CN111304529A - Seamless steel tube for multi-stage oil cylinder and manufacturing method thereof - Google Patents
Seamless steel tube for multi-stage oil cylinder and manufacturing method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
- C21D9/14—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes wear-resistant or pressure-resistant pipes
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/02—Rigid pipes of metal
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Abstract
The invention relates to a seamless steel tube for a multistage oil cylinder, which comprises the following chemical components, by mass, 0.24-0.30% of C, 1.20-1.40% of Si, 1.20-1.40% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.025-0.055% of Al, less than or equal to 0.15% of Mo, less than or equal to 0.15% of Cr, less than or equal to 0.15% of Ni, less than or equal to 0.20% of Cu, and the balance of Fe. The DJG27SiMn seamless steel tube for the thin-wall hot-rolled quenched and tempered cylinder barrel and the plunger can be obtained, and the requirements of thin wall and excellent other performances can be met in production, so that the effect of reducing vehicle load is achieved; the wear resistance and the sealing performance are good, and the problem of hydraulic oil leakage caused by frequent use is avoided; the high-performance high-temperature-resistant composite material has good low-temperature performance, namely, the high-performance high-temperature-resistant composite material still has good performance under low-temperature conditions, and the conditions of cylinder expansion, cylinder explosion and the like cannot occur.
Description
Technical Field
The invention relates to the field of steel pipe manufacturing, in particular to a seamless steel pipe for a multistage oil cylinder and a manufacturing method thereof.
Background
Seamless steel pipes for multi-stage hydraulic oil cylinders (hereinafter referred to as multi-stage cylinders) in the processing machinery industry and the automobile industry are continuously used for manufacturing seamless steel pipes for hydraulic props used for fully mechanized mining support equipment in the coal industry, namely 27SiMn seamless steel pipes delivered in a hot rolling state according to GB/T17396 standard. Because the steel grade is not reasonable, the problems of processing and using the multi-stage cylinder are caused.
In the processing technology of the multistage cylinder, the problems of thicker selected seamless steel pipe, larger processing amount and the like exist.
In the use of the multi-stage cylinder, the multi-stage cylinder has worse use environment (high temperature and low temperature) and higher use frequency than a hydraulic prop, and the problems of oil leakage and even cylinder explosion of the multi-stage cylinder exist all the time, thereby causing potential safety hazards to vehicles or machinery using the multi-stage cylinder.
Modern construction machinery and dump trucks are increasingly demanding on multi-stage cylinders, and semitrailer manufacturers are reducing weight in order to carefully carry out 2016 (2016 nd 62 nd 2016 (department of transportation) highway administration regulations for over-limit transportation vehicles) that begin to be carried out in 9/21 th of 2016. The multi-stage oil cylinder of the hydraulic dumper has six parts, so that the hydraulic dumper becomes a key for reducing weight.
Therefore, how to develop a lightweight seamless steel tube for a multi-stage oil cylinder with up-to-standard quality and solve the problems of poor wear resistance of the oil cylinder, poor sealing of the oil cylinder and the like caused by unqualified dark spots (inclusions exposed) on the inner and outer surfaces generated by the cylinder barrel and the plunger in the processing process of the multi-stage oil cylinder in the prior art.
The DJG seamless pipe delivered in a quenched and tempered state can adopt a new sealing process, is thinner and lighter than a 27SiMn steel pipe delivered in a rolled state by adopting the existing process, has standard quality and has other advantages.
Disclosure of Invention
The invention aims to solve the technical problem of providing a DJG27SiMn seamless steel tube for a thin-wall hot-rolled quenched and tempered cylinder barrel and a plunger and a manufacturing method thereof.
The technical scheme for solving the technical problems is as follows: a seamless steel tube for a multistage oil cylinder comprises the chemical components of, by mass, 0.24-0.30% of C, 1.20-1.40% of Si, 1.20-1.40% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.025-0.055% of Al, less than or equal to 0.15% of Mo, less than or equal to 0.15% of Cr, less than or equal to 0.15% of Ni, less than or equal to 0.20% of Cu, and the balance of Fe.
The invention has the beneficial effects that: the DJG27SiMn seamless steel tube for the thin-wall hot-rolled quenched and tempered cylinder barrel and the plunger can be obtained, has the characteristic of thin wall in production and meets the requirements of other excellent performances, so that the effect of reducing the load of a vehicle is achieved; the wear resistance and the sealing performance are good, and the problem of hydraulic oil leakage caused by frequent use is avoided; the high-temperature-resistant high.
