CN109423580B - Steel pipe for automobile hollow stabilizer bar and manufacturing method thereof - Google Patents
Steel pipe for automobile hollow stabilizer bar and manufacturing method thereof Download PDFInfo
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- CN109423580B CN109423580B CN201710761716.7A CN201710761716A CN109423580B CN 109423580 B CN109423580 B CN 109423580B CN 201710761716 A CN201710761716 A CN 201710761716A CN 109423580 B CN109423580 B CN 109423580B
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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
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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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
- 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
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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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
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- Vehicle Body Suspensions (AREA)
Abstract
A steel pipe for an automobile hollow stabilizer bar and a manufacturing method thereof are disclosed, wherein the steel pipe comprises the following chemical components in percentage by mass: c: 0.28-0.40%, Si: 0.05 to 0.35%, Mn: 1.05 to 1.60%, Mo: 0.1-0.6%, B: 0.001-0.006%, Al: 0.015-0.060%, Cr: 0.1-0.8%, Ti: 0.003-0.06 percent of S, less than or equal to 0.006 percent of P, less than or equal to 0.015 percent of P, less than or equal to 0.003 percent of O, and the following requirements are met: mo +50B + Cr is more than or equal to 0.7 percent and less than or equal to 1.3 percent, and the balance is Fe and other inevitable impurities. The steel pipe has good strength and plasticity, has high anti-torsion fatigue performance under a larger stress level, can meet the use requirement of a stabilizer bar under a large stress condition, and has the following specific performance indexes: the quenching tensile strength is more than or equal to 1700MPa, the quenching yield strength is more than or equal to 1300MPa, the quenching elongation is more than or equal to 12 percent, the depth of the inner and outer surface decarburized layers is 0, and the torsional fatigue frequency is more than 120 ten thousand times under the condition of 550MPa stress.
Description
Technical Field
The invention relates to a steel pipe for an automobile hollow stabilizer bar and a manufacturing method thereof.
Background
The stabilizer bar for the transmission shaft of the automobile is an auxiliary elastic element in an automobile suspension system, and the stabilizer bar has the function of preventing the automobile body from generating overlarge transverse rolling during turning, keeping the automobile body balanced as much as possible and aiming at reducing the transverse rolling degree of the automobile and improving the smoothness. The stabilizer bar is in fact a torsion bar spring lying transversely and can be considered functionally as a special elastic element. When the vehicle body only moves vertically, the suspensions on the two sides deform the same, and the transverse stabilizer bar does not work. When the automobile turns, the automobile body inclines, the suspensions on the two sides jump inconsistently, the suspensions on the outer sides press the stabilizer bars, the stabilizer bars are twisted, and the elastic force of the rod bodies can prevent the wheels from being lifted, so that the automobile body is kept balanced as much as possible, and the transverse stabilizing effect is achieved.
The conventional stabilizer bars are all produced by adopting solid bars, and in recent years, the requirements for energy conservation and emission reduction are increasingly strengthened due to the light weight of the car body. The stabilizer bar mainly bears the rotation torque in the use, and when the stabilizer bar is stressed, the farther away from the circle center, the larger the rotation torque borne by the stabilizer bar, and the zero torsion torque borne by the stabilizer bar at the circle center, so that the transmission shaft is replaced by a solid bar material through a hollow steel pipe, the weight of a vehicle body can be greatly reduced, and the use of the vehicle body cannot be greatly influenced.
According to the using conditions of the stabilizer bar, the stabilizer bar is generally designed with higher strength, and meanwhile, in order to ensure the anti-torsion fatigue performance of the stabilizer bar, the dimensional precision of the product, the quality of the inner surface and the outer surface, the decarburization condition of the inner surface and the outer surface and the like need to be controlled. Therefore, the steel pipe product for the stabilizer bar is generally produced by adopting a small-caliber welded pipe and cold machining mode.
Chinese patent CN104395487A discloses a steel tube for a hollow stabilizer bar, the tube for a hollow stabilizer bar designed by the stabilizer bar has better fatigue performance, but more alloy elements are added, the manufacturing cost of the product is higher, and the torsional fatigue performance of the product cannot meet the requirement of the tube for a hollow stabilizer bar with higher stress.
