JPS6152348A - High efficiency carbon steel wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the field of drawn carbon steel wires and their applications, particularly high-strength pearlitic steel wires with a special composition and a large area reduction.

Normal 2000 N7m5" (N is the symbol representing Newton, IN = 10 Gui 101kliFf = 9.8
It relates to improved performance that can have an effective tensile strength in excess of N0). The steel wire of the present invention is suitable for reinforced rubber products such as cords and bead wires for tires, belt cords for rubber belts, hose wires for high-pressure hoses, and the like.

Traditionally commonplace carbon steel wires and their low alloy variants containing sufficient carbon content are approximately 2000? Used for materials with high tensile strength up to C2. In order to obtain a predetermined high tensile strength, such steel wires are subjected to a martensitic air-cooling and tempering treatment or to a metallurgical patenting treatment (note: the steel wire is heated to a temperature above the transformation point and then melted). A treatment method in which the material is immersed in lead or salt and rapidly cooled to form a tough sorbite structure.) followed by cold stretching. The latter is the case in the present invention.

Today, such drawn pearlitic steel IiI usually has a general composition of 0.50 to 1.00% by weight of C, 0.05 to 1.00% of Sl, and 0.2% of Mn.
It is made from ordinary high carbon steel consisting of 0 to 2.00%, P up to 0.035%, S up to 0.035%, and the balance is PE and impurities unavoidable during smelting.

Additionally, alloyed compositions of the common high carbon steels are sometimes used. These variants include Cr, Ni,
Cu, Mo, Co, W, Nb, V, Ti
, Al, and one or more other elements, the content of which varies depending on the alloying purpose of the steel wire.

When producing and applying drawn carbon steel wires with conventional compositions for high-grade applications, inconsistent drawing behavior and breakage of the steel wire during production, as well as insufficient steel wire ductility and steel wire People often encounter serious problems regarding sudden breakage during use.

These problems that arise in high tensile applications above 2000 N7 m'' become even more important when the tensile strength is increased to approximately 2200 M and above.
Generally well known to art technicians. As the normal limits of effective strength for a given steel wire diameter are approached, the above-mentioned difficulties become so severe that drawing the steel wire becomes impractical and unfeasible. Thus, the conventional production of high-strength steel wires based on traditional carbon steel compositions often suffers from poor drawing operations and unsatisfactory wire properties (e.g. insufficient ductility during twisting or bending). (e.g., weak parts, low fatigue life, etc.).

Moreover, normal practice does not allow for further increases in the effective strength limit without risking premature embrittlement of the steel wire. Premature embrittlement of steel wires is a serious obstacle to expanding the applicability of steel wires. Apart from the important role of the steel variety and related steel wire manufacturing considerations, according to normal practice for steel wires, the practically effective tensile strength limit depends on the wire diameter as follows: is generally known.

Wire diameter Maximum average tensile strength Approximately 2- or more 2000 N/m Between 21m+ and 2m
2200 Nets”0,5 m to l+e+ 240ON/ll112 approx. 0.5 m or less
2500-27002 Sea 2 In the past, there has been an increase in the effective strength limit as mentioned above, and manufacturing problems (unexpected fracture, over-stretching, embrittlement, etc.) when manufacturing high-strength steel wire.
Several proposals have been made with the aim of reducing the

We are aware that some of these proposals have stricter compositional acceptance requirements, particularly regarding purity (non-metallic inclusions) and extra elements for steel. Therefore, in high performance applications residual sulfur and phosphorus are often limited to a maximum of 0.025%.

However, despite these improvements, it cannot be said that the above-mentioned difficulties have yet been completely or completely resolved in the field of manufacturing high-strength steel wires.

Steelmakers have attempted special and/or additional refining steps to further improve the purity and quality of the steel and reduce undesirable impurities below existing stringent specifications. On the other hand, there are many alloying transformations that are effective in increasing the strength of carbon steel paper.
It has been proposed and attempted with the aim of increasing the ultimate strength of steel wire without losing toughness.

Such methods have been found to be effective in the manufacture of rare types of steel wire, such as rocket wire, and other difficult and specialized thin wires. However, great success has not been achieved in the case of general industrial steel wire or in the case of mass production.

This is because it is unfavorable and uneconomical. In fact, the production of ultra-pure steel requires sophisticated melting and refining equipment and sophisticated purification processes that result in prohibitively high costs. Moreover, such super-improved luxury products are rarely actually needed.

