A manufacturing process of a cab rollover bracket for heavy truck

Abstract

The application discloses a preparation process of a new material cab turnover support for a heavy truck, and the cab turnover support is made of a new alloy material by adopting a temperature control rolling and air quenching and partitioning heat treatment process.The Ti element is added in the alloy composition, and compared with other alloy elements, the carbide of the Ti element has super-high hardness; the process of temperature control rolling is adopted, a large number of dislocations are introduced into austenite, and austenite grains are refined; the heat treatment process of air cooling quenching and partitioning is adopted, a kind of wear-resistant steel with a complex structure of martensite + austenite is obtained, the strength of the steel plate is improved, and good toughness and plasticity are simultaneously achieved.Compared with the cab turnover support made of the DC04 steel by adopting the cold continuous rolling and annealing heat treatment in the prior art, the cab turnover support has high strength and wear resistance, the mechanical property is improved by nearly 4 times, and the light weight requirement of the cab turnover support is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy truck lightweight technology, in particular to a preparation process of a new material cab rollover bracket for heavy truck. BACKGROUND

[0002] The truck head is composed of a frame and a cab, the cab is installed on the frame, and the engine and other components are installed on the frame below the cab, therefore, in order to facilitate maintenance, the cab needs to be connected to the frame through a rollover bracket, and the rollover bracket can realize the rollover of the cab on the frame, so as to expose the engine and other components.

[0003] As a key energy-saving technology, the automobile lightweight technology is of great significance for heavy commercial vehicles to achieve energy saving and emission reduction. The cab rollover bracket, as a key component connecting the cab and the frame, has strict requirements on strength and wear resistance. The cab rollover bracket used at present is made of DC04 steel by ordinary cold continuous rolling and annealing process, and has low strength and wear resistance. Only by increasing the thickness of the material can the use requirements of the cab rollover bracket be met, but at the same time, the weight of the cab is also increased, which cannot meet the lightweight requirements of the cab rollover bracket. SUMMARY

[0004] In view of the above problems, the present application provides a preparation process of a new material cab rollover bracket for heavy truck. The cab rollover bracket made of new alloy material by temperature control rolling and air quenching-partitioning heat treatment process has the advantages of high strength and good wear resistance, and at the same time, the weight is reduced, which meets the lightweight requirements of the cab rollover bracket.

[0005] In order to achieve the above purpose, the present application provides a preparation process of a new material cab rollover bracket for heavy truck, characterized by comprising the following steps:

[0006] (1) Chemical composition design of alloy steel

[0007] The chemical composition (wt.%) of the alloy steel is: carbon 0.28-0.32%, manganese 1.8-2.2%, titanium 0.4-0.6%, silicon 1.0-1.4%, molybdenum 0.28-0.32%, copper 0.25-0.35%, nickel 0.8-1.0%, chromium 0.28-0.32%;

[0008] (2) Rolling process

[0009] Put the cut steel plate with a thickness of 60mm into a heat treatment furnace, heat to complete austenitization at 1150-1200℃, and then control the temperature and rolling to 38mm thick at 940-960℃; then control the temperature and rolling to 20mm thick at 840-860℃, and air cool to room temperature;

[0010] (3) Steel plate heat treatment process

[0011] The finished steel plate is heated to 850℃ in a heat treatment furnace for 280-320 seconds, the heat treated steel plate is cooled to 275-285℃ in air, and then is kept in a 275-285℃ salt bath furnace for 24-26 seconds, and then is kept in a 340-360℃ salt bath furnace for 850-950 seconds, and finally is cooled to room temperature in air.

[0012] Preferably, the chemical composition of the alloy material of step (1) is: carbon 0.30%, manganese 2.0%, titanium 0.5%, silicon 1.2%, molybdenum 0.30%, copper 0.30%, nickel 0.9%, and chromium 0.30%.

[0013] Preferably, the rolling process of step (2) (see Table 2) is: the cut steel plate with a thickness of 60mm is put into a heat treatment furnace, complete austenitization is performed at 1180℃ for 1h, and then the steel plate is taken out and controlled rolling at 950℃ to a thickness of 38mm (firstly rolling from a thickness of 60mm to a thickness of 48mm, and then rolling to a thickness of 38mm); and then controlled rolling at 850℃ to a thickness of 20mm (in turn rolling from a thickness of 38mm to a thickness of 29mm, then to a thickness of 22mm, and finally to a thickness of 20mm), and finally air cooling to room temperature.

