High-quality wire rod for rubber hose and method for producing the same

Abstract

The application discloses a high-quality wire rod for rubber hose steel wire and a preparation method thereof. The wire rod comprises the following components in percentage by mass: C: 0.80-0.84%, Si: 0.10-0.20%, Mn: 0.50-0.60%, P≤0.014%, S: 0.0030-0.010%, total oxygen: 0.0020-0.0045%, Als: 0.0005-0.0015%, Nb: 0.0001-0.0010%, Co: 0.0004-0.0010%, Cr: 0.01-0.10%, and the balance of iron and inevitable impurities. The wire rod has a strength difference of less than or equal to 35 MPa, a cross-section hardness difference of less than or equal to 40 HV1 and satisfies the requirement of a higher fatigue life of the rubber hose steel wire. ， ​

Description

TECHNICAL FIELD

[0001] The present application relates to the field of materials and metallurgy, and more particularly, to a high-quality wire rod for rubber hose steel wire and a preparation method thereof. BACKGROUND

[0002] High-carbon steel wire rods are widely used in the production of steel cord, bead wire, automobile control wire, and rubber hose steel wire, etc. The strength uniformity of high-strength rubber hose steel wire has an important influence on the service performance of the steel wire. Rubber hose steel wire with a large strength difference will cause the service fatigue life of the rubber hose to decrease, affecting the service performance of the product.

[0003] A Chinese patent with application number CN202310976619.5 discloses a wire rod for super-high-strength hot-dip galvanized steel wire rope and a production method thereof. The chemical composition of the wire rod is as follows: C: 0.85-0.88%, Si: 0.18-0.25%, Mn: 0.50-0.55%, Cr: ≤0.05%, P≤0.012%, S≤0.008%, Ni≤0.05%, Cu≤0.05%, Mo≤0.03%, Al≤0.0020%, Ti≤0.0012%, O≤0.0030%, N≤0.0050%, and the balance is Fe and unavoidable impurities. The wire rod can be produced by sequentially passing through molten steel smelting, LF refining, continuous casting, and rolling, which can solve the problems of improving the strength of the wire rod while solving the center segregation, reticular cementite, and insufficient sorbite content of the wire rod. However, the composition and production process of the wire rod are not designed from the perspective of controlling the strength uniformity of the rubber hose steel wire.

[0004] With the increasing requirements for the service performance of equipment in the field of production and manufacturing, there is an urgent need to design a high-quality wire rod for rubber hose steel wire that can improve the strength uniformity of the steel wire, so that the rubber hose steel wire has a longer fatigue life and meets the requirements of the field of equipment manufacturing for the fatigue life of equipment. SUMMARY

[0005] The present application aims to overcome the above-mentioned defects in the prior art and provide a high-quality wire rod for rubber hose steel wire and a preparation method thereof. By designing the chemical composition and production process of the wire rod, the strength difference of the rubber hose steel wire made of the wire rod is reduced, meeting the requirements of the rubber hose steel wire for a higher fatigue life.

[0006] To achieve the above-mentioned purpose, the technical solutions of the present application are as follows:

[0007] A high-quality wire rod for rubber hose steel wire comprises the following components in percentage by mass: C: 0.80% to 0.84%, Si: 0.10% to 0.20%, Mn: 0.50% to 0.60%, P: 0.014% or less, S: 0.0030% to 0.010%, total oxygen: 0.0020% to 0.0045%, Als: 0.0005% to 0.0015%, Nb: 0.0001% to 0.0010%, Co: 0.0004% to 0.0010%, Cr: 0.01% to 0.10%, and the balance being iron and inevitable impurities.

[0008] The application further discloses a preparation method of the high-quality wire rod for rubber hose steel wire.

