CN116174517A - Production method of forging for 6xxx aluminum alloy vehicle - Google Patents

Abstract

A production method of a 6xxx aluminum alloy vehicle forging belongs to the field of aluminum alloy material processing, and specifically comprises the following production procedures: smelting, casting, extruding a special-shaped rod, homogenizing heat treatment, sawing and forging, solution treatment and aging treatment, wherein the method is the greatest difference from the traditional production flow: extrusion and homogenization heat treatment are in different orders; the forging blank is prepared in different processes. Meanwhile, the method is suitable for producing all the forgings for the 6xxx aluminum alloy vehicles. The invention also provides a high-strength and high-toughness 6xxx aluminum alloy material, which comprises the following alloy components: (0.9 to 1.1 wt.%) Mg, (1.1 to 1.3 wt.%) Si, (0.5 to 0.7 wt.%) Cu, (0.5 to 0.7 wt.%) Mn, (0.1 to 0.3 wt.%) Cr, (less than 0.5 wt.%) Fe, the balance consisting of Al and unavoidable impurity elements.

Description

Production method of forging for 6xxx aluminum alloy vehicle

Technical Field

The invention belongs to the field of aluminum alloy material processing, and particularly relates to a production method of a forging for a 6xxx aluminum alloy vehicle.

Background

The biggest application market of aluminum alloy forging is automobile chassis part, including key security spare parts such as control arm, knuckle, sub-frame, connecting rod. Because the automobile chassis is used as an assembly for supporting and installing various parts of the automobile, chassis parts are important structural safety parts of the automobile, and the chassis parts are required to have good strength, rigidity, fatigue resistance and comprehensive performance. Currently, aluminum alloy forgings for automobiles are mostly prepared from 6082 or 6061 aluminum alloy, and the process flow is shown in figure 1. The forging for the aluminum alloy vehicle prepared by the process currently faces the following problems: (1) the material performance is low. With the high requirement of automobile light weight, the performance of the existing aluminum alloy materials, such as 6061 or 6082 aluminum alloy, cannot be met. In addition, as the service requirement is less than 0.15wt.% for Fe content, the material cost is increased, and the use of the regenerated aluminum is limited; (2) coarse crystals are easy to generate and the fatigue resistance is low. Under the existing technology, a great amount of deformation energy is accumulated after the alloy is extruded, and the deformation energy is further reserved at some parts of the parts in the subsequent forging process, so that the accumulated deformation energy becomes the power for recrystallization and coarse recrystallization of the alloy during solution treatment of the alloy, and coarse grain structures are frequently generated in the final structure of the forging, and fatigue fracture and danger occur in the service process of the automotive forging; (3) the process flow is long and the cost is high. In the preparation process of the vehicle forging, the homogenization process consumes the most time, and simultaneously has relatively large energy consumption and high equipment occupancy rate. In addition, in the forging blank preparation process, the steps of roll forging, bending, preforming and the like are mainly performed, so that the process is long and complex, and waste is laborious.

Currently, some businesses have respective solutions based on the problems presented above.

(1) Aiming at the problem of low material performance. For the commonly used 6082 and 6061 aluminum alloys with low performance, some enterprises develop a plurality of high-strength and high-toughness aluminum alloys, such as Japanese Kokai steel making [ US 8372220], european Kennel aluminum industry general [ WO 2016071257A1], china aluminum industry company [ CN102337434B ] and the like, the performances can reach the yield strength of more than 380MPa and the elongation of more than 10 percent. The following alloying ideas are adopted: the types and the quantity of strengthening phases are changed by adding Cu elements in the contents of Mg and Si, and meanwhile, the quantity of dispersed phases is increased by increasing the contents of Mn and Cr, so that the generation of coarse recrystallization is effectively inhibited. However, an alloying thought related to the tolerance of the regenerated aluminum and Fe element is not reported for the aluminum alloy vehicle forging.

(2) Aiming at the problems of easy generation of coarse crystals and low fatigue resistance. In order to effectively inhibit generation of coarse crystals, the deformation energy reserved in the extrusion process is effectively eliminated mainly by heating at high temperature for a long time before forging. The method has the main problems of increasing the occupied time of equipment and higher energy consumption.