Disclosure of Invention
The steel pipe for the stabilizer bar has the quenching tensile strength of not less than 1700MPa, the quenching yield strength of not less than 1300MPa, the quenching elongation of not less than 12 percent, the depth of inner and outer surface decarburized layers of 0 and the torsional fatigue times of more than 120 ten thousand times under the condition of 550MPa stress. The steel pipe for the stabilizer bar has good strong plasticity, has high anti-torsion fatigue performance under a larger stress level, and can meet the use requirement of the stabilizer bar under a large stress condition.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the steel for the automobile hollow stabilizer bar comprises the following chemical components in percentage by mass: c: 0.28-0.40%, Si: 0.05 to 0.35%, Mn: 1.05 to 1.60%, Mo: 0.1-0.6%, B: 0.001-0.006%, Al: 0.015-0.060%, Cr: 0.1-0.8%, Ti: 0.003-0.06 percent of S, less than or equal to 0.006 percent of P, less than or equal to 0.015 percent of P, less than or equal to 0.0030 percent of O, and the following relations are satisfied at the same time: mo +50B + Cr is more than or equal to 0.7 percent and less than or equal to 1.3 percent, and the balance is Fe and other inevitable impurities.
Preferably, the steel for the automotive hollow stabilizer bar comprises the following components: 0.28 to 0.35 percent.
Preferably, the steel for the automotive hollow stabilizer bar comprises the following components: 0.1 to 0.3 percent.
Further, the microstructure of the steel for the automotive hollow stabilizer bar is a ferrite pearlite structure and a dispersion carbide structure.
The invention also provides a steel pipe made of the steel for the automobile hollow stabilizer bar, and the steel pipe for the automobile hollow stabilizer bar comprises the following chemical components in percentage by mass: c: 0.28-0.40%, Si: 0.05 to 0.35%, Mn: 1.05 to 1.60%, Mo: 0.1-0.6%, B: 0.001-0.006%, Al: 0.015-0.060%, Cr: 0.1-0.8%, Ti: 0.003-0.06 percent of the total weight of the alloy, less than or equal to 0.006 percent of S, less than or equal to 0.015 percent of P, less than or equal to 0.0030 percent of O, and the elements simultaneously satisfy the following relations: mo +50B + Cr is more than or equal to 0.7 percent and less than or equal to 1.3 percent, and the balance is Fe and other inevitable impurities.
Preferably, in the steel pipe composition for an automotive hollow stabilizer bar, C: 0.28 to 0.35 percent.
Preferably, in the steel pipe composition for an automotive hollow stabilizer bar, Si: 0.1 to 0.3 percent.
Preferably, the wall thickness of the steel pipe for the automotive hollow stabilizer bar is 1.5-8 mm.
Preferably, the outer diameter of the steel pipe for the hollow stabilizer bar is 15 to 50 mm.
Further, the microstructure of the steel pipe for the automobile hollow stabilizer bar is a ferrite pearlite structure and a dispersion carbide structure, the inner surface and the outer surface of the steel pipe are in a bright state, decarburized structures are not arranged on the inner surface and the outer surface, the metal flow direction in the microstructure of the welding line part is clear, and the metal flow direction of the welding line is not perpendicular to the inner surface and the outer surface.
The steel pipe for the automobile hollow stabilizer bar has the quenching tensile strength of more than or equal to 1700MPa, the quenching yield strength of more than or equal to 1300MPa, the quenching elongation of more than or equal to 12 percent, the depth of the inner and outer surface decarburized layers of 0, and the torsional fatigue times of more than 120 ten thousand times under the condition of 550MPa stress.
In the composition design of the steel of the invention:
c: the element C is one of main elements for improving the strength of the steel, is mainly used for solving the strength of the hollow stabilizer bar, can effectively improve the strength of the steel through the formation of carbide, and has low addition cost. In order to achieve a high finished strength with a small addition of alloying elements, the lower limit of the C content is set to 0.28%, and when the C content exceeds 0.40%, there is a problem that quench cracks are generated at the weld portion. Therefore, the C content in the present invention is controlled to be 0.28 to 0.40%, preferably 0.28 to 0.35%.