[0009] In the converter smelting, scrap steel and molten iron are used as furnace charges, and the proportion of scrap steel is 5% to 15%;

[0010] In the continuous casting, the molten steel treated by the LF refining is continuously cast to obtain a continuous casting billet;

[0011] In the continuous casting billet heating and continuous rolling, the continuous casting billet discharged from the continuous casting process is sent into a heating furnace for heating, and the heated continuous casting billet is continuously rolled, and the final rolling temperature is 920 DEG C to 990 DEG C;

[0012] In the wire rod rolling, the continuously rolled steel billet is heated in a heating furnace, and then sequentially passes through rough rolling, intermediate rolling, pre-precision rolling, precision rolling and wire drawing;

[0013] In the wire rod cooling, the wire rod after wire drawing is cooled on an air cooling roller way to obtain the wire rod for rubber hose steel wire.

[0014] The application has the following beneficial effects:

[0015] The application has the following beneficial effects: Specific Embodiment

[0016] The application is further described below in combination with specific embodiments, but the application is not limited by the embodiments in any way.

[0017] I. Chemical composition and mechanical properties

[0018] The application discloses a high-quality wire rod for rubber hose steel wire, which comprises the following components in percentage by mass: C: 0.80%-0.84%, Si: 0.10%-0.20%, Mn: 0.50%-0.60%, P: not higher than 0.014%, S: 0.0030%-0.010%, total oxygen: 0.0020%-0.0045%, Als: 0.0005%-0.0015%, Nb: 0.0001%-0.0010%, Co: 0.0004%-0.0010%, Cr: 0.01%-0.10%, and the balance is iron and inevitable impurities.

[0019] Specifically, the mechanism of each alloy component in the wire rod is as follows:

[0020] Carbon is a main element for controlling the strength of the wire rod. If the carbon content of the wire rod is too low, the strength of the rubber hose steel wire cannot meet the requirements of users. If the carbon content is too high, the strength of the rubber hose steel wire will exceed the requirements of users; therefore, the carbon content is controlled to be 0.80%-0.84% in the application.

[0021] Silicon can increase the eutectoid transformation temperature of the steel, and make pearlite transform at a high temperature zone, so that the pearlite structure of the wire rod is coarse and is not beneficial to the complex deformation of the steel wire. If the silicon content is low, the deoxidization of the molten steel will be insufficient. If the silicon content in the steel is too high, coarse silicate inclusions will appear in the steel, which will cause the rubber hose steel wire to be cracked or broken during drawing. Therefore, the silicon content is controlled to be 0.10%-0.20% in the application.

[0022] Manganese is an element for improving the strength of the wire rod, so that the steel wire can meet the tensile strength requirements of users. Manganese can reduce the eutectoid transformation temperature of the steel, refine the pearlite structure of the wire rod, improve the coordinated deformation ability of the wire rod at different positions during the processing of the rubber hose steel wire, and improve the strength uniformity of the rubber hose steel wire. However, too high manganese content will cause the wire rod to have banding segregation, and increase the wire breaking rate of the wire rod during the processing of the rubber hose steel wire. Therefore, the manganese content is controlled to be 0.50%-0.60% in the application.

[0023] Phosphorus is easy to form banding segregation in the wire rod, which reduces the coordinated deformation ability of the wire rod at different positions during the processing of the steel wire, causes the rubber hose steel wire to be cracked or broken during drawing, and reduces the strength uniformity of the rubber hose steel wire. Therefore, the phosphorus content is controlled to be not higher than 0.014% in the application.

[0024] Since MnS inclusions have good deformation ability, appropriate sulfur content in the steel can reduce the harm of non-deformable inclusions in the steel, prevent the generation of micro-cracks caused by inclusions, and improve the strength uniformity of the rubber hose steel wire. However, too high sulfur content in the steel reduces the cold working performance of the wire rod. Therefore, the sulfur content is controlled to be 0.0030%-0.010% in the application.

[0025] When the oxygen content is high, the size of the inclusions in the steel is large, which is easy to cause the micro-cracks in the wire rod processing, and causes the wire to crack. When the oxygen content is low, the deformation ability of the inclusions in the wire rod is poor, and the cracks are easy to appear between the inclusions and the matrix, which is not conducive to the processing of the tire bead tube steel wire; therefore, the total oxygen content of the wire rod in the application is controlled to be 0.0020% to 0.0045%.