(3) Aiming at the problems of long process flow and high cost. The problem is that the aluminum alloy vehicle forging is the biggest problem at present, the application range of the aluminum alloy vehicle forging is greatly limited, and the aluminum alloy vehicle forging can only be applied to high-end vehicle types. In order to solve the problem, some enterprises cancel the extrusion link and directly forge the cast rod, but the process needs to forge the cast rod with larger deformation to eliminate casting tissues, so that the blank preparation process is more complicated. In addition, the forging obtained by this process of direct forging of cast bars has properties that are lower than those of conventional processes, and therefore, the process uses a high alloyed 6xxx aluminum alloy in many cases.

Disclosure of Invention

In view of the above-mentioned problems, it is an object of the present invention to provide a method for producing a forging for a 6xxx aluminum alloy vehicle. The method is particularly suitable for the production of all 6xxx aluminum alloy vehicle forgings, wherein the 'all 6xxx aluminum alloys' comprise conventional 6xxx aluminum alloy materials, high strength and toughness 6xxx aluminum alloy materials and 6xxx aluminum alloy materials with high tolerance for Fe content.

It is another object of the present invention to provide a method of producing a forging for a 6xxx aluminum alloy vehicle with a high tolerance for Fe content.

The high-strength and high-toughness 6xxx aluminum alloy material has the following properties: the yield strength is more than 400MPa, the elongation is more than 10 percent, and the fatigue strength is more than 140MPa.

The high-strength and high-toughness 6xxx aluminum alloy material comprises the following specific alloy components: (0.9 to 1.1 wt.%) Mg, (1.1 to 1.3 wt.%) Si, (0.5 to 0.7 wt.%) Cu, (0.5 to 0.7 wt.%) Mn, (0.1 to 0.3 wt.%), cr, (less than 0.5 wt.%) Fe, the balance consisting of Al and unavoidable impurity elements. While satisfying Cu (wt.%) - [ Si (wt.%) -Mg (wt.%) ] =0.4 wt.%.

Wherein the Mg, si and Cu elements are mainly used for forming a nano reinforced phase in the aging process. The strength design of the 6xxx aluminum alloy is based on controlling the Mg, si content and ratio ₂ The amount of Si phase is such that,namely, when the atomic ratio of Mg/Si is 2 (mass ratio of 1.73), the Mg can be maximized ₂ Si content. However, the β "phase formed by the strengthening phase precipitated during aging is not in this proportion, and Si is usually used in excess to maximize the amount of the strengthening phase, thereby obtaining higher strength. In addition, the addition of Cu to a 6xxx aluminum alloy may form a Q phase with Mg, si, such as 6061 aluminum alloy, which alters the strengthening phase species from Mg ₂ Si to Mg ₂ Si and Q phases, thereby improving the alloy strength. Thus, 6xxx aluminum alloys generally employ Mg, si, cu as the primary alloying element for higher strength and higher levels of the alloying elements result in higher strength, but due to the limited solid solubility of the alloying elements, excessive levels of alloying elements can result in excessive coarse second phases in grain boundaries in the product, reducing the toughness and fatigue resistance of the material. The invention provides that the content of Mg, si and Cu is (0.9-1.1 wt%) Mg, (1.1-1.3 wt%) Si, (0.5-0.7 wt%) Cu, and simultaneously satisfies Cu (wt%) - [ Si (wt%) -Mg (wt%)]=0.4 wt.%. Under the alloy composition, the alloy strengthening phase is a large amount of Q phase and a small amount of Mg ₂ Si, and the most amount, the alloy achieves the best performance.

Wherein Mn and Cr elements are mainly used for submicron disperse phase in the homogenization process. Mn, cr, al, fe and Si mainly form alpha-Al (FeMn) Si phase and Cr-containing phase in the homogenization process, and the phases effectively pin dislocation in the subsequent deformation of the alloy, inhibit the occurrence of recrystallization and coarse recrystallization, and have better dislocation pinning effect as the content is higher. However, too high content of the alloy element can cause excessive coarse second phases to be generated in grain boundaries of products due to the limitation of solid solubility of the alloy element, and the toughness and fatigue resistance of the material are reduced. The invention provides Mn, cr content (0.5-0.7 wt%) Mn and Cr content (0.1-0.3 wt%). Under the condition of the alloy composition, the quantity of the dispersed phase obtained after the homogenization of the alloy is the largest, the proportion of the sub-crystals in the product is large, and coarse crystals are avoided.

