阅读说明：本技术 一种620MPa级汽车桥壳冷冲压钢板及其制备方法 (620MPa grade automobile axle housing cold stamping steel plate and preparation method thereof ) 是由 郭营利 姜军 景伟德 余伟 程磊 刘国良 李金泽 董建军 贾为峰 杨新龙 于鹏 于 2020-07-01 设计创作，主要内容包括：本发明属于材料制造领域,具体涉及一种620MPa级汽车桥壳冷冲压钢板及其制备方法,其中钢板的化学成分按如下质量分数配制：C≤0.10％、Si≤0.45％、Mn≤1.60％、P≤0.010％、S≤0.005％、V≤0.060％、Nb≤0.060％、Als≤0.035％,余量为Fe。本发明通过桥壳制造材料的强度及综合性能指标的提升,屈服强度≥520MPa,抗拉强度≥620MPa,延伸率≥23％,已经超越了标准GB/T33166《汽车桥壳用热轧钢板和钢带》中最高级别钢种QK460的要求,强度提升可实现桥壳减重14.3％,同时桥壳生产改变了传统的热冲压成型工艺,采用免加热的冷冲压成型工艺,减低了桥壳的生产制造成本,节能环保。本发明钢板强韧性匹配较好,焊接性能优异,制造的桥壳刚度好,疲劳寿命超出桥壳要求50％。(The invention belongs to the field of material manufacturing, and particularly relates to a 620 MPa-grade automobile axle housing cold stamping steel plate and a preparation method thereof, wherein the steel plate comprises the following chemical components in percentage by mass: less than or equal to 0.10 percent of C, less than or equal to 0.45 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.060 percent of V, less than or equal to 0.060 percent of Nb, less than or equal to 0.035 percent of Als, and the balance of Fe. According to the invention, through the improvement of the strength and comprehensive performance indexes of the axle housing manufacturing material, the yield strength is more than or equal to 520MPa, the tensile strength is more than or equal to 620MPa, and the elongation is more than or equal to 23%, the requirement of the highest grade steel grade QK460 in the standard GB/T33166 hot rolled steel plate and steel belt for the automobile axle housing is exceeded, the weight reduction of the axle housing can be realized by 14.3% through the strength improvement, meanwhile, the traditional hot stamping forming process is changed in the axle housing production, the heating-free cold stamping forming process is adopted, the production and manufacturing cost of the axle housing is reduced, and the energy. The steel plate has good obdurability matching and excellent welding performance, and the manufactured axle housing has good rigidity and the fatigue life exceeds the requirement of the axle housing by 50 percent.)

1. The 620 MPa-grade cold-stamped steel plate for the automobile axle housing is characterized by being prepared from the following chemical components in percentage by mass: less than or equal to 0.10 percent of C, less than or equal to 0.45 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.060 percent of V, less than or equal to 0.060 percent of Nb, less than or equal to 0.035 percent of Als, and the balance of Fe.

2. The 620 MPa-grade cold-stamped steel plate for the automobile axle housing is characterized by comprising the following steps of:

s1: smelting in a converter: smelting by adopting a 120t top-bottom combined blown converter; the smelting period is 24-28 minutes; the alloy smelted by the converter adopts 300Kg of low-carbon ferromanganese, 250 Kg of steel sand aluminum and 50Kg to 100Kg of aluminum iron; slag is prevented from falling in the tapping process; the tapping temperature of the converter is 1620-1630 ℃;

s2: refining in an LF furnace: adopting a white slag system with alkalinity of 6-8 and white slag retention time of more than or equal to 15 min; argon blowing is carried out in the whole process, and the tapping temperature is 1570-; 20-50Kg of steel slag calcium preparation; adding 150-200m aluminum wire;

s3: continuous casting: special covering slag is adopted for continuous casting; the whole process is poured under the protection of nitrogen; the water cooling system adopts a weak water cooling mechanism; cutting the continuous casting billets and then putting the cut continuous casting billets into a slow cooling pit for slow cooling for 48 hours; the pulling speed is 0.8-1.0 m/min;

