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Low-carbon micro-alloy steel with gradient ultra-fine grain structure and preparation method for same

A technology of ultra-fine grain and alloy steel, applied in the field of low-carbon micro-alloy steel with gradient ultra-fine grain structure and its preparation, can solve the problems of complex process control, unfavorable steel materials, and inability to undergo phase transformation of samples, and achieve the production process The effect of simplicity, excellent mechanical properties, excellent work hardening ability and formability

Active Publication Date: 2019-05-10
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the control of the process program is relatively complicated. The sample surface needs to be processed before the laser surface heat treatment. The parameters such as laser spot, lap rate, scanning rate, and laser power need to cooperate with each other within a certain range to form a good size gradient structure. In addition, limitations Because the sample cannot undergo phase transformation during heat treatment, it is not conducive to the application of steel materials that are prone to phase transformation during heat treatment

Method used

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  • Low-carbon micro-alloy steel with gradient ultra-fine grain structure and preparation method for same
  • Low-carbon micro-alloy steel with gradient ultra-fine grain structure and preparation method for same
  • Low-carbon micro-alloy steel with gradient ultra-fine grain structure and preparation method for same

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Embodiment 1

[0036]A low-carbon microalloy steel plate with a gradient ultra-fine grain structure, which contains chemical components and the mass percentages of each chemical component are: C is 0.12%, Mn is 1.35%, Si is 0.49%, Nb is 0.035%, and Ti is 0.019% %, the balance is Fe and unavoidable impurities.

[0037] A method for preparing a low-carbon microalloy steel plate with a gradient ultrafine grain structure, specifically comprising the following steps:

[0038] (1) Melting: according to the chemical composition and ingredients of the above-mentioned low-carbon microalloy steel plate with gradient ultra-fine grain structure, it is added to a vacuum induction melting furnace, melted at a temperature of 1650 ° C, and cast to obtain a 50 kg round ingot;

[0039] (2) Forging: heat a 50kg round ingot at 1150°C for 3 hours, forge it, and air-cool it to room temperature to obtain a 100mm×100mm square ingot. Cut the square ingot into 30mm×100mm×100mm to obtain a cut square ingot;

[0040] ...

Embodiment 2

[0047] A kind of low-carbon microalloy steel plate with gradient ultra-fine grain structure. After the same smelting, forging, and conventional hot rolling as in Example 1, the hot-rolled steel plate is heated at 950 ° C, kept for 15 minutes, and asynchronously rolled at 800 ° C. The ratio is 2:1, the reduction is 75%, and a steel plate with a thickness of 1.50 mm is obtained, and then water quenched to room temperature to obtain a low-carbon microalloy steel plate with a gradient ultrafine grain structure. Its mechanical performance parameters are: tensile strength is 937MPa, yield strength is 662MPa, elongation is 21.6%, uniform elongation is 18%, and yield ratio is 0.71. The low-carbon microalloy steel plate with gradient ultra-fine grain structure prepared in this embodiment is along the thickness direction 1 / 8 (a), 2 / 8 (b), 3 / 8 (c), 4 / 8 (d), 5 / 8 ( The metallographic microstructure corresponding to the regions e), 6 / 8(f), 7 / 8(g) and 8 / 8(h) are shown in image 3 , the grai...

Embodiment 3

[0049] A kind of low-carbon microalloy steel plate with gradient ultra-fine grain structure. After the same smelting, forging, and conventional hot rolling as in Example 1, the hot-rolled steel plate is heated at 950°C, kept for 15 minutes, and asynchronously rolled at 750°C. The ratio is 2:1, the reduction is 75%, and a steel plate with a thickness of 1.50 mm is obtained, and then water quenched to room temperature to obtain a low-carbon microalloy steel plate with a gradient ultrafine grain structure. Its mechanical performance parameters are: tensile strength is 905MPa, yield strength is 628MPa, elongation is 16.8%, uniform elongation is 13.4% and yield ratio is 0.73. The low-carbon microalloy steel plate with gradient ultra-fine grain structure prepared in this embodiment is along the thickness direction 1 / 8 (a), 2 / 8 (b), 3 / 8 (c), 4 / 8 (d), 5 / 8 ( The metallographic microstructure corresponding to the regions e), 6 / 8(f), 7 / 8(g) and 8 / 8(h) are shown in Figure 5 , the grain ...

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Abstract

Low-carbon micro-alloy steel with a gradient ultra-fine grain structure and a preparation method for the same belong to the technical field of processing and preparation of metal materials. The low-carbon micro-alloy steel with the gradient ultra-fine grain structure comprises, by mass, the ingredients including 0.08%-0.15% of C, 0.5%-1.5% of Mn, 0%-1.0% of Si, 0%-0.05% of Nb, 0%-0.1% of Ti as well as Fe and inevitable impurities. The preparation method comprises steps of smelting, forging, regular hot rolling and asynchronous hot rolling. During the asynchronous hot rolling, a plate is heatedto 950 DEG C-1,200 DEG C and then treated with heat preservation of 10-30 min; and the plate is processed with water quenching and then reaches a room temperature, so the product is obtained. The method is characterized in that an asymmetrical rolling compression-shear composite mechanism and a strain induced ferrite phase change mechanism are combined; a strain gradient and a dynamic phase change gradient are introduced; ultra-fine grains are obtained and an organizational form of gradient distribution of grain sizes along the thickness direction is obtained; and thus, plasticity and tenacity of a metal material are maintained; strength and hardness of the metal material are effectively enhanced; and comprehensive performance of the material is improved.

Description

technical field [0001] The invention belongs to the technical field of metal material processing and preparation, and in particular relates to a low-carbon microalloy steel with gradient ultrafine grain structure and a preparation method thereof. Background technique [0002] Improving the plasticity, toughness and formability of high-strength steel or ultra-high-strength steel is the key direction of "new generation steel materials" research. As a representative of the "new generation of steel materials", ultra-fine-grained steel has significant strengthening and toughening characteristics. Through the ultra-fine grain size, the strength and toughness can be improved at the same time. The amount of steel has a good application prospect. However, the generation of a large number of defects is inevitable in the process of ultra-refinement of grains. Along with the significant increase in strength level, the plasticity, toughness and work hardening ability of the material usu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/12C22C38/14C21D8/02C22C33/04
CPCC21D8/02C22C33/04C22C38/02C22C38/04C22C38/12C22C38/14
Inventor 蔡明晖刘姗李文霞苏俊华
Owner NORTHEASTERN UNIV
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