[0026] When the acid-soluble aluminum content is high, the Al2O3 content of the inclusions in the steel increases, which is easy to cause the cracking in the processing of the tube steel wire. When the acid-soluble aluminum content in the wire rod is too low, the melting point of the inclusions in the steel is high, which is not conducive to the processing of the tube steel wire. Therefore, the acid-soluble aluminum content is controlled to be 0.0005% to 0.0015% in the application.

[0027] A higher niobium content causes the wire rod to be severely work-hardened in the wire processing, which causes the tube steel wire to be drawn and cracked. However, a proper niobium content prevents the grain from being coarsened in the billet heating process, ensures that the structure of the wire rod meets the processing requirements of the tube steel wire, and improves the strength uniformity of the tube steel wire. Therefore, the niobium content is controlled to be 0.0001% to 0.0010% in the application.

[0028] The cobalt element increases the precipitation temperature of the pro-eutectoid ferrite, reduces the grade of the widmanstatten structure in the wire rod, improves the uniform deformation performance of the wire rod, and is conducive to the improvement of the strength uniformity of the tube steel wire. The cobalt element is solid-solved into the steel to improve the strength of the steel. However, the cobalt content in the steel should not be too high, so as to prevent the high strength of the wire rod from reducing the drawing performance of the wire rod. Therefore, the cobalt content is controlled to be 0.0004% to 0.0010% in the application.

[0029] The chromium element improves the hardenability of the wire rod, refines the structure of the wire rod, and is conducive to the improvement of the mechanical property uniformity of the tube steel wire made of the wire rod. However, a too high chromium content deteriorates the processing performance of the wire rod. Therefore, the chromium content is controlled to be 0.01% to 0.1% in the application.

[0030] In a specific embodiment, the ferrite grain size of the wire rod of the application is ≤30μm; the size distribution of the ferrite grain of the wire rod is that the number ratio of the grain size ≤5μm is 62% to 68%, the number ratio of the grain size ≤10μm is 78% to 84%, and the number ratio of the grain size ≤15μm is 83% to 92%.

[0031] In a specific embodiment, the interlamellar spacing of the pearlite at the surface position of the wire rod of the application is 0.10μm to 0.15μm, the interlamellar spacing of the pearlite at the position 1 / 4 diameter from the surface is 0.13μm to 0.18μm, and the interlamellar spacing of the pearlite at the core position is 0.15μm to 0.22μm.

[0032] In a specific embodiment, the wire rod surface position carbon segregation index of the present application is ≤1.05, the carbon segregation index at 1 / 4 diameter from the surface position is ≤1.08, and the wire rod core position carbon segregation index is ≤1.14.

[0033] In a specific embodiment, the wire rod strength difference is ≤35 MPa, and the wire rod cross-section hardness difference is ≤40 HV1.

[0034] II. Production process technology

[0035] The present application also discloses a preparation method of the high-quality wire rod for rubber tube steel wire according to any of the embodiments of the present application, comprising the following steps: converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, and wire rod cooling.

[0036] Further, the method specifically comprises the following steps:

[0037] S1, in the converter smelting, scrap steel and molten iron are used as the furnace charge, and the proportion of scrap steel is 5% to 15%.

[0038] S2, in the LF refining, the molten steel treated by the LF refining is continuously cast to obtain a continuous casting billet.

[0039] In a specific embodiment, the molten steel after tapping in the converter smelting is subjected to refining treatment in the LF furnace, the LF furnace refining temperature is 1450°C to 1540°C, and the refining time is 30 min to 50 min.

[0040] S3, in the continuous casting, the molten steel treated by the LF refining is continuously cast to obtain a continuous casting billet.

[0041] In a specific embodiment, the continuous casting billet has a cross-sectional size of (250-300) mm x (350-400) mm; the surface temperature of the edge of the continuous casting billet in the straightening process is 900°C to 930°C, and the temperature of the corner of the continuous casting billet is 790°C to 830°C; the size of the inclusions in the molten steel at the converter post position is ≤100 μm, the size of the inclusions after the LF furnace refining treatment is ≤50 μm, and the size of the inclusions in the molten steel at the tundish position is ≤40 μm.

