Automobile part high-strength steel sheet and method for manufacturing the same

Abstract

The application relates to an automobile part high-strength steel plate and a manufacturing method thereof, and belongs to the technical field of automobile steel materials, and comprises the following steps: first, pickling a steel plate, immediately water quenching after heating, and then carrying out dual-phase tempering treatment to obtain a first steel plate; then, cold rolling the first steel plate at room temperature, hot stamping forming, and then carrying out laser surface treatment to obtain the automobile part high-strength steel plate. Through adding Ti, Nb, V and Zr and other micro-alloy elements in the steel plate raw material, the application effectively refines the grains and enhances the formation of carbides, Ti promotes grain refinement, Nb can further reduce the phase transition temperature, V and Zr refine the grains and form carbides, so that the tensile strength and toughness of the steel are improved, and through the operations of heating, water quenching, dual-phase tempering treatment, cold rolling, hot stamping forming and laser surface treatment, the high-strength steel plate with high strength and excellent low-temperature performance is synergistically prepared, and the modern industrial demand is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobile steel materials, and relates to a high-strength steel plate for automobile parts and a manufacturing method thereof. BACKGROUND

[0002] A high-strength steel plate is a kind of steel material with high strength and good toughness. Through special alloy composition design and heat treatment process, the steel material has a strength far higher than that of ordinary steel material while maintaining a certain toughness. The high-strength steel material is called so because its strength indicators (such as yield strength and tensile strength) are much higher than those of ordinary steel material. These strength indicators are important parameters for measuring the deformation resistance and fracture resistance of steel material under stress. Compared with ordinary steel material, the high-strength steel material can maintain stability under greater stress and is not prone to plastic deformation or fracture.

[0003] In modern automobile manufacturing, the plate material of automobile parts is usually mainly high-strength steel, aluminum alloy and composite material. High-strength steel, due to its excellent strength and toughness, has become an important part of vehicle body structure and is widely used in automobile parts such as vehicle body frame, door and collision protection system.

[0004] Although high-strength steel plates play an important role in automobile manufacturing, the toughness of high-strength steel plates is relatively low, especially in low-temperature environments, which is prone to brittle fracture, affecting the service life and safety of the parts. Secondly, the formability of high-strength steel plates is lower than that of traditional steel materials, and cracks or deformations may occur during the forming process, which limits the actual application and increases the manufacturing difficulty and cost. SUMMARY

[0005] The purpose of the present application is to provide a high-strength steel plate for automobile parts and a manufacturing method thereof. The present application adds micro-alloying elements such as Ti, Nb, V and Zr to the steel plate raw material, effectively refines the grains and enhances the formation of carbides, thereby improving the tensile strength and toughness of the steel. With the help of heating, water quenching, dual-phase tempering, cold rolling, hot stamping forming and laser surface treatment, a high-strength steel plate with high strength and excellent low-temperature performance is prepared, which meets the needs of modern industry.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A preparation method of a high-strength steel plate for automobile parts, the preparation method of the high-strength steel plate for automobile parts comprising the following steps:

[0008] (1) Pickling the steel plate, immediately water quenching after heating, and then performing dual-phase tempering to obtain a first steel plate;

[0009] (2) Cold rolling the first steel plate at room temperature, hot stamping forming, and then performing laser surface treatment to obtain the high-strength steel plate for automobile parts.

[0010] Further, the raw material of the steel plate in step (1) comprises C: 0.08-0.12%, Mn: 1.2-1.3%, Mg: 0.02-0.04%, Si: 0.28-0.32%, Cr: 0.28-0.32%, Ti: 0.06-0.1%, Nb: 0.03-0.04%, V: 0.05-0.07%, Zr: 0.015-0.025%, B: 0.001-0.003% and the balance of Fe in percentage by mass.

[0011] Further, the pickling in step (1) uses a sulfuric acid solution with a concentration of 8-12%, and the pickling time is 5-15 min.

