High-strength and high-glossiness cold-rolled strip steel for sliding rail, production method and application of high-strength and high-glossiness cold-rolled strip steel and pre-judging method for surface glossiness of strip steel

Abstract

The invention belongs to the technical field of steel preparation, and particularly relates to a high-strength and high-glossiness cold-rolled strip steel for a sliding rail, a production method, application and a strip steel surface glossiness pre-judging method. The invention provides a production method of high-strength and high-glossiness cold-rolled strip steel for a sliding rail. The production method comprises the following steps: (1) molten steel smelting and continuous casting; (2) hot rolling; (3) acid continuous rolling; the roughness Ra1 of an upper working roller of a tail rack is 0.4-0.45 [mu] m, the roughness Ra2 of a lower working roller of the tail rack is Ra1 + 0.05 [mu] m, a roller of the tail rack is operated, and after the operation distance of the roller of the tail rack meets the kilometers, acid continuous rolling is carried out, and a rolled hard steel coil is obtained; and (4) annealing. According to the production method, the requirements for high glossiness and high hardness are met at low cost, certain forming performance is guaranteed, and the yield is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of steel material preparation, and specifically relates to high-strength and high-gloss cold-rolled strip steel for slide rails, a production method and application thereof, and a method for predicting the surface glossiness of the strip steel. Background Art

[0002] The slide rails used in heavy-duty tool cabinets are drawer slide rails. Tool cabinet drawers need to place different tools and have a large load. They also need to be pulled out enough times to ensure their service life. Therefore, the drawers of general heavy-duty tool cabinets must meet the requirements of 45kg load-bearing and 50,000 pull-out times. The slide rail material is required to have a certain hardness and surface gloss. The heavy-duty tool cabinet slide rails are made using a rolling manufacturing process. If the hardness of the slide rail steel is too high, the life of the rolling mold will be greatly reduced and the parts will rebound severely. If the hardness is too low, it cannot meet the load-bearing and wear-resistant requirements, so the hardness of the slide rail steel is required to be 55-65HRB. The high number of pull-out times requires the surface gloss of the slide rail steel to be ≥160GU.

[0003] Common slide rail steels on the market include hot-rolled slide rail steel, hard-rolled slide rail steel, cold-rolled galvanized slide rail steel, and cold-rolled annealed slide rail steel. Hot-rolled slide rail steel cannot meet the high gloss requirements; hard-rolled slide rail steel cannot meet the hardness requirements; cold-rolled galvanized slide rail steel is made of galvanized steel coils, and the zinc layer is easy to fall off during the rolling process. The slide rail fracture is not protected by the zinc layer and is easy to rust, which does not meet the corrosion resistance requirements. Cold-rolled annealed slide rail steel can better overcome the above problems and is often selected as the slide rail of heavy tool cabinets. High gloss means low roughness. The roughness of cold-rolled annealed slide rail steel is related to the cold rolling and continuous annealing processes. In the prior art, the frames of the cold rolling process often use low-roughness working rolls, which are difficult to process and prone to slipping. The roughness of the upper and lower surfaces of the hardened steel coils obtained is quite different, and the gloss requirement cannot be met. The smooth roller leveling and straightening functions are used to ensure the low surface roughness and plate shape of the steel coil, but in reality, the surface roughness of the steel coil will increase after leveling. The prior art cannot meet the low-cost and stable production of cold-rolled slide rail steel that meets the requirements of heavy-duty tool boxes. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art such as the inability to prepare cold-rolled slide rail steel with both high gloss and high hardness, high cost and low preparation efficiency when preparing slide rails, and being not conducive to rolling forming, thereby providing high-strength and high-gloss cold-rolled strip steel for slide rails, a production method and application, and a method for predicting the surface gloss of the strip steel.

[0005] To this end, the present invention provides the following technical solutions.

[0006] The present invention provides a method for producing high-strength and high-gloss cold-rolled strip steel for a slide rail, comprising the following steps:

[0007] (1) Molten steel smelting and continuous casting; the composition of the molten steel includes, by mass percentage, C: 0.21-0.23%, Si: ≤0.03%, Mn: 0.10-0.20%, P: ≤0.015%, S: ≤0.015%, Al: 0.05-0.07%, and the rest is Fe and other inevitable impurities;

[0008] (2) Hot rolling;

[0009] (3) Acid continuous rolling; the roughness Ra1 of the upper working roll of the final stand is 0.4-0.45 μm, the roughness Ra2 of the lower working roll is Ra1+0.05 μm, the final stand roll is operated, and when the running distance of the final stand roll meets the kilometer number, the acid continuous rolling is performed to obtain a hardened steel coil;

[0010] (4) Annealing

[0011] Specifically, the step (1) specifically analyzes and explains the main functions of each component in the molten steel composition and the selection of its dosage in the present invention:

[0012] Carbon (C): C is an important element for improving the strength of steel. According to the hardness required for the cold-rolled slide rail steel for heavy tool boxes and the springback of the rolled parts, the C content in the present invention is controlled at 0.21-0.23%. If the C content is higher than 0.23%, the plasticity of the steel will decrease, affecting the forming performance of the steel, and the hardness required for the cold-rolled slide rail steel for heavy tool boxes will not be met; if the C content is lower than 0.21%, the energy consumption cost of the steelmaking process will increase, which is not conducive to environmental protection.