[0042] S4, in the continuous casting billet heating and continuous rolling, the continuous casting billet discharged from the continuous casting process is sent into a heating furnace for heating, and the heated continuous casting billet is subjected to continuous rolling, and the continuous rolling final rolling temperature is 920°C to 990°C.

[0043] In a specific embodiment, the total furnace time of the continuous casting billet heating is 3.5 h to 4.5 h; the preheating section temperature is 980°C to 1080°C, the heating section temperature is 1150°C to 1180°C, the soaking section temperature is 1200°C to 1220°C, and the soaking time of the billet in the soaking section is 40 min to 50 min.

[0044] S5, in the wire rod rolling, the continuously rolled billet is heated in a heating furnace, and then sequentially passes through rough rolling, intermediate rolling, pre-precision rolling, precision rolling and wire rod laying.

[0045] In a specific embodiment, in the wire rod rolling, the wire rod is produced by using a bloom, the total billet time in the furnace is 140 min to 160 min, the soaking temperature is 1100℃ to 1150℃, the billet soaking time is 30 min to 50 min, the segregation of carbon, manganese and other elements is reduced by high-temperature diffusion of the billet, and the billet grain size is controlled; the residual oxygen content in the heating furnace is 3% to 9%, and the furnace atmosphere pressure is 2 Pa to 12 Pa; after the billet is heated, it passes through rough rolling, intermediate rolling, pre-precision rolling and precision rolling, and then wire rod laying operation is performed; the wire rod temperature after pre-precision rolling is 985℃ to 1005℃; the wire rod temperature after entering the precision rolling is 890℃ to 930℃; the wire rod temperature after entering the double module is 880℃ to 940℃; and the wire rod laying temperature is 910℃ to 940℃. By using a higher wire rod laying temperature, the cooling speed of the wire rod on the air cooling roller is increased, thereby laying a foundation for controlling the final structure of the wire rod. The wire rod rolling specification is 5.0 mm to 6.5 mm.

[0046] S6, in the wire rod cooling, the wire rod after wire laying is cooled on the air cooling roller to obtain a high-quality wire rod for rubber hose steel wire.

[0047] In a specific embodiment, in the wire rod cooling, the wire rod after wire laying is cooled on the air cooling roller, the wire rod cementite precipitation temperature is controlled to be 700℃ to 730℃, the wire rod cooling speed is controlled to be 15℃ / s to 25℃ / s, the wire rod austenite to pearlite phase transformation undercooling degree is controlled to be 80℃ to 120℃, and the phase transformation time is 12 s to 18 s. After final cooling, the wire rod cord steel wire rod is mainly in sorbite structure, which is beneficial to the user wire rod drawing.

[0048] The following is a specific embodiment

[0049] Embodiments 1-6

[0050] The wire rod chemical composition, preparation process and performance parameters of the embodiments 1-6 of the application are shown in Table 1.

[0051] Table 1: Wire rod chemical composition, preparation process and performance parameters of embodiments 1-6

[0052]

[0053]

[0054] According to the above results, the present application has carried out a large number of and systematic experimental researches from the aspects of alloy element screening and proportioning, converter smelting, LF refining, continuous casting, continuous casting blank heating and continuous rolling, wire rod rolling, wire rod cooling process design optimization, etc., finally determines the component system and manufacturing process which can meet the purpose of the present application, and finally obtains a high-quality wire rod for rubber hose steel wire with a strength difference of less than or equal to 35MPa and a cross-section hardness difference of less than or equal to 40HV1.