On the basis of the technical scheme, the invention can be further improved as follows:
further, the chemical components constituting the seamless steel pipe include, by mass%, 0.28% C, 1.29% Si, 1.31% Mn, 0.010% P, 0.009% S, 0.027% Al, 0.04% Mo, 0.08% Cr, 0.06% Ni, 0.09% Cu, and the balance Fe.
The beneficial effect of adopting the further scheme is that the obtained steel pipe has excellent properties under the condition of the content of the components.
Further, the chemical components constituting the seamless steel pipe include, by mass%, 0.27% C, 1.31% Si, 1.29% Mn, 0.012% P, 0.006% S, 0.037% Al, 0.008% Mo, 0.006% Cr, 0.002% Ni, 0.009% Cu, and the balance Fe.
The beneficial effect of adopting the further scheme is that the obtained steel pipe has excellent properties under the condition of the content of the components.
Further, the out-of-roundness of the seamless steel pipe is not more than the outer diameter, the wall thickness unevenness is not more than 80% of the wall thickness tolerance, the allowable deviation of the fixed length is 0-30mm, the bending degree is not more than 1.5mm/m, the grain size is not less than 7 grades, and the depth of a decarburized layer is not more than 0.15 mm.
Further, the seamless steel pipe is a multi-stage oil cylinder seamless steel pipe for a vehicle.
Further, the seamless steel pipe contains refined grain element Al; the surface of the seamless steel tube was free of visually observable cracks, folds, roll-offs, delamination, pits, and scarring.
The invention also relates to a manufacturing method of the seamless steel tube for the multistage oil cylinder, which comprises the following steps: step 1: mixing the raw materials and smelting to obtain molten iron; step 2: carrying out primary smelting on the molten iron to obtain primary-smelted molten steel; and step 3: carrying out external refining on the primarily refined molten steel to obtain refined molten steel; step 4: continuously casting the refined molten steel to obtain a continuously cast steel billet; and 5: piercing and rolling the continuous casting billet to obtain a hot-rolled seamless steel tube; step 6: and sequentially quenching and tempering the hot-rolled seamless steel pipe to obtain the seamless steel pipe for the multi-stage oil cylinder.
The method has the advantages that the method is simple to operate, high in safety, easy in parameter control and easy in scheme realization, and the produced seamless steel tube for the multistage oil cylinder is excellent in processing performance, high in safety and high in yield; meanwhile, the problems of large metal cutting amount, multiple processing procedures and long processing time in the processing process of the multi-stage oil cylinder are solved.
Further, the manufacturing method of the seamless steel tube for the multi-stage oil cylinder is characterized in that the smelting is blast furnace iron making, and the tapping temperature is 1890-1910 ℃; carrying out primary smelting by adopting an oxygen top-blown converter or an electric furnace, wherein the tapping temperature of the primary smelting is 1610-; performing the external refining by adopting VOD, wherein the external refining temperature is 1550-; the quenching process comprises the steps of heating the hot-rolled seamless pipe to 850-shaped sand 900 ℃ and preserving heat for 20 minutes, then carrying out water quenching to obtain a quenched pipe blank, and the tempering process comprises the steps of heating the quenched steel pipe to 600-shaped sand 650 ℃ and preserving heat for 90 minutes, and then carrying out water cooling to obtain the seamless steel pipe.
The further scheme has the beneficial effects that the argon blowing can be used for homogenizing the molten steel temperature and the molten steel components, so that the molten steel components can better meet the requirements; the quenching and tempering conditions are relatively warm, the quenching temperature is reduced, overheating is avoided, the structure of the quenched steel can be effectively controlled and optimized, the structure stress after quenching can be effectively reduced through high-temperature tempering, the elongation after fracture is improved, the tempering effect can be realized under the conditions, and a finished product with excellent properties can be obtained; the aluminum feeding in and out of the station can ensure that the amount of aluminum element meets the requirement; the seamless steel pipe manufactured by the method has good processing technology performance, and can meet the service performance of the DJG27SiMn seamless steel pipe for the medium-thin wall hot rolling quenched and tempered cylinder barrel and the plunger for the multistage oil cylinder with the wall thickness less than or equal to 15.5 mm.
Further, the tensile strength of the seamless steel tube obtained in the step 4 is 750-.
The further scheme has the beneficial effects that the product obtained by the method has good performance and is superior to other steel pipes for oil cylinders in the market.
