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Alpha+beta type titanium alloy based on cold forming composite low-temperature nitriding treatment and nitriding layer forming method thereof

A low-temperature nitriding, titanium alloy technology, applied in the direction of metal material coating process, coating, solid-state diffusion coating, etc., can solve the problems of increased grain size, poor wear resistance of titanium alloys, and reduced matrix toughness, etc. Conducive to the overall cold forming effect

Active Publication Date: 2021-02-26
HARBIN ENG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the nitriding treatment temperature of α + β titanium alloy is concentrated at about 900 ° C. Nitriding treatment under such high temperature conditions will lead to an increase in the grain size in the titanium alloy matrix and reduce the toughness of the matrix.
Moreover, the thickness of the conventional high-temperature (900°C) nitriding layer can only reach the nanometer or micrometer level, resulting in poor wear resistance of titanium alloys.

Method used

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  • Alpha+beta type titanium alloy based on cold forming composite low-temperature nitriding treatment and nitriding layer forming method thereof
  • Alpha+beta type titanium alloy based on cold forming composite low-temperature nitriding treatment and nitriding layer forming method thereof
  • Alpha+beta type titanium alloy based on cold forming composite low-temperature nitriding treatment and nitriding layer forming method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] This embodiment takes the TC4 titanium alloy sheet as the processing object, and the specific steps are as follows:

[0055] Quenching treatment: put TC4 titanium alloy in a vacuum furnace, keep at 850℃ for 50min, and cool with circulating water at 15℃;

[0056] Cold forming: After quenching, cold forming is carried out at room temperature, and the deformation amount is 30% to obtain TC4 titanium alloy sheet;

[0057] Workpiece cleaning: Use sandpaper to polish the surface of the workpiece, and perform ultrasonic cleaning in acetone solution;

[0058] Low-temperature nitriding: place the cleaned workpiece in a pulsed plasma furnace, and the atmosphere selected in the nitriding process is N 2 and H 2 Two kinds of gas infiltration agents, the flow ratio is 1:1, N 2 , H 2 The flow rate is 0.21m 3 / h, the voltage is 650V, the pressure rise rate is 0.13P / min, the duty cycle is 45%, the nitriding temperature is 480℃, and the holding time is 16h;

[0059] Thermal diffusi...

Embodiment 2

[0065] The difference between Example 2 and Example 1 is that the deformation amount of cold forming is 20%, and the nitriding time is 14h.

[0066] The nitrided workpiece obtained after low-temperature nitriding in Example 2 and the nitrided workpiece obtained after thermal diffusion treatment were tested. After thermal diffusion treatment, the surface N concentration of the TC4 alloy is 19%, the core concentration is 15.6%, the thickness of the infiltrated layer is 3.6mm, the friction coefficient is 0.39, and the surface hardness reaches