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Control v-ti composite bainitic non-quenched and tempered steel structure and its manufacturing method

A technology of non-quenched and tempered steel and production method, which is applied in the field of high-strength toughness non-quenched and tempered steel manufacturing, which can solve the problems of high hydrogen embrittlement sensitivity, insufficient cooling rate control, and affecting safe service, etc., to achieve low cost and optimize hydrogen embrittlement The effect of sensitivity

Active Publication Date: 2022-03-25
BEIJING JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method of controlling the cooling rate after forging faces the risk of insufficient control of the cooling rate
[0004] In addition to further improving the strength and toughness, the bainitic non-quenched and tempered steel has a high susceptibility to hydrogen embrittlement after the strength is increased, especially after it is increased to 1000MPa, which affects its safe service in the service environment

Method used

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  • Control v-ti composite bainitic non-quenched and tempered steel structure and its manufacturing method
  • Control v-ti composite bainitic non-quenched and tempered steel structure and its manufacturing method
  • Control v-ti composite bainitic non-quenched and tempered steel structure and its manufacturing method

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Experimental program
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Effect test

Embodiment 1

[0035] In order to overcome the disadvantages of low strength, complex production process and high cost of bainitic non-quenched and tempered steel, the object of the present invention is to provide a process for controlling the microstructure and properties of V-Ti composite bainitic non-quenched and tempered steel, designed steel There are no expensive molybdenum Mo and boron B elements, and by controlling different deformations, different bainite structures can be obtained: granular bainite, lath bainite, directly air-cooled after forging, eliminating the need for complicated cooling The speed is controlled, and the optimal resistance to hydrogen embrittlement is obtained through a suitable heat treatment process, so as to be suitable for different performances.

[0036]In non-quenched and tempered steel, the mechanical properties of the material are mainly controlled by the precipitation strengthening and fine grain strengthening of V, Ti, Nb and other microalloying element...

Embodiment 2

[0043] The chemical composition of V-Ti bainite non-quenched and tempered steel is shown in Table 1.

[0044] Table 1V-Ti complex bainite non-quenched and tempered steel chemical composition (wt%)

[0045] Element C Si mn P S Cr V Ti Al N content 0.23 0.45 2.03 0.008 0.044 0.55 0.14 0.045 0.029 0.006

[0046] Put the billet of the above composition into a vacuum induction furnace and smelt it into a steel ingot. After peeling off the skin, the steel ingot is heated to 1200°C in a frequency induction heating furnace. After holding for 1 hour, it is immediately changed to forging. The forging ratio is 12, and the final forging temperature is 850°C. After forging Air-cooled to room temperature, the bar is a fire-forged steel. Fig. 1 (a) is the optical microscope schematic diagram of the first-fire-forged steel structure of the embodiment 2 of the present invention, and Fig. 1 (b) is the scanning electron microscope schematic diagram of th...

Embodiment 3

[0056] The chemical composition of V-Ti bainite non-quenched and tempered steel is shown in Table 4.

[0057] Table 4V-Ti complex bainite non-quenched and tempered steel chemical composition (wt%)

[0058] Element C Si mn P S Cr V Ti Al N content 0.25 0.40 1.96 0.007 0.035 0.50 0.11 0.03 0.029 0.008

[0059] Put the billet of the above composition into a vacuum induction furnace and smelt it into a steel ingot. After peeling off the skin, the steel ingot is heated to 1200°C in a frequency induction heating furnace. After holding for 1 hour, it is immediately changed to forging. The forging ratio is 12, and the final forging temperature is 850°C. After forging Air-cooled to room temperature, the bar is a fire-forged steel. The mechanical properties are shown in Table 5.

[0060] Heat the above-mentioned first-fire bar steel to 1100°C in an intermediate frequency induction heating furnace, and immediately re-forge after holding the heat...

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Abstract

The invention provides a control V-Ti composite bainitic non-quenched and tempered steel structure and a manufacturing method thereof. The composition according to mass percentage is: C 0.20%~0.25%; Si 0.40%~0.50%; Mn 1.90%~2.10%; P≤0.0080%; S 0.035%~0.055%; Cr 0.50%~0.60%; V 0.10 %~0.20%; Ti 0.030%~0.050%; Al 0.015%~0.035%; N 0.006%~0.008%; O≤0.001%, and the rest are iron and impurities. The production method includes: weighing the ingredients according to the above-mentioned ingredients, and then adopting vacuum smelting to form steel ingots; heating the steel ingots to 1200 ° C for 1 to 2 hours, then forging, the forging ratio is greater than or equal to 3, and the final forging temperature is above 800 ° C. The strength can reach 1100~1420MPa, the yield strength is 710~1040MPa, and the shrinkage rate can be 44~55%. After tempering at 200℃~500℃, the hydrogen embrittlement susceptibility of the material can be optimized. The bainitic non-quenched and tempered steel of the present invention can solve the problem of low strength and poor toughness of the ferrite + pearlite non-quenched and tempered steel, and can also optimize the hydrogen embrittlement sensitivity of the bainitic non-quenched and tempered steel after proper tempering treatment , can be used to replace quenched and tempered steel to produce security parts such as automobile bumpers. It has the advantages of environmental protection and low cost.

Description

technical field [0001] The invention relates to the technical field of manufacturing high-strength toughness non-quenched and tempered steel, in particular to a control V-Ti composite bainitic non-quenched and tempered steel structure and a manufacturing method thereof. Background technique [0002] The bainite structure has a good matching of strength and toughness, and has attracted the attention of researchers at home and abroad. Bainite has also been used in the field of non-quenched and tempered steels. Currently reported bainitic non-quenched and tempered steels include 25MnCrSiVB6, 12Mn2VBS and 25Mn2CrV (FAS2225), etc. The main structure is granular bainite, and its tensile strength does not exceed 1000MPa. [0003] The invention patent CN 101333633B in the prior art discloses a low-carbon bainitic Nb-V composite microalloyed non-quenched and tempered steel and its preparation method. It is proposed to use Nb-V composite to improve the strength of bainitic steel, and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/06C22C38/24C22C38/28C22C38/38C21D1/18C21D6/00C21D8/00C22C33/04
CPCC22C38/02C22C38/002C22C38/06C22C38/001C22C38/38C22C38/24C22C38/28C22C33/04C21D1/18C21D6/002C21D6/005C21D6/008C21D8/005C21D2211/002C21D2211/005C21D2211/009
Inventor 张永健王占花惠卫军赵晓丽
Owner BEIJING JIAOTONG UNIV