Further, the method also comprises the step 7: inspecting the seamless steel tube in the step 6; the step 7 comprises the following steps: geometric dimension inspection, mechanical property inspection, non-metallic inclusion inspection, grain size inspection, full decarburization depth inspection, surface quality inspection and nondestructive inspection.
The beneficial effect of adopting the further scheme is that the inspection is necessary for ensuring that the produced seamless steel tube for the oil cylinder does not generate dark spots in the processing process of the multi-stage oil cylinder plunger and the sleeve and does not expand the cylinder in the using process of the multi-stage oil cylinder.
Compared with the prior art, this application seamless steel pipe for multi-stage cylinder, reached following effect:
(1) provided is a seamless steel tube for a multi-stage oil cylinder of a vehicle (including but not limited to a dump truck) and a machine. The vehicle comprises but is not limited to a self-discharging vehicle) and the multi-stage oil cylinder seamless steel tube for machinery is superior to the seamless steel tube for the hydraulic prop produced by the national standard of ferrous metallurgy of the people's republic of China GB/T7396 in performance.
(2) The seamless steel tube for the multi-stage oil cylinder of the vehicle (including but not limited to a dump truck) and the machinery produced by the method is provided. The problems of complex processing technology and high rejection rate in the production process of the multi-stage oil cylinder are solved.
(3) The seamless steel tube for the multistage oil cylinder has simple reprocessing steps in application, is suitable for large-scale production, and has good popularization value.
(4) The seamless steel tube for the multistage oil cylinder provided by the invention has the advantages of good safety performance and high yield.
(5) The manufacturing method of the seamless steel tube for the multistage oil cylinder provided by the invention has the advantages of mild implementation conditions, simplicity in operation, high safety, easiness in parameter control and easiness in implementation of a scheme. The produced seamless steel tube for the multi-stage oil cylinder has excellent processing performance, high safety and high yield.
(6) The manufacturing method of the seamless steel tube for the multistage oil cylinder provided by the invention improves the performance of the alloy steel tube under the condition of reasonable cost by establishing a strict geometric accuracy control range.
(7) The manufacturing method of the seamless steel tube for the multistage oil cylinder has strict inspection standards, can ensure that the produced steel tube has good quality, high safety and yield, excellent fatigue resistance and long service life.
Detailed Description
The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
Aiming at the processing characteristics of the multi-stage oil cylinder, the inventor redesigns the chemical component formula and reforms the heat treatment process for the seamless steel tube which is the raw material for manufacturing the multi-stage oil cylinder, thereby obtaining the novel seamless steel tube material.
Example 1
A seamless steel tube for a multistage oil cylinder comprises the chemical components of, by mass, 0.24% of C, 1.20% of Si, 1.20% of Mn, 0.015% of P, 0.010% of S, 0.025% of Al, 0.15% of Mo, 0.15% of Cr, 0.15% of Ni and 0.20% of Cu, and the balance of Fe.
The production of the seamless steel pipe for the oil cylinder comprises the following steps: step 1: mixing raw materials (including iron ore with the grade of 56% and coke) and smelting to obtain molten iron; the smelting is blast furnace smelting, and the tapping temperature is 1890 degree; step 2: carrying out primary smelting on the molten iron to obtain primary-smelted molten steel, and carrying out primary smelting by adopting an oxygen top-blown converter or an electric furnace, wherein the tapping temperature of the primary smelting is 1610 ℃, and the primary smelting time is 45 minutes; and step 3: carrying out external refining on the primarily refined molten steel to obtain refined molten steel, wherein the molten steel comprises, by mass, 0.24% of C, 1.20% of Si, 1.20% of Mn, 0.015% of P, 0.010% of S, 0.025% of Al, 0.15% of Mo, 0.15% of Cr, 0.15% of Ni and 0.20% of Cu, and the balance of Fe; adopting VOD to carry out external refining, wherein the external refining temperature is 1550 ℃, the external refining time is 50 minutes, argon is blown in the whole external refining process, the argon blowing amount is 7 liters/minute, aluminum is fed in and out of a station in the external refining process, the aluminum feeding amount in the station is 2 kilograms/ton of steel, and the aluminum feeding amount out of the station is 6 kilograms/ton of steel; and 4, step 4: continuously casting the refined molten steel to obtain a continuously cast steel billet; and 5: perforating and rolling the continuous casting steel billet (adopting PQF or MPM or other seamless steel tube continuous rolling mills for hot rolling) to obtain a hot-rolled seamless steel tube; step 6: sequentially quenching and tempering the hot-rolled seamless steel pipe to obtain a multi-stage seamless steel pipe for the oil cylinder; the quenching process comprises the steps of heating the hot-rolled seamless steel pipe to 850 ℃ and preserving heat for 20 minutes, and then carrying out water quenching to obtain a quenched pipe blank, and the tempering process comprises the steps of heating the quenched steel pipe to 600 ℃ and preserving heat for 90 minutes, and then carrying out water cooling to obtain the seamless steel pipe.