s4: heating: heating in a furnace in a weakly reducing atmosphere; a three-stage heating system: the second addition section is 1000-;

s5: rolling: rolling by adopting a TMCP (thermal mechanical control processing) process, wherein the initial rolling temperature of the billet in the first stage is 1050-1080 ℃, the thickness of the billet to be rolled is 1.5-3 times of the thickness of a finished product, the initial rolling temperature in the second stage is 880-920 ℃, and the final rolling temperature is 700-780 ℃; the thickness dimension precision of the steel plate is controlled to strictly control the service quantity of the rolling roller, the rolling in the middle service period of the roller is ensured, and the precision control range is 0-0.4 mm; removing scale by high-pressure water of the three secondary rolling mills to reduce the thickness of secondary oxidized iron scales on the surface;

s6: and (3) cooling: cooling by adopting aerial fog, wherein the ratio of the upper water amount to the lower water amount is 1: 1.3; the roller speed is 0.8-1.2m/s, the start-cooling temperature is 700 ℃ and 760 ℃, the cooling speed is 5-12 ℃/s, and the final-cooling temperature is 630-680 ℃. Sectional cooling is adopted, water is not added in the middle section, and the pearlite structure content is ensured.

Background

In recent years, environmental protection is increasingly emphasized by subsequent development, and all industries actively develop research in the direction of environmental protection to promote the development of the industries. The light weight of the automobile is an effective way for reducing the oil consumption of the automobile, and the reduction of the oil consumption has important significance for reducing the energy consumption and the environmental pollution.

The reduction accessible of the whole weight of car adopts high strength automobile steel to realize, and make full use of high strength material realizes the thickness attenuate under the circumstances that the assurance design bore a weight of to realize the lightweight. The automobile axle housing is an important bearing part of an automobile, particularly an automobile drive axle at the tail end of a transmission system, is a main force transmission part and a bearing part, provides the differential function of left and right driving wheels of the automobile, and simultaneously, the drive axle is required to bear vertical force, transverse force and longitudinal force.

The traditional steel for the axle housing and the axle housing manufacturing process are characterized in that: the traditional axle housing is made of materials with low strength, thick thickness and heavy weight. Secondly, the traditional axle housing production process adopts hot stamping forming, the plate needs to be heated to 820 and 920 ℃, the process equipment is added, the energy consumption is increased, and the environment is not protected. Traditional low-strength level axle housing steel generally adopts the hot continuous rolling production line to produce, and the product width specification can not carry out the production of customization width according to different specification axle housings, is unfavorable for improving the sheet material utilization ratio.

Disclosure of Invention

In view of the above, the invention aims to provide a 620 MPa-grade cold-stamped steel plate for an automobile axle housing and a preparation method thereof, so as to solve the defects of the prior art.

The technical scheme adopted by the invention is as follows:

the 620 MPa-grade cold stamping steel plate for the automobile axle housing and the preparation method thereof are characterized in that the steel plate is prepared from the following chemical components in percentage by mass: less than or equal to 0.10 percent of C, less than or equal to 0.45 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.060 percent of V, less than or equal to 0.060 percent of Nb, less than or equal to 0.035 percent of Als, and the balance of Fe.

The 620 MPa-grade automobile axle housing cold stamping steel plate and the preparation method thereof provided by the invention can be further set as that the preparation method of the steel plate comprises the following steps:

s1: smelting in a converter: smelting by adopting a 120t top-bottom combined blown converter; the smelting period is 24-28 minutes; the alloy smelted by the converter adopts 300Kg of low-carbon ferromanganese, 250 Kg of steel sand aluminum and 50Kg to 100Kg of aluminum iron; slag is prevented from falling in the tapping process; the tapping temperature of the converter is 1620-1630 ℃;

s2: refining in an LF furnace: adopting a white slag system with alkalinity of 6-8 and white slag retention time of more than or equal to 15 min; argon blowing is carried out in the whole process, and the tapping temperature is 1570-; 20-50Kg of steel slag calcium preparation; adding 150-200m aluminum wire;

