CN113621884A - Lightweight automobile roof rear cross beam lower plate, preparation method and rear cross beam assembly - Google Patents
Lightweight automobile roof rear cross beam lower plate, preparation method and rear cross beam assembly Download PDFInfo
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- CN113621884A CN113621884A CN202110922978.3A CN202110922978A CN113621884A CN 113621884 A CN113621884 A CN 113621884A CN 202110922978 A CN202110922978 A CN 202110922978A CN 113621884 A CN113621884 A CN 113621884A
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/02—Pressure casting making use of mechanical pressure devices, e.g. cast-forging
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D25/00—Superstructure or monocoque structure sub-units; Parts or details thereof not otherwise provided for
- B62D25/06—Fixed roofs
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
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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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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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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- 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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Abstract
The invention discloses a light-weight automobile roof rear cross beam lower plate, a preparation method and a rear cross beam assembly, which comprise the following components in percentage by weight: c: 0.03-0.10%, Mn: 1.3-1.5%, less than or equal to 0.04% of Si, less than or equal to 0.02% of P, less than or equal to 0.01% of S, more than or equal to 0.02% of Alt, and the balance of iron and inevitable impurities. The invention adopts high-strength steel and variable-thickness plates to combine, flexibly obtains materials from the consideration of the service characteristics of parts, and is prepared by thickening rolling, annealing, flattening and shearing; compared with a laser tailor-welded blank, the lower plate of the rear cross beam of the lightweight automobile roof replaces welding seams with transition sections, has better service performance, makes up the defects of tailor-welded welding seams on the basis of high strength and weight reduction, realizes automobile lightweight, and promotes the lightweight of automobile industrial materials to be developed to a higher level.
Description
Technical Field
The invention belongs to the technical field of automobiles, and particularly relates to a light-weight automobile roof rear cross beam lower plate, a manufacturing method and a rear cross beam assembly.
Background
The general trend of the current automobile technology development is energy conservation, environmental protection, safety, comfort and intelligence, and the reduction of oil consumption and emission on the premise of ensuring performance is one of the problems which need to be solved urgently in the field of the current automobile light weight, wherein the light weight of automobile part materials is an important way for solving the problem and becomes the mainstream of the modern automobile design and manufacture. As the weight of the automobile is reduced by 100 kilograms, at least 0.6L of fuel oil can be saved per hundred kilometers, and the CO can be reduced by 5g per kilometer2Therefore, the light weight of the automobile body is vital to reducing the self weight of the whole automobile, improving the fuel economy of the whole automobile, saving energy and protecting environment.
In the existing automobile roof part assembly technology, the use of a high-strength steel plate becomes one of the preferred schemes for lightweight materials of an automobile roof structure; the automobile roof cover rear cross beam is used as an important part of an automobile roof cover part assembly, plays an important role in twisting an upper automobile body of an automobile body, also plays roles in supporting a back door, bearing the pressure of a back door air pressure supporting rod and the like, and plays a key role in preventing the back door from falling down and the back door frame from cracking; when high-strength steels with different thicknesses are used for manufacturing the lower plate of the top cover rear cross beam, the annealed materials with different thicknesses are required to be subjected to laser tailor welding and then are formed into parts through cold stamping, but the strength and the forming performance of a welding seam of the tailor welding plate are different from those of a base metal, the requirement on the quality of the welding seam is high during forming, and a sudden change structure of the welding seam inevitably brings certain challenges to the subsequent stamping process, the manufacturing of a die and the assembly.