Si: si element is added as a reducing agent and a deoxidizer in a steel-making process, does not form carbide in steel, has a high solid solubility in steel, and can strengthen ferrite in steel to improve the strength of steel, so that the present steel suitably increases Si content to improve the strength of steel in a quenched state. Therefore, when the lower limit of the Si content is 0.05% and the Si content exceeds 0.35%, the toughness of the steel pipe is lowered. Therefore, the Si content in the present invention is controlled to 0.05% to 0.35%, preferably 0.1 to 0.3%.
Mn: mn is an important alloying element and a weak carbide-forming element. Mn mainly improves the strength of steel through solid solution strengthening, and the addition of Mn content can effectively increase the hardenability of steel, and is an important guarantee for ensuring that the finished steel pipe has high strength. Therefore, the lower limit of the Mn content is set to 1.05%, but if the Mn content exceeds 1.6%, the plasticity and impact toughness of the steel are remarkably reduced, which adversely affects the torsional fatigue resistance of the finished steel pipe, and therefore, the Mn content is controlled to 1.05-1.6% in the present invention.
Mo: mo has the effects of solid solution strengthening and improving the hardenability of steel, and because the steel needs to achieve high tensile strength and plasticity after quenching, the steel has the remarkable effects of solid solution strengthening and improving the hardenability when the Mo content reaches 0.1%, so that the lower limit of the Mo content is set to be 0.1%. When the Mo content is too large, the plasticity of the steel pipe is adversely affected. Meanwhile, cost factors are also considered, so that the Mo content is controlled to be 0.1-0.6% in the invention.
B: b has a remarkable effect of improving the hardenability of steel, B with the content of more than 0.001 percent has a remarkable effect of increasing the hardenability and strength, and the hardenability of the steel can be remarkably increased by compounding B and Mo, but the B content once exceeding 0.006 percent has an influence on the toughness of the steel pipe, and the B is controlled to be 0.001-0.006 percent in the invention by considering the factor of addition cost.
Al: al has a deoxidizing effect in steel and it contributes to improving the plasticity, toughness and workability of steel. When the Al content reaches more than 0.015 percent, the effect of improving the plasticity, the toughness and the processability of the steel is obvious, but when the Al content exceeds 0.06 percent, sulfide inclusions in the steel are increased, and the torsional fatigue resistance of the steel pipe is greatly influenced. Therefore, the invention controls the Al content to be 0.015-0.06%.
Cr: cr is a medium-strength carbide-forming element. Part of Cr in the steel is replaced by iron to form alloy cementite so as to improve the stability of the alloy cementite, and the other part of Cr is dissolved in ferrite to play a role in solid solution strengthening so as to improve the strength and hardness of the ferrite. Meanwhile, Cr is also a main element for improving the hardenability of steel. When the Cr content exceeds 0.8%, the plasticity and toughness of the steel pipe base and the weld joint portion are greatly affected, so the upper limit of the Cr content is selected to be 0.8%. Therefore, the Cr content in the present invention is controlled to be 0.1 to 0.8%.
Ti: ti is a strong nitride forming element and forms a TiN compound with N in the steel, thereby suppressing precipitation of brittle BN in the steel due to addition of B element, improving toughness and plasticity of the steel, and the Ti content is controlled to 0.003-0.06% in consideration of the alloy addition cost in the present invention.
The inevitable impurities in the technical scheme of the invention are mainly S and P elements, and particularly the increase of the S content has great influence on the sulfide content in the steel, so that the S content is controlled to be below 0.006 percent and the P content is controlled to be below 0.015 percent as much as possible. Meanwhile, the O content in the steel has a large influence on oxide inclusions in the steel, so the O content is controlled to be less than 0.0030%.
The steel and the steel pipe for the automobile hollow stabilizer bar do not contain Ca, Mg or rare earth metal and other additive elements with higher cost, C, Mn is used as a main strengthening element through the optimized design of chemical components, and the combination addition of Mo, B and Cr is controlled by limiting Mo +50B + Cr to be more than or equal to 0.7% and less than or equal to 1.3%, so that the hardenability of a product is ensured, the high-strength requirement can be met after a finished product is subjected to a heat treatment process of quenching and tempering in the machining process, and simultaneously, the reduction of steel plasticity caused by over-high addition of alloy elements and cold bending cracks easily generated during the subsequent cold bending forming of the steel pipe can be avoided. Meanwhile, the Ti element is added to improve the strong plasticity of the steel and ensure the cold-bending forming performance of the product and the anti-torsion fatigue performance of the finished product. Furthermore, the toughness of the steel is improved by controlling P, S, O and other elements in the steel, and the final torsion fatigue resistance of the product is ensured.
