JPS62238354A - Direct air pateniting-type wire - Google Patents

Abstract

PURPOSE:To develop a wire excellent in strength and ductility in the as-rolled condition and having high wire drawing workability and bendability, by adding, in combination, specific amounts of V and Ti to a direct air patenting-type wire. CONSTITUTION:As the direct air patenting-type wire, a steel having a composition containing, by weight, 0.5-1.0% C, <0.5% Si, 0.3-1.0% Mn, <0.3% Cr, 0.01-0.05% solid solution Al, 0.03-0.020% V, 0.005-0.050% Ti, and 0.004-0.020% N is rolled into a wire with 5.5-8mm diameter, which is subjected to direct air patenting by means of air blast on a stelmore line and is further wire-drawn to 1.8-4mm diameter by means of a wire drawing machine. As Ti is contained, a part of N forms into TiN and austenitic grain during rolling is inhibited to undergo refining, and further, solid solution N in steel is reduced, so that workability and ductility are improved. Moreover, the fine carbonitride of V is precipitated by the addition of trace amount of V, so that a wire having superior strength and ductility can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a direct air patented wire rod, which has high strength and ductility as a rolled material and has excellent workability after wire drawing. Regarding.

[Prior art 1] There is a strong demand for products such as wire lobes and springs made of high carbon steel wire to be smaller and lighter while ensuring performance equivalent to or better than conventional products. In addition, in the manufacturing process of steel for prestressed concrete (hereinafter abbreviated as PC steel), lead patenting (hereinafter referred to as LP) has traditionally been applied by customers such as wire drawing manufacturers. It is desirable to omit this LP from the viewpoint of energy and pre-processing. In order to meet these demands, it is necessary to increase the strength and ductility of the as-rolled wire rod.

[Problems to be Solved by the Invention] However, conventional wire rods have not yet achieved sufficient strength and ductility. There is a known technology to increase the strength of wire rods by increasing their carbon (C), manganese (Mn), and chromium (Cr) content by 11 degrees, but it is difficult to obtain strength equivalent to that of LP materials while still rolling. In order, C, M
It is necessary to contain n and Cr, and although this increases the strength, it has the disadvantage of significantly reducing ductility. In addition, when manufacturing wire rods from continuous casting materials, if large amounts of these components are contained, they will promote center segregation of the continuous casting materials and cause center marten sieves that are harmful to wire drawing.
-Or grain boundary cementite becomes more likely to occur. For this reason,
This technique is not practical.

On the other hand, there is a technology that uses microalloying technology that has been developed in recent years to add 1 ml of niobium (Nb) and vanadium (V) to high carbon steel to increase its strength. This is to increase the strength by finely precipitating carbonitrides of these elements during the cooling process after rolling. However, the wire rod manufactured in this manner has the disadvantage that it has lower elasticity and workability than LP material.

The present invention has been made in view of the above circumstances, and provides a direct air patented wire rod that has high strength and ductility, and has improved properties required for final products such as wire drawability and bending workability. The purpose is to

[Means for Solving the Problems] The direct air battening type wire rod according to the present invention has a diameter of 0.5
1.0% to 1.0% by weight carbon, less than 0.5% silicon, 0
．． 3 to 1.0% by weight of manganese, 0.3% by weight or less of glue L comb, 0.01 to 0.05% by weight of solid solution aluminum, 0.03 to 0.20% by weight of vanadium, 0.
005 to 0.050% by weight of titanium, and O1○04
It is characterized by containing 0.020% by weight of nitrogen, with the balance being iron and unavoidable impurities.

[Effect 1] The present inventors have carried out various experimental studies in order to develop a wire rod that has strength and ductility equal to or higher than conventional LP materials and has high wire drawability and bending workability even when rolled. As a result of repeated experiments, it was found that it is effective to add 1 and titanium crr> to 4 in combination.

In other words, due to the addition of Ti, nitrogen present in steel
A part of the steel becomes TiN nitride, which suppresses the growth of austenite grains during rolling and turns into atom, and the solid solution N remaining in the steel decreases. This improves ductility such as workability. Also, by adding ■, @
Delicate carbonitrides precipitate, improving strength. Therefore,
The wire rod according to the present invention has high strength and ductility even after being rolled.

The wire rod according to the present invention is subjected to direct air patenting (CJX, abbreviated as DP) in a Stelmore line. As a result, a high carbon steel wire rod having excellent wire drawing properties and mechanical properties of high strength and high ductility can be obtained.

Example 1 The reason for adding each component and the reason for its limitation will be explained below.

C is an element necessary to increase strength, and C is added in an amount of 0.5% or more for reformation. However, C is 1
．． If 0% by weight is used, processability will decrease, so 1 of C.
One degree is 0.5 to 1.0%.

Silicon (S + >), when added in an amount of less than 0.5% by weight, acts as a deoxidizer and a reinforcing element for ferrite.