[0012] Further, the water quenching immediately after heating in step (1) refers to heating to 880-920℃ and keeping for 20-30 min, and then quenching into 5℃ water.

[0013] Further, the duplex tempering treatment in step (1) refers to tempering the water quenched steel plate at 450-550℃, and the tempering time is 30-60 min.

[0014] Further, the deformation rate of the cold rolling in step (2) is controlled at 70-85%.

[0015] Further, the hot stamping forming in step (2) refers to heating the cold rolled steel plate to 850-900℃, heating for 6-10 min, and then transferring into a preheated mold at 150-300℃ for stamping forming, keeping for 6-10 s, and then cooling to room temperature at a cooling rate of 30-40℃ / s.

[0016] Further, the laser surface treatment in step (2) refers to using a laser with a power of 900-1100W to perform surface treatment to a depth of 0.2mm.

[0017] The beneficial effects of the present application are as follows:

[0018] (1) The present application adds Ti, Nb, V and Zr in the raw material of the steel plate, wherein Ti can promote grain refinement, improve the tensile strength of the steel and the toughness at low temperature; Nb can further reduce the phase transition temperature, so that the material can still maintain good toughness at low temperature; V and Zr further improve the strength of the steel plate by refining the grain and forming carbides.

[0019] (2) The application quickly forms high-strength martensite structure through the heating and water quenching steps, then softens part of the martensite and precipitates fine carbides by means of the dual-phase tempering treatment, thereby not only reducing the internal stress of the steel, but also improving the toughness and ductility thereof; the combination of the cold rolling and hot stamping forming steps not only improves the strength and surface quality of the steel, but also ensures good processing performance in the forming process; in addition, the application finally adopts laser surface treatment, and a high-hardness hardened layer is formed on the surface, thereby significantly enhancing the wear resistance of the steel plate; the synergistic treatment of the steps prepares a high-strength steel plate with high strength, good low-temperature performance and low cracking or deformation, thereby meeting the needs of modern industry. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the application to achieve the predetermined application purposes, the specific embodiments, structures, features and effects according to the application are described in detail below in combination with examples.

[0021] Example 1

[0022] A preparation method of an automobile part high-strength steel plate, the preparation method of the automobile part high-strength steel plate of the embodiment comprises the following steps:

[0023] (1) pickling a steel plate, immediately water quenching after heating, and then performing dual-phase tempering treatment to obtain a first steel plate;

[0024] (2) cold rolling the first steel plate at room temperature, hot stamping forming, and then performing laser surface treatment to obtain an automobile part high-strength steel plate.

[0025] The raw material of the steel plate in step (1) of the embodiment comprises C: 0.08%, Mn: 1.2%, Mg: 0.02%, Si: 0.28%, Cr: 0.28%, Ti: 0.06%, Nb: 0.03%, V: 0.05%, Zr: 0.015%, B: 0.001% and the balance of Fe according to the mass percentage.

[0026] The pickling in step (1) of the embodiment uses a sulfuric acid solution with a concentration of 8%, and the pickling time is 5 min.

[0027] The immediate water quenching after heating in step (1) of the embodiment refers to first heating to 880℃ and maintaining for 20 min, and then quenching into 5℃ water.

[0028] The dual-phase tempering treatment in step (1) of the embodiment refers to tempering the water quenched steel plate at 450℃, and the tempering time is 30 min.

[0029] The deformation rate of the cold rolling in step (2) of the embodiment is controlled at 70%.

[0030] The hot stamping forming in step (2) of the embodiment refers to heating the cold-rolled steel plate to 850℃, transferring into the preheated mold to 150℃ after heating for 6 min to perform stamping forming, and then cooling to room temperature at a cooling rate of 30℃ / s after holding for 6 s.

[0031] The laser surface treatment in step (2) of the embodiment refers to using a laser of 900W to perform surface treatment to a depth of 0.2mm.