[0013] Silicon (Si): Si is a ferrite-forming element that can increase the strength of the solid solution in steel and significantly increase the tensile strength of steel. However, excessive Si is not conducive to improving formability and surface pickling. Therefore, the Si content is less than 0.03%.

[0014] Manganese (Mn): Mn is one of the important solid solution strengthening elements in steel and is also an austenite stabilizing element. It can expand the austenite region in the iron-carbon phase diagram, promote the medium-temperature structural transformation of steel, and obtain a microstructure dominated by pearlite and ferrite. The microstructure has good uniformity, high strength and good toughness. However, too high a Mn content will reduce elongation, toughness, corrosion resistance and welding performance, and will also increase manufacturing costs. Therefore, the Mn content is controlled at 0.10-0.20%, and the mechanical properties can be controlled through subsequent processes.

[0015] Al: Cold-rolled slide rails for heavy tool cabinets adopt the rolling forming process, which has strict requirements on inclusions. Al, as a deoxidizer, can reduce the oxygen content in steel, reduce the inclusions in steel, and thus improve the toughness of steel. However, if the Al content is too high, it is easy to form coarse AlN particles, reduce the toughness of steel, and increase the Al2O3 inclusions. Therefore, the Al content is 0.05-0.07%.

[0016] In an optional implementation, the calculation formula for the kilometers is as follows:

[0017]

[0018] Wherein, L is kilometers, km; Ra is the preset roughness of the hardened steel coil surface, Ra≤0.25μm; Ra2 is the roughness of the lower working roll, 0.45-0.5μm.

[0019] The final stand is rolled with smooth rollers, and the working rollers are made of Cr5;

[0020] In an optional embodiment, the continuous casting speed is 1.0-1.5 m / min;

[0021] In an optional embodiment, the continuous casting obtains a continuous casting billet with a thickness of 180-220 mm.

[0022] In an optional embodiment, the hot rolling obtains a hot-rolled steel strip having a thickness of 4.0-4.5 mm;

[0023] In an optional embodiment, the hot rolling furnace temperature is 1170-1200°C; as an example, the hot rolling furnace temperature is selected from 1170°C, 1175°C, 1180°C, 1185°C, 1190°C, 1195°C, 1200°C or in the range of any two of the above values;

[0024] In an optional embodiment, the hot rolling finishing temperature is 840-880°C; as an example, the hot rolling finishing temperature is selected from 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, 870°C, 875°C, 880°C or in the range of any two of the above values;

[0025] In an optional embodiment, the coiling temperature of the hot rolling is 600-640° C. As an example, the coiling temperature of the hot rolling is selected from 600° C., 605° C., 610° C., 615° C., 620° C., 625° C., 630° C., 635° C., 640° C., or in a range consisting of any two of the above values.

[0026] In an optional embodiment, the thickness of the hardened steel coil is 1.0-1.8 mm;

[0027] In an optional embodiment, the reduction rate of the acid continuous rolling is 60-75%.

[0028] In an optional embodiment, the annealing is a continuous annealing process;

[0029] Preferably, the continuous annealing process includes a heating section and a soaking section;

[0030] Preferably, the heating period is 210-485s; as an example, the heating period is selected from 210s, 280s, 330s, 350s, 370s, 380s, 400s, 420s, 485s or in the range of any two of the above values;

[0031] Preferably, the soaking period is 75-180 seconds; as an example, the soaking period is selected from 75 seconds, 105 seconds, 115 seconds, 120 seconds, 125 seconds, 130 seconds, 135 seconds, 140 seconds, 150 seconds, 180 seconds or in the range of any two of the above values;

[0032] Preferably, the temperature of the soaking section is 770-790° C. As an example, the temperature of the soaking section is selected from 770° C., 772° C., 776° C., 778° C., 780° C., 783° C., 785° C., 788° C., 790° C., or in a range consisting of any two of the above values.

[0033] In an optional embodiment, the acid continuous rolling further includes a step of spraying an emulsion;

[0034] Preferably, the saponification value of the emulsion is 165-170 mgKOH / g.

[0035] The present invention also provides a high-strength and high-gloss cold-rolled steel strip for a slide rail produced by the above production method;

[0036] Preferably, the yield strength of the high-strength and high-gloss cold-rolled steel strip for the slide rail is 360-400 MPa;

[0037] Preferably, the tensile strength of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is 450-490 MPa;

[0038] Preferably, the elongation of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is ≥32%;

[0039] Preferably, the hardness of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is 55-65HRB;

[0040] Preferably, the glossiness of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is ≥160GU.

[0041] The present invention also provides an application of the high-strength and high-gloss cold-rolled strip steel for slide rails produced by the production method in heavy-duty tool cabinets.

[0042] The present invention also provides a method for predicting the surface glossiness of a steel strip. The method uses equation 2 to obtain the surface glossiness of the steel strip:

[0043] SG=265e -2×Ra Relation 2

[0044] Among them, SG is the glossiness of the slide rail steel, ≥160GU; Ra is the surface roughness of the hardened steel coil, μm.

