Hot rolled ferrite/martensite double phase steel and production method thereof

Abstract

The invention relates to hot rolled ferrite / martensite double phase steel and a production method thereof. The double phase steel comprises the following components, by mass, 0.06-0.10% of C, 1.00-2.00% of Mn, 0.40-0.60% of Si, equal to or less than 0.02% of P, equal to or less than 0.02% of S, 0.08-0.12% of Ti, and the balance Fe and inevitable impurities. The double phase steel provided in the invention contains less than 0.5% of Si, so the surface quality of the steel can be easily controlled; and additionally, the low cost Ti element is added to improve the strength of the steel as a precipitation strengthening element, so costs of steel products are reduced.

Description

technical field

[0001] The invention relates to the field of steel rolling, in particular to a hot-rolled dual-phase steel with a tensile strength of 780 MPa and a production method thereof. Background technique

[0002] In recent years, with the development of automobiles in the direction of energy saving, weight reduction and safety, hot-rolled dual-phase steel has been widely used in the manufacture of automobile reinforcement plates due to its high strength, fatigue resistance, high hole expansion performance and high formability , wheels, chassis, bumpers, various frames of the car body and other components. Under the ULSAB program, most high-strength automotive panels are made of duplex steel.

[0003] At present, the composition of ferritic-martensitic dual-phase steel disclosed in published patent documents and other documents has the following characteristics: (1) adding more Si elements and Al elements, the functions include expanding the ferrite transformation zo...

Examples

Embodiment 1

[0024] The smelted molten steel conforming to the composition scheme described in Component 1 in Table 1 was cast into billets, and then the billets were heated up to 1200°C with the furnace and kept for 0.5h before rolling. Among them, the starting rolling temperature of the austenite recrystallization zone is 1180°C, and the deformation amount is 65%; the starting rolling temperature of the austenite non-recrystallization zone is 930°C, the billet deformation amount is 35%, and the final rolling temperature is 800°C. After the steel plate is rolled, it is warmed in the air. After the temperature reaches 600°C, water cooling is started. The cooling rate of water cooling is 45°C / s, and it is cooled to 300°C, reaching the coiling temperature, and then coiled.

Embodiment 2

[0026] The smelted molten steel conforming to the composition scheme described in component 2 in Table 1 was cast into billets, and then the billets were heated up to 1200°C with the furnace and kept for 0.5h before rolling. Among them, the starting rolling temperature of the austenite recrystallization zone is 1150°C, and the deformation is 60%; the starting rolling temperature of the austenite non-recrystallization zone is 910°C, the billet deformation is 40%, and the final rolling temperature is 780°C. After the steel plate is rolled, it is warmed in the air. After the temperature reaches 580°C, water cooling is started. The cooling rate of water cooling is 50°C / s, and it is cooled to 250°C, reaching the coiling temperature, and then coiled.

Embodiment 3

[0028] The smelted molten steel conforming to the composition scheme described in Component 3 in Table 1 was cast into billets, and then the billets were heated up to 1200°C with the furnace and kept for 0.5h for rolling. Among them, the starting rolling temperature of the austenite recrystallization zone is 1100°C, the deformation amount is 50%; the starting rolling temperature of the austenite non-recrystallization zone is 910°C, the billet deformation amount is 50%, and the final rolling temperature is 750°C. After the steel plate is rolled, it is warmed in the air. After the temperature reaches 550°C, water cooling is started. The cooling rate of water cooling is 60°C / s, and it is cooled to 210°C, reaching the coiling temperature, and then coiled.

technical field

[0001] The invention relates to the field of steel rolling, in particular to a hot-rolled dual-phase steel with a tensile strength of 780 MPa and a production method thereof. Background technique

[0002] In recent years, with the development of automobiles in the direction of energy saving, weight reduction and safety, hot-rolled dual-phase steel has been widely used in the manufacture of automobile reinforcement plates due to its high strength, fatigue resistance, high hole expansion performance and high formability , wheels, chassis, bumpers, various frames of the car body and other components. Under the ULSAB program, most high-strength automotive panels are made of duplex steel.

[0003] At present, the composition of ferritic-martensitic dual-phase steel disclosed in published patent documents and other documents has the following characteristics: (1) adding more Si elements and Al elements, the functions include expanding the ferrite transformation zo...

Examples

Embodiment 1

[0024] The smelted molten steel conforming to the composition scheme described in Component 1 in Table 1 was cast into billets, and then the billets were heated up to 1200°C with the furnace and kept for 0.5h before rolling. Among them, the starting rolling temperature of the austenite recrystallization zone is 1180°C, and the deformation amount is 65%; the starting rolling temperature of the austenite non-recrystallization zone is 930°C, the billet deformation amount is 35%, and the final rolling temperature is 800°C. After the steel plate is rolled, it is warmed in the air. After the temperature reaches 600°C, water cooling is started. The cooling rate of water cooling is 45°C / s, and it is cooled to 300°C, reaching the coiling temperature, and then coiled.

Embodiment 2

[0026] The smelted molten steel conforming to the composition scheme described in component 2 in Table 1 was cast into billets, and then the billets were heated up to 1200°C with the furnace and kept for 0.5h before rolling. Among them, the starting rolling temperature of the austenite recrystallization zone is 1150°C, and the deformation is 60%; the starting rolling temperature of the austenite non-recrystallization zone is 910°C, the billet deformation is 40%, and the final rolling temperature is 780°C. After the steel plate is rolled, it is warmed in the air. After the temperature reaches 580°C, water cooling is started. The cooling rate of water cooling is 50°C / s, and it is cooled to 250°C, reaching the coiling temperature, and then coiled.

Embodiment 3

[0028] The smelted molten steel conforming to the composition scheme described in Component 3 in Table 1 was cast into billets, and then the billets were heated up to 1200°C with the furnace and kept for 0.5h for rolling. Among them, the starting rolling temperature of the austenite recrystallization zone is 1100°C, the deformation amount is 50%; the starting rolling temperature of the austenite non-recrystallization zone is 910°C, the billet deformation amount is 50%, and the final rolling temperature is 750°C. After the steel plate is rolled, it is warmed in the air. After the temperature reaches 550°C, water cooling is started. The cooling rate of water cooling is 60°C / s, and it is cooled to 210°C, reaching the coiling temperature, and then coiled.

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