[0032] Embodiment 2

[0033] A preparation method of an automobile part high-strength steel plate, the preparation method of the automobile part high-strength steel plate of the embodiment comprises the following steps:

[0034] (1) pickling the steel plate, immediately water quenching after heating, and then performing dual-phase tempering treatment to obtain a first steel plate;

[0035] (2) cold rolling the first steel plate at room temperature, hot stamping forming, and then performing laser surface treatment to obtain the automobile part high-strength steel plate.

[0036] The raw material of the steel plate in step (1) of the embodiment comprises C: 0.12%, Mn: 1.3%, Mg: 0.04%, Si: 0.32%, Cr: 0.32%, Ti: 0.1%, Nb: 0.04%, V: 0.07%, Zr: 0.025%, B: 0.003%, and the balance of Fe according to the mass percentage.

[0037] The pickling in step (1) of the embodiment uses a sulfuric acid solution with a concentration of 12%, and the pickling time is 15 min.

[0038] The immediate water quenching after heating in step (1) of the embodiment refers to first heating to 920℃ and holding for 30 min, and then quenching into 5℃ water.

[0039] The dual-phase tempering treatment in step (1) of the embodiment refers to tempering the water quenched steel plate at 550℃, and the tempering time is 60 min.

[0040] The deformation rate of the cold rolling in step (2) of the embodiment is controlled at 85%.

[0041] The hot stamping forming in step (2) of the embodiment refers to heating the cold-rolled steel plate to 900℃, transferring into the preheated mold to 300℃ after heating for 10 min to perform stamping forming, and then cooling to room temperature at a cooling rate of 40℃ / s after holding for 10 s.

[0042] The laser surface treatment in step (2) of the embodiment refers to using a laser of 1100W to perform surface treatment to a depth of 0.2mm.

[0043] Embodiment 3

[0044] The application discloses a preparation method of an automobile part high-strength steel plate.

[0045] (1) pickling a steel plate, immediately water quenching after heating, and then performing a dual-phase tempering treatment to obtain a first steel plate;

[0046] (2) cold rolling the first steel plate at room temperature, hot stamping forming, and then performing a laser surface treatment to obtain the automobile part high-strength steel plate.

[0047] The raw material of the steel plate in step (1) of the embodiment comprises, in percentage by mass, C: 0.1%, Mn: 1.25%, Mg: 0.03%, Si: 0.3%, Cr: 0.3%, Ti: 0.08%, Nb: 0.035%, V: 0.06%, Zr: 0.02%, B: 0.002%, and the balance of Fe.

[0048] The pickling in step (1) of the embodiment uses a sulfuric acid solution with a concentration of 10%, and the pickling time is 10 min.

[0049] The immediate water quenching after heating in step (1) of the embodiment refers to heating to 900 DEG C first and maintaining for 25 min, and then quenching into 5 DEG C water.

[0050] The dual-phase tempering treatment in step (1) of the embodiment refers to tempering the water quenched steel plate at 500 DEG C, and the tempering time is 45 min.

[0051] The deformation rate of the cold rolling in step (2) of the embodiment is controlled at 77.5%.

[0052] The hot stamping forming in step (2) of the embodiment refers to heating the cold rolled steel plate to 875 DEG C, heating for 8 min, and then transferring into a die preheated to 225 DEG C to perform stamping forming, maintaining for 8 s, and then cooling to room temperature at a cooling rate of 35 DEG C / s.

[0053] The laser surface treatment in step (2) of the embodiment refers to using a 1000 W laser to perform surface treatment to a depth of 0.2 mm.

[0054] Comparative Example 1

[0055] On the basis of Example 3, Ti in the raw material of the steel plate is removed, and an equal weight of Fe is used to replace Ti, and the other conditions are the same as those in Example 3.

[0056] Comparative Example 2

[0057] On the basis of Example 3, Nb in the raw material of the steel plate is removed, and an equal weight of Fe is used to replace Nb, and the other conditions are the same as those in Example 3.

[0058] Comparative Example 3

[0059] On the basis of Example 3, V in the steel plate raw material was removed and replaced with an equal weight of Zr, and the other conditions were consistent with Example 3.