s3: continuous casting: special covering slag is adopted for continuous casting; the whole process is poured under the protection of nitrogen; the water cooling system adopts a weak water cooling mechanism; cutting the continuous casting billets and then putting the cut continuous casting billets into a slow cooling pit for slow cooling for 48 hours; the pulling speed is 0.8-1.0 m/min;

s4: heating: heating in a furnace in a weakly reducing atmosphere; a three-stage heating system: the second addition section is 1000-;

s5: rolling: rolling by adopting a TMCP (thermal mechanical control processing) process, wherein the initial rolling temperature of the billet in the first stage is 1050-1080 ℃, the thickness of the billet to be rolled is 1.5-3 times of the thickness of a finished product, the initial rolling temperature in the second stage is 880-920 ℃, and the final rolling temperature is 700-780 ℃; the thickness dimension precision of the steel plate is controlled to strictly control the service quantity of the rolling roller, the rolling in the middle service period of the roller is ensured, and the precision control range is 0-0.4 mm; removing scale by high-pressure water of the three secondary rolling mills to reduce the thickness of secondary oxidized iron scales on the surface;

s6: and (3) cooling: cooling by adopting aerial fog, wherein the ratio of the upper water amount to the lower water amount is 1: 1.3; the roller speed is 0.8-1.2m/s, the start-cooling temperature is 700 ℃ and 760 ℃, the cooling speed is 5-12 ℃/s, and the final-cooling temperature is 630-680 ℃. Sectional cooling is adopted, water is not added in the middle section, and the pearlite structure content is ensured.

Advantageous effects

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. compared with the traditional axle housing, the material adopted by the axle housing has high strength, breaks through the level of the GB/T33166 hot rolled steel plate and steel strip for the automobile axle housing with the maximum standard of 460MPa, has the material yield strength of more than or equal to 520MPa, the tensile strength of more than or equal to 620MPa, the extension of more than or equal to 23 percent, the impact of more than or equal to 120J, and has strong weldability and good comprehensive performance, and the material is brand-new steel for cold stamping of the automobile axle housing.

2. The material can be directly used for producing the automobile axle housing by adopting a cold stamping heating-free forming process, the heating process and the hot stamping process of the traditional axle housing hot stamping forming production are shortened, and the production and manufacturing cost of the axle housing is reduced. The traditional axle housing needs to be heated to 820 and 920 ℃ before being manufactured and stamped, and the process equipment is added, so that the energy consumption is increased, and the environment is polluted.

3. Traditional low-strength level steel for axle housing generally adopts hot continuous rolling production line production, and product width specification is limited, can not carry out customization width production according to different specification axle housings, is unfavorable for improving the sheet material utilization ratio. The steel for the cold stamping axle housing is produced by adopting a medium plate production line, the problem of width limitation of hot continuous rolling is solved, flexible customized width production can be realized, and the utilization rate of materials is improved.

4. The high-strength material is adopted to replace the low-strength material, the cold stamping heating-free forming process replaces the hot forming process, and the thickness of the axle housing plate can be reduced from 14mm to 12mm and reduced by 14.3% under the condition of ensuring the same safety coefficient. The automobile fuel tank conforms to the development trend of light weight of automobiles and reduces fuel consumption.

The method has popularization significance, overcomes the limitation of single width specification of a hot continuous rolling production line, exerts the advantage of customization of the width specification of a medium plate production line, improves the utilization rate of steel plates of axle housing manufacturing enterprises, increases the selection range of materials and suppliers of automobile manufacturing enterprises, promotes the manufacturing process of gradually replacing cold stamping heating-free forming by hot stamping forming in the industry, and promotes the progress of the traditional axle housing material and the processing and manufacturing method.