The invention also provides a manufacturing method of the steel pipe for the automobile hollow stabilizer bar, which comprises the following steps:
(1) smelting and casting according to the proportion of the chemical components, and rolling into a coil, wherein the coiling temperature of the coil is controlled to be 780-900 ℃;
(2) uncoiling and slitting shearing are carried out on the plate coil;
(3) forming and welding the plate coil after splitting, removing burrs on the inner surface and the outer surface after welding, and carrying out heat treatment on the weld joint, wherein the heat treatment temperature is 550-800 ℃;
(4) acid washing, phosphorization and saponification;
(5) cold working to finished product size: cold working in multiple passes is carried out in a cold drawing or cold rolling mode, intermediate heat treatment is carried out between two adjacent cold working passes, the temperature of the intermediate heat treatment is 500-700 ℃, and the heat preservation time is 30-60 min;
(6) and carrying out heat treatment on the finished product in a reducing atmosphere furnace with controllable atmosphere, wherein the heat treatment temperature is 700-930 ℃.
Further, in the step (1), the yield strength of the coil is controlled to be 280-380MPa, and the tensile strength is controlled to be 550-700MPa, so as to ensure the forming performance of the coil and ensure the final strength of the product.
In the step (3), the heat treatment of the welding seam adopts on-line induction heating treatment, the heat treatment temperature is 550-800 ℃, so as to eliminate the internal stress of the welding seam structure after the plate coil is formed and welded, ensure that the hardness and the strength of the welding seam and a heat affected zone are consistent with those of the base material, and prevent cracks from being generated at the welding seam in the subsequent cold bending forming process.
In the step (5), the elongation coefficient of each cold working pass is 1.3-1.8, so that the best cold formability of the product is ensured, the deformation of each cold working pass is maximized, the manufacturing efficiency is improved, the cost is reduced, and the defects of cracking and the like of the steel pipe after cold working are avoided. An intermediate heat treatment process of heat preservation at the temperature of 500-700 ℃ for 30-60min is adopted between cold working of each pass to eliminate the processing stress, so that the steel pipe is softened, and the best cold forming performance is ensured in the cold working process of the steel pipe.
In the step (6), the heat treatment temperature of the finished product is 700-930 ℃, and the heat treatment atmosphere in the reducing atmosphere furnace contains reducing gas H2Or CO, reducing gas H2Or the volume percentage content of CO is 15-40%, the surface of the steel pipe is ensured to be in a bright state, and the decarburization of the inner surface and the outer surface is prevented in the heating process.
The invention ensures the strength and plasticity of the finished steel pipe by the composite addition of the relatively low-cost alloy elements C, Mn, Mo, Cr and B, and simultaneously controls the temperature of welding seam heat treatment of 550-800 ℃, the intermediate heat treatment temperature of 500-700 ℃ in the cold working process, the final heat treatment temperature of 700-930 ℃ and the reducing protective atmosphere to ensure that no decarburized structure exists in the structure of the finished steel pipe, and the inner and outer surfaces of the steel pipe are in a bright state. The invention not only ensures the production efficiency of manufacturing the steel pipe, but also effectively avoids the cracking of the steel pipe by controlling the heat treatment system of the welding seam after welding forming and the elongation coefficient of each cold working.
The microstructure of the steel pipe for the stabilizer bar is a ferrite plus pearlite structure and a carbide structure which is dispersed, so that the strong plasticity of the product is ensured, and a basic guarantee is provided for the high torsional fatigue resistance of the product; the inner surface and the outer surface of the steel pipe are in a bright state, the inner surface and the outer surface of the steel pipe are free of decarburized structures, the surface is free of weak and easily-broken links in the torsional fatigue process, the metal flow direction in the microstructure of the welding line part is clear, and the metal flow direction of the welding line is not perpendicular to the inner surface and the outer surface, so that the welding line part is not a fracture source in the torsional fatigue process, and the whole product has high torsional fatigue resistance.