[0045] The technical solution of the present invention has the following advantages:

[0046] 1. The production method of high-strength and high-gloss cold-rolled strip steel for slide rails provided by the present invention comprises the following steps:

[0047] (1) molten steel smelting and continuous casting; in terms of mass percentage, the composition of the molten steel includes: C: 0.21-0.23%, Si: ≤0.03%, Mn: 0.10-0.20%, P: ≤0.015%, S: ≤0.015%, Al: 0.05-0.07%, and the rest is Fe and other inevitable impurities; (2) hot rolling; (3) acid continuous rolling; the roughness Ra1 of the upper working roll of the last stand is 0.4-0.45μm, and the roughness Ra2 of the lower working roll is Ra1+0.05μm, and the last stand roll is operated. When the running distance of the last stand roll meets the kilometer number, the acid continuous rolling is carried out to obtain a hardened steel coil; (4) annealing. The invention starts from the continuous production process of steelmaking-hot rolling-cold rolling-annealing, and through the coordinated optimization of the whole process, the high-strength and high-gloss cold-rolled strip steel for the slide rail is obtained with a gloss of ≥160GU, a hardness of 55-65HRB, a yield strength of 360-400MPa, a tensile strength of 450-490MPa, and an elongation of ≥32%. The high-strength and high-gloss cold-rolled strip steel for the slide rail has the characteristics of low cost, high gloss, high hardness, certain forming performance, etc. Specifically, the present invention limits the content of C component to ensure that the cold-rolled steel strip can be rolled and formed while having high strength; in the acid continuous rolling process, the roughness Ra1 of the upper working roll of the last stand is specified to be 0.4-0.45μm, and the roughness Ra2 of the lower working roll is specified to be Ra1+0.05μm. In actual operation, the roughness attenuation of the lower working roll is greater than that of the upper working roll. The provision of Ra2=Ra1+0.05μm can avoid the color difference between the upper and lower surfaces of the steel coil, and the roughness of the hardened steel coil after cold rolling does not meet the requirements. In addition, the acid continuous rolling process of the present invention has no special requirements for the rolls, the rolls are easy to process, have a long service life, are not easy to slip, and the acid continuous rolling production process is stable and low in cost. The production method of the present invention meets the requirements of high gloss and high hardness at a relatively low cost, ensures certain forming performance, and improves the yield rate.

[0048] 2. The production method of high-strength and high-gloss cold-rolled strip steel for slide rails provided by the present invention obtains suitable hardness by controlling the content of C component, without adding other alloy elements, the method is simple and the cost is low. The present invention determines the rolling mileage of the last stand by the roughness of the working roll under the last stand and the preset roughness of the surface of the hardened steel coil. When the running distance of the last stand exceeds the kilometer, the acid continuous rolling is carried out to make the hardened steel coil reach the target roughness, which improves the problem of color difference of the hardened steel coil due to the inconsistent surface roughness of the upper and lower working rolls. The present invention adopts a continuous annealing process. Compared with the hood annealing process, its production cycle is short, the efficiency is high, the output is large, and the surface quality of the high-strength and high-gloss cold-rolled strip steel for slide rails is good, and a high-gloss surface can be obtained without a flattening process. The annealing soaking temperature is 770-790℃, which makes the grains completely recover and recrystallize to obtain a uniform grain structure; it also ensures the hardness of the high-strength and high-gloss cold-rolled strip steel for slide rails.

[0049] The present invention adopts an emulsion with a saponification value of 165-170 mgKOH / g to be added between the last rack and the previous rack to avoid defects such as color difference and oil spots on the surface of the hardened steel coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 is the metallographic structure diagram of the 4.0 mm hot-rolled strip steel in Example 1 of the present invention;

[0052] Figure 2 This is a metallographic structure diagram of the high-strength and high-gloss cold-rolled strip steel for slide rails prepared in Example 1 of the present invention;

[0053] Figure 3 is the metallographic structure diagram of the 4.5 mm hot-rolled strip steel in Example 2 of the present invention;

[0054] Figure 4 This is a metallographic structure diagram of the high-strength and high-gloss cold-rolled strip steel for slide rails prepared in Example 2 of the present invention;

[0055] Figure 5 is the metallographic structure diagram of the 4.0 mm hot-rolled strip steel in Example 3 of the present invention;

[0056] Figure 6 This is the metallographic structure diagram of the high-strength and high-gloss cold-rolled strip steel for slide rails prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0057] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0058] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0059] The present invention provides a method for producing high-strength and high-gloss cold-rolled strip steel for slide rails, which is specifically as follows:

[0060] (1) Steelmaking: molten iron pretreatment - converter smelting - refining - slab continuous casting; specifically, molten steel pretreatment is to melt the molten steel components, and the molten steel components include (by mass percentage): C: 0.21-0.23%, Si: ≤0.03%, Mn: 0.10-0.20%, P: ≤0.015%, S: ≤0.015%, Al: 0.05-0.07%, and the rest are Fe and other inevitable impurities; wherein, the parameters of converter smelting are not specifically limited, such as the temperature is 1648-1658°C and the time is 49-51min. The refining includes LF refining and RH refining; conventional processes in the field can be used, and the present invention does not make any restrictions. The slab continuous casting includes continuous casting at a pulling speed of 1.0-1.5m / min to obtain a continuous casting billet with a thickness of 180-220mm.