In view of the above circumstances, it is urgently needed to develop a new automobile roof rear cross beam lower plate and a production method thereof, which can take parts from service characteristics and flexibly obtain materials, make up for the defects of a laser tailor-welding process, lighten the plate again on the basis of high strength and weight reduction, and promote the lightweight of automobile industrial materials to develop to a higher level.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the rear cross beam lower plate of the lightweight automobile roof, the preparation method and the rear cross beam assembly, wherein the rear cross beam lower plate of the lightweight automobile roof is prepared by combining high-strength steel and a variable-thickness plate, flexibly obtaining materials from the consideration of service characteristics of parts, and performing variable-thickness rolling, annealing, flattening and shearing; compared with a laser tailor-welded blank, the lower plate of the rear cross beam of the lightweight automobile roof replaces welding seams with transition sections, has better service performance, makes up the defects of tailor-welded welding seams on the basis of high strength and weight reduction, realizes automobile lightweight, and promotes the lightweight of automobile industrial materials to be developed to a higher level.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a lightweight automobile roof rear cross beam lower plate, which comprises the following components in percentage by weight: c: 0.03-0.10%, Mn: 1.3-1.5%, less than or equal to 0.04% of Si, less than or equal to 0.02% of P, less than or equal to 0.01% of S, more than or equal to 0.02% of Alt, and the balance of iron and inevitable impurities;
the rear cross beam lower plate of the lightweight automobile roof cover is composed of 5 sections, and comprises a first equal-thickness section, a first transition section, a second equal-thickness section, a second transition section and a third equal-thickness section; the first equal-thickness section is connected with the second equal-thickness section through a first transition section, and the second equal-thickness section is connected with the third equal-thickness section through a second transition section.
Preferably, the tensile strength of the lower plate of the rear cross beam of the lightweight automobile roof cover is more than or equal to 400MPa, the yield strength is 250-360 MPa, the elongation is more than or equal to 30%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
Preferably, the thickness of the first equal-thickness section and the third equal-thickness section is 1.2 +/-0.05 mm, and the length of the first equal-thickness section and the third equal-thickness section is 405 +/-2 mm; the thickness of the second equal-thickness section is 0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the length of the first transition section and the second transition section is 40 +/-2 mm.
The invention provides a preparation method of a rear cross beam lower plate of a lightweight automobile roof cover, which comprises the following steps:
(1) according to the composition of the rear cross beam lower plate of the lightweight automobile roof cover, a hot-rolled pickled equal-thickness steel coil is selected;
(2) and the hot-rolled and pickled equal-thickness steel coil is subjected to thickening rolling, annealing, flattening and shearing to obtain the rear cross beam lower plate of the light automobile roof.
Preferably, in the step (2), the annealing process is: and (3) placing the thickened rolled coil into a bell-type furnace, heating to 330-420 ℃, preserving heat for 3-5 h, heating to an annealing temperature of 615-635 ℃, preserving heat for 8-12 h, stopping heating, changing a cooling cover for cooling after stewing for 2-5 h, and taking the cover out of the furnace when the temperature is reduced to be less than or equal to 50 ℃.
Preferably, in the step (2):
the thickening rolling and the flattening processes both adopt a thickening plate rolling mill with automatic roll gap control; and/or
The annealing process adopts an all-hydrogen bell-type furnace; and/or
The shearing process adopts a variable thick plate shearing line with automatic paragraph identification.
Preferably, the tensile strength of the lower plate of the rear cross beam of the lightweight automobile roof cover is more than or equal to 400MPa, the yield strength is 250-360 MPa, the elongation is more than or equal to 30%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent; and/or
The thickness of the first equal-thickness section and the third equal-thickness section of the rear cross beam lower plate of the light-weight automobile roof cover is 1.2 +/-0.05 mm, and the length of the first equal-thickness section and the third equal-thickness section is 405 +/-2 mm; the thickness of the second equal-thickness section is 0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the length of the first transition section and the second transition section is 40 +/-2 mm.
The invention provides a lightweight automobile roof rear cross beam assembly, which is provided with the lightweight automobile roof rear cross beam lower plate.
In a fourth aspect of the present invention, a lightweight automobile is provided, wherein a lightweight automobile roof rear cross beam assembly of the lightweight automobile is provided with the lightweight automobile roof rear cross beam lower plate of the first aspect of the present invention.
The invention has the following beneficial effects:
1) the lower plate of the rear cross beam of the whole lightweight automobile roof has no welding seam, and the surface quality is good;
2) the transition section is used for replacing a welding seam, so that the connection strength is greatly improved, and the weight can be reduced on the basis of laser tailor welding with the same strength;
3) continuous production can be realized, and the production efficiency is high;
4) the transition sections are smoothly connected, the metal fluidity is good during stamping, and the design of the die is simple;
5) the transition section has good energy absorption effect and better shock resistance.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic specification view of a rear cross member lower panel of a lightweight automotive roof cover according to the present invention.