The invention has the beneficial effects that:
1) the steel pipe for the automobile hollow stabilizer bar improves the hardenability of the steel mainly through the composite addition of Mn, Ti and a small amount of Cr, Mo and B elements, achieves the purposes of high strength and plasticity and high torsion fatigue resistance, does not contain noble metal elements, and has lower cost of raw materials of the product.
2) The steel pipe for the automobile hollow stabilizer bar takes C, Mn as a main strengthening element, controls Mo +50B + Cr to be more than or equal to 0.7% and less than or equal to 1.3% to improve the hardenability of the steel pipe and ensure that the steel pipe has high strength after being processed, and also adds 0.003-0.06% of Ti to improve the plasticity of the steel, and ensures that the steel pipe has high strength and high plasticity in a quenching state through the optimized control of a manufacturing process so as to further obtain high torsion fatigue resistance.
3) The steel pipe for the automobile hollow stabilizer bar prepared by the invention has higher strength and plasticity and good anti-torsion fatigue performance, and the specific performance indexes are as follows: the quenching tensile strength is more than or equal to 1700MPa, the quenching yield strength is more than or equal to 1300MPa, the quenching elongation is more than or equal to 12 percent, the depth of the inner and outer surface decarburized layers is 0, and the torsional fatigue frequency is more than 120 ten thousand times under the condition of 550MPa stress.
Drawings
FIG. 1 is a photograph of the microstructure of a weld of example 4 of the present invention.
FIG. 2 is a photograph showing the microstructure of a steel pipe of example 4 of the present invention.
Detailed Description
The invention is further illustrated by the following examples and figures.
Table 1 shows the chemical compositions of the steel pipes of examples 1-10 and comparative examples 1-5 of the present invention, Table 2 shows the preparation process parameters of the steel pipes of examples 1-10 and comparative examples 1-5 of the present invention, and Table 3 shows the properties of the steel pipes of examples 1-10 and comparative examples 1-5 of the present invention.
Examples 1 to 10 and comparative examples 1 to 5
The steel pipes 1 to 10 for an automotive stabilizer bar according to the present invention and comparative examples 1 to 5 were manufactured according to the following steps, which included the steps of:
(1) smelting, casting and rolling the plate coil according to the mass percentage of chemical elements shown in the table 1, wherein the coiling temperature of the plate coil is 780-900 ℃;
(2) uncoiling and slitting shearing are carried out on the plate coil;
(3) welding in a high-frequency resistance welding mode to obtain a mother pipe, removing internal and external burrs, and performing online induction heat treatment at the temperature of 550-800 ℃ after welding;
(4) carrying out acid washing, phosphorization and saponification on the welded mother pipe;
(5) cold-drawing or cold-rolling to the size of a finished product, wherein the elongation coefficient of each cold working pass is 1.3-1.8, an intermediate heat treatment process of heat preservation at the temperature of 500-700 ℃ for 30-60min is adopted between cold working passes to eliminate the processing stress, and the size of the finished product of the cold-processed steel pipe is 1.5-8mm in wall thickness and 15-50mm in outer diameter;
(6) by the introduction of a gas containing H2Or heat treatment is carried out in a heat treatment furnace with CO reducing atmosphere, the heat treatment temperature is 700-930 ℃, and the heat preservation time is 40-70 min.
Comparing the performance of the welded and drawn steel pipes in the above examples and comparative examples, the concrete judgment whether the steel pipe for a hollow stabilizer bar meets the standard is as follows: 1) the tensile strength in the quenching state is more than or equal to 1700MPa, 2) the yield strength is more than or equal to 1300MPa, 3) the elongation is more than or equal to 12%, 4) the surface structure decarburized layer depth is 0, 5) the torsional fatigue test is carried out under the condition of 550MPa loading stress, the torsional fatigue times are more than 120 ten thousand, and the test is marked as qualified, otherwise, the test is marked as unqualified. Namely, the seamless steel pipe is qualified when the seamless steel pipe simultaneously meets the standards 1) to 5); otherwise, the steel pipe is not qualified, and the comprehensive mechanical property parameters of the steel pipes in examples 1 to 10 of the present invention and comparative examples 1 to 5 are shown in Table 3.