To make alloyed steels, ordinary grade carbon steel can be used without increasing the price, which varies widely depending on the type of alloy and the amount of alloying component additions. Unfortunately, in the field of steel wire manufacturing, alloying elements often have undesirable side effects (e.g. prolonged heat treatment time, decreased pearlite transformation,
(difficulty in dissolving stable carbide-forming substances, etc.) These effects then have a significant productivity impact (particularly in the production of fine wires, for example tire cords) and make many intermediate patenting operations necessary.

The solution provided by the invention does not possess the above-mentioned disadvantages. Moreover, it is possible to obtain a decisive and unexpected improvement over conventional steel wire manufacturing techniques. This satisfies the important objective of efficiently and economically obtaining the effective steel wire strength that has been achieved to date, that is, a strength exceeding 200 ON/IIN''.

Another object of the present invention is to reduce the incidence of broken steel wire and to suppress the undesirable brittleness encountered when drawing conventional steel wire to high strength levels. Yet another object is to provide a steel wire with increased deformation capacity and a greater standard area reduction compared to conventional carbon copper wire.

In accordance with the present invention, the above and other aspects result in a substantially modified microstructure of pearlite (which is) 4-1 to 4-lite. It is obtained by treatment by a tenting method or similar isothermal modification method, followed by shading to the required stretched corrugation. ) and has an effective strength of 200 ON/lII+2 or higher, usually achieved by making a drawn steel wire with a radius of 5 or less. The steel wire is made from a special and simple carbon steel composition to which a small amount of boron is added, and the composition contains 0.6 to 1.2% by weight (the same applies hereinafter) of C, Q to 1,0. Mn, Q or 1.0% St, maximum 0.
035% (7) P, up to 0.035% S.

It is characterized by having a composition consisting of 0.0005 to 0.015% B, the remainder F) and unavoidable impurities.

According to another aspect of the invention, a drawn pearlitic carbon steel wire is produced having the steel composition defined above and having an increased tensile strength equal to or greater than the following values depending on the final wire diameter.

≧2 m 200ON/1ml” preferably 22
00 N/a++”1~2// 2200 //
/f 2400 #0.5~11 24
00 # // 2600 /1<0.5
〃2600 // l/ 2800 //<
, o, 3zz 2700 7/ // 3
000/F According to another additional aspect of the invention, the steel wire can have a coating to which rubber is deposited.

According to a preferred form of the invention, from 0.6 to 1.2 inches of C,
O ~ 0.35% 81.0.60% or less Mns max o, oos%17) N, max 0.025% S, max 0
．． It is possible to produce a drawn carbon steel wire with a tensile strength exceeding 2200 N/- by using a special composition consisting of 025% P, o, o o i ~ o, o i% B, the balance being Fe and unavoidable impurities. can. In a further additional manner, according to the invention, the special composition described above can be used to reduce the tensile strength from 0.1 to 0.5 w with a diameter of 42700 N/II".
AS carbon steel wires, preferably with a tensile strength of at least 3000 N7m'' for diameters up to 0.3 m, can be obtained.These steel wires can also be suitably rubber-reinforced for purposes of rubber reinforcement. A bronze coating for rubber adhesion can be applied to the surface.

Furthermore, products made of pearlite steel wire having the above composition and high tensile strength as above can also be provided by the present invention. The steel wire element and its structure are made from the steel wire material of the present invention and covered with a coating having rubber adhesive properties. Examples include bronze-plated bead wire, steel wire cord for tires, bronze-plated steel wire for hoses, Peltoco-P for rubber belts made from bronze-plated or rubber-coated steel wire, etc.

Compared to the conventional manufacturing process for high-strength steel wires of 2000 N7- or higher, the steel wire according to the present invention has a higher A large wavefront ratio can be achieved. The latter phenomenon (ie, increased wire breakage and overdrawing) results in inconsistent ductility of the steel wire, inflexibility in twisting, and a significant increase in the number of rejects. These disadvantages are significantly overcome in the case of the steel wire according to the invention.

One important advantage of the steel wire produced according to the invention is that
lies in the improved residual ductility of the iron wire.

This ductility remains sufficient after large total draw strains to further increase the effective tensile strength beyond the practical safety limits of conventional steel wire.