The short-process production method of the forging for the 6xxx aluminum alloy vehicle specifically comprises the following steps: smelting, casting, extruding a profiled bar, homogenizing heat treatment, sawing and forging, solution treatment and aging treatment, as shown in fig. 2. The method specifically comprises the following steps:

a. smelting

Melting the raw materials into alloy liquid, refining in a furnace, and standing.

b. Casting

And pouring the treated alloy liquid into a flow channel by adopting a conventional external refining and filtering method, refining the alloy liquid through an external degassing tank, and filtering the alloy liquid. Casting is carried out by a conventional semi-continuous casting method, and the round casting rod is manufactured by adopting DC casting or electromagnetic casting and other technologies.

c. Extrusion shaped rod

The method for producing the aluminum alloy vehicle forging provided by the invention has certain differences between the set extrusion technological parameters and the conventional 6xxx aluminum alloy, and specifically comprises the following steps: (1) and (5) an extrusion mode. The forward extrusion and the backward extrusion can be adopted, and the backward extrusion is preferred, because the forward extrusion surface is subjected to larger shearing deformation and coarse crystals are easy to generate, and the special-shaped extrusion rod provided by the invention can not be peeled, so that the coarse crystals on the surface must be driven into flash in the forging process, and the material utilization rate is too low; and backward extrusion is preferable because the internal and external deformations are uniform during extrusion, and the problem of surface coarse crystals is rarely generated. (2) Extrusion ratio: the method of the invention requires a large and moderate extrusion ratio, and the extrusion ratio is required to be 30-70. The extrusion ratio is too small, and the second phase of the grain boundary is not sufficiently crushed, so that the second phase in the forging is thick, and the toughness and fatigue resistance of the forging are reduced. The extrusion ratio is too large, the deformation energy of material reserve in the extrusion process is too large, and recrystallized grains are too large after homogenization, so that the forging structure is thick, and the toughness and fatigue resistance of the forging are reduced. (3) And (5) an extrusion process. The extrusion process of the traditional 6xxx aluminum alloy for vehicles requires high-temperature (more than 500 ℃) medium-speed (2-3 mm/s) online water quenching, and aims to ensure that the extrusion temperature is as close as possible to the solid-solution line of the alloy so as to realize the maximum element solid-solution quantity, and simultaneously, the extrusion process is matched with water quenching so as to ensure that no strengthening phase is separated out in the cooling process. The extrusion starting point of the invention is different from the traditional extrusion starting point, and mainly the special-shaped section is obtained, and meanwhile, after the subsequent homogenization heat treatment, the forging blank has a thinner fibrous structure or a thinner recrystallization structure, so that the extrusion process adopted by the invention is as follows: the extrusion temperature is 400-480 ℃, the extrusion speed is 3.5-6 mm/s, the extrusion ratio is 30-70, and the online air quenching or water quenching is performed, because the extrusion temperature is too high, the extrusion speed cannot be too high, dynamic recrystallization also occurs, the structure is coarser, in addition, the rheological stress of the aluminum matrix is too low, so that the hard particles of the second phase are not easy to break and flow along with the matrix. The extrusion temperature is too low, the deformation energy of the extrusion rod stock is too great, and coarse recrystallization (secondary recrystallization) occurs in the subsequent homogenization process to generate coarse grains.

d. Homogenization heat treatment

The purpose of the homogenization heat treatment is to reduce micro segregation, reduce or eliminate secondary phases at grain boundaries, and control precipitation of dispersed phases. The invention provides two homogenization heat treatment processes.

Homogenization heat treatment process-1. The three-step process of temperature rising, constant temperature and cooling is mainly used for 6xxx aluminum alloys without Mn in the field, and belongs to the conventional method in the field. However, based on the method for producing the aluminum alloy vehicle forgings, the homogenization heat treatment is obviously different from the traditional process, mainly because the traditional process is based on an as-cast structure and the process is based on an extrusion structure, the method is corresponding to a three-step process of heating-constant temperature-cooling, the required homogenization time is shorter, the cooling rate is required to be faster, and the method specifically comprises the following steps: heating to 550-570 ℃ at a heating rate of 1-5 ℃/min, preserving heat for 4-6 hours, cooling to 350 ℃ at a speed of not less than 8 ℃/min, and cooling to room temperature at a speed of not less than 4 ℃/min, wherein the reason is that the grain size and the second phase size become small after extrusion, the element diffusion time is shortened, the homogenizing heat preservation time is shorter than that of the traditional process, and the homogenizing heat preservation time is directly used as a forging blank, so that the second phase at the grain boundary in the blank is ensured to be as small as possible, and therefore, a high cooling rate is required to be adopted at the temperature of more than 350 ℃ in the cooling process to ensure that the second phase (Mg ₂ Si phase or Q phase).