[0061] (2) Hot rolling: heating of the ingot - rough rolling - finishing rolling - layer cooling - coiling; specifically, the furnace temperature is 1170-1200°C; then rough rolling is performed at 1017-1025°C, and the reduction rate of the rough rolling is 82%; finishing rolling is performed at 840-880°C, layer cooling is performed, and coiling is performed at 600-640°C to obtain a hot-rolled strip with a thickness of 4.0-4.5 mm.

[0062] (3) Acid continuous rolling: acid rolling uncoiling - welding - pickling - rinsing - continuous rolling mill cold rolling - acid continuous rolling - coiling; specifically, the acid rolling uncoiling, welding, pickling and rinsing are carried out according to the conventional process in the art, and the present invention does not make any limitation; the purpose of the pickling is to remove the oxide on the surface of the hot-rolled strip; when cold rolling, the continuous rolling mill can be a five-stand cold rolling mill, the last stand is the fifth stand, the fifth stand adopts bare rolling, and the material of the working roll can be but not limited to Cr5 material; the roughness Ra1 of the upper working roll of the last stand is 0.4-0.45μm, and the roughness Ra2 of the lower working roll is Ra1+0.05μm. According to the requirement for the surface glossiness of the strip, the roughness Ra2 is calculated and Determine the preset roughness Ra of the surface of the hardened steel coil, calculate the kilometer number according to the relationship 1, run the last stand roller, and carry out acid continuous rolling when the running distance of the last stand roller meets the kilometer number. The acid continuous rolling is carried out at room temperature, and the reduction rate of the acid continuous rolling is 60-75%; obtain a hardened steel coil with a thickness of 1.0-1.8mm. It should be noted that Ra1 is the initial roughness of the upper working roller, and Ra2 is the roughness of the lower working roller. As the last stand runs, the roughness of the upper working roller and the lower working roller will decay. When the running distance of the last stand meets the kilometer number, a qualified strip steel that meets the requirements can be produced; the coiling is carried out according to the conventional process in this field; the present invention does not make any restrictions. Among them, the kilometer number refers to the distance that the working roller of the last stand runs from the initial roughness to the distance that can produce the hardened steel coil that meets the requirements. It should be noted that when the running distance of the working rollers of the last stand is less than the number of kilometers L, the strip steel produced by the working rollers does not meet the glossiness requirements of the strip steel of the present invention. Therefore, when the running distance of the working rollers is less than the number of kilometers L, it cannot be used to produce the strip steel of the present invention, but can be used to produce other types of products.

[0063] During the acid continuous rolling, an emulsion is sprayed between the last stand and the previous stand (i.e., the 4th and 5th stands), wherein the saponification value of the emulsion is 165-170 mgKOH / g. The purpose of the spraying is to control the surface quality of the hardened steel coil and improve the production stability. The emulsion is treated by an emulsion oil skimmer before use, in order to prevent defects such as color difference and oil spots on the surface of the hardened steel coil.

[0064] The roughness Ra1 of the upper working roll of the final stand is 0.4-0.45μm, and the roughness Ra2 of the lower working roll is Ra1+0.05μm; if the initial roughness of the upper working roll and the lower working roll are the same, the upper working roll of the final stand is better lubricated by emulsion, and its roughness attenuation is smaller; while the roughness attenuation of the lower working roll of the final stand is larger, which will cause the upper and lower surfaces of the hardened steel coil to have different roughness and color difference; therefore, the roughness Ra2 of the lower working roll is limited to be greater than the roughness Ra1 of the upper working roll, so as to reduce the color difference between the upper and lower surfaces of the steel coil due to inconsistent attenuation of the upper and lower working rolls during operation, so that a hardened steel coil with roughness meeting the requirements and uniform color can be obtained.

[0065] When the high-strength and high-gloss cold-rolled steel strip for the slide rail is used in heavy-duty tools, the glossiness of the high-strength and high-gloss cold-rolled steel strip for the slide rail is required to be ≥160GU;

[0066] SG=265e -2×Ra Relation 2

[0067] According to equation 2, when the glossiness is ≥160GU, the corresponding surface roughness of the hardened steel coil is Ra≤0.25μm, that is, when the glossiness of the strip meets ≥160GU, the surface roughness of the hardened steel coil needs to meet Ra≤0.25μm. Using the preset roughness Ra of the hardened steel coil surface and the initial roughness Ra2 of the lower working roll, combined with equation 1, it is determined how long the working roll can run to produce a hardened steel coil that meets the roughness requirements, and then the timing of acid continuous rolling is determined to obtain a hardened steel coil with a roughness that meets the requirements, and finally obtain a strip with a glossiness that meets the requirements. When the difference between the measured roughness of the strip and the preset roughness is within 0.02μm, it means that the error is small and meets the requirements. The actual glossiness of the strip is higher than the target glossiness, which means that the product is qualified.

[0068] It should be further explained that, for the hardened steel coil with specific composition produced by the present invention, the glossiness of the strip steel and the surface roughness of the hardened steel coil can be correlated with the relational expression 2.