Example 2
A seamless steel tube for a multistage oil cylinder comprises the chemical components of, by mass, 0.28% of C, 1.29% of Si, 1.31% of Mn, 0.010% of P, 0.009% of S, 0.027% of Al, 0.04% of Mo, 0.08% of Cr, 0.06% of Ni and 0.09% of Cu, and the balance of Fe.
Step 1: mixing raw materials (comprising iron ore with the grade of 58% and coke) and smelting to obtain molten iron; the smelting is blast furnace smelting, and the tapping temperature is 1895 ℃; step 2: primarily smelting the molten iron to obtain primarily smelted molten steel, and primarily smelting by adopting an oxygen top-blown converter or an electric furnace, wherein the primary smelting temperature is 1640 ℃, and the primary smelting time is 50 minutes; and step 3: carrying out external refining on the primarily refined molten steel to obtain refined molten steel, wherein the molten steel comprises, by mass, 0.28% of C, 1.29% of Si, 1.31% of Mn, 0.010% of P, 0.009% of S, 0.027% of Al, 0.04% of Mo, 0.08% of Cr, 0.06% of Ni and 0.09% of Cu, and the balance of Fe; adopting VOD to carry out external refining, wherein the external refining temperature is 1560 ℃, the external refining time is 55 minutes, argon is blown in the whole external refining process, the argon blowing amount is 7.5 liters/minute, aluminum is fed in and out of a station in the external refining process, the aluminum feeding amount in the station is 2 kilograms/ton steel, and the aluminum feeding amount out of the station is 6 kilograms/ton steel; and 4, step 4: continuously casting the refined molten steel to obtain a continuously cast steel billet; and 5: perforating and rolling the continuous casting billet (adopting PQF or MPM or other seamless steel tube continuous rolling units for hot rolling) to obtain a hot-rolled seamless steel tube; step 6: sequentially quenching and tempering the hot-rolled seamless steel pipe to obtain a seamless steel pipe for the multi-stage oil cylinder; the quenching process comprises the steps of heating the hot-rolled seamless steel pipe to 870 ℃ and preserving heat for 20 minutes, and then carrying out water quenching to obtain a quenched pipe blank, and the tempering process comprises the steps of heating the quenched steel pipe to 625 ℃ and preserving heat for 90 minutes, and then carrying out water cooling to obtain the seamless steel pipe.
Example 3
A seamless steel tube for a multistage oil cylinder comprises the chemical components of, by mass, 0.30% of C, 1.40% of Si, 1.40% of Mn, 0.013% of P, 0.008% of S, 0.055% of Al, 0.03% of Mo, 0.04% of Cr, 0.03% of Ni and 0.08% of Cu, and the balance of Fe.
Step 1: mixing raw materials (including iron ore with the grade of 63% and coke) and smelting to obtain molten iron; smelting is blast furnace ironmaking, and the tapping temperature is 1910 ℃; step 2: carrying out primary smelting on the molten iron to obtain primary-smelted molten steel, and carrying out primary smelting by adopting an oxygen top-blown converter or an electric furnace, wherein the primary smelting temperature is 1670 ℃, and the primary smelting time is 60 minutes; and step 3: carrying out external refining on the primarily refined molten steel to obtain refined molten steel, wherein the molten steel comprises, by mass, 0.30% of C, 1.40% of Si, 1.40% of Mn, 0.013% of P, 0.008% of S, 0.055% of Al, 0.03% of Mo, 0.04% of Cr, 0.03% of Ni and 0.08% of Cu, and the balance of Fe; adopting VOD to carry out external refining, wherein the external refining temperature is 1590 ℃, the external refining time is 60 minutes, argon is blown in the whole external refining process, the argon blowing amount is 8 liters/minute, aluminum is fed in and out of a station in the external refining process, the aluminum feeding amount in the station is 2 kilograms/ton of steel, and the aluminum feeding amount out of the station is 6 kilograms/ton of steel; and 4, step 4: continuously casting the refined molten steel to obtain a continuously cast steel billet; and 5: perforating and rolling the continuous casting billet (adopting PQF or MPM or other seamless steel tube continuous rolling units for hot rolling) to obtain a hot-rolled seamless steel tube; step 6: sequentially quenching and tempering the hot-rolled seamless steel pipe to obtain a seamless steel pipe for the multi-stage oil cylinder; the quenching process comprises the steps of heating the hot-rolled seamless steel pipe to 900 ℃ and preserving heat for 20 minutes, and then carrying out water quenching to obtain a quenched pipe blank, and the tempering process comprises the steps of heating the quenched steel pipe to 650 ℃ and preserving heat for 90 minutes, and then carrying out water cooling to obtain the seamless steel pipe.