Mn is an important element for ensuring the strength and ductility of direct patented wire rods, but when Mll is 0.3
If Mn is less than 1.0%, the effect of its addition is small;
If it exceeds the weight percentage, harmful central martensite and grain boundary cementite are likely to occur. For this reason, Mn
The concentration range of is set to 0.3 to 1.0% by weight.

Cr acts similarly to Mn. However, Cr is 0.3
When it exceeds the weight fi%, center martensite and grain boundary cementite are likely to occur, and the wire drawing processability is also reduced. Therefore, the CrM degree is set to 02311% or less.

Aluminum (A1) is an important element as a deoxidizing agent, and is added to prevent the bonding between Ti and M element (0) to effectively generate TiN. If the solid solution A1 is less than 0.01% by weight, the above effects will be insufficient. Moreover, solid solution A1 is 0.
If it exceeds 0.05% by weight, non-metallic inclusions will increase, which is harmful to wire drawability, so the 0 degree range of solid solution A1 is 0.0
1% to 0.05% by weight.

■ exhibits a patenting effect when added in small amounts, but
Further, V combines with N or C to precipitate fine carbonitrides, thereby increasing strength. Such effect 1 is that the V'a degree is less than 0103103% by weight, and (2) the concentration is 0.
If it exceeds 20% by weight, other ductility decreases, so ■
The concentration G is 10.03 to 0.20% by weight.

TI is a strong nitride forming element. Ti combines with N to form TiN, which refines austenite grains to increase strength, and reduces solid solution N in steel to increase ductility. However, if Ti11 degrees is less than 0.005% by weight, this addition effect is small, and conversely, this effect is fully exhibited when added up to 0.05% by weight, so the range of Ti11 degrees is 0.005% by weight. The content should be between 0.05% and 0.05% by weight.

In practice, the amount of Ti added depends on the degree of N1 in the steel, and the amount of Ti added depends on the degree of N1 in the steel.
It is determined according to the degree. In other words, Ti is added so that some N that is not fixed by Ti remains, and this remaining N
This effectively precipitation hardens V. For this reason,
Approximately 40DDm of N is chemical! In order to remain logically,
Add Ti.

N is an element necessary for adjusting the austenite grain size and effectively precipitation hardening, but the amount of N is 01004% by weight.
If it is less than 0.020% by weight, the effect of this addition will be small, and if it is added in an amount exceeding 0.020% by weight, the improvement effect will be small. Moreover, if the N1 degree is high, wire drawability etc. will deteriorate. For this reason,
The concentration of N is 0.004 to 0.020% by weight.

Next, embodiments of the invention will be described.

Example 1 This example was made for the purpose of increasing the strength and reducing the weight of the wire lobes and springs.

The steel shown in Example 1 (l) in Table 1 below has a diameter of 5
．． The wires were rolled to 5 m11 and 81 m, and directly air patented by blow blast using Stelmore Line 1, and then drawn to 1.8111 and 4 II m, respectively, using a wire drawing machine.

Table 1 C8iMr+PS Example 1 0.64 0.30 0.84 0.01
70.012 Comparative Example 1 0.64 0.30 0.8
3 Q, 0190.00? Conventional example 1 0.63 0
．． 24 0.82 0.0180.008CrAIVT
iN Example 1 0.10 0.0280.050.015
0.0079 Comparative Example 1 0.09 0.024 Q
, 06 - 0.0066 Conventional example 1 0.08 0.
022 - - 0.0075 For comparison, steel with the composition shown in Comparative Example is (added only V) and Conventional Example 11
Steel having the composition shown in Example 1 (■ and no Ti added) was also subjected to stretching processing in the same manner as in Example 1. The mechanical properties of each wire rod (after rolling) and steel wire (after direct air patenting) are shown in Tables 2 and 3 below, respectively.

Table 2 Diameter Tensile strength Elongation Drawing example 1 5.5 112 16 59 Comparative example 1 5.5 113 1t3 52 Conventional example 1 5.5 102 16 55 Example 1
8 107 16 5G comparison piece 1 8
1G8 15 50 Conventional example 113 9
81553 Table 3 Diameter Tensile strength Elongation Torsion value Example 1 1.8 215 47 33 Comparative example 1 1.8217 40 23 Conventional example 1
1.3 206 44 26 Example 14
1605441 Comparative Example 1 4 162 46 29 Conventional Example 14 1474933 However, the unit of tensile strength is kaf/mi2, the unit of elongation and reduction of area is %, and the unit of twist value is turns.

As is clear from Table 3, in the case of Comparative Example 1 in which only ■ was added, the strength was higher than in Conventional Example 1, but the reduction of area and viscosity were lower. However, in the case of Example 1, in addition to having higher strength, the reduction of area and viscosity are also higher than that of Conventional Example 1. FIG. 1 is a graph showing changes in tensile strength (work hardening), reduction of area, and twist value during the expansion and contraction process of a wire having a diameter of 5.5 nm. As is clear from this figure, the steel according to Example 1 has higher drawing area and torsion values than the steels according to Comparative Example 1 and Conventional Example 1 even during the wire drawing process.
It can be seen that it has excellent elasticity.