[0069] (4) Annealing: continuous unwinding and uncoiling - cleaning - annealing - straightening - oiling - coiling; specifically, the continuous unwinding and uncoiling and cleaning are carried out according to conventional processes in the art; the present invention does not make any limitation; the annealing of the present invention is a continuous annealing process, which includes a heating section, a soaking section, and a cooling section, and the belt speed is 70-160 m / min; the appropriate belt speed can be selected according to the thickness of the hardened steel coil, the heating section is heated to 770-790°C at 210-485s, and the soaking section is kept at 770-790°C for 75-180s;

[0070] The cooling section includes a slow cooling section, a fast cooling section and an aging section, and is air-cooled by a fan in a nitrogen and hydrogen mixed atmosphere; specifically, the holding time of the slow cooling section is 29-67s, the holding time of the fast cooling section is 7-15s, and the holding time of the aging section is 281-642s; the purpose of the aging section is to stabilize the organization and release the internal stress, improve the mechanical properties of the material, improve the hardness and wear resistance of the hardened steel coil, improve its strength, and reduce its elongation;

[0071] The elongation of the tension leveling is 0.4-0.8%; its purpose is to control the plate shape; the type of oil in the oiling is not limited, and any common oil in the field can be used; the amount of oil applied is 350-400mg / m 2The purpose of the oiling is to prevent rust and friction damage during the transportation of steel strips; the coiling is carried out according to the conventional process in the field; the present invention does not make any limitation. The present invention does not require a flattening process.

[0072] Finally, a high-strength and high-gloss cold-rolled steel strip for slide rails is obtained, and the high-strength and high-gloss cold-rolled steel strip for slide rails has a yield strength of 360-400MPa, a tensile strength of 450-490MPa, an elongation of ≥32%, a hardness of 55-65HRB, and a glossiness of ≥160GU.

[0073] Example 1

[0074] This embodiment provides a method for producing high-strength and high-gloss cold-rolled steel strip for a slide rail, comprising the following steps:

[0075] (1) Molten steel smelting and continuous casting: The composition of the molten steel, in percentage by mass, includes: C: 0.23%, Si: 0.03%, Mn: 0.20%, P: 0.013%, S: 0.012%, Al: 0.055%, and the remainder is Fe and other inevitable impurities; the molten steel is smelted in a converter at 1652°C for 51 min, LF refined at 1587°C for 35 min, and continuously cast at a pulling speed of 1.2 m / min to obtain a continuous casting billet with a thickness of 220 mm.

[0076] (2) Hot rolling: The hot rolling furnace temperature is 1180℃, the rough rolling temperature is 1017℃, and the rough rolling reduction rate is 82%; the average finishing temperature is 862℃, and the layer cooling is carried out. The hot rolled strip is coiled at 603℃ to obtain a hot rolled strip with a thickness of 4.0mm. The metallographic structure of the hot rolled strip is shown in Figure 1 .

[0077] (3) Acid continuous rolling: pickling at a belt speed of 100 m / min at 78°C, the pickling solution is a hydrochloric acid aqueous solution (the mass concentration of hydrochloric acid is 18%), continuous rolling at room temperature, the roughness Ra1 of the upper working roll is 0.4 μm, the roughness Ra2 of the lower working roll is 0.45 μm, the target glossiness SG of the strip is 160GU, and the preset roughness Ra of the hardened steel coil surface is calculated to be 0.25 μm according to Relationship 2; the mileage L of the roller operation of the last stand is calculated to be 52.1 km using Relationship 1;

[0078]

[0079] SG=265e -2×Ra Relation 2

[0080] After the working rolls have run 52.1 km, acid continuous rolling is carried out. At the same time, an emulsion is sprayed between the last stand and the previous stand. The saponification value of the emulsion is 167 mgKOH / g, and a hardened steel coil with a thickness of 1.4 mm is obtained. The reduction rate of the acid continuous rolling is 65%. The average roughness of the plate surface of the hardened steel coil is measured to be 0.23 μm, and the error with the preset roughness Ra0.25 μm is -0.02 to 0 μm. The error is small, and a qualified hardened steel coil is obtained.

[0081] (4) Annealing: Continuous annealing is carried out at a belt speed of 100 m / min, the heating period is 340 s, and after heating to 780°C, it enters the soaking section. After soaking at 780°C for 125 s, it enters the cooling section. It is first kept in the slow cooling section for 47 s to cool down to 680°C, and then kept in the fast cooling section for 11 s to cool to 420°C. It enters the aging section. The aging section is kept for 449 s, the terminal temperature is 380°C, and the elongation is stretched to 0.4-0.8%; oil is applied with Quaker 6130, and the oil application amount is 400 mg / m 2 , coiled to produce high-strength and high-gloss cold-rolled strip steel for slide rails.

[0082] This embodiment provides a high-strength and high-gloss cold-rolled steel strip for slide rails produced by the above production method. The surface roughness is measured to be 0.23 μm, the upper and lower surface roughness of the steel strip is basically the same, the gloss is 175 GU, the hardness is 62.1 HRB, the yield strength is 373 MPa, the tensile strength is 475 MPa, and the elongation is 33.8%. The metallographic structure of the high-strength and high-gloss cold-rolled steel strip for slide rails is shown in Figure 2 The actual glossiness of the steel strip produced by the present invention is 175 GU, which is greater than the target glossiness of 160 GU, indicating that the present method can produce steel strip that meets the requirements.