Detailed Description
In order to better understand the technical solutions of the present invention, the following further describes the technical solutions of the present invention with reference to the accompanying drawings and examples.
As shown in fig. 1, the light-weight automotive roof rear cross beam lower plate provided by the invention comprises the following components in percentage by weight: c: 0.03-0.10%, Mn: 1.3-1.5%, less than or equal to 0.04% of Si, less than or equal to 0.02% of P, less than or equal to 0.01% of S, more than or equal to 0.02% of Alt, and the balance of iron and inevitable impurities. Wherein the crossbeam hypoplastron behind lightweight vapour car roof comprises 5 sections, 3 sections of equalling thickness: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. The tensile strength of the lower plate of the rear cross beam of the lightweight automobile roof cover is more than or equal to 400MPa, the yield strength is 250-360 MPa, the elongation is more than or equal to 30%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent; in a further preferable scheme, the tensile strength of the rear cross beam lower plate of the lightweight automobile roof cover is 410-440 MPa, and the yield strength is 300-360 MPa. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the length of the first transition section and the length of the second transition section are 40 +/-2 mm, and the first transition section and the second transition section replace the original welding structure, so that the weight is reduced under the same strength.
The invention provides a preparation method of a rear cross beam lower plate of a lightweight automobile roof, which comprises the following steps:
(1) selecting a hot-rolled pickled equal-thickness steel coil according to the components of the lower plate of the rear cross beam of the lightweight automobile roof;
the specific process is as follows: before the light-weight automobile roof rear cross beam lower plate is prepared, raw material selection is firstly carried out, and a hot-rolled pickled equal-thickness steel coil with the composition requirement of the composite light-weight automobile roof rear cross beam lower plate is adopted, wherein the specific components are as follows in percentage by weight: c: 0.03-0.10%, Mn: 1.3-1.5%, less than or equal to 0.04% of Si, less than or equal to 0.02% of P, less than or equal to 0.01% of S, more than or equal to 0.02% of Alt, and the balance of iron and inevitable impurities.
(2) And the steel coil with the same thickness as the hot-rolled and pickled steel coil is subjected to thickening rolling, annealing, flattening and shearing to obtain the rear cross beam lower plate of the lightweight automobile roof cover.
The specific process is as follows: performing thickening rolling and annealing on the hot-rolled and acid-washed equal-thickness steel coil selected in the step (1) to obtain an annealed coil, and flattening and shearing to finally prepare the rear cross beam lower plate of the light-weight automobile roof, wherein the thickening rolling and the flattening processes are finished on a thickening plate rolling mill with automatic roll gap control; the annealing process comprises the following steps: placing the thickened rolled coil in a cover furnace, heating to 330-420 ℃, preserving heat for 3-5 h, heating to an annealing temperature of 615-635 ℃, preserving heat for 8-12 h, stopping heating, changing a cooling cover for cooling after stewing for 2-5 h, and taking the cover out of the furnace when the temperature is reduced to be less than or equal to 50 ℃; the bell-type furnace is an all-hydrogen bell-type furnace with the temperature control precision of +/-10 ℃; the shearing process adopts a variable thick plate shearing line with automatic paragraph identification; and finally, flattening and shearing the annealed coil obtained by annealing to obtain the light-weight automobile roof rear cross beam lower plate which is good in surface plate shape and stable in mechanical property of each thickness section, wherein the light-weight automobile roof rear cross beam lower plate consists of 5 sections, and 3 equal-thickness sections: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. The tensile strength of the lower plate of the rear cross beam of the lightweight automobile roof cover is more than or equal to 400MPa, the yield strength is 250-360 MPa, the elongation is more than or equal to 30%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent; in a further preferable scheme, the tensile strength of the rear cross beam lower plate of the lightweight automobile roof cover is 410-440 MPa, and the yield strength is 300-360 MPa. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the length of the first transition section and the length of the second transition section are 40 +/-2 mm, and the first transition section and the second transition section replace the original welding structure, so that the weight is reduced under the same strength.