Example 2 Konomi 7I! One example is one that was made for the purpose of omitting LP, which was conventionally performed by wire drawing manufacturers, in the manufacture of PCI wires. The sheets having the compositions shown in Table 4 below were rolled to diameters of 8Ill and 1011 as shown in Table 5, and after rolling, they were directly air-pattened with blast air on the Stelmore line. These were drawn using a wire drawing machine to diameters of 41,111 m and 5,111 m, respectively, as shown in Tables 6 and 7. Table 5 shows the mechanical properties of the wires, and Table 6 shows the wires before bluing. The mechanical properties of the as-drawn steel wire and Table 7 show the mechanical properties of the blued steel wire.However, the bluing conditions were 38
It was kept in a salt bath at 0° C. for 12 seconds. The bending value was determined by repeated bending at 90 degrees, and the radius of the bent portion was 151 mIn.

Furthermore, Example 2 and Comparative Examples 2 and 3 were directly patented, and Conventional Example 2 was lead patented.

Table 4 C8iMnPS Example 2 0.85 0.30 0.88 0.01
50.007 Comparative Example 2 0.84 0.29 0.8
7 0.0130.009 Comparative Example 3 0.90 0.3
1 0.90 0.0180.008 Conventional example 2 0.8
2 0.21 0.75 0.0190.009CrA
IVTiN Example 2 0.06 0.0170.060.016
0.0084 Comparative example 20.07 0.0210.06
- 0.0081 Comparative Example 3 0.12 0.020
- - 0.0076 Conventional example 2 0.09 0.0
19 - - 0.0073 Table 5 Diameter Tensile strength Elongation Drawing example 2 8 128 13 46 Comparative example 2 8 127 12 41 Comparative example 3
8 126 13 40 Conventional example 2 8
128 11 46 Example 2 10 1
26 12 42 Comparative example 2 10 126
11 36 Comparative Example 3 10 122
11 36 Conventional example 2 10 126 1
2 44 Table 6 Diameter Tensile strength Aperture Flexure value Example 2 4 184 55 18 Comparative example 2 4 185 48 15 Comparative example 3
4 180 45 14 Conventional example 2 4
182 54 18 Example 2 5 18
2 44 15 Comparative example 2 5 180
38 13 Comparative Example 3 5 178 35
11 Conventional example 2 5 184 46 1
4 Table 7 Diameter Tensile strength Aperture Flexure value Example 2 4 190 4G 15 Comparative example 2 4 189 40 13 Comparative example 3
4 185 38 12 Conventional tlA24
188 46 14 Example 2 5 1
93 42 11 Comparative example 2 5 190
32 9 Comparative Example 3 5 186 30
7 Conventional example 2 5 189 43 12
As is clear from Tables 6 and 7, Comparative Example 2,
The steel according to Example 3 has the same tensile strength as the steel according to Conventional Example 2, but the reduction of area and the bending value are low. However, Example 2
The steel according to Conventional Example 2 is at the same level as the steel according to Conventional Example 2 in all of the strength, area of area, and bending value.

FIGS. 2 and 3 are micrographs (magnification: 400 times) showing micro-ins of wires with a diameter of 10 nn in Example 2 and Conventional Example 2, respectively. The wire rod according to Example 2 has finer crystal grains than the wire rod (LP material) according to Conventional Example 2. This is an effect due to the combined addition of V and Ti.

FIG. 4 shows changes in tensile strength (work hardening), reduction of area, and bending value during the wire drawing process of a wire having a diameter of 811111. As is clear from FIG. 4, even in the wire drawing process, the reduction of area and bending values of the steel according to Example 2 are higher than those of the steels according to Comparative Examples 2 and 3, and the characteristics are similar to those of the steel according to Conventional Example 2. have.

[Effects of the Invention] In this invention, by adding appropriate amounts of ■ and Ti in combination, a direct air patented wire rod having strength and ductility equal to or higher than conventional lead patented wire rods as rolled can be obtained. be able to.

[Brief explanation of drawings]

FIG. 1 is a graph showing the change in characteristics during the wire drawing process in the first embodiment of the present invention, and FIGS. 2 and 3 are @gL mirror photographs showing the micro-weave of this invention and the conventional ll1I material, respectively. , and FIG. 4 are graphs showing changes in characteristics during the wire drawing process in the second embodiment of the present invention. Applicant's agent Patent attorney Takehiko Suzue Tisa-m) 5.54.7 3,6 272.11.8 God 4 Rat Ball Figure 1

Claims (1)

[Claims] 0.5 to 1.0% by weight carbon, less than 0.5% silicon, 0.3 to 1.0% manganese, 0.3% by weight
The following chromium, 0.01 to 0.05 wt% solid solution aluminum, 0.03 to 0.
Direct air containing 20% by weight of vanadium, 0.005 to 0.050% by weight of titanium, and 0.004 to 0.020% by weight of nitrogen, the balance being iron and unavoidable impurities. Patented wire rod.