As can be seen from figure 1, the metal flow direction in the microstructure of the welding seam part of the steel pipe is clear, the metal flow direction of the welding seam is not vertical to the inner surface and the outer surface, the angle between the streamline of the welding seam and the inner surface is 55 degrees, and the strong plasticity and the torsional fatigue resistance of the welding seam structure are ensured.
As can be seen from FIG. 2, the microstructure of the steel pipe produced by the present invention is: the strip ferrite pearlite structure matrix is dispersed with fine carbide particles, which ensures the strong plasticity of the matrix, thereby ensuring the steel pipe to have good anti-torsional fatigue performance.
As can be seen from Table 3, the steel pipes for stabilizer bars of automobile hollow bars of examples 1 to 10 had a quenched tensile strength of 1700MPa or more, a quenched yield strength of 1300MPa or more, a quenched elongation of 12% or more, and a depth of decarburized layers of inner and outer surface structures of 0, and were subjected to a torsional fatigue test under a stress of 550MPa, and the number of torsional fatigue times was 120 ten thousand or more. However, since at least one of the comprehensive mechanical properties of each of the steel pipes in comparative examples 1 to 5 did not meet the standard.
Claims (12)
1. A steel pipe for an automobile hollow stabilizer bar comprises the following chemical components in percentage by mass: c: 0.28-0.40%, Si: 0.05 to 0.35%, Mn: 1.05 to 1.60%, Mo: 0.1-0.6%, B: 0.001-0.006%, Al: 0.015-0.060%, Cr: 0.1-0.8%, Ti: 0.003-0.06 percent of S, less than or equal to 0.006 percent of P, less than or equal to 0.015 percent of P, less than or equal to 0.0030 percent of O, and the following relations are satisfied at the same time: mo, 50B and Cr are more than or equal to 0.7 percent and less than or equal to 1.3 percent, and the balance is Fe and other inevitable impurities;
the microstructure of the steel pipe for the automobile hollow stabilizer bar is a ferrite plus pearlite structure and a carbide structure which is dispersedly distributed, the metal flow direction in the microstructure of a welding seam part is clear, and the metal flow direction of the welding seam is not vertical to the inner surface and the outer surface;
the steel pipe for the automobile hollow stabilizer bar has the quenching tensile strength of more than or equal to 1700MPa, the quenching yield strength of more than or equal to 1300MPa, the quenching elongation of more than or equal to 12 percent, the depth of the inner and outer surface decarburized layers of 0, and the torsional fatigue times of more than 120 ten thousand times under the condition of 550MPa stress.
2. The steel pipe for an automotive hollow stabilizer bar according to claim 1, wherein the steel pipe for an automotive hollow stabilizer bar comprises, in the composition C: 0.28 to 0.35 percent.
3. The steel pipe for an automotive hollow stabilizer bar according to claim 1, wherein the steel pipe for an automotive hollow stabilizer bar comprises, in the composition, Si: 0.1 to 0.3 percent.
4. The steel pipe for an automotive hollow stabilizer bar according to any one of claims 1 to 3, characterized in that the wall thickness of the steel pipe for an automotive hollow stabilizer bar is 1.5 to 8 mm.
5. The steel pipe for an automotive hollow stabilizer bar according to any one of claims 1 to 3, characterized in that the outer diameter of the steel pipe for an automotive hollow stabilizer bar is 15 to 50 mm.
6. The steel pipe for an automotive hollow stabilizer bar according to claim 4, wherein the steel pipe for an automotive hollow stabilizer bar has an outer diameter of 15 to 50 mm.
7. A method of manufacturing a steel pipe for an automotive hollow stabilizer bar as set forth in any one of claims 1 to 3, comprising the steps of:
1) smelting, casting and rolling into a coil according to the proportion of the chemical components in any one of claims 1 to 3, wherein the coiling temperature of the coil is controlled to be 780-900 ℃;
2) uncoiling and slitting shearing are carried out on the plate coil;
3) forming and welding the plate coil after splitting, removing burrs on the inner surface and the outer surface after welding, and carrying out heat treatment on the weld joint, wherein the heat treatment temperature is 550-800 ℃;
4) acid washing, phosphorization and saponification;
5) cold working to finished product size: cold working in multiple passes is carried out in a cold drawing or cold rolling mode, intermediate heat treatment is carried out between two adjacent cold working passes, the temperature of the intermediate heat treatment is 500-700 ℃, and the heat preservation time is 30-60 min;
6) and carrying out heat treatment on the finished product in a reducing atmosphere furnace, wherein the heat treatment temperature is 700-930 ℃.