Example 4
A seamless steel tube for a multistage oil cylinder comprises, by mass, 0.27% of C, 1.31% of Si, 1.29% of Mn, 0.012% of P, 0.006% of S, 0.037% of Al, 0.008% of Mo, 0.006% of Cr, 0.002% of Ni and 0.009% of Cu, and the balance of Fe.
Step 1: mixing raw materials (comprising iron ore with the grade of 60% and coke) and smelting to obtain molten iron; the smelting is blast furnace ironmaking, and the tapping temperature is 1900 ℃; step 2: primarily smelting the molten iron to obtain primarily smelted molten steel, and primarily smelting by adopting an oxygen top-blown converter or an electric furnace, wherein the primary smelting temperature is 1660 ℃, and the primary smelting time is 55 minutes; and step 3: performing furnace external refining on the primarily refined molten steel to obtain refined molten steel, wherein the molten steel comprises, by mass, 0.27% of C, 1.31% of Si, 1.29% of Mn, 0.012% of P, 0.006% of S, 0.037% of Al, 0.008% of Mo, 0.006% of Cr, 0.002% of Ni and 0.009% of Cu, and the balance of Fe; adopting VOD to carry out external refining, wherein the external refining temperature is 1580 ℃, the external refining time is 58 minutes, argon is blown in the whole external refining process, the argon blowing amount is 7.5 liters/minute, aluminum is fed in and out of a station in the external refining process, the aluminum feeding amount in the station is 2 kilograms/ton steel, and the aluminum feeding amount out of the station is 6 kilograms/ton steel; and 4, step 4: continuously casting the refined molten steel to obtain a continuously cast steel billet; and 5: perforating and rolling the continuous casting billet (adopting PQF or MPM or other seamless steel tube continuous rolling units for hot rolling) to obtain a hot-rolled seamless steel tube; step 6: sequentially quenching and tempering the hot-rolled seamless steel pipe to obtain a seamless steel pipe for the multi-stage oil cylinder; the quenching process comprises the steps of heating the hot-rolled seamless steel pipe to 880 ℃, preserving heat for 20 minutes, and then carrying out water quenching to obtain a quenched pipe blank, and the tempering process comprises the steps of heating the quenched steel pipe to 640 ℃, preserving heat for 90 minutes, and then carrying out water cooling to obtain the seamless steel pipe.
Through the matching of the raw materials and the parameters in the embodiment, the steel pipe with corresponding content can be obtained.
TABLE 1 test results of examples 1 to 4
The invention realizes the guarantee of the components of the seamless steel tube for the multi-stage oil cylinder by limiting carbon, manganese, silicon (reducing the component range), low phosphorus and sulfur, adding aluminum and controlling residual elements and five-harmful elements on the basis of GB/T17396. Element control is higher than YB/T4203 as a whole. The method has the advantages of mild implementation conditions, simple operation, high safety, easy parameter control and easy realization of the scheme. The produced seamless steel tube for the multi-stage oil cylinder has excellent processing performance, high safety and high yield, and the performance detection result shows that the performance of the seamless steel tube for the multi-stage oil cylinder is superior to that of the seamless steel tube for the common oil cylinder in the world in all aspects. In the present invention, the most preferable examples are example 2 and example 4, all of which are based on the combination of the properties.
The steel pipe of the invention comprises the following components:
0.24-0.30% of C, and carbon is a carbide forming element, so that the strength of the steel can be improved, the effect is not obvious when the steel is too low, the toughness of the steel can be greatly reduced when the steel is too high, the strength index can not be ensured when the content is lower than 0.24% in the multi-stage oil cylinder pipe, and the plasticity index can not be ensured when the content is higher than 0.32%.
Si 1.20-1.40%, and Si can raise the strength, wear resistance and oxidation resistance of steel, but the toughness and plasticity of steel decrease with the increase of its content.