[0060] Comparative Example 4

[0061] On the basis of Example 3, Zr in the steel plate raw material was removed and replaced with an equal weight of V, and the other conditions were consistent with Example 3.

[0062] Comparative Example 5

[0063] On the basis of Example 3, the temperature and time of the dual-phase tempering treatment in step (1) were changed to 560°C and 20 min, and the other conditions were consistent with Example 3.

[0064] Comparative Example 6

[0065] On the basis of Example 3, the temperature and time of the dual-phase tempering treatment in step (1) were changed to 430°C and 20 min, and the other conditions were consistent with Example 3.

[0066] Comparative Example 7

[0067] On the basis of Example 3, the cold rolling deformation rate in step (1) was controlled at 60%, and the other conditions were consistent with Example 3.

[0068] Comparative Example 8

[0069] On the basis of Example 3, the cold rolling deformation rate in step (2) was controlled at 90%, and the other conditions were consistent with Example 3.

[0070] Comparative Example 9

[0071] On the basis of Example 3, the laser surface treatment in step (2) was removed, and the other conditions were consistent with Example 3.

[0072] The high-strength steel plates prepared in Examples 1-3 and Comparative Examples 1-9 were used as samples, the samples were processed into dumbbell shapes, the fracture elongation of the samples was tested according to GB / T 228.1-2010, each sample was tested 3 times and the average value was taken, and the results are shown in Table 1; the low-temperature impact performance of the samples was tested according to GB / T 229-2020, the samples were processed into long strip-shaped samples with a V-shaped notch, the size was about 55mmx10mmx10mm, the notch depth was 2mm, the samples were placed in a low-temperature box and pre-cooled to -60°C, then taken out and impacted using a pendulum within 5s, the fracture of the samples was observed, and the results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] As shown in Table 1, the high-strength steel plates prepared by the embodiments 1-3 of the present application have excellent mechanical properties, and no fracture occurs under impact at-60℃, and have good application prospect.

[0077] The above description is only the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as the above preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any indirect modification, equivalent change and modification of the above embodiments, which are made according to the technical essence of the present application, still belong to the scope of the technical solution of the present application.

Claims

1. A method for manufacturing a high-strength steel sheet for an automobile part, characterized by: The preparation method of the automobile part high-strength steel plate comprises the following steps: (1) pickling the steel plate, immediately water quenching after heating, and then performing dual-phase tempering treatment to obtain a first steel plate; the immediately water quenching after heating refers to first heating to 880-920 ℃ and maintaining for 20-30 min, and then quenching into 5 ℃ water; (2) cold rolling the first steel plate at room temperature, hot stamping forming, and then performing laser surface treatment to obtain the automobile part high-strength steel plate; the deformation rate of the cold rolling is controlled to be 77.5-85%; the hot stamping forming refers to heating the cold-rolled steel plate to 850-875 ℃, heating for 6-10 min, and then transferring into a mold preheated to 150-300 ℃ to perform stamping forming, and then cooling to room temperature at a cooling rate of 30-40 ℃ / s after maintaining for 6-10 s; the laser surface treatment refers to using a laser with a power of 900-1100 W to perform surface treatment to a depth of 0.2 mm; In step (1), the raw material of the steel plate comprises, according to mass percentage, C: 0.08-0.12%, Mn: 1.2-1.3%, Mg: 0.02-0.04%, Si: 0.28-0.32%, Cr: 0.28-0.32%, Ti: 0.06-0.1%, Nb: 0.03-0.04%, V: 0.05-0.07%, Zr: 0.015-0.025%, B: 0.001-0.003%, and the balance of Fe; the dual-phase tempering treatment refers to tempering the water-quenched steel plate at 450-550 ℃, and the tempering time is 30-60 min.

2. The method of claim 1, wherein the method further comprises: In step (1), the pickling uses a sulfuric acid solution with a concentration of 8-12%, and the pickling time is 5-15 min. ​

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