The curve diagram of FIG. 1 clearly illustrates the principal features and advantages of the present invention. The figure shows a comparison of the sinusization behavior of a boron alloyed carbon steel wire according to the invention and a conventional high carbon steel wire. Curves 1 and 2 show the tensile strength (saw) and degree of deformation (expressed as the diameter ratio d p/d, where dp is The relationship between the initial diameter of the tenting and d (d is the stretched diameter) is shown. Shaded bands 3 and 4 relate to cold work hardening by drawing of patented conventional carbon steel wire with carbon contents of 0.65-0.70 and 0.80-0.85%, respectively. Reference numeral 5 indicates the beginning 9 of the embrittlement behavior when drawing the steel wire. The comparative curves in the drawings clearly show how the steel wire of the invention is superior in terms of ultimate drawing capacity and achievable effective tensile strength. Curve 2 is further
The use of this new composition resulted in enhanced deformation hardening after proper tightening. (due to unmanageable bainite formation when tenting to have a fine pearlite structure).

Returning to the role of the unexpectedly favorable boron component in the production of high-strength steel wire, we must state that legendary metallurgical knowledge cannot provide a fully satisfactory explanation.

Based on the legendary metallurgical knowledge and related prior art experience, the linear carbon content of the fibrous component is approximately 0.5 to 0.
．． It is said to increase the cold hardenability of carbon steels up to 6 inches. By adding boron to steels which usually have a C content of 0.1 to 0.4%, greater martensitic deep hardening can be obtained. Therefore, cellulose is another t
It is used as a partial substitute for necessary and expensive alloying elements when fluorine is not available.

First British patent as prior art for application of ferrous steel to steel wire
, No. 203,779, Cr-Ti-Zr
KSn, Sb, or As is added as an extra element in a multiple alloy steel, and the alloy steel has a strength of at least 1000 N/-, a relaxed martensitic structure, and a delayed rupture resistance. In French Patent No. 2,058,914, a boron-containing carbon steel composition has a martensitic structure and is said to have improved resistance to O
The application as a cold-worked spring with a strength of 00 to 170 ON/III+2 is described.

German patent application DB 3,312,205 describes a low-alloy carbon steel treated with borides using a required amount of acid-soluble borons together with small amounts of Al and T1, the composition of which The material is said to be suitable for greasing steel wires with a relaxed martensitic structure. Tensile strength is 1500
It is about N/11m".

U.S. Pat. No. 2,527,731 describes spring wire drawn from air-patented carbon steel, offering an alternative to expensive lead-on IP tenting for thick air-patented wire. Neither of these prior art techniques has shown that the fluoridation is carried out without sacrificing the mechanical properties normally obtained. Unexpected #! We have not deduced the existence of any beneficial boron effect and also the possibility of obtaining benefits from it of improving the drawability and mechanical properties of ordinary carbon steel wires and obtaining ultra-high-grade strength. is not implied.

(high degree of drawing) is carried out for the purpose of increasing the effective strength level in parent-lite steel wires, improving the reliability and efficiency of drawing operations, and controlling the tendency for embrittlement due to cold drawing. From our numerous studies, we have found the following. In other words, boronate is 0.0005
8 to 0.015% (preferably 0.015%).
001 to 0.01%), C is 0.60- or more,
It has been found that when added to a simple high carbon steel composition containing no other special alloying ingredients, it has a significant effect as described above. Our findings show that the use of high carbon steel wires, particularly those alloyed with boron, provides greater reductions in overall diameter than usual, higher normal strength levels with consistent ductility, and It has been found that drawing reductions beyond 100°C also avoid undesirable collateral overstretching, thus converting the initial embrittlement to a greater degree of deformation. Expanding the total drawing range and improving the effective tensile strength level are the most important matters in the production and application of high-grade steel wires, especially for thin cord steel wires that are drawn with an area reduction of 95-96% or more. This is true when manufacturing diameter bronze-plated steel wire. Thus, the demands of industrial reinforcement, such as the practical need for a consistent increase in wave front ratio without the occurrence of middle-aged failure, are most advantageously met by the steel wire of the present invention.

Although we do not wish to dwell on theoretical explanations for the high carbon content in martensitic steels for example, and for the increased hardening effect of boron on non-martensitic structures, virtually no or monolithic structures exist. The particular improvement obtained by adding boron to a high-carbon steel wire having a ) and the inherent steel properties (such as wave strain embrittlement due to the more favorable inclusion theory type nitrogen).

An additional surprising effect of the boron steel wire according to the invention is that the patenting heat treatment of the coated steel wire results in a light or tensile strength (P, T, S) after tenting.

) has the ability to be increased beyond the best standards obtainable for conventional steel wires with substantially similar carbon content without the risk of forming hard components in the pearlite structure. The highest strength of the non-deformable No5rite steel wire is determined by the well-known scale calculation of P, T, S, (
N/vm2)=500+1000X given by C.