[0083] Example 2

[0084] This embodiment provides a method for producing high-strength and high-gloss cold-rolled steel strip for a slide rail, comprising the following steps:

[0085] (1) Molten steel smelting and continuous casting: The composition of the molten steel, in terms of mass percentage, includes: C: 0.21%, Si: 0.02%, Mn: 0.15%, P: 0.009%, S: 0.014%, Al: 0.062%, and the remainder is Fe and other inevitable impurities; the molten steel is smelted in a converter at 1648°C for 51 min, LF refined at 1587°C for 40 min, and continuously cast at a pulling speed of 1.1 m / min to obtain a continuous casting billet with a thickness of 220 mm.

[0086] (2) Hot rolling: The hot rolling furnace temperature is 1200℃, the rough rolling temperature is 1025℃, and the rough rolling reduction rate is 82%; the average finishing temperature is 875℃, and the layer cooling is carried out. The hot rolled strip is coiled at 635℃ to obtain a hot rolled strip with a thickness of 4.5mm. The metallographic structure of the hot rolled strip is shown in Figure 3 .

[0087] (3) Acid continuous rolling: pickling at 82°C at a belt speed of 110 m / min, the pickling solution is a hydrochloric acid aqueous solution (the mass concentration of hydrochloric acid is 18%), and continuous rolling is performed at room temperature, wherein the roughness Ra1 of the upper working roll is 0.45 μm, the roughness Ra2 of the lower working roll is 0.5 μm, the target glossiness SG of the strip is 160 GU, and the preset roughness Ra of the rolled hardened steel coil surface is calculated to be 0.25 μm according to Relationship 2; the mileage L of the roller operation of the last stand is calculated to be 67.1 km using Relationship 1;

[0088] After the working rolls have run 67.1 km, acid continuous rolling is carried out. At the same time, an emulsion is sprayed between the last stand and the previous stand. The saponification value of the emulsion is 168 mgKOH / g, and a hardened steel coil with a thickness of 1.6 mm is obtained. The reduction rate of the acid continuous rolling is 64.4%. The average roughness of the plate surface of the hardened steel coil is measured to be 0.24 μm, and the error with the preset roughness of 0.25 μm is -0.01 to 0 μm. The error is small, and a qualified hardened steel coil is obtained.

[0089] (4) Annealing: Continuous annealing is carried out at a belt speed of 90 m / min, the heating section time is 377 s, and after heating to 789°C, it enters the soaking section. After soaking at 789°C for 139 s, it enters the cooling section. It is first kept in the slow cooling section for 52 s to cool down to 680°C, and then kept in the fast cooling section for 12 s to cool to 420°C. It enters the aging section. The aging section is kept for 499 s, the terminal temperature is 380°C, and the elongation is stretched to 0.4-0.8%; oil is applied with Quaker 6130, and the oil application amount is 350 mg / m on one side. 2 , coiled to produce high-strength and high-gloss cold-rolled strip steel for slide rails.

[0090] This embodiment provides a high-strength and high-gloss cold-rolled steel strip for slide rails produced by the above production method. The surface roughness is measured to be 0.24 μm, the upper and lower surface roughness of the steel strip is basically the same, the gloss is 172 GU, the hardness is 61.5 HRB, the yield strength is 362 MPa, the tensile strength is 469 MPa, and the elongation is 34.2%. The metallographic structure of the high-strength and high-gloss cold-rolled steel strip for slide rails is shown in Figure 4 The actual glossiness of the steel strip produced by the present invention is 172 GU, which is greater than the target glossiness of 160 GU, indicating that the present method can produce steel strip that meets the requirements.

[0091] Example 3

[0092] This embodiment provides a method for producing high-strength and high-gloss cold-rolled steel strip for a slide rail, comprising the following steps:

[0093] (1) Molten steel smelting and continuous casting: The composition of the molten steel, in terms of mass percentage, includes: C: 0.22%, Si: 0.02%, Mn: 0.10%, P: 0.010%, S: 0.012%, Al: 0.065%, and the remainder is Fe and other inevitable impurities; the molten steel is smelted in a converter at 1658°C for 49 min, LF refined at 1587°C for 32 min, and continuously cast at a pulling speed of 1.15 m / min to obtain a continuous casting billet with a thickness of 220 mm.

[0094] (2) Hot rolling: The hot rolling furnace temperature is 1175℃, the hot rolling rough rolling temperature is 1025℃, and the rough rolling reduction rate is 82%; the average finishing temperature is 820℃, and the layer cooling is carried out. The hot rolled strip is coiled at 620℃ to obtain a hot rolled strip with a thickness of 4.0mm. The metallographic structure of the hot rolled strip is shown in Figure 5 .