Homogenizing heat treatment process-2. The two-stage homogenization heat treatment process, namely five steps of temperature rise-low temperature constant temperature-temperature rise-high temperature constant temperature-cooling, is adopted, and is suitable for the 6xxx aluminum alloy containing Mn. A low temperature treatment was added to the Mn-containing 6xxx aluminum alloy for the purpose of: the Mn element is added in the 6xxx aluminum alloy to precipitate alpha-Al (FeMn) Si phase in the homogenization process, the phase is formed in the nucleation and growth process, namely, in the homogenization heating process, the transition phase u phase is nucleated on the beta ' phase, the u phase is rich in Mn and Cr elements, and then the alpha dispersed phase is non-homogenized and nucleated on the u phase, so that the quantity of the beta ' phase is required to be increased to realize the increase of the alpha dispersed phase, and the invention increases a low-temperature constant-temperature section to precipitate a large quantity of beta ' phases. The two-stage homogenization heat treatment process provided by the invention specifically comprises the following steps: heating to 300-355 ℃ at a speed of not more than 3 ℃/min, preserving heat for 6-8 hours, heating to 550-570 ℃ at a speed of not more than 3 ℃/min, preserving heat for 4-6 hours, cooling to 350 ℃ at a speed of not less than 8 ℃/min, and cooling to room temperature at a speed of not less than 4 ℃/min.

e. Sawing and forging

Slicing the extruded rod subjected to homogenization heat treatment along the extrusion direction, wherein the slicing thickness meets the forging requirement.

f. Solid solution and aging treatment

And carrying out T6 heat treatment on the forging by a solid solution and aging treatment method.

The production flow of the aluminum alloy vehicle forging provided by the invention is the most different from the traditional production flow in that: (1) extrusion and homogenization heat treatment are in different orders. The traditional production process firstly carries out homogenization heat treatment and then extrudes the round bar to provide blanks for the follow-up, but because a large amount of deformation energy is stored in the material during extrusion, the deformation energy is further accumulated in the follow-up forging, coarse crystals are generated in solution heat treatment, the fatigue resistance is greatly reduced, and on the basis, high-temperature long-time annealing is usually carried out before forging, so that the long-time heating at high temperature is required before and after extrusion, and the defects of high equipment occupancy rate, high energy consumption and high cost are overcome. The invention exchanges extrusion and homogenization heat treatment, and has the advantages that: the second phase (shown in figure 3) at the grain boundary in the cast ingot is crushed under the action of high temperature and high pressure in the extrusion process, the size is obviously reduced (shown in figure 4), the time required by the subsequent homogenization heat treatment is also obviously reduced (shown in figure 5), the high-temperature long-time annealing is not required before forging, and the energy consumption and the cost in the production process are greatly reduced. (2) The forging blank is prepared in different processes. Forgings for aluminum alloy vehicles are generally complex in shape, as shown in fig. 6. The traditional forging blank preparation process mainly comprises the steps of roll forging, bending, preforming and the like, and is long and complex in process, and waste is laborious. The invention provides a method for preparing a forging blank, which comprises the following steps: the forging piece is directly and precisely forged into a vehicle forging piece (shown in fig. 8) by extruding the forging piece into a special-shaped material and slicing the special-shaped material (shown in fig. 7).

In conclusion, the production method of the aluminum alloy vehicle forging provided by the invention has the advantages of short flow, energy conservation, high efficiency, low cost and the like.

The invention also provides a production method of the forging for the 6xxx aluminum alloy vehicle with high Fe tolerance.