The light-weight automobile roof rear cross beam assembly is provided with the light-weight automobile roof rear cross beam lower plate prepared in the above manner, and compared with a laser tailor-welded blank, the light-weight automobile roof rear cross beam assembly has more excellent service performance, can be high in strength and reduce weight, and overcomes the defects of tailor-welded welds.
The rear cross beam assembly of the lightweight automobile roof cover on the lightweight automobile is provided with the rear cross beam lower plate of the lightweight automobile roof cover, so that the lightweight automobile industrial material can be conveniently pushed to be developed to a higher level.
The invention further discloses a lightweight automobile roof rear cross beam lower plate, a preparation method and a rear cross beam assembly by combining specific examples; the apparatus used in the following examples: the device comprises a variable-thickness plate rolling mill, a full-hydrogen bell-type furnace and a variable-thickness plate straightening and shearing line, wherein the variable-thickness plate rolling mill is a variable-thickness plate rolling mill with automatic roll gap control, the temperature control precision of the full-hydrogen bell-type furnace is +/-10 ℃, and the variable-thickness plate straightening and shearing line has automatic paragraph identification.
Example 1
The light-weight automobile roof cover rear cross beam lower plate is prepared by the following method:
(1) the adopted hot-rolled and pickled equal-thickness steel coil base material comprises the following chemical components (in percentage by weight): 0.05%, Mn: 1.37%, Si: 0.02%, P: 0.012%, S: 0.002%, Alt: 0.038%, the balance being iron and unavoidable impurities.
(2) Rolling the hot-rolled and pickled equal-thickness steel coil base material on a thickening mill into thickened coils which are connected end to end according to the design size shown in figure 1, and annealing in a bell-type furnace to obtain an annealed coil, wherein the annealing process comprises the following steps: firstly heating to 350 ℃, preserving heat for 4h, then heating to an annealing temperature of 620 ℃, preserving heat for 10h, stopping heating, replacing a cooling cover for cooling after braising for 4h, and taking out the cover when the temperature is reduced to 50 ℃; and flattening the annealed coil on a variable thickness plate mill, and shearing the annealed coil on a variable thickness plate shearing line to obtain the lightweight automobile roof rear cross beam lower plate with good surface plate shape, accurate size and stable mechanical property of each thickness section. The mechanical properties of the rear cross beam lower plate of the lightweight automobile roof cover are as follows: the tensile strength is 440Mpa, the yield strength is 320Mpa, the elongation is 31%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
As shown in figure 1, the rear cross beam lower plate of the lightweight automobile roof cover is composed of 5 sections, 3 equal-thickness sections: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the lengths of the first transition section and the second transition section are 40 +/-2 mm; the total length of the lower plate of the rear cross beam of the lightweight automobile roof cover is 1030 +/-2 mm, and the width of the lower plate is 460 +/-1 mm.
Experiments prove that the precision of each section of the lower plate of the rear cross beam of the lightweight automobile roof cover is +/-2 mm, the thickness tolerance is +/-0.05, the surface quality is good, the strength and the elongation of each section are consistent, the molding design requirements are met, the material is continuous, no hidden danger of weld joint cracking and hidden cracking exists, the metal fluidity is good during stamping, the impact resistance is good when the material is placed in service, and the weight is reduced at high strength.
Example 2
The light-weight automobile roof cover rear cross beam lower plate is prepared by the following method:
(1) the adopted hot-rolled and pickled equal-thickness steel coil base material comprises the following chemical components (in percentage by weight): 0.06%, Mn: 1.4%, Si: 0.01%, P: 0.015%, S: 0.003%, Alt: 0.033% and the balance iron and inevitable impurities.
