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A hot rolling preparation method of 1700mpa grade high cr-si thin gauge hot forming steel

A hot-formed steel, thin-gauge technology, applied in the field of metal processing, can solve the problems of reducing production efficiency and product qualification rate, insufficient toughness of hot-stamped parts, and increasing production costs, reducing hydrogen embrittlement susceptibility, grain size Small size and high productivity

Active Publication Date: 2022-03-01
NORTHEASTERN UNIV LIAONING +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the insufficient toughness of hot stamping parts and the potential hydrogen-induced delayed fracture cannot be ignored.
[0006] Existing thin-gauge hot-forming steel plates are all produced after hot-rolling and additional cold-rolling process, and this kind of hot-forming steel of 1500MPa level or above has high alloy content and strong hardenability, so the rolling force in the cold rolling process Large, even exceeding the upper limit of the cold rolling unit, and the complex process of intermediate annealing and secondary cold rolling often causes problems such as edge cracking and poor shape of the steel plate, greatly increasing production costs, reducing production efficiency and product qualification rate

Method used

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  • A hot rolling preparation method of 1700mpa grade high cr-si thin gauge hot forming steel
  • A hot rolling preparation method of 1700mpa grade high cr-si thin gauge hot forming steel
  • A hot rolling preparation method of 1700mpa grade high cr-si thin gauge hot forming steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] Preparation of 1700MPa grade high Cr-Si thin-gauge hot-rolled steel sheet for thermoforming with a thickness of 1.5mm, the process steps are as follows:

[0061] (1) Controlled rolling and controlled cooling treatment

[0062] The chemical composition of the alloy billet by weight percentage is: C: 0.30%, Mn: 0.8%, Si: 1.8%, S: 0.005%, P: 0.008%, Al: 0.01%, Cr: 3.0%, Nb: 0.03%, V: 0.01%, Ti: 0.03%, Cu: 0.05%, the balance is Fe and other unavoidable impurities; the continuous casting slab of the above components is heated to 1300 ° C with the furnace and kept for 2.5 h; after one descaling, Remove the furnace-generated iron scale, the rough rolling start temperature is 1170°C, after 6 rough rolling passes, the total reduction rate of the rough rolling is 87%, and the thickness of the intermediate billet is 30.55mm; the secondary oxidation is removed before the finish rolling After the iron sheet, the steel strip with a thickness of 1.5mm is formed by 7 passes of finish ro...

Embodiment 2

[0066] After decoiling and straightening the hot-rolled steel plate obtained in Example 1, remove the iron scale by mechanical means, heat to 930°C, keep it warm for 350s, and then quickly transfer it to a hot stamping die for hot stamping within 10s, and keep it under pressure. The pressure is 20MPa, and then quenched at a cooling rate of 150°C / s to below 200°C to obtain a hot-formed steel. The structure is martensite and a small amount of retained austenite, such as figure 2 shown.

[0067] The mechanical property experiment of the hot-formed steel was carried out, and finally the yield strength of the hot-formed steel was 1390MPa, the tensile strength was 1750MPa, the elongation was 8.5%, and the bending angle was 65°. The surface oxide scale thickness of the bare hot-rolled steel plate after hot forming is about 0.9 μm, such as image 3 As shown, no shot peening is required.

Embodiment 3

[0069] The hot-rolled steel plate obtained in Example 1 is subjected to decoiling tension leveling, and the tension leveling elongation setting range is 1.0%;

[0070] The concentration of hydrochloric acid in the first acid tank: 120 g / L±20 g / L, the temperature of the acid solution is 80±10°C,

[0071] The concentration of hydrochloric acid in the second acid tank: 150 g / L±20 g / L, the temperature of the acid solution is 80±10°C,

[0072] The concentration of hydrochloric acid in the third acid tank: 190 g / L±20 g / L, the temperature of the acid solution is 80±10°C;

[0073] The concentration of iron ions is required to be no more than 100 g / L;

[0074] The process speed is 60m / min.

[0075] After pickling with hydrochloric acid, most of the iron scale on the edge and middle of the hot-rolled steel plate has been removed. The thickness of the iron oxide scale at the edge is 0.7 μm to 1 μm, and the thickness of the iron oxide scale at the middle is between 0.7 μm and 4 μm. bet...

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Abstract

The invention belongs to the technical field of metal processing, and in particular relates to a hot-rolling preparation method of 1700MPa high-Cr-Si thin-gauge hot-formed steel. Aiming at the problems in the prior art that steel sheets for hot forming need to be added with cold rolling to be prepared, and coatings are required for hot forming, the present invention provides a low-cost 1700MPa high-Cr-Si alloyed coating-free hot-forming steel, and A hot-rolling preparation method for thin-gauge coating-free hot-formed steel with this composition is proposed. The hot forming steel of the invention has simple preparation process and low cost, and the produced hot forming steel has uniform microstructure, excellent mechanical properties and high temperature oxidation resistance.

Description

technical field [0001] The invention belongs to the technical field of metal processing, and in particular relates to a hot rolling preparation method of 1700MPa grade high Cr-Si thin gauge hot forming steel. Background technique [0002] Safety, environmental protection, and energy saving are the themes of the development of the current automobile manufacturing industry. The body made of high-strength steel plates can not only effectively reduce the weight of the body and reduce fuel consumption, but also improve the safety and comfort of the car. The best way to improve crash safety. With the improvement of the strength of advanced high-strength steel for automobiles, the plastic deformation range is narrowed, the stamping force is increased, the forming springback of the parts is serious, and the dimensional and shape stability is deteriorated, which has an adverse effect on the formability and weldability of the material, resulting in conventional Cold stamping is very ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/38C22C38/28C22C38/34C22C38/26C22C38/24C22C38/20C21D8/04C21D1/26C21D1/74C23G1/08B21C37/02
CPCC22C38/02C22C38/04C22C38/06C22C38/38C22C38/28C22C38/34C22C38/26C22C38/24C22C38/20C21D8/0421C21D8/0426C21D8/0447C21D1/26C21D1/74C23G1/08B21C37/02C21D2211/005C21D2211/009C21D2211/002
Inventor 徐伟王鲁宁胡军杨得草苗隽柴志松
Owner NORTHEASTERN UNIV LIAONING
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