The alloy adopted by the forging for the aluminum alloy vehicle has strict requirement on Fe content, which is usually less than 0.15wt.%, because the Fe content is increased, a large amount of coarse Fe-containing second phases exist at the grain boundary of the forging, and the toughness and fatigue resistance of the forging are seriously reduced. The kinds and proportions of the secondary aluminum used in the production process under the conditions are limited, so that the material cost and carbon emission of the vehicle forging are increased. The production method of the vehicle forging provided by the invention can be effectively compatible with the 6xxx aluminum alloy with high tolerance Fe content, and specifically comprises the following steps: the casting rod is directly extruded, and the Fe-containing second phase at the grain boundary in the casting rod can be crushed and dispersed under the conditions of high temperature and high pressure by adopting a large extrusion ratio (the extrusion ratio is 30-70), the crushed second phase is dissolved and spheroidized in the subsequent homogenization heat treatment, the second phase in the final forging is tiny and uniform, and the toughness and fatigue performance loss of the forging are small.

The invention has the beneficial effects that:

the invention provides a high-strength and high-toughness 6xxx aluminum alloy material, which has yield strength of more than 400MPa, elongation of more than 10 percent and fatigue strength of more than 140MPa and is suitable for hot working methods such as forging, extrusion and the like. The invention also provides a production method of the aluminum alloy vehicle forging and production of the 6xxx aluminum alloy forging adapting to the high-tolerance Fe content. The production method of the aluminum alloy vehicle forging provided by the invention has the advantages of short flow, energy conservation, high efficiency, low cost and the like, and meanwhile, the production method can be effectively compatible with the 6xxx aluminum alloy with high tolerance Fe content.

Drawings

FIG. 1 is a production flow of a conventional aluminum alloy automotive forging;

FIG. 2 shows a production flow of the aluminum alloy automotive forgings of the invention;

FIG. 3 shows the microstructure of a casting rod of the alloy according to the invention;

FIG. 4 shows the microstructure of an alloy after extrusion according to the present invention;

FIG. 5 shows the microstructure of the homogenized alloy according to the present invention;

FIG. 6 aluminum alloy automotive control arm forging;

FIG. 7 is an extrusion blank provided by the present invention;

FIG. 8 shows an aluminum alloy forging for a vehicle, which is prepared by the process provided by the invention.

Detailed Description

The following describes a method for producing a high strength and toughness 6xxx aluminum alloy material and a 6xxx aluminum alloy material automotive forgings.

The alloying of the high-strength and high-toughness 6xxx aluminum alloy is not limited to the manufacturing method of the invention, but is also applicable to other hot working methods such as forging and extrusion, and the specific alloy components comprise: (0.9 to 1.1 wt.%) Mg, (1.1 to 1.3 wt.%) Si, (0.5 to 0.7 wt.%) Cu, (0.5 to 0.7 wt.%) Mn, (0.1 to 0.3 wt.%), cr, (less than 0.5 wt.%) Fe, the balance consisting of Al and unavoidable impurity elements, while satisfying: cu (wt.%) - [ Si (wt.%) -Mg (wt.%) ] =0.4 wt.%. The components have the following functions:

mg, si, cu action

The Mg, si and Cu elements are mainly used for forming a nano reinforced phase in the aging process, and the nano reinforced phase comprises a beta phase and a Q 'phase, wherein the beta phase consists of Mg and Si, and the Q' phase consists of Mg, si and Cu. The quantity of the strengthening phases is increased when the contents of Mg, si and Cu are increased, and excessive quantity of the strengthening phases can cause excessive quantity of grain boundary second phases in the final product, so that the toughness and fatigue resistance of the product are reduced. In addition, the content relation of Mg, si and Cu can effectively control the composition of beta 'and Q' phases, so the invention clearly specifies that the content relation of Mg, si and Cu is as follows: cu (wt.%) - [ Si (wt.%) -Mg (wt.%) ] =0.4 wt.%, in which relationship the strengthening phase is constituted by a large amount of Q' phase and a small amount of β ", and the quantity is the largest, the alloy achieves the best performance.

Mn, cr action

Mn and Cr elements are mainly used for submicron disperse phase in the homogenization process. Mn, cr, al, fe and Si are used for effectively pinning dislocation in the subsequent deformation of the alloy in the homogenization process, and the higher the content of the Mn, cr, al, fe and Si is, the better the dislocation pinning effect is. However, too high content of the alloy element can cause excessive coarse second phases to be generated in grain boundaries of products due to the limitation of solid solubility of the alloy element, and the toughness and fatigue resistance of the material are reduced. The invention provides Mn, cr content (0.5-0.7 wt%) Mn and Cr content (0.1-0.3 wt%). Under the condition of the alloy composition, the maximum quantity of the dispersion phases is obtained after the homogenization of the alloy, the proportion of the sub-crystals in the product is large, and coarse crystals are avoided.