[0014] Preferably, the steel plate heat treatment process of step (3) (see Table 3) is: the finished steel plate is heated to 850℃ in a heat treatment furnace for 300s, the heat treated steel plate is cooled to 280℃ in air (cooling rate 5℃ / s), and then is kept in a 280℃ salt bath furnace for 25s, and then is kept in a 350℃ salt bath furnace for 900s, and finally is cooled to room temperature in air (cooling rate 5℃ / s). Figure 1

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. The existing cab turnover support adopts DC04 steel, and the present application determines the alloy composition as shown above by using Thermo-Calc simulation calculation with the purpose of uniform carbon content in the organization. Ti element is added in the alloy composition, compared with other alloy elements, the carbide of Ti has ultra-high hardness (3200HV) and very high melting point (3140℃), stable high-temperature performance, and low density (4.93g / cm 3 ), and can obtain a higher volume fraction under the same mass condition, and in the solidification process, C and Ti combine to form TiC, improving the hardness and wear resistance of the steel.

[0017] ​2. Existing cab tilting brackets use a cold continuous rolling process. This invention, through a temperature-controlled rolling process, introduces a large number of dislocations into the austenite, refines the austenite grains, and forms a multi-scale austenite grain morphology. This results in moderate austenite stability, preventing the TRIP effect from occurring too early or too late. At the same time, it refines and homogenizes large-scale TiC grains, improving the elongation and tensile strength of the material, and achieving superior comprehensive mechanical properties.

[0018] 3. Existing cab tilting supports employ annealing heat treatment, while this invention utilizes an air-cooled quenching-partitioning heat treatment process to obtain a wear-resistant steel with a martensitic + austenitic dual-phase microstructure. This improves the steel plate's strength while also exhibiting good toughness and plasticity. A schematic diagram of the microstructure under a scanning electron microscope is shown below. Figure 4 As shown.

[0019] 4. Existing technologies use DC04 steel, cold-rolled and annealed, to obtain the cab tilting bracket. Its mechanical properties are: tensile strength approximately 270 MPa, yield strength approximately 210 MPa, elongation after fracture approximately 36%, and Vickers hardness approximately 75. The cab tilting bracket prepared using the process of this invention has a tensile strength of 980 MPa, a yield strength of 730 MPa, an elongation after fracture of 28%, and a Vickers hardness of 350. Although the elongation after fracture is slightly lower than that of existing technologies, the strength and hardness are increased by nearly four times, thus meeting the requirement for lightweight cab tilting brackets.

[0020] In summary, based on the design of the alloy composition, and through appropriate rolling and heat treatment, this invention has high strength and wear resistance, and its mechanical properties are nearly four times higher than those of the currently used DC04 steel, thus meeting the requirements for lightweight cab tilting brackets. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 : Heat treatment process diagram for alloy steel of this invention;

[0023] Figure 2 Exploded view of a cab tilting bracket for heavy-duty trucks; 1. Left component of the cab tilting bracket; 2. Front reinforcement component of the cab tilting bracket; 3. Rear reinforcement component of the cab tilting bracket; 4. Right component of the cab tilting bracket.

[0024] Figure 3 : Structural diagram of a cab tilting support for heavy-duty trucks;

[0025] Figure 4These are schematic diagrams of tissues under a scanning electron microscope; where (a), (b), (c), and (d) are schematic diagrams of different parts of the tissue (the locations were randomly selected). Detailed Implementation

[0026] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. It should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0027] In this embodiment, the tensile test of mechanical properties is performed in accordance with GB / T228.1-2021 Metallic materials, tensile testing - Part 1: Test method at room temperature; the hardness test of mechanical properties is performed in accordance with GB / T4340.1-2009 Metallic materials, Vickers hardness test - Part 1: Test method.

[0028] Exploded view of the cab tilting support Figure 2 As shown in the diagram, the cab tilting support structure is as follows: Figure 3 As shown. The left part 1 and the right part 4 of the cab tilting bracket are connected to the vehicle frame and the cab lifting device at their front and rear ends by bolts, respectively. The cab is raised and lowered by the extension and retraction of the lifting device. The front reinforcing part 2 and the rear reinforcing part 3 of the cab tilting bracket play a reinforcing role at the connection between the tilting bracket and the vehicle frame and the cab.

[0029] Example 1:

[0030] (1) The chemical composition of the alloy steel is designed as shown in Table 1 below.

[0031] Table 1: Chemical composition of alloy steel / wt.%

[0032]

[0033] (2) Rolling process (as shown in Table 2), including steps S1 to S3:

[0034] S1: Place the cut 60mm thick steel plate into a heat treatment furnace and hold at 1180℃ for 1 hour to fully austenitize it.

