent years, there has been an increasing movement to reduce the weight of wire ropes, springs, PC steel wires, bead wires, steel cords and the like for various purposes. For this reason, high strength is required for the above-mentioned various products, and a high C content allows a steel wire to have high strength, and furthermore, a wire rod excellent in wire drawing workability, that is, a wire rod having excellent drawability. The demand for high-carbon steel wires excellent in wire workability has become extremely large. [0005] In response to the recent demands from the industrial world, techniques for controlling the microstructure of the wire to improve the strength and drawability of the wire have been studied. [0006] For example, in the 141st and 142nd Nishiyama Memorial Technical Lecture, "Strengthening of steel products" (1992, p.
187, the Iron and Steel Institute of Japan), the lamella spacing of pearlite is reduced in order to increase the strength of high-carbon steel wires. On the other hand, in order to enhance the drawability of a high carbon steel wire, it is effective to reduce the pearlite colony diameter. However, in the past, quantitative studies have not been performed on the lamella spacing and the colony diameter of pearlite for achieving both high strength and high wire drawing workability. For this reason, it has been difficult to increase the strength while maintaining good drawability. SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has as its object to provide a wire rope, a spring, a PC steel wire, a bead wire, a steel cord suitable for use. An object of the present invention is to provide a high carbon steel wire having excellent wire workability. [0008] The gist of the present invention resides in a high-carbon steel wire having excellent drawability as described below. That is, "in terms of% by weight, C: 0.5-1.
3%, Si: 0.1 to 1.7%, Mn: 0.3 to 0.9
%, P: 0.02% or less, S: 0.02% or less, the balance being Fe and unavoidable impurities, and 90% or more of the structure is a pearlite structure, and the average lamella spacing of pearlite is 0%. 0.1 to 0.4 μm and an average colony diameter of 150 μm or less ”. The inventors of the present invention have determined that the structure of hot-rolled high-carbon steel wire, in particular, the proportion occupied by the pearlite structure, and the microstructure of the pearlite structure, that is, the lamella spacing and the colony diameter, are the strength and strength of the high-carbon steel wire. Investigations and studies were conducted on the effects on wire drawing workability. As a result, the following findings were obtained. (A) In order to increase the strength of a high-carbon steel wire by wire drawing, 90% or more of the structure of the wire to be processed should be a pearlite structure. (B) When a wire rod having a pearlite structure in which 90% or more of the structure of the above (a) is drawn, there is a pearlite lamella interval at which the processing limit value is maximized. (C) When the pearlite lamella spacing is above (b)
If the processing limit value is near the pearlite lamella interval at which the processing limit value becomes the maximum, a larger processing limit value can be obtained by further reducing the colony diameter to a specific value or less. The present invention has been completed based on the above findings. Hereinafter, the present invention will be described in detail. In addition, “%” of the content of the chemical component means “% by weight”. (A) Chemical composition C of the wire rod: 0.5 to 1.3% C is an element effective for securing the strength. But,
When the content is less than 0.5%, a wire rope,
In final products such as springs, PC steel wires, bead wires, and steel cords, it is difficult to stably ensure high strength. On the other hand, if the content of C is too large, the steel material becomes hard and causes a reduction in cold workability. In particular, when the C content exceeds 1.3%, not only is the wire hardened,
It is difficult to prevent the formation of proeutectoid cementite (that is, cementite along the prior austenite grain boundaries), and the wire drawing workability is reduced. Therefore, the content of C is set to 0.5 to 1.3.
%. Si: 0.1-1.7% Si is an effective element for increasing the strength. Further, it is an element necessary as a deoxidizing agent. However, if the content is less than 0.1%, the effect of addition is poor. On the other hand, if the content exceeds 1.7%, a decarburized layer is formed upon heating, and the wire rope, spring, PC steel wire, bead wire, steel cord, etc. The fatigue resistance of the final product is reduced. Further, the ductility is reduced and the processing limit value in the wire drawing is reduced. Therefore, the Si content is set to 0.1 to 1.7%. Mn: 0.3-0.9% Mn has the effect of deoxidizing in the steel making process, miniaturizing pearlite, securing hardenability and increasing the strength. However, if the content is less than 0.3%, it is difficult to obtain the above-mentioned effects. On the other hand, Mn is an element that tends to segregate. If it exceeds 0.9%, it segregates especially at the center of the wire, and martensite and bainite are formed at the segregated portion, so that the wire drawing workability decreases. . Therefore, the content of Mn is set to 0.3 to 0.1.