[0095] (3) Acid continuous rolling: pickling at 85°C at a belt speed of 105 m / min, the pickling solution is a hydrochloric acid aqueous solution (the mass concentration of hydrochloric acid is 17.5%), and continuous rolling is performed at room temperature, wherein the roughness Ra1 of the upper working roll is 0.43 μm, the roughness Ra2 of the lower working roll is 0.48 μm, the target glossiness SG of the strip is 160 GU, and the preset roughness Ra of the rolled hardened steel coil surface is calculated to be 0.25 μm according to Relationship 2; the mileage L of the roller operation of the last stand is calculated to be 62 km according to Relationship 1;

[0096] After the working rolls have run 62 km, acid continuous rolling is carried out, and at the same time, an emulsion is sprayed between the last stand and the previous stand. The saponification value of the emulsion is 170 mgKOH / g, and a hardened steel coil with a thickness of 1.0 mm is obtained. The reduction rate of the acid continuous rolling is 75%; the average roughness of the plate surface of the hardened steel coil is measured to be 0.23 μm, and the error with the preset roughness of 0.25 μm is -0.02 to 0 μm, and the error is small, so a qualified hardened steel coil is obtained.

[0097] (4) Annealing: Continuous annealing is carried out at a belt speed of 160 m / min, the heating period is 212 s, and after heating to 770°C, it enters the soaking section. After soaking at 770°C for 78 s, it enters the cooling section. It is first kept in the slow cooling section for 29 s to cool down to 680°C, and then kept in the fast cooling section for 7 s to cool to 420°C. It enters the aging section. The aging section is kept for 281 s, and the terminal temperature is 380°C. It is straightened to an elongation of 0.4-0.8%; oil is applied with Quaker 6130, and the oil application amount is 350 mg / m on one side. 2 , coiled to produce high-strength and high-gloss cold-rolled strip steel for slide rails.

[0098] This embodiment provides a high-strength and high-gloss cold-rolled steel strip for slide rails produced by the above production method. The surface roughness is measured to be 0.23 μm, the upper and lower surface roughness of the steel strip is basically the same, the gloss is 172 GU, the hardness is 61.2 HRB, the yield strength is 360 MPa, the tensile strength is 462 MPa, and the elongation is 33.5%. The metallographic structure of the high-strength and high-gloss cold-rolled steel strip for slide rails is shown in Figure 6 The actual glossiness of the steel strip produced by the present invention is 172 GU, which is greater than the target glossiness of 160 GU, indicating that the present method can produce steel strip that meets the requirements.

[0099] Comparative Example 1

[0100] This comparative example provides a method for producing cold-rolled steel strip, which is different from Example 1 in that step (3) is different. After steps (1) and (2) of Example 1, step (3) of this comparative example is:

[0101] Acid continuous rolling: pickling at a belt speed of 100m / min at 78°C, the pickling solution is a hydrochloric acid aqueous solution (the mass concentration of hydrochloric acid is 18%), continuous rolling at room temperature, wherein the roughness Ra1 of the upper working roll is 0.45μm, the roughness Ra2 of the lower working roll is 0.45μm, and the mileage L of the last stand roll is 20km; after running for 20km, acid continuous rolling is carried out, and at the same time, an emulsion is sprayed between the last stand and the previous stand, and the saponification value of the emulsion is 167mgKOH / g. After acid continuous rolling, a hardened steel coil with a thickness of 1.4mm is obtained, and the acid continuous rolling reduction rate is 65%; the average roughness of the upper surface of the hardened steel coil obtained is measured to be 0.34μm, and the average roughness of the lower surface is 0.30μm.

[0102] Then, step (4) is carried out according to the steps of Example 1 to obtain a cold-rolled steel strip.

[0103] This comparative example provides a cold-rolled steel strip produced by the above production method, and the average roughness of the upper surface is 0.34μm, the glossiness of the upper surface is 146GU, the average roughness of the lower surface is 0.3μm, the glossiness of the lower surface is 146GU, the hardness is 62.1HRB, the yield strength is 373MPa, the tensile strength is 475MPa, and the elongation is 33.8%. The glossiness of the steel strip obtained in this comparative example is lower than 160GU, and there is a color difference between the upper and lower surfaces, which does not meet the use requirements; it shows that when the roughness of the upper and lower working rolls of the final stand is the same, the inconsistent attenuation of the upper and lower working rolls during operation will cause the color difference between the upper and lower surfaces of the cold-rolled steel strip produced, and the roughness does not meet the requirements.

[0104] Comparative Example 2

[0105] This comparative example provides a method for producing cold-rolled steel strip, which is different from Example 1 in that step (1) is different. Step (1) of this comparative example is:

[0106] (1) Molten steel smelting and continuous casting: The composition of the molten steel, in terms of mass percentage, includes: C: 0.19%, Si: 0.02%, Mn: 0.12%, P: 0.015%, S: 0.009%, Al: 0.059%, and the remainder is Fe and other inevitable impurities; the molten steel is smelted in a converter at 1652°C for 51 min, LF refined at 1587°C for 35 min, and continuously cast at a pulling speed of 1.2 m / min to obtain a continuous casting billet with a thickness of 220 mm.

[0107] Then, steps (2), (3) and (4) are carried out according to the steps of Example 1 to obtain cold-rolled steel strip.