[0035] S2: After removal, it is rolled to 38mm under controlled temperature at 950℃; then rolled to 20mm thickness under controlled temperature at 850℃.

[0036] S3: Air is cooled to room temperature.

[0037] Table 2: Rolling Process of New Alloy Materials

[0038]

[0039] (3) a heat treatment process (specifically as shown in Figure 1 The steps include S4-S6:

[0040] S4: put the rolled steel plate into a heat treatment furnace and heat to 850℃ for 300S;

[0041] S5: cool the heat treated steel plate in air to 280℃ (cooling rate 5℃ / S), and then put it into a 280℃ salt bath furnace for 25S, and then into a 350℃ salt bath furnace for 900S;

[0042] S6: finally cool in air to room temperature (cooling rate 5℃ / S).

[0043] The alloy material of the present application is treated by temperature and rolling control and air quenching and partitioning heat treatment process, and the actual measured mechanical properties are: tensile strength 980MPa, yield strength 730MPa, elongation after fracture 28%, Vickers hardness 350.

[0044] The cab turnover support obtained by cold continuous rolling and annealing heat treatment of DC04 steel needs a steel plate thickness of 3mm, and the weight of the cab turnover support is 10.8kg. By using the alloy composition of the present application and the heat treatment method of hot continuous rolling and air quenching and partitioning, the steel plate thickness is reduced by 1mm, and the use strength and wear resistance of the cab turnover support can be completely met by using a 2mm thick steel plate, the weight of the cab turnover support is 7.2kg, the weight of the single-sided cab turnover support is reduced by 3.6kg, the weight of the whole cab is reduced by 7.2kg, and the use requirement of light weight of the cab is met.

Claims

1. A process for the production of a cab roll-over bracket for heavy duty trucks, characterized in that, It comprises the following steps: (1) Chemical composition design of alloy steel The chemical composition of the alloy steel is: carbon 0.28-0.32%, manganese 1.8-2.2%, titanium 0.4-0.6%, silicon 1.0-1.4%, molybdenum 0.28-0.32%, copper 0.25-0.35%, nickel 0.8-1.0%, chromium 0.28-0.32%, and the balance of iron; (2) Rolling process The cut alloy steel plate with a thickness of 60 mm and the above chemical composition is placed in a heat treatment furnace, and is kept at 1150-1200℃ until complete austenitization, and after being taken out, is controlled to be rolled at 940-960℃ to a thickness of 38 mm; then is controlled to be rolled at 840-860℃ to a thickness of 20 mm, and is air-cooled to room temperature; (3) Steel plate heat treatment process The rolled steel plate is placed in a heat treatment furnace and heated to 850℃ for 280-320 seconds, the heat-treated steel plate is cooled to 275-285℃ in air, and is kept at 275-285℃ in a salt bath furnace for 24-26 seconds, then is kept at 340-360℃ in a salt bath furnace for 850-950 seconds, and finally is air-cooled to room temperature.

2. The production process according to claim 1, wherein The chemical composition of the alloy material of step (1) is: carbon 0.30%, manganese 2.0%, titanium 0.5%, silicon 1.2%, molybdenum 0.30%, copper 0.30%, nickel 0.9%, and chromium 0.30%.

3. The production process according to claim 1, wherein The rolling process of step (2) is: the cut steel plate with a thickness of 60 mm is placed in a heat treatment furnace, is kept at 1180℃ for 1h for complete austenitization, and after being taken out, is controlled to be rolled at 950℃ to a thickness of 38 mm; then is controlled to be rolled at 850℃ to a thickness of 20 mm, and finally is air-cooled to room temperature.

4. The production process according to claim 3, wherein The controlled rolling at 950℃ to a thickness of 38 mm is: first rolling from a thickness of 60 mm to a thickness of 48 mm, and then rolling to a thickness of 38 mm.

5. The production process according to claim 1, wherein The steel plate heat treatment process of step (3) is: the rolled steel plate is placed in a heat treatment furnace and heated to 850℃ for 300S, the heat-treated steel plate is cooled to 280℃ in air, and is kept at 280℃ in a salt bath furnace for 25S, then is kept at 350℃ in a salt bath furnace for 900S, and finally is air-cooled to room temperature.

6. The production process according to claim 5, wherein The air cooling rate is 5℃ / S.

7. The cab roll-over bracket for heavy-duty trucks prepared by the preparation process of any one of claims 1-6.

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