Cover annealing method for high-Cr-Si alloyed hot-formed steel

A technology of hot forming steel and bell annealing, which is applied in the field of heat treatment, can solve the problems of limited bending performance of martensitic structure, poor uniformity of structure and performance, large performance fluctuation, etc., and achieve high overall yield, high utilization rate, and improved uniformity sexual effect

Active Publication Date: 2022-02-18
NORTHEASTERN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] For the high hardenability of high Cr-Si alloyed hot forming steel, the uniformity of structure and properties after coiling is poor, the bending performance of martensitic structure after hot forming is limited, and the process of pickling welding, uncoiling blanking and hot forming is unstable. As a result of problems such as low yield and large performance fluctuations, the present invention provides a low-cost, simple-process, and easy-to-achieve-industrialization bell-type mold that improves the uniformity and bending properties of high-Cr-Si alloyed high-hardenability hot-rolled hot-formed steel. Annealing method

Method used

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  • Cover annealing method for high-Cr-Si alloyed hot-formed steel
  • Cover annealing method for high-Cr-Si alloyed hot-formed steel
  • Cover annealing method for high-Cr-Si alloyed hot-formed steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Prepare Cr-Si alloyed 1700MPa grade hot-rolled coating-free hot-formed steel with a thickness of 1.5mm, and add the cover-back step after hot-rolling and preparing steel coils:

[0038] (1) Controlled rolling and controlled cooling treatment

[0039] 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%, and the balance is Fe and other unavoidable impurities.

[0040] The continuous casting slab with the above components was heated to 1300°C with the furnace and held for 2.5 hours; after one descaling, the furnace-generated iron scale was removed, the rough rolling start temperature was 1170°C, and after 6 passes of rough rolling, the rough rolling The total reduction rate is 87%, and the thickness of the intermediate billet is 30.55mm; after removing the secondary oxide scale before finish rolling, it is rolled into a hot-rolled plate with...

Embodiment 3

[0055] To prepare Cr-Si alloyed 1500MPa-grade hot-rolled coating-free hot-formed steel with a thickness of 3.5mm, add the cover-back step after hot-rolling and preparing steel coils:

[0056] (1) Controlled rolling and controlled cooling treatment

[0057] The chemical composition of the alloy billet by weight percentage is: C: 0.21%, Mn: 2.2%, Si: 2.6%, S: 0.008%, P: 0.007%, Al: 0.05%, Cr: 1.5%, Nb: 0.01%, V: 0.04%, Ti: 0.02%, Cu: 0.09%, and the balance is Fe and other unavoidable impurities.

[0058] The continuous casting slab with the above components is heated to 1285°C with the furnace and kept for 2 hours; after one descaling, the furnace scale is removed, the rough rolling start temperature is 1108°C, after 6 passes of rough rolling, the rough rolled The total reduction rate is 86%, and the thickness of the intermediate billet is 32.5mm; after removing the secondary oxide scale before finish rolling, it is rolled into a hot-rolled plate with a thickness of 3.5mm by 7 ...

Embodiment 5

[0071] To prepare Cr-Si alloyed 1500MPa-grade hot-rolled coating-free hot-formed steel with a thickness of 6.0mm, add the cover step after hot-rolling and preparing steel coils:

[0072] (1) Controlled rolling and controlled cooling treatment

[0073] The chemical composition of the alloy billet by weight percentage is: C: 0.15%, Mn: 3.1%, Si: 0.8%, S: 0.005%, P: 0.008%, Al: 0.01%, Cr: 3.6%, Nb: 0.05%, V: 0.01%, Ti: 0.03%, Cu: 0.05%, and the balance is Fe and other unavoidable impurities.

[0074] The continuous casting slab with the above components was heated to 1284°C with the furnace and held for 2 hours; after one descaling, the furnace oxide scale was removed, and the starting temperature of rough rolling was 1118°C. After 6 passes of rough rolling, the rough rolling The total reduction rate is 83%, and the thickness of the intermediate billet is 40mm; after removing the secondary oxide scale before finish rolling, it is rolled into a hot-rolled plate with a thickness o...

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Abstract

The invention belongs to the technical field of heat treatment, and particularly relates to a cover annealing method for high-Cr-Si alloyed hot-formed steel. Aiming at the problems of low yield, large performance fluctuation and the like caused by poor structure property uniformity after coiling of high-hardenability high-Cr-Si alloyed hot-formed steel, limited martensitic structure bending properties after hot forming, and unstable processes of acid pickling welding, uncoiling blanking and hot forming processes, the invention provides the cover annealing method for improving uniformity and bending properties of high-Cr-Si alloyed high-hardenability hot-rolled hot-formed steel. According to the invention, after cover annealing, structure uniformity of a hot-formed steel coil is greatly improved, internal stress is reduced, a performance difference between the head and tail of the steel coil and the coil center is reduced, uncoiling buckling is improved, and the material loss of the edge and the head and tail is reduced. In addition, in a cover annealing process, a decarburized layer with certain thickness can be generated on a surface of the steel coil containing the components provided by the invention under the reduction action of high-temperature hydrogen, so that bending properties of hot-formed steel manufactured through subsequent hot forming processing are improved.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, in particular to a bell annealing method for high Cr-Si alloyed hot forming steel. Background technique [0002] With the deterioration of the environment and the increasing shortage of energy, the consideration of safety, environmental protection and energy saving has become the main development direction of the automobile manufacturing industry. Among the many measures to reduce fuel consumption and exhaust emissions, reducing the weight of the vehicle body has the most obvious effect. Statistics show that for every 10% reduction in vehicle quality, fuel consumption can be reduced by 6% to 8%, and exhaust emissions can be reduced by 5% to 6%. Therefore, the lightweight of automobiles has become the key to the competitiveness of major automobile manufacturers. The body made of high-strength steel plate can not only effectively reduce the weight of the body and reduce fuel consumption, b...

Claims

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Application Information

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IPC IPC(8): C21D1/26C22C38/04C22C38/02C22C38/06C22C38/34C22C38/38C22C38/26C22C38/24C22C38/28C22C38/20C21D8/02C21D1/30C21D1/74
CPCC21D1/26C22C38/04C22C38/02C22C38/06C22C38/34C22C38/38C22C38/26C22C38/24C22C38/28C22C38/20C21D8/0205C21D8/0226C21D8/0257C21D1/30C21D1/74C21D2211/005C21D2211/009C21D2211/002
Inventor 徐伟王鲁宁胡军王飞陈宇徐宁
Owner NORTHEASTERN UNIV
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