8. The method for manufacturing a steel pipe for an automotive hollow stabilizer bar as recited in claim 7, wherein in step 1), the yield strength of said coil is 280-380MPa, and the tensile strength is 550-700 MPa.
9. The method for manufacturing a steel pipe for an automotive hollow stabilizer bar according to claim 7, wherein the elongation coefficient of each cold working of step 5) is 1.3 to 1.8.
10. The method for producing a steel pipe for an automotive hollow stabilizer bar as set forth in claim 7, wherein in the step 6), the reducing atmosphere furnace contains a reducing gas H2Or CO, reducing gas H2Or the volume percentage of CO is 15-40%.
11. The method for manufacturing a steel pipe for an automotive hollow stabilizer bar according to claim 7, characterized in that the steel pipe for an automotive hollow stabilizer bar has a wall thickness of 1.5 to 8 mm.
12. The method for producing a steel pipe for an automotive hollow stabilizer bar according to claim 7 or 11, characterized in that the steel pipe for an automotive hollow stabilizer bar has an outer diameter of 15 to 50 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710761716.7A CN109423580B (en) | 2017-08-30 | 2017-08-30 | Steel pipe for automobile hollow stabilizer bar and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710761716.7A CN109423580B (en) | 2017-08-30 | 2017-08-30 | Steel pipe for automobile hollow stabilizer bar and manufacturing method thereof |
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| CN110038913A (en) * | 2019-04-26 | 2019-07-23 | 张家港保税区亚鑫精密制管有限公司 | Hollow stabilizer rod of automobile metal pipe processing technique |
| CN113265581B (en) * | 2020-02-17 | 2022-10-21 | 宝山钢铁股份有限公司 | Steel pipe for stabilizer bar and manufacturing method thereof |
| CN111394558B (en) * | 2020-03-12 | 2021-12-03 | 唐山不锈钢有限责任公司 | Steel belt for automobile hollow stabilizer bar and production method thereof |
| CN113444864B (en) * | 2020-03-24 | 2022-06-28 | 宝山钢铁股份有限公司 | Control process for surface decarburization of automobile hollow transmission shaft tube and hollow transmission shaft tube thereof |
| CN112322974A (en) * | 2020-10-26 | 2021-02-05 | 首钢集团有限公司 | High-fatigue-life strip steel and preparation method and application thereof |
| CN112281078A (en) * | 2020-11-23 | 2021-01-29 | 湖州南浔中盛金属热处理有限公司 | Be applied to cementation steel pipe in automotive filed |
| CN112981255A (en) * | 2021-02-09 | 2021-06-18 | 鞍钢股份有限公司 | Pickling and EPS steel plate for automobile hollow stabilizer bar steel pipe and manufacturing method thereof |
| CN113862569B (en) * | 2021-09-18 | 2022-09-30 | 马鞍山钢铁股份有限公司 | Steel with low friction coefficient and excellent fatigue property for automobile hollow stabilizer bar and production method thereof |
| CN115058663A (en) * | 2022-06-10 | 2022-09-16 | 唐山不锈钢有限责任公司 | Steel pipe for high-light-weight automobile hollow stabilizer bar and production method thereof |
| CN117286395A (en) * | 2022-06-17 | 2023-12-26 | 宝山钢铁股份有限公司 | High-strength and high-toughness seamless steel tube for free-cutting motor shaft and manufacturing method thereof |
| CN115122053A (en) * | 2022-07-22 | 2022-09-30 | 隆昌山川机械有限责任公司 | Processing technology for pickling-free phosphating of metal pipe of working cylinder of automobile shock absorber |
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| JP3432950B2 (en) * | 1995-04-17 | 2003-08-04 | 新日本製鐵株式会社 | Steel material for induction hardened shaft parts that has both cold workability and torsional fatigue strength characteristics |
| JP2001011575A (en) * | 1999-06-30 | 2001-01-16 | Nippon Steel Corp | Bar steel and steel wire for machine structure excellent in cold workability and its production |
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