9%. P: 0.02% or less P lowers the toughness and also lowers the drawability. In particular, when the content exceeds 0.02%, the toughness and the drawability are significantly reduced. Therefore, the content of P is set to 0.02% or less. S: not more than 0.02% S reduces the toughness and also the wire drawing workability. In particular, when the content exceeds 0.02%, the toughness and the drawability are significantly reduced. Therefore, the content of S is set to 0.02% or less. (B) When the percentage of pearlite in the microstructure of the wire is less than 90%, it is difficult to obtain a high strength even if the wire is drawn at a high working ratio. Therefore, 90% or more of the structure of the wire rod to be processed was defined as a pearlite structure. The pearlite structure may be 100%. In the case where a wire rod having 90% or more of the structure is a pearlite structure is drawn, as shown in an example in FIG. 1, when the average lamella spacing of the pearlite is 0.1 to 0.4 μm, the processing limit value is increased. growing. Therefore, the average lamella spacing of pearlite was set to 0.1 to 0.4 μm. 90% or more of the structure is a pearlite structure, and the average lamella spacing of the pearlite is 0.1 to 0.5 mm.
In the case of drawing a wire rod in a range of 4 μm, FIG.
As shown in the example, the average colony diameter of perlite was 150
If it is less than μm, the processing limit value increases. Therefore, the average colony diameter of pearlite was set to 150 μm or less. The smaller the average colony diameter of this pearlite, the better the wire drawing processability. Hereinafter, the present invention will be described in detail with reference to examples. EXAMPLES Steels A to J having the chemical compositions shown in Table 1 were produced by a conventional method. Steels A to J in Table 1 are all examples of the present invention in which the chemical composition is within the range defined by the present invention. [Table 1] Next, these steels were hot-rolled based on preliminary experiments by adjusting the heating temperature of the rolling and the cooling rate after the rolling, and the average lamella spacing and the average colony diameter of pearlite were changed to obtain a diameter of 5 mm. Finished into a wire of 0.5 mm. In addition, each steel was finished into a wire rod under three conditions, and its structure (the ratio of pearlite in the structure (area ratio), the average lamella spacing of pearlite, and the average colony diameter of pearlite) was examined. Each of the wires finished to 5.5 mm in diameter was subjected to cold drawing by a usual method, and the limit value of the drawing was examined. Table 2 summarizes the results of various investigations. [Table 2] As is clear from Table 2, the chemical composition is within the range defined by the present invention,
In the case of the present invention example in which 0% or more has a pearlite structure and the average lamella spacing and average colony diameter of pearlite are within the range specified in the present invention, all of the processing limit values are 95% or more, and the wire drawing workability is poor. It is clear that it is excellent. Since the wire of the present invention is excellent in wire drawing workability, a wire rope, a spring, a PC steel wire, a bead wire, a steel cord, or the like can be used as a material at a high yield with a high productivity. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of the effect of the average lamella spacing of pearlite on the processing limit value when a wire having 90% or more of the pearlite structure is drawn. FIG. 2 shows that the average lamella spacing of pearlite is the processing limit value when 90% or more of the pearlite structure is drawn and a wire having an average lamella spacing of pearlite in the range of 0.1 to 0.4 μm is drawn. It is a figure showing an example of the influence which it has.

Claims (1)

Claims: 1. Weight percent C: 0.5-1.3%, Si:
0.1-1.7%, Mn: 0.3-0.9%, P: 0.
02% or less, S: 0.02% or less, the balance being Fe
90% or more of the structure is a pearlite structure, and the average lamella spacing of the pearlite is 0.1 to 0.4 μm and the average colony diameter is 150 μm or less. Steel wire rod.