1.20 to 1.40 percent of Mn and manganese as an austenite forming element, can improve the hardenability and strength of steel, increase the residual austenite amount in the steel, influence the uniformity of hot rolling structure and increase the rust resistance of the steel. The carbon equivalent is seriously influenced by over-low or over-high of the seamless steel pipe for the multistage oil cylinder, so that the machinability of the steel pipe for the multistage oil cylinder is influenced.
P is less than or equal to 0.015 percent, phosphorus obviously improves the strength and the hardness of the steel, but reduces the plasticity and the toughness, particularly improves the brittle transition temperature and the cold brittleness of the steel, and is related to a plurality of cracks generated in the using process of the multi-stage oil cylinder.
S is less than or equal to 0.010 percent, sulfur can improve the machinability of steel, but the hot brittleness of steel is increased, the strength and the toughness of the steel are reduced, the brittleness is increased, the content in the steel is better, and more cracks are generated in the processing process of the seamless steel pipe for the multi-stage oil cylinder.
Al is more than or equal to 0.025 percent and less than or equal to 0.055 percent, the aluminum has the functions of refining grains and improving the oxidation resistance of steel, the effect of refining the grains is smaller when the content is lower, the high temperature strength and toughness of the steel can be reduced, and the seamless steel pipe for the multistage oil cylinder contains a proper amount of aluminum, so that the processing performance of the steel can be obviously improved.
Mo is less than or equal to 0.15 percent, the molybdenum mainly improves the strength and the hardenability of the steel through carbides and solid solution strengthening forms, the toughness of the steel is reduced due to the excessively high content of the molybdenum, the graphitization tendency of the alloy molybdenum steel is caused, and the less the molybdenum is, the better the molybdenum is, the more the molybdenum is, the limitation is carried out according to residual elements.
Cr is less than or equal to 0.15 percent, and the chromium can improve the mechanical property, the corrosion resistance and the hardenability of the steel, but increases the temper brittleness of the steel. The seamless steel tube for the multi-stage oil cylinder is preferably less, and the control is performed according to residual elements.
Ni is less than or equal to 0.15 percent, the Ni mainly improves the obdurability of the steel, improves the corrosion resistance and the processing performance of the steel, and reduces the brittle transition temperature of the steel, and the seamless steel tube for the multistage oil cylinder is more preferable, and is limited according to residual elements.
Cu is less than or equal to 0.20 percent, the strength and the atmospheric corrosion resistance of the steel can be improved by the copper in the alloy steel, and the steel becomes brittle by the excessive addition. The seamless steel pipe for the multi-stage oil cylinder is preferably less, and is limited according to residual elements.
According to the inventor's experience in production practice:
the Al element is creatively added into the seamless steel pipe for the multistage oil cylinder, the content of the Al element is controlled within a certain range, in the prior art, the Al element is used as a deoxidizer instead of being used as an additive of the component, and in the prior knowledge, if the Al element is added, the Al element becomes B-type impurities, sharp-angled and string-shaped inclusions occur, so that cracks occur, and the condition of high rejection rate is easy to occur. The invention adds Al and controls in a proper range, which can play a role of refining crystal grains, overcomes the technical bias in the field, and makes the combination of all components better after the crystal grains are refined, thereby obviously improving the strength, plasticity and shock resistance of steel materials, so that the steel materials can reach the steel pipes meeting the standard without thick and heavy steel pipes, namely thin-walled steel pipes with excellent performance can be produced, on one hand, the material consumption is less, the cost is greatly saved, on the other hand, the effect of weight reduction is realized, the produced vehicle can be pulled more and run faster, and in addition, the problems of the cylinder being not wear-resistant and the hydraulic oil leakage caused by unqualified inner surface dark spots (inclusions exposed) generated in the traditional cylinder processing process can be avoided. The elements of the existing refined crystal grains are Nb, V and Ti, and compared with the Al element added in the invention, the elements have the safety problems of difficult processing, cylinder explosion and cylinder expansion caused by high price and high hardness of the refined material. That is, the components of the present invention reduce the production cost of the steel pipe, realize the weight reduction of the vehicle, thereby having the effect brought by this and greatly improving the safety factor.
The content of P and S is reduced, the condition that the cylinder is easily exploded when the material is applied under the low-temperature condition in the prior art is reduced, the content of P and S is reduced, Al is added, the P and S content, the Al and the Al are cooperated to improve the plasticity and the impact resistance, the low-temperature performance of the oil cylinder is improved, particularly in winter, the driving temperature of a vehicle can sometimes reach-60 ℃, and the oil cylinder can still ensure the plasticity and the impact resistance without safety problems such as cylinder explosion and the like.