[0108] This comparative example provides a cold-rolled steel strip produced by the above production method, whose surface roughness is measured to be 0.25 μm, glossiness is 162 GU, hardness is 52.4 HRB, yield strength is 340 MPa, tensile strength is 434 MPa, and elongation is 35.7%.

[0109] It can be seen from the various properties of cold-rolled strip that although the glossiness of the produced cold-rolled strip meets the requirements for heavy-duty tool cabinets, the hardness is too small and cannot meet the load-bearing and wear-resistant requirements.

[0110] Comparative Example 3

[0111] This comparative example provides a method for producing cold-rolled steel strip, which is different from Example 1 in that step (1) is different. Step (1) of this comparative example is:

[0112] (1) Molten steel smelting and continuous casting: The composition of the molten steel, in percentage by mass, includes: C: 0.25%, Si: 0.01%, Mn: 0.15%, P: 0.010%, S: 0.011%, Al: 0.059%, and the remainder is Fe and other inevitable impurities; the molten steel is smelted in a converter at 1652°C for 51 min, LF refined at 1587°C for 35 min, and continuously cast at a speed of 1.2 m / min to obtain a continuous casting billet with a thickness of 220 mm.

[0113] Then, steps (2), (3) and (4) are carried out according to the steps of Example 1 to obtain cold-rolled steel strip.

[0114] This comparative example provides a cold-rolled steel strip produced by the above production method, whose surface roughness is measured to be 0.25 μm, glossiness is 162 GU, hardness is 68 HRB, yield strength is 385 MPa, tensile strength is 495 MPa, and elongation is 31.2%.

[0115] It can be seen from the various properties of cold-rolled strip that although the glossiness of the produced cold-rolled strip meets the requirements for heavy-duty tool cabinets, the hardness is too high. When the rolling manufacturing process is used to make slide rails, the loss of the rolling mold will increase, and its elongation is less than 32%, which makes the rolling punches easy to crack and the parts rebound severely, which greatly reduces the life of the rolling mold and increases the cost.

[0116] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for producing high-strength and high-gloss cold-rolled strip steel for slide rails, characterized in that: The steps include: (1) Molten steel smelting and continuous casting; the composition of the molten steel includes, by mass percentage, C: 0.21-0.23%, Si: ≤0.03%, Mn: 0.10-0.20%, P: ≤0.015%, S: ≤0.015%, Al: 0.05-0.07%, and the rest is Fe and other inevitable impurities; (2) Hot rolling; (3) Acid continuous rolling; the roughness Ra1 of the upper working roll of the final stand is 0.4-0.45 μm, the roughness Ra2 of the lower working roll is Ra1+0.05 μm, the final stand roll is operated, and when the running distance of the final stand roll meets the kilometer number, the acid continuous rolling is performed to obtain a hardened steel coil; (4) Annealing 2. The production method according to claim 1, characterized in that The calculation formula for the kilometres is as follows: Wherein, L is kilometers, km; Ra is the preset roughness of the surface of the rolled hardened steel coil, Ra≤0.25μm.

3. The production method according to claim 1, characterized in that The continuous casting speed is 1.0-1.5 m / min; and / or, The continuous casting obtains a continuous casting billet with a thickness of 180-220 mm.

4. The production method according to claim 1, characterized in that The hot rolling obtains a hot rolled steel strip having a thickness of 4.0-4.5 mm; and / or, The hot rolling furnace temperature is 1170-1200°C; and / or, The hot rolling finishing temperature is 840-880°C; and / or, The coiling temperature of the hot rolling is 600-640°C.

5. The production method according to claim 1, characterized in that: The thickness of the hardened steel coil is 1.0-1.8 mm; and / or, The reduction rate of the acid continuous rolling is 60-75%.

6. The production method according to claim 1, characterized in that: The annealing is a continuous annealing process; Preferably, the continuous annealing process includes a heating section and a soaking section; Preferably, the heating period is 210-485s; Preferably, the soaking period is 75-180 seconds; Preferably, the temperature of the soaking section is 770-790°C.

7. The production method according to claim 1, characterized in that: The method further comprises the step of spraying emulsion during the acid continuous rolling; Preferably, the saponification value of the emulsion is 165-170 mgKOH / g.

8. High-strength and high-gloss cold-rolled steel strip for slide rails produced by the production method according to any one of claims 1 to 7; Preferably, the yield strength of the high-strength and high-gloss cold-rolled steel strip for the slide rail is 360-400 MPa; Preferably, the tensile strength of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is 450-490 MPa; Preferably, the elongation of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is ≥32%; Preferably, the hardness of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is 55-65HRB; Preferably, the glossiness of the high-strength and high-gloss cold-rolled steel strip used for the slide rail is ≥160GU.

9. Use of the high-strength and high-gloss cold-rolled steel strip for slide rails produced by the production method according to any one of claims 1 to 7 or the high-strength and high-gloss cold-rolled steel strip for slide rails according to claim 8 in heavy-duty tool cabinets.

10. A method for predicting the surface glossiness of a steel strip, characterized in that: The prediction method uses equation 2 to obtain the surface gloss of the strip steel: SG=265e -2×Ra Relation 2 Among them, SG is the glossiness of the strip, ≥160GU; Ra is the surface roughness of the hardened steel coil, μm.

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