[0055] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A high-quality wire rod for hose steel wire, characterized by comprising: Comprise the following components by mass percentage: C: 0.80%~0.84%, Si: 0.10%~0.20%, Mn: 0.50%~0.60%, P≤0.014%, S: 0.0030%~0.010%, total oxygen: 0.0020%~0.0045%, Als: 0.0005%~0.0015%, Nb: 0.0001%~0.0010%, Co: 0.0004%~0.0010%, Cr: 0.01%~0.10%, and the balance of iron and inevitable impurities; The ferrite grain size of the wire rod is ≤30μm; The size distribution of the ferrite grain of the wire rod is: the grain size is ≤5μm, the quantity ratio is 62%~68%; the grain size is ≤10μm, the quantity ratio is 78%~84%; the grain size is ≤15μm, the quantity ratio is 88.2%~92%; The pearlite lamellar spacing at the surface position of the wire rod is 0.10μm~0.15μm, the pearlite lamellar spacing at the 1 / 4 diameter position away from the surface is 0.13μm~0.18μm, and the pearlite lamellar spacing at the core position is 0.15μm~0.22μm; The carbon segregation index at the surface position of the wire rod is ≤1.05, the carbon segregation index at the 1 / 4 diameter position away from the surface is ≤1.08, and the carbon segregation index at the core position of the wire rod is ≤1.14; The strength difference of the wire rod is ≤35MPa, and the hardness difference of the cross section of the wire rod is ≤40HV1.

2. A process for the production of high quality wire rod for rubber hose steel wire as claimed in claim 1, wherein, Comprise the following steps: Converter smelting, LF refining, continuous casting, continuous casting billet heating and continuous rolling, wire rod rolling, wire rod cooling; In the converter smelting, scrap steel and molten iron are used as the furnace charge, and the scrap steel ratio is 5%~15%; In the continuous casting, the molten steel treated by the LF refining is continuously cast to obtain a continuous casting billet; In the continuous casting billet heating and continuous rolling, the continuous casting billet discharged from the continuous casting process is sent into a heating furnace for heating, and the heated continuous casting billet is continuously rolled, and the final rolling temperature is 920℃~990℃; In the wire rod rolling, the continuously rolled steel billet is heated in a heating furnace, and then sequentially passes through rough rolling, intermediate rolling, pre-precision rolling, precision rolling and wire drawing; In the wire rod cooling, the wire rod after wire drawing is cooled on an air cooling roller way to obtain the wire rod for steel cord.

3. The preparation method according to claim 2, characterized in that, In the LF refining, the molten steel after tapping in the converter smelting is refined in an LF furnace, the LF furnace refining temperature is 1450℃~1540℃, and the refining time is 30min~50min.

4. The preparation method according to claim 2, characterized in that, In the continuous casting, the cross section size of the continuous casting billet is (250~300)mm×(350~400)mm; the surface temperature of the edge of the continuous casting billet during straightening is 900℃~930℃, and the corner temperature of the continuous casting billet is 790℃~830℃; the size of the inclusions in the molten steel at the converter post position is ≤100μm, the size of the inclusions after the LF furnace refining treatment is ≤50μm, and the size of the inclusions in the molten steel at the tundish position is ≤40μm.

5. The preparation method according to claim 2, characterized in that, In the continuous casting billet heating and continuous rolling, the total heating time of the continuous casting billet is 3.5h-4.5h; the temperature of the preheating section is 980-1080℃, the temperature of the heating section is 1150-1180℃, the temperature of the soaking section is 1200-1220℃, and the soaking time of the billet in the soaking section is 40-50min.

6. The preparation method according to claim 2, characterized in that, In the wire rod rolling, the total heating time of the billet is 140-160min, the temperature of the soaking section is 1100-1150℃, the soaking time of the billet in the soaking section is 30-50min, the residual oxygen content in the heating furnace is 3-9%, and the pressure of the atmosphere in the furnace is 2-12Pa; after the billet is heated, the wire rod is drawn after rough rolling, intermediate rolling, pre-precision rolling and precision rolling; the temperature of the wire rod after the pre-precision rolling is 985-1005℃; the temperature of the wire rod after the precision rolling is 890-930℃; the temperature of the wire rod after entering the double module is 880-940℃; the temperature of the wire rod after drawing is 910-940℃; and the specification of the wire rod is 5.0-6.5mm.

7. The preparation method according to claim 2, characterized in that, In the wire rod cooling, the wire rod is cooled on the air cooling roller way after drawing, the temperature of the wire rod for the precipitation of cementite is controlled to be 700-730℃, the cooling speed of the wire rod is controlled to be 15-25℃ / s, the undercooling degree of the austenite of the wire rod to the pearlite phase change is controlled to be 80-120℃, and the phase change time is 12-18s.

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