The reduction of the range of the components of silicon and manganese is beneficial to improving the stability of the performance after quenching and tempering.
The quenching temperature is reduced, overheating is avoided, the steel tissue after quenching can be effectively controlled and optimized, the tissue stress after quenching can be effectively reduced by high-temperature tempering, and the elongation after fracture is improved.
All the materials are delivered in a hardened and tempered state, so that the problems of large metal cutting amount, multiple processing procedures, long processing time and the like in the processing process of the multi-stage oil cylinder can be effectively solved; all adopt the quenching and tempering state to deliver, the inner surface of the sleeve is not processed, and the problem of waste products caused by dark spots and the like generated on the inner surface of the sleeve can be effectively solved.
The invention provides a comparison result of a multi-stage oil cylinder and a hydraulic prop:
TABLE 2 Multi-stage Cylinder to Hydraulic strut comparison
Table 3 comparison of chemical compositions of the multi-stage oil cylinder and GB/17396-
As can be seen from comparison, the components of the invention are added with aluminum (Al), carbon (C), silicon (Si), manganese (Mn) and phosphorus (P) and sulfur (S).
Table 4 comparison of the heat treatment system of the multi-stage oil cylinder of the present invention with that of GB/17396-
As can be seen from the comparison, the invention adopts the measures of reducing the quenching temperature, increasing the tempering temperature, changing the cooling medium and the like, and simultaneously adopts the quenching and tempering state to deliver
TABLE 5 comparison of the Performance of the multi-stage cylinder of the present invention with that of the GB/17396-2018 hydraulic prop
As can be seen from comparison, the seamless steel tube for the multi-stage oil cylinder provided by the invention has the advantages that the strength indexes (tensile strength and yield strength) meet the use performance, and meanwhile, the plasticity index (elongation after fracture) is improved so as to increase the safety. And the strength indexes (tensile strength and yield strength) can better meet the processing performance of the multi-stage cylinder steel pipe.
1. The following method is adopted for the inspection:
(1) the size and the shape of the steel pipe are measured one by adopting a measuring tool meeting the precision requirement.
(2) The inner and outer surfaces of the steel pipe should be visually inspected one by one under sufficient lighting conditions.
(3) Other test items, the number of samples and the test method of the steel pipe should meet the specifications of table 1.
2. The test standards meet the following specifications:
(1) the geometric dimension precision test comprises the following steps:
a. the geometric dimensional accuracy check includes the table 2 specifications,
b. out-of-roundness and wall thickness non-uniformity: respectively not more than 80% of the tolerance of the outer diameter
c. Curvature: the bending degree of the steel pipe is not more than 1.2mm/m
d. Length: the specific length of the steel pipe is in accordance with the contract, and the allowable deviation of the fixed length is 0-+30mm
(2) And (4) mechanical property inspection, namely, the longitudinal mechanical property measured by a sample prepared from the steel pipe after heat treatment.
TABLE 1 sampling and testing methods for steel pipes
| Serial number | Inspection item | Test method | Sampling method | Number of samples taken |
| 1 | Size of | Caliper and micrometer | Whole steel material | One by one |
| 2 | Surface of | Visualization | Whole steel material | One by one |
| 3 | Smelting composition | GB/T 223 GB/T 4336 | GB/T 20066 | Taking 1 sample per furnace (tank) |
| 4 | Finished ingredients | GB/T4336 | Different ones can be taken at will | 2 pieces/batch |
| 5 | Tensile test | GB/T 228.1 | GB/T 2975 | One sample is taken from each batch of two steel pipes |
| 6 | Impact test | GB/T 229 | GB/T 2975 | Each batch of 3 samples are taken from two steel pipes |
| 7 | Non-metallic inclusions | GB/T 10561 | GB/T10561 | One sample is taken from each batch of two steel pipes |
| 8 | Decarburized layer | GB/T 224 | GB/T 224 | One sample is taken from each batch of two steel pipes |
| 9 | Grain size | GB/T 6394 | GB/T 6394 | One sample is taken from each batch of two steel pipes |
| 10 | Ultrasonic flaw detection | GB/T 5777 | Whole steel material | Root by root |
| 11 | Magnetic leakage flaw detection | GB/T 12606 | Whole steel material | Root by root |
| 12 | Eddy current flaw detection | GB/T 7735 | Whole steel material | Root by root |
TABLE 2 tolerance of outside diameter and wall thickness
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A seamless steel tube for a multistage oil cylinder is characterized in that the chemical components of the seamless steel tube comprise, by mass, 0.24-0.30% of C, 1.20-1.40% of Si, 1.20-1.40% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.025-0.055% of Al, less than or equal to 0.15% of Mo, less than or equal to 0.15% of Cr, less than or equal to 0.15% of Ni, less than or equal to 0.20% of Cu, and the balance of Fe.
