800 MPa-grade low-cost tempered dual-phase steel and preparation method thereof

A low-cost, dual-phase steel technology, applied in the field of dual-phase steel for automobile manufacturing and its preparation, can solve the problems of high production cost of 800MPa-grade dual-phase steel, and achieve easy realization of process parameters, simple production control, high intensity effect

Inactive Publication Date: 2019-07-19
BENGANG STEEL PLATES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the 800MPa grade cold-rolled dual-phase steel sold on the market still adds expensive alloying elements such as Nb and Mo, or a large amount of Cr elements, resulting in high production costs of 800MPa grade dual-phase steel. Many steel enterprises have production capacity, and the sales profits of manufacturers are gradually thinning. Therefore, the existing 800MPa dual-phase steel urgently needs to be optimized and upgraded

Method used

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  • 800 MPa-grade low-cost tempered dual-phase steel and preparation method thereof
  • 800 MPa-grade low-cost tempered dual-phase steel and preparation method thereof
  • 800 MPa-grade low-cost tempered dual-phase steel and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] An 800MPa low-cost tempered dual-phase steel, by weight percentage, its chemical composition is, C: 0.15%; Si: 0.29%; Mn: 1.89%; Cr: 0.25%; Ti: 0.019%; P: 0.032 %; S: 0.008%; Al: 0.065%; the balance is Fe and unavoidable inclusions.

[0018] To prepare the above-mentioned 800MPa low-cost tempered dual-phase steel, the following process flow is adopted: molten iron pretreatment → converter smelting → external refining → continuous casting → heating → controlled rolling and controlled cooling → coiling → pickling → cold rolling → continuous annealing →Smoothness→Functional inspection→Packing and leaving the factory; including the following steps:

[0019] The heating temperature of the hot-rolled slab is 1230°C, the starting rolling temperature is 1080°C, and the finishing rolling temperature is 860°C; laminar flow cooling is adopted after rolling, the cooling rate is 30°C / s, and the coiling temperature is 550°C; the cold rolling adopts 56 % reduction ratio, continuous a...

Embodiment 2

[0024] A low-cost tempered dual-phase steel of 800MPa grade, by weight percentage, its chemical composition is, C: 0.15%; Si: 0.26%; Mn: 1.92%; Cr: 0.26%; Ti: 0.024%; P: 0.026 %; S: 0.006%; Al: 0.070%; the balance is Fe and unavoidable inclusions.

[0025] To prepare the above-mentioned 800MPa low-cost tempered dual-phase steel, the following process flow is adopted: molten iron pretreatment → converter smelting → external refining → continuous casting → heating → controlled rolling and controlled cooling → coiling → pickling → cold rolling → continuous annealing →Smoothness→Functional inspection→Packing and leaving the factory; including the following steps:

[0026] The heating temperature of the hot-rolled slab is 1210°C, the starting rolling temperature is 1060°C, and the finishing rolling temperature is 850°C; laminar flow cooling is adopted after rolling, the cooling rate is 25°C / s, and the coiling temperature is 530°C; the cold rolling adopts 55°C % reduction ratio, co...

Embodiment 3

[0032] An 800MPa low-cost tempered dual-phase steel, the chemical composition of which is, by weight percentage, C: 0.16%; Si: 0.29%; Mn: 1.84%; Cr: 0.26%; Ti: 0.022%; P: 0.038 %; S: 0.007%; Al: 0.056%; the balance is Fe and unavoidable inclusions.

[0033] To prepare the above-mentioned 800MPa low-cost tempered dual-phase steel, the following process flow is adopted: molten iron pretreatment → converter smelting → external refining → continuous casting → heating → controlled rolling and controlled cooling → coiling → pickling → cold rolling → continuous annealing →Smoothness→Functional inspection→Packing and leaving the factory; including the following steps:

[0034] The heating temperature of the hot-rolled slab is 1260°C, the rolling start temperature is 1100°C, and the final rolling temperature is 890°C; laminar flow cooling is adopted after rolling, the cooling rate is 35°C / s, and the coiling temperature is 580°C; the cold rolling adopts 56 % reduction ratio, continuous...

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Abstract

The invention provides 800 MPa-grade low-cost tempered dual-phase steel and a preparation method thereof. The 800 MPa-grade low-cost tempered dual-phase steel comprises, by mass, 0.10%-0.30% of C, 0.10%-0.60% of Si, 1.60%-2.20% of Mn, 0.10%-0.50% of Cr, 0.01%-0.04% of Ti, less than or equal to 0.05% of P, less than or equal to 0.01% of S, less than or equal to 0.08% of Al, and the balance Fe and inevitable impurities. The technological process for preparing the dual-phase steel comprises the following steps of molten iron pretreatment, converter smelting, external refining, continuous casting,heating, controlled rolling and controlled cooling, reeling, acid pickling, cold rolling, continuous annealing, leveling, function inspection and packaging and delivery. According to the preparationmethod, original grain tissues are obtained through hot rolling and controlled rolling and controlled cooling, the hardness of martensite is controlled by adopting continuous annealing and overaging tempering, the mechanical property and the surface quality of the steel are ensured, and the requirements of the 800 MPa-grade dual-phase steel are met.

Description

technical field [0001] The invention relates to a dual-phase steel used in the automobile manufacturing industry and a preparation method thereof, in particular to an 800MPa low-cost tempered dual-phase steel and a preparation method thereof. Background technique [0002] As the global environmental and energy crisis intensifies, energy conservation and emission reduction have become major issues facing the automobile manufacturing industry. Therefore, automobiles need to significantly reduce weight and improve fuel efficiency. Due to its low yield ratio, high initial work hardening rate, good strength and ductility fit, dual-phase steel is widely used in the automotive industry for structural parts and reinforcements that require high strength and certain forming requirements. The market demand Larger, tons of steel are lucrative. In recent years, the demand for dual-phase steel has gradually increased, especially the application of 800MPa-level dual-phase steel in automob...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/28C22C38/38C21D8/02C22C33/04
CPCC21D8/0205C21D8/0226C21D8/0263C21D2211/00C22C33/04C22C38/02C22C38/04C22C38/06C22C38/28C22C38/38
Inventor 李春诚刘宏亮王亚东刘敏陈宇胡洋
Owner BENGANG STEEL PLATES
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