Production method of forging for 6xxx aluminum alloy vehicle

The method is suitable for producing all the forgings for the 6xxx aluminum alloy vehicles, and comprises the following specific working procedures: smelting, casting, extruding a special-shaped rod, homogenizing heat treatment, sawing and forging, solution treatment and aging treatment. The method specifically comprises the following steps:

a. smelting

Raw materials (raw aluminum or liquid aluminum, secondary aluminum and various raw materials) are melted into alloy liquid by a conventional smelting method in the field, and are subjected to furnace refining and standing.

b. Casting

And pouring the treated alloy liquid into a flow channel by using a conventional external refining and filtering method in the field, refining by using nitrogen or argon in an external degassing box (at least two rotors), and filtering (adopting a double-stage filtering box or a deep bed or tubular filtering).

The round casting rod is manufactured by a conventional semi-continuous casting method in the field, casting at 720-680 ℃ and adopting DC casting or electromagnetic casting and other technologies.

c. Extrusion shaped rod

The method for producing the forging for the aluminum alloy vehicle, disclosed by the invention, needs extrusion process parameters which are obviously different from those of the conventional 6xxx aluminum alloy, and specifically comprises the following steps: (1) the extrusion mode is as follows: both forward and backward extrusion are possible, with backward extrusion being preferred. (2) Extrusion ratio: based on the method of the present invention, a large and moderate extrusion ratio is required, and the extrusion ratio is set to 30 to 70. (3) The extrusion process comprises the following steps: the adopted process is that the extrusion temperature is 400-480 ℃, the extrusion speed is 3.5-6 mm/s, and the online air quenching or water quenching is carried out.

d. Homogenization heat treatment

The invention provides two homogenization heat treatment processes.

Homogenization heat treatment process-1. The method adopts the conventional method in the field, namely three steps of heating-constant temperature-cooling, and comprises the following specific steps: heating to 550-570 ℃ at a heating rate of 1-5 ℃/min, preserving heat for 4-6 hours, cooling to 350 ℃ at a speed of not less than 8 ℃/min, and cooling to room temperature at a speed of not less than 4 ℃/min.

Homogenizing heat treatment process-2. Adopts a two-stage homogenization heat treatment process, namely five steps of temperature rise, low temperature constant temperature, temperature rise, high temperature constant temperature and cooling, and specifically comprises the following steps: heating to 300-355 ℃ at a speed of not more than 3 ℃/min, preserving heat for 6-8 hours, heating to 550-570 ℃ at a speed of not more than 3 ℃/min, preserving heat for 4-6 hours, cooling to 350 ℃ at a speed of not less than 8 ℃/min, and cooling to room temperature at a speed of not less than 4 ℃/min.

e. Sawing and forging

The extrusion rod subjected to homogenization heat treatment is sliced along the extrusion direction, and the slice thickness meets the forging requirement. The forging is carried out by adopting a conventional forging method in the field, and the extrusion rod slice shape is similar to the forging shape, so that the forging is finished by precision forging compared with the traditional forging method.

f. Solid solution and aging treatment

T6 heat treatment is carried out on the forging by a conventional solid solution and aging treatment method in the field.

High Fe-tolerant 6xxx aluminum alloying schemes

This approach applies to all wrought 6xxx aluminum alloys, but the method of production thereof is applicable only to the method of production provided by the present invention. The Fe content is best to reach 0.5wt.% by the forging production method, the Fe-containing second phase at the grain boundary in the casting rod can be crushed and dispersed under the conditions of high temperature and high pressure during extrusion, the crushed second phase is dissolved and spheroidized during the subsequent homogenization heat treatment, the second phase in the final forging is fine and uniform, and the toughness and fatigue performance loss of the forging are small. When the Fe content exceeds 0.5wt.%, the method of the invention is more difficult to control the Fe-containing second phase in the product, and the toughness and fatigue performance loss of the forging piece are larger.