For a creeping unadded steel wire, after well-controlled isothermal patenting, a tensile strength increased by more than 100 M- from the value according to the above formula can be obtained.

This advantage could be attributed to the additional refining effect of 11 uranium on the isothermally deformed pearlite for a given austenite decomposition temperature. This advantage is also due to the undesirable reaction by-products that tend to appear when the /4' tenting temperature is lowered to a critical level depending on the thinnest lamina morphology (such as bainite or separated /4'-lite). This can be attributed to suppressing the production of

The steel wire of the present invention can be formed into any suitable cross-sectional shape ranging from a square strip shape obtained by smooth rolling to a polygonal shape. However, substantially circular cross-sections are generally preferred for most end-use applications. These steel wires are usefully used in the manufacture of a variety of heavy-duty steel-containing wire products, such as twisted yarn, traction cables, ropes, steel wire cords, and springs.

A particular embodiment of the invention is directed to steel wire elements formed from the steel wire of the invention used as rubber reinforcements (e.g. bead wires, tire beads, tire cords, steel belt cords, etc.) and reinforced thereby. Found in rubber products.

For this purpose, the steel wire is provided with a rubber-adherable coating, ie a thin bronze alloy coating with a thickness of 0.1 to 0.4 μm. This alloy consists of at least 55 inches of copper (preferably 60 to 75 inches of copper) and the balance zinc (sometimes containing small amounts of tertiary alloying elements such as cobalt and nickel).
Consisting of

When applied to steel cords for tire reinforcement, the wire diameter is 0.10 to 0.40 m, and the wire tensile strength is 2500 to 280 ON/l 1 m2 (for bronze-coated steel wire corded by twisting and twisting). Preferably 2
800 sui or more).

The improved residual plasticity of the high tensile strength steel wire after drawing according to the invention has been found to be particularly advantageous with regard to the mechanical properties of the comb-coated cord during cord manufacturing operations and tire manufacturing. The result is overstretching, twist failure, and inconsistent and unsatisfactory cord properties (e.g., pitiful cord fatigue life and tendency to embrittlement and stress corrosion fracture).
The effective tensile strength of the cord can be increased to more than 3000 N7w'' without the difficulties arising from this.

The following examples will explain important aspects of the invention in more detail without departing from the scope of the invention.

In the test results, φ is the diameter of the steel wire, T, 8° is the tensile strength, EL is the total length, X is the wave front ratio at tensile rupture, N
b is the number of inversion mills until rupture in the bending test;
Nt represents the number of twists in a simple twist test (a wire with a length 100 times the diameter M is twisted around the axis by 9 degrees to rupture it).

Example 1 Table 1 shows the chemical composition of the steel wire of the present invention in comparison with a conventional carbon steel wire.

Table 1: Chemical composition of steel (wt%) Table 2 shows the mechanical properties of steel wires manufactured from the steels in Table 1, which were hot rolled, patented, and cold drawn, respectively. indicate a property.

Table 2 Mechanical properties of steel wire The results of the drawability test and the mechanical property test show that B steel has a high degree of work hardening behavior and final rollability from rod diameter to the smallest possible intermediate steel wire size. It turns out that C steel is far superior to C steel. In the case of borosilicate, a large amount of residual ductility remained.

Example 2 #1 boron-treated B steel wire and #1 ordinary music steel wire, both containing approximately 0.80 g of C, were predrawn and
Patenting was performed at a wire diameter of 1.50 wm at an austenitizing temperature of 930°C and a lead bath temperature of 560°C. After being plated with bronze, these steel wires have a final diameter of 0.
．． It was extended to 30 wr. Table 3 shows the chemical composition of the streaks.

Table 3 Chemical composition of steel wire (weight%) Table 4 shows the mechanical properties of the streaks.

From Table 4, it can be seen that the mechanical properties of the B@ wire are excellent, although they are slightly better than the musical steel wire.

Example 3 Chemical composition: C0.73%, Mn 0.9%, St
O, 25chi, Po, 012chi, SO, 0221Bo,
007% of the invention steel was treated at various lead patenting temperatures and then cold drawn into successively smaller diameter wires to evaluate the final strengthening behavior and residual ductility. Table 5 summarizes the relevant properties of the steel wire.

Table 5 Mechanical properties of treated steel wire (1.50 m long steel wire treated at a temperature of 580°C) (
(1.0-length steel wire treated at a temperature of 525°C) This boron steel can be deformed to a very high total wavefront ratio, giving ultra-high tensile strength without complete loss of ductility, as shown in the tJ5 table. The results further show that this boron steel has an unexpected ability to refine pearlitic microstructures (tunable in combination with the highest transition temperature). This A'-lite microstructure is virtually free of undesirable components (bainite, separated pearlite, etc.) that are inevitable in ordinary steel wires patented at low temperatures.

