Automobile beam steel plate with tensile strength of 750MPa grade and heavy gauge, and preparation method of automobile beam steel plate

A technology for automobile girders and tensile strength, which is applied in the field of metallurgy, and can solve problems such as increasing the difficulty of descaling, thicker oxide scales, and high deformation resistance

Active Publication Date: 2019-05-07
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

On the other hand, during the rolling process of thick product specification automobile frame steel, the rolling rhythm slows down, coupled with the high temperature of the furnace, the strip steel is in a high temperature state above 950°C throughout the rolling process, so that the final hot-rolled products The oxide scale becomes thicker, which increases the difficulty of subsequent descaling
In addition, high-strength grade steel for automobile beams has a large deformation resistance, which will cause serious oxide scale shedding defects in the subsequent deep processing process
Based on the above problems, the production technology of traditional low-strength grade pickling-free steel is no longer suitable for high-strength steel with a tensile strength of 750MPa. Therefore, in order to meet market demand, it is urgent to develop a new pickling-free technology to meet the tensile strength of 750MPa. Production of pickling-free high-strength steel above grade

Method used

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  • Automobile beam steel plate with tensile strength of 750MPa grade and heavy gauge, and preparation method of automobile beam steel plate
  • Automobile beam steel plate with tensile strength of 750MPa grade and heavy gauge, and preparation method of automobile beam steel plate
  • Automobile beam steel plate with tensile strength of 750MPa grade and heavy gauge, and preparation method of automobile beam steel plate

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Experimental program
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Effect test

Embodiment 1

[0033] Preparation of thick gauge automobile frame steel with a tensile strength of 750MPa and a thickness specification of 6mm:

[0034] Heat the slab with a thickness of 230mm to 1200°C and hold it for 240min. The chemical composition of the slab is: C: 0.03, Si: 0.05%, Mn: 1.0%, S: 0.015%, P: 0.025%, Als : 0.015%, Cr: 0.2%, Ti: 0.07%, Nb: 0.02%, and the rest are Fe and unavoidable impurities during smelting. Rough rolling is carried out on the steel slab after being released from the furnace, the rolling temperature is 1130°C, and the rolling is carried out for 5 passes to obtain an intermediate slab with a thickness of 34 mm; the rough rolled intermediate slab is subjected to finish rolling, and the finishing rolling passes are 7 passes. The finish rolling entrance temperature is 1050°C, the finish rolling temperature is 890°C, and the rolling speed of the F7 stand is 8m / s to obtain a 6mm thick strip. The descaling water pressure for heating furnace descaling, rough rolli...

Embodiment 2

[0036] Preparation of thick gauge automobile frame steel with a tensile strength of 750MPa and a thickness specification of 6mm:

[0037]Heat the slab with a thickness of 210mm to 1300°C and hold it for 180min. The chemical composition of the slab is: C: 0.12%, Si: 0.60%, Mn: 2.5%, S: 0.010%, P: 0.020%, Als: 0.045%, Cr: 1.0%, Ti: 0.15%, Nb: 0.08%, and the rest are Fe and unavoidable impurities during smelting. Rough rolling is carried out on the steel slab after being released from the furnace, the rolling temperature is 1180°C, and rolling is carried out for 5 passes to obtain an intermediate slab with a thickness of 48 mm; the rough rolled intermediate slab is subjected to finish rolling, and the finishing rolling passes are 7 passes. The finish rolling entrance temperature is 1050°C, the finish rolling temperature is 850°C, and the rolling speed of the F7 stand is 7m / s to obtain a 6mm thick strip. The descaling water pressure for heating furnace descaling, rough rolling de...

Embodiment 3

[0039] Preparation of thick gauge automobile frame steel with a tensile strength of 750MPa and a thickness specification of 8mm:

[0040] Heat the slab with a thickness of 230mm to 1250°C and hold it for 200min. The chemical composition of the slab is: C: 0.05%, Si: 0.05%, Mn: 1.5%, S: ≤0.015%, P: ≤0.025 %, Als: 0.025%, Cr: 0.2%, Ti: 0.09%, Nb: 0.03%, and the rest are Fe and unavoidable impurities during smelting. The steel slab after being released from the furnace is subjected to rough rolling at a starting temperature of 1130°C for 5 passes to obtain an intermediate slab with a thickness of 52mm; the rough rolled intermediate slab is subjected to finish rolling with 7 passes. The finish rolling entrance temperature is 1040°C, the finish rolling temperature is 880°C, and the rolling speed of the F7 stand is 6m / s to obtain a strip with a thickness of 8mm. The descaling water pressure for heating furnace descaling, rough rolling descaling and finishing rolling descaling is 20...

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Abstract

The invention relates to an automobile beam steel plate with tensile strength of 750MPa grade and heavy gauge, and a preparation method of the automobile beam steel plate. The steel plate comprises, by mass, 0.03 to 0.12% of C, 0.05 to 0.60% of Si, 0.2 to 1.0% of Cr, 1.0 to 2.5% of Mn, not greater than 0.015% of S, not greater than 0.025% of P, 0.015 to 0.045% of Als, 0.07 to 0.15% of Ti, 0.02 to0.08% of Nb, and the balance being Fe and impurities that are unavoidable during smelting. During preparation, a steel billet adopting the above chemical composition proportion is subjected to reasonable process design, so as to prevent the pickling preparation process from replacing the original process, reduce the thickness of the scale, and obtain the scale complex structure of Fe3O4, FeO and eutectoid Fe3O4 coexisting with alpha-Fe, so that the surface quality of the steel plate is significantly improved, and the requirements of the use of pickling-free direct stamping or roll forming andeliminate the pickling process can be met, production efficiency is improved, environmental pollution is reduced and production cost is reduced.

Description

Technical field: [0001] The invention belongs to the technical field of metallurgy, and in particular relates to an automobile frame steel plate with a tensile strength of 750 MPa and a thick specification and a preparation method thereof. Background technique: [0002] With the development of the automobile industry and the automobile industry, automobile lightweight has become a new trend in the development of the automobile industry. In order to meet the requirements of lightweight automobiles, the demand for high-strength steels for automobiles is increasing. Therefore, the development of high-strength automotive frame steels has become a research hotspot for automotive steels. As the main structural part of the car, the car frame steel bears most of the weight of the car body. In order to ensure the safety of the car, the car frame steel must have sufficient strength and rigidity to withstand the load from the car and the impact from the wheels, and resist tension. The...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/26C22C38/28C21D8/02C22C33/04
Inventor 李志峰刘振宇曹光明崔春圆王皓李成刚
Owner NORTHEASTERN UNIV
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