2. The seamless steel tube for the multistage cylinder according to claim 1, wherein the seamless steel tube comprises, by mass, 0.28% of C, 1.29% of Si, 1.31% of Mn, 0.010% of P, 0.009% of S, 0.027% of Al, 0.04% of Mo, 0.08% of Cr, 0.06% of Ni, 0.09% of Cu, and the balance of Fe.
3. The seamless steel tube for the multistage cylinder according to claim 1, wherein the seamless steel tube comprises, by mass, 0.27% of C, 1.31% of Si, 1.29% of Mn, 0.012% of P, 0.006% of S, 0.037% of Al, 0.008% of Mo, 0.006% of Cr, 0.002% of Ni, and 0.009% of Cu, with the balance being Fe.
4. The seamless steel tube for the multistage oil cylinder as claimed in claim 1, wherein the non-roundness of the seamless steel tube is not more than the outer diameter, the wall thickness non-uniformity is not more than 80% of the wall thickness tolerance, the allowable deviation of the length at length is 0-30mm, the bending degree is not more than 1.5mm/m, the grain size is not less than 7 grades, and the depth of the decarburized layer is not more than 0.15 mm.
5. The seamless steel tube for a multistage cylinder according to claim 1, wherein the seamless steel tube is a seamless steel tube for a multistage cylinder for a vehicle.
6. The seamless steel tube for the multistage oil cylinder according to claim 1, wherein the seamless steel tube contains refined grain element Al; the surface of the seamless steel tube was free of visually observable cracks, folds, roll-offs, delamination, pits, and scarring.
7. A method for manufacturing a seamless steel tube for a multi-stage cylinder according to any one of claims 1 to 6, comprising the steps of:
step 1: mixing the raw materials and smelting to obtain molten iron;
step 2: carrying out primary smelting on the molten iron to obtain primary-smelted molten steel;
and step 3: carrying out external refining on the primarily refined molten steel to obtain refined molten steel;
and 4, step 4: continuously casting the refined molten steel to obtain a continuously cast steel billet;
and 5: piercing and rolling the continuous casting billet to obtain a hot-rolled seamless steel tube;
step 6: and sequentially quenching and tempering the hot-rolled seamless steel pipe to obtain the seamless steel pipe for the multi-stage oil cylinder.
8. The method for manufacturing the seamless steel tube for the multi-stage oil cylinder as claimed in claim 7, wherein the smelting is blast furnace ironmaking, and the tapping temperature is 1890-1910 ℃; carrying out primary smelting by adopting an oxygen top-blown converter or an electric furnace, wherein the tapping temperature of the primary smelting is 1610-; performing the external refining by adopting VOD, wherein the external refining temperature is 1550-; the quenching process comprises the steps of heating the hot-rolled seamless steel pipe to 850-shaped sand 900 ℃ and preserving heat for 20 minutes, then carrying out water quenching to obtain a quenched pipe blank, and the tempering process comprises the steps of heating the quenched steel pipe to 600-shaped sand 650 ℃ and preserving heat for 90 minutes, and then carrying out water cooling to obtain the seamless steel pipe.
9. The method as claimed in claim 7, wherein the seamless steel tube obtained in step 6 has a tensile strength of 750-.
10. The manufacturing method of the seamless steel tube for the multistage cylinder according to claim 7, further comprising the step of 7: inspecting the seamless steel tube in the step 6; the step 7 comprises the following steps: geometric dimension inspection, mechanical property inspection, non-metallic inclusion inspection, grain size inspection, full decarburization depth inspection, surface quality inspection and nondestructive inspection.
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| CN201911215612.1A CN111304529A (en) | 2019-12-02 | 2019-12-02 | Seamless steel tube for multi-stage oil cylinder and manufacturing method thereof |
| RU2020138422A RU2758739C1 (en) | 2019-12-02 | 2020-11-24 | Seamless steel pipe for multistage oil cylinder and its manufacturing method |
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