(2) Rolling the hot-rolled and pickled equal-thickness steel coil base material on a thickening mill into thickened coils which are connected end to end according to the design size shown in figure 1, and annealing in a bell-type furnace to obtain an annealed coil, wherein the annealing process comprises the following steps: firstly heating to 370 ℃, preserving heat for 5h, then heating to an annealing temperature of 625 ℃, preserving heat for 10h, stopping heating, replacing a cooling cover for cooling after braising for 4h, and taking out the cover when the temperature is reduced to 50 ℃; and flattening the annealed coil on a variable thickness plate mill, and shearing the annealed coil on a variable thickness plate shearing line to obtain the lightweight automobile roof rear cross beam lower plate with good surface plate shape, accurate size and stable mechanical property of each thickness section. The mechanical properties of the rear cross beam lower plate of the lightweight automobile roof cover are as follows: the tensile strength is 430Mpa, the yield strength is 315Mpa, the elongation is 32%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
As shown in figure 1, the rear cross beam lower plate of the lightweight automobile roof cover is composed of 5 sections, 3 equal-thickness sections: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the lengths of the first transition section and the second transition section are 40 +/-2 mm; the total length of the lower plate of the rear cross beam of the lightweight automobile roof cover is 1030 +/-2 mm, and the width of the lower plate is 460 +/-1 mm.
Experiments prove that the precision of each section of the lower plate of the rear cross beam of the lightweight automobile roof cover is +/-2 mm, the thickness tolerance is +/-0.05, the surface quality is good, the strength and the elongation of each section are consistent, the molding design requirements are met, the material is continuous, no hidden danger of weld joint cracking and hidden cracking exists, the metal fluidity is good during stamping, the impact resistance is good when the material is placed in service, and the weight is reduced at high strength.
Example 3
The light-weight automobile roof cover rear cross beam lower plate is prepared by the following method:
(1) the adopted hot-rolled and pickled equal-thickness steel coil base material comprises the following chemical components (in percentage by weight): 0.05%, Mn: 1.32%, Si: 0.01%, P: 0.011%, S: 0.004%, Alt: 0.041%, and the balance of iron and inevitable impurities.
(2) Rolling the hot-rolled and pickled equal-thickness steel coil base material on a thickening mill into thickened coils which are connected end to end according to the design size shown in figure 1, and annealing in a bell-type furnace to obtain an annealed coil, wherein the annealing process comprises the following steps: firstly heating to 400 ℃, preserving heat for 3h, then heating to an annealing temperature of 630 ℃, preserving heat for 9h, stopping heating, replacing a cooling cover for cooling after braising for 5h, and taking out the cover when the temperature is reduced to 50 ℃; and flattening the annealed coil on a variable thickness plate mill, and shearing the annealed coil on a variable thickness plate shearing line to obtain the lightweight automobile roof rear cross beam lower plate with good surface plate shape, accurate size and stable mechanical property of each thickness section. The mechanical properties of the rear cross beam lower plate of the lightweight automobile roof cover are as follows: the tensile strength is 410Mpa, the yield strength is 300Mpa, the elongation is 33%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
As shown in figure 1, the rear cross beam lower plate of the lightweight automobile roof cover is composed of 5 sections, 3 equal-thickness sections: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the lengths of the first transition section and the second transition section are 40 +/-2 mm; the total length of the lower plate of the rear cross beam of the lightweight automobile roof cover is 1030 +/-2 mm, and the width of the lower plate is 460 +/-1 mm.
Experiments prove that the precision of each section of the lower plate of the rear cross beam of the lightweight automobile roof cover is +/-2 mm, the thickness tolerance is +/-0.05, the surface quality is good, the strength and the elongation of each section are consistent, the molding design requirements are met, the material is continuous, no hidden danger of weld joint cracking and hidden cracking exists, the metal fluidity is good during stamping, the impact resistance is good when the material is placed in service, and the weight is reduced at high strength.
Example 4
The light-weight automobile roof cover rear cross beam lower plate is prepared by the following method:
(1) the adopted hot-rolled and pickled equal-thickness steel coil base material comprises the following chemical components (in percentage by weight): 0.03%, Mn: 1.3%, Si: 0.01%, P: 0.011%, S: 0.002%, Alt: 0.032%, and the balance of iron and inevitable impurities.