In this way, the effective strength of the tented article is significantly increased, thereby resulting in higher deformation strengthening rates than usual and extraordinary strength values of the final steel wire. t′! of the present invention! In theory, it would be necessary to increase the carbon content of ordinary copper wire by more than 0.15% to obtain the same enhanced mechanical properties compared to boron steel wire. .

In practice, however, even the highest quality ordinary carbon steel wires become brittle at tensile strengths of 3300 to 3400 N7m'' and above, which limits their suitability for advanced applications.Table 6 Shows the fatigue limits obtained for highly drawn carbon steel wires. (Compare with Table 5.) Table 6 Bending Fatigue Limits and Fatigue vs. Strength of Steel Wires of the Invention -/Cb Invention A high fatigue limit can be obtained with the steel wire, and the ratio of the fatigue limit to the ultimate tensile strength is more than 0.30 despite the high tensile strength.This shows that boron steel wire is excellent in various applications. It shows that there is.

Example 4 Furthermore, the properties of the steel wire of the present invention were evaluated for application to cord wires and cable wires. Therefore.

The cabling loss was determined for a single-strand steel cord with a diameter of 0.25 m made from borosilicate steel and high-grade ordinary carbon steel according to the present invention and having the following chemical composition.

As the remaining elements, Al<o, oichi (Cu + Cr + Ni + Mo) (0,15'1
6(Sn+As+Sb) (0.01%) These steels were cold drawn to obtain steel wires having a diameter of 0.25 m and a tensile strength of 3000 to 3200 N7m'' class.

Table 7 shows the tensile strength loss after twisting (in the original tone wire before twisting) for various cord constructions.

TABLE 7 Cabling Losses (% vs. Original Fiber Strength) As can be seen from Table 7, the steel wires of the present invention tend to reduce the strength losses that occur as a result of cord manufacturing. This means that the steel wire according to the invention has a higher residual ductility and therefore a higher resistance to structural failure than ordinary carbon steel wire.

As can be seen from the examples described above, the steel wire composition of the present invention exhibits excellent drawability and signs of embrittlement after drawing. Compared to ordinary high-grade steel wires, the steel wires of the present invention can obtain significant strain hardening, and the unexpectedly favorable effect of borons on the microstructure and ductility can bring this to extraordinary strength levels. Can be stretched.

One advantage of the present invention is that without departing from the scope of the invention,
Minor changes or modifications to the specified steel composition (e.g. Nb,
Addition of finer metal crystal particle improvers such as V, Ti, Zr, and Ta, and small amounts of desulfurization agents such as Cs and Ca. ) would be obvious to art technicians.

[Brief explanation of drawings]

The figure is a curve diagram showing a comparison of the sinusization behavior of the boron carbon steel wire according to the present invention and a conventional carbon steel wire that does not contain boron.

Claims (6)

[Claims] (1) Chemical composition is C0.6-1.2% by weight (the same applies below)
, Si0-1%, Mn0-1%, P0-0.035%,
S0~0.01%, N0~0.01%, B0.0005
~0.015%, the balance consisting of Fe and unavoidable impurities, with a tensile strength of at least 2000N
/mm^2 and has a deformed microstructure consisting essentially of pearlite. (2) Wire diameter up to 2mm, tensile strength 2200N/mm
The high-performance carbon steel wire according to claim 1, which has higher plasticity and torsional ductility than ordinary carbon steel wires which have a similar tensile strength but do not contain boron. . (3) Wire diameter is 0.05 to 1 mm and at least 250
The high-performance carbon steel wire according to claim 2, which has a tensile strength of 0 N/mm^2 and exceeds 2700 N/mm^2 when the wire diameter is 0.5 mm or less. (4) The content limit of unavoidable impurity elements is Al: maximum 0.01% (preferably maximum 0.005%)
Cu+Cr+Ni+Mo+Co+W+Ti+Nb+V etc.: maximum 0.15% (preferably maximum 0.12%) Sn+
The high-performance carbon steel wire according to claim 1, characterized in that As+Sb+Pb: maximum 0.01%. (5) The high-performance carbon steel wire according to claim 1, which has a maximum diameter of 2 mm and is coated with rubber on the surface of the steel wire. (6) The high-performance carbon steel wire according to claim 5, wherein the coating to which the rubber is attached is bronze plating.