Example 1

A method of producing a forging for a 6xxx aluminum alloy vehicle, comprising the operations of:

the high strength and toughness 6xxx aluminum alloys listed in table 1 and compositions thereof were employed, with the alloys provided by the present invention differing from the alloys compared thereto in whether the relationship Cu (wt.%) - [ Si (wt.%) -Mg (wt.%) ] =0.4 wt.% was satisfied, and not as a comparative alloy set. After casting the alloy into ingots with the diameter of 512mm by DC casting, forward extruding the ingot into special-shaped extruded bars (the section is shown in figure 7) according to the extrusion ratio of 30.3, the extrusion temperature of 400 ℃ and the extrusion speed of 6mm/s by an online water quenching process, heating to 350 ℃ at the speed of 3 ℃/min, preserving heat for 8 hours, cooling to 350 ℃ at the speed of 8 ℃/min after heating to 560 ℃ at the speed of 3 ℃/min, preserving heat for 4 hours, slicing after cooling to room temperature at the speed of 4 ℃/min (the homogenization heat treatment process-2) of the invention), heating the slices to 450 ℃ and preserving heat for 15min, forging the slices into a control arm forging (shown in figure 8), and finally carrying out T6 heat treatment on the forging pieces.

The properties of the forgings for each alloy vehicle are shown in Table 2.

Table 1 high strength and toughness 6xxx aluminum alloys and comparative alloy compositions (wt.%) of the present invention

TABLE 2 high strength and toughness 6xxx aluminum alloys of the invention, and comparative alloys, mechanical and fatigue properties

Example 2

A production method of a 6061 aluminum alloy vehicle forging containing different Fe contents comprises the following operations:

6061 aluminum alloy materials with different Fe contents as listed in table 3 were used. The forging piece for the vehicle multi-connecting rod is used as a product and is produced according to the following process: after casting ingots with the diameter of 358mm by DC casting, reversely extruding the alloy into special-shaped extrusion bars according to the extrusion ratio of 48.2, the extrusion temperature of 450 ℃ and the extrusion speed of 4.5mm/s by an online water quenching process, heating to 560 ℃ at the speed of 3 ℃/min, preserving heat for 6 hours, cooling to 350 ℃ at the speed of 8 ℃/min, cooling to room temperature at the speed of 4 ℃/min, carrying out homogenization heat treatment (homogenization heat treatment process-1) and slicing, heating the slices to 480 ℃ and preserving heat for 15min, forging to form a control arm forging for a vehicle, and finally carrying out T6 heat treatment on the forging.

The properties of the forgings for alloy vehicles obtained under different process conditions are shown in Table 4.

Table 3 composition (wt.%) of 6061 aluminum alloy with different Fe contents

TABLE 4 mechanical and fatigue Properties of 6061 aluminum alloys with different Fe contents

The conventional production method described in table 4 is performed according to the production flow of fig. 1, and the specific process is as follows: after casting the alloy into ingots with the diameter of 300mm through DC casting, heating to 560 ℃ at the speed of 3 ℃/min, preserving heat for 9 hours, cooling to room temperature at the speed of 2-3 ℃/min, carrying out homogenization heat treatment, forward extruding the alloy into round bars with the diameter of 60 according to the extrusion ratio of 25, the extrusion temperature of 500 ℃ and the extrusion speed of 3mm/s through an online water quenching process, sawing into fixed-length short bars, heating the short bars to 480 ℃ and preserving heat for 25 minutes, carrying out roll forging, bending, preforming and finish forging to obtain a control arm forging for a vehicle, and finally carrying out T6 heat treatment on the forging.

Example 3

A production method of a 6082 aluminum alloy vehicle forging containing different Fe contents comprises the following operations:

6082 aluminum alloy materials with different Fe contents as listed in table 5 were used. The forging piece for the vehicle multi-connecting rod is used as a product and is produced according to the following process: after the alloys are cast into ingots with the diameter of 425mm through DC casting, the ingots are reversely extruded into special-shaped extrusion bars according to the extrusion ratio of 69.1, the extrusion temperature of 450 ℃ and the extrusion speed of 3.5mm/s by an online gas quenching process, then the special-shaped extrusion bars are heated to 350 ℃ at the speed of 3 ℃/min, are insulated for 8 hours, are heated to 570 ℃ at the speed of 3 ℃/min, are insulated for 6 hours, are cooled to 350 ℃ at the speed of 8 ℃/min, are cooled to room temperature at the speed of 4 ℃/min, are subjected to homogenization heat treatment (the homogenization heat treatment process-2) and are then sliced, the sliced is heated to 490 ℃ and are insulated for 15min, and then are forged into a vehicle control arm forging (shown in figure 7), and finally, the forging is subjected to T6 heat treatment.