(2) Rolling the hot-rolled and pickled equal-thickness steel coil base material on a thickening mill into thickened coils which are connected end to end according to the design size shown in figure 1, and annealing in a bell-type furnace to obtain an annealed coil, wherein the annealing process comprises the following steps: firstly heating to 330 ℃, preserving heat for 5h, then heating to an annealing temperature of 615 ℃, preserving heat for 12h, stopping heating, replacing a cooling cover after stewing for 2h, cooling, and taking out the cover when the temperature is reduced to 48 ℃; and flattening the annealed coil on a variable thickness plate mill, and shearing the annealed coil on a variable thickness plate shearing line to obtain the lightweight automobile roof rear cross beam lower plate with good surface plate shape, accurate size and stable mechanical property of each thickness section. The mechanical properties of the rear cross beam lower plate of the lightweight automobile roof cover are as follows: the tensile strength is 400MPa, the yield strength is 250MPa, the elongation is 32%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
As shown in figure 1, the rear cross beam lower plate of the lightweight automobile roof cover is composed of 5 sections, 3 equal-thickness sections: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the lengths of the first transition section and the second transition section are 40 +/-2 mm; the total length of the lower plate of the rear cross beam of the lightweight automobile roof cover is 1030 +/-2 mm, and the width of the lower plate is 460 +/-1 mm.
Experiments prove that the precision of each section of the lower plate of the rear cross beam of the lightweight automobile roof cover is +/-2 mm, the thickness tolerance is +/-0.05, the surface quality is good, the strength and the elongation of each section are consistent, the molding design requirements are met, the material is continuous, no hidden danger of weld joint cracking and hidden cracking exists, the metal fluidity is good during stamping, the impact resistance is good when the material is placed in service, and the weight is reduced at high strength.
Example 5
The light-weight automobile roof cover rear cross beam lower plate is prepared by the following method:
(1) the adopted hot-rolled and pickled equal-thickness steel coil base material comprises the following chemical components (in percentage by weight): 0.10%, Mn: 1.5%, Si: 0.04%, P: 0.02%, S: 0.01%, Alt: 0.041%, and the balance of iron and inevitable impurities.
(2) Rolling the hot-rolled and pickled equal-thickness steel coil base material on a thickening mill into thickened coils which are connected end to end according to the design size shown in figure 1, and annealing in a bell-type furnace to obtain an annealed coil, wherein the annealing process comprises the following steps: heating to 420 ℃, preserving heat for 3h, heating to 635 ℃, preserving heat for 8h, stopping heating, replacing a cooling cover for cooling after stewing for 5h, and taking out the cover when the temperature is reduced to 45 ℃; and flattening the annealed coil on a variable thickness plate mill, and shearing the annealed coil on a variable thickness plate shearing line to obtain the lightweight automobile roof rear cross beam lower plate with good surface plate shape, accurate size and stable mechanical property of each thickness section. The mechanical properties of the rear cross beam lower plate of the lightweight automobile roof cover are as follows: the tensile strength is 450MPa, the yield strength is 360MPa, the elongation is 34%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
As shown in figure 1, the rear cross beam lower plate of the lightweight automobile roof cover is composed of 5 sections, 3 equal-thickness sections: first equal-thickness section, second equal-thickness section and third equal-thickness section, 2 transition sections: the first equal-thickness section is connected with the second equal-thickness section through the first transition section, and the second equal-thickness section is connected with the third equal-thickness section through the second transition section. Wherein the thickness of the first equal-thickness section and the third equal-thickness section is T1-T3-1.2 +/-0.05 mm, and the length is 405 +/-2 mm; the thickness of the second equal-thickness section is T2-0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the lengths of the first transition section and the second transition section are 40 +/-2 mm; the total length of the lower plate of the rear cross beam of the lightweight automobile roof cover is 1030 +/-2 mm, and the width of the lower plate is 460 +/-1 mm.
Experiments prove that the precision of each section of the lower plate of the rear cross beam of the lightweight automobile roof cover is +/-2 mm, the thickness tolerance is +/-0.05, the surface quality is good, the strength and the elongation of each section are consistent, the molding design requirements are met, the material is continuous, no hidden danger of weld joint cracking and hidden cracking exists, the metal fluidity is good during stamping, the impact resistance is good when the material is placed in service, and the weight is reduced at high strength.