Drawings

FIG. 1 is a metallographic structure diagram of a stamped steel sheet according to the invention;

FIG. 2 is a metallographic structure diagram of a stamped steel sheet according to the invention;

FIG. 3 is a partial parameter information diagram of a stamped steel sheet according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention mainly adopts the following technical steps:

the process flow comprises the following steps: converter smelting → refining → continuous casting → stacking of slabs, cutting and sizing → inspection of blanks → heating in furnace of slabs → descaling → rolling → cooling → straightening → cooling bed → inspection of surface turning plate → bilateral shear → sizing shear, sampling → marking → warehousing.

The main technical content is as follows:

(1) the chemical components are prepared according to the following mass fractions: less than or equal to 0.10 percent of C, less than or equal to 0.45 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.060 percent of V, less than or equal to 0.060 percent of Nb, less than or equal to 0.035 percent of Als, and the balance of Fe.

(2) Key process control

The method comprises the following steps: smelting in a converter

Smelting by adopting a 120t top-bottom combined blown converter; the smelting period is 24-28 minutes; the alloy smelted by the converter adopts 300Kg of low-carbon ferromanganese, 250 Kg of steel sand aluminum and 50Kg to 100Kg of aluminum iron; slag is prevented from falling in the tapping process; the tapping temperature of the converter is 1620-1630 ℃.

Secondly, the step of: refining in LF furnace

Adopting a white slag system with alkalinity of 6-8 and white slag retention time of more than or equal to 15 min; argon blowing is carried out in the whole process, and the tapping temperature is 1570-; 20-50Kg of steel slag calcium preparation; the aluminum line was added at 150-200 m.

③: continuous casting

Special covering slag is adopted for continuous casting; the whole process is poured under the protection of nitrogen; the water cooling system adopts a weak water cooling mechanism; cutting the continuous casting billets and then putting the cut continuous casting billets into a slow cooling pit for slow cooling for 48 hours; the pulling speed is 0.8-1.0 m/min. Blank specification 220 x 1580 x L (thickness, width, length)

Fourthly, the method comprises the following steps: heating of

Heating in a furnace in a weakly reducing atmosphere; a three-stage heating system: the second addition section is 1000-.

Fifthly: rolling of

Rolling by adopting a TMCP (thermal mechanical control processing) process, wherein the initial rolling temperature of the billet in the first stage is 1050-1080 ℃, the thickness of the billet to be rolled is 1.5-3 times of the thickness of a finished product, the initial rolling temperature in the second stage is 880-920 ℃, and the final rolling temperature is 700-780 ℃; the thickness dimension precision of the steel plate is controlled to strictly control the service quantity of the rolling roller, the rolling in the middle service period of the roller is ensured, and the precision control range is 0-0.4 mm; and (3) descaling by using high-pressure water of the three secondary rolling mills to reduce the thickness of secondary oxidized iron scales on the surface.

Sixthly, the method comprises the following steps: cooling down

Cooling by adopting aerial fog, wherein the ratio of the upper water amount to the lower water amount is 1: 1.3; the roller speed is 0.8-1.2m/s, the start-cooling temperature is 700 ℃ and 760 ℃, the cooling speed is 5-12 ℃/s, and the final-cooling temperature is 630-680 ℃. Sectional cooling is adopted, water is not added in the middle section, and the pearlite structure content is ensured.

According to the invention, through the improvement of the strength and comprehensive performance indexes of the axle housing manufacturing material, the yield strength is more than or equal to 520MPa, the tensile strength is more than or equal to 620MPa, the elongation is more than or equal to 23%, and the impact energy is more than or equal to 120J, the requirements of the highest-grade steel grade QK460 in the standard GB/T33166 hot rolled steel plate and steel strip for automobile axle housings are exceeded, the strength improvement can realize the weight reduction of the axle housing by 14.3%, meanwhile, the traditional hot stamping forming process is changed in the axle housing production, and the heating-free cold stamping forming process is adopted, so that the production and manufacturing cost of the axle housing. The steel plate has good obdurability matching and excellent welding performance, and the manufactured axle housing has good rigidity and the fatigue life exceeds the requirement of the axle housing by 50 percent.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.