The forgings for each alloy car obtained under different process conditions are shown in table 6.

Table 5 composition (wt.%) of 6082 aluminum alloy with different Fe contents

TABLE 6 mechanical and fatigue Properties of 6082 aluminium alloys with different Fe contents

The conventional production method described in table 6 is performed according to the production flow of fig. 1, and the specific process is as follows: after casting the alloy into ingots with the diameter of 300mm through DC casting, heating to 560 ℃ according to the speed of 3 ℃/min, preserving heat for 9 hours, cooling to room temperature at the speed of 2-3 ℃/min, carrying out homogenization heat treatment, positively extruding the alloy into round bars with the diameter of 60 according to the extrusion ratio of 25, the extrusion temperature of 500 ℃ and the extrusion speed of 3mm/s through an online water quenching process, sawing into fixed-length short bars, heating the short bars to 480 ℃ and preserving heat for 25 minutes, carrying out roll forging, bending, preforming and finish forging to obtain a control arm forging for a vehicle, and finally carrying out T6 heat treatment on the forging.

Claims (9)

1. The production method of the 6xxx aluminum alloy vehicle forging is characterized by comprising the following production procedures: smelting, casting, extruding a special-shaped rod, homogenizing heat treatment, sawing and forging, solution treatment and aging treatment.

2. The method of producing a forging for a 6xxx aluminum alloy vehicle according to claim 1, wherein the extrusion method for extruding the shaped rod is forward extrusion or backward extrusion.

3. The method of producing a forging for a 6xxx aluminum alloy vehicle according to claim 1 or 2, characterized in that the extrusion ratio is 30 to 70.

4. The method of producing a forging for a 6xxx aluminum alloy vehicle according to claim 1 or 2, wherein the extrusion process is: the extrusion temperature is 400-480 ℃, the extrusion speed is 3.5-6 mm/s, and the online air quenching or water quenching is performed.

5. The method of producing a forging for a 6xxx aluminum alloy vehicle according to claim 1, wherein the homogenizing heat treatment process for the Mn-free 6xxx aluminum alloy is: heating to 550-570 ℃ at a heating rate of 1-5 ℃/min, preserving heat for 4-6 hours, cooling to 350 ℃ at a speed of not less than 8 ℃/min, and cooling to room temperature at a speed of not less than 4 ℃/min.

6. The method of producing a forging for a 6xxx aluminum alloy vehicle according to claim 1, wherein the homogenizing heat treatment process for the Mn-containing 6xxx aluminum alloy is: heating to 300-355 ℃ at a speed of not more than 3 ℃/min, preserving heat for 6-8 hours, heating to 550-570 ℃ at a speed of not more than 3 ℃/min, preserving heat for 4-6 hours, cooling to 350 ℃ at a speed of not less than 8 ℃/min, and cooling to room temperature at a speed of not less than 4 ℃/min.

7. The method of producing a 6xxx aluminum alloy vehicular forging in accordance with claim 1, wherein the vehicular forging 6xxx aluminum alloy has an Fe content tolerance of 0.5wt.%.

8. The method of producing a 6xxx aluminum alloy vehicular forging in accordance with claim 1, wherein the 6xxx aluminum alloy is a high strength 6xxx aluminum alloy material having an alloy composition of: (0.9 to 1.1 wt.%) Mg, (1.1 to 1.3 wt.%) Si, (0.5 to 0.7 wt.%) Cu, (0.5 to 0.7 wt.%) Mn, (0.1 to 0.3 wt.%) Cr, (less than 0.5 wt.%) Fe, the balance consisting of Al and unavoidable impurity elements.

9. The method of producing a 6xxx aluminum alloy vehicular forging in accordance with claim 8, wherein the high strength and toughness 6xxx aluminum alloy material is composed of a composition satisfying the condition Cu (wt.%) - [ Si (wt.%) -Mg (wt.%) ] = 0.4wt.%.

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