It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that changes and modifications to the above described embodiments are within the scope of the claims of the present invention as long as they are within the spirit and scope of the present invention.
Claims (9)
1. The lower plate of the rear cross beam of the light automobile roof cover is characterized by comprising the following components in percentage by weight: c: 0.03-0.10%, Mn: 1.3-1.5%, less than or equal to 0.04% of Si, less than or equal to 0.02% of P, less than or equal to 0.01% of S, more than or equal to 0.02% of Alt, and the balance of iron and inevitable impurities;
the rear cross beam lower plate of the lightweight automobile roof cover comprises a first equal-thickness section, a second equal-thickness section and a third equal-thickness section; the first equal-thickness section is connected with the second equal-thickness section through a first transition section, and the second equal-thickness section is connected with the third equal-thickness section through a second transition section.
2. The rear cross beam lower plate of the light weight automobile roof cover as claimed in claim 1, wherein the tensile strength of the rear cross beam lower plate of the light weight automobile roof cover is not less than 400MPa, the yield strength is 250-360 MPa, the elongation is not less than 30%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent.
3. The light weight automotive roof back rail lower panel of claim 1, wherein the first and third equal-thickness sections have a thickness of 1.2 ± 0.05mm and a length of 405 ± 2 mm; the thickness of the second equal-thickness section is 0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the length of the first transition section and the second transition section is 40 +/-2 mm.
4. A preparation method of a light-weight automobile roof rear cross beam lower plate is characterized by comprising the following steps:
(1) the composition selection hot-rolled pickled equal-thickness steel coil for the rear cross beam lower plate of the light-weight automobile roof cover according to claim 1;
(2) and the hot-rolled and pickled equal-thickness steel coil is subjected to thickening rolling, annealing, flattening and shearing to obtain the rear cross beam lower plate of the light automobile roof.
5. The manufacturing method according to claim 4, wherein in the step (2), the annealing process is: and (3) placing the thickened rolled coil into a bell-type furnace, heating to 330-420 ℃, preserving heat for 3-5 h, heating to an annealing temperature of 615-635 ℃, preserving heat for 8-12 h, stopping heating, changing a cooling cover for cooling after stewing for 2-5 h, and taking the cover out of the furnace when the temperature is reduced to be less than or equal to 50 ℃.
6. The production method according to claim 4, wherein in the step (2):
the thickening rolling and the flattening processes both adopt a thickening plate rolling mill with automatic roll gap control; and/or
The annealing process adopts an all-hydrogen bell-type furnace; and/or
The shearing process adopts a variable thick plate shearing line with automatic paragraph identification.
7. The preparation method according to any one of claims 4 to 6, wherein the tensile strength of the rear cross beam lower plate of the lightweight automobile roof cover is not less than 400MPa, the yield strength is 250 to 360MPa, the elongation is not less than 30%, and the tensile strength, the yield strength and the elongation of each thickness section are consistent; and/or
The thickness of the first equal-thickness section and the third equal-thickness section of the rear cross beam lower plate of the light-weight automobile roof cover is 1.2 +/-0.05 mm, and the length of the first equal-thickness section and the third equal-thickness section is 405 +/-2 mm; the thickness of the second equal-thickness section is 0.8 +/-0.05 mm, and the length is 240 +/-2 mm; the length of the first transition section and the second transition section is 40 +/-2 mm.
8. A light-weight automobile roof cover rear cross beam assembly is characterized in that the light-weight automobile roof cover rear cross beam assembly is provided with the light-weight automobile roof cover rear cross beam lower plate according to any one of claims 1 to 3.
9. A lightweight automobile, characterized in that a lightweight automobile roof cover rear cross member assembly of the lightweight automobile is provided with the lightweight automobile roof cover rear cross member lower plate according to any one of claims 1 to 3.
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| US20140134450A1 (en) * | 2012-11-14 | 2014-05-15 | Muhr Und Bender Kg | Method for Manufacturing a Product from a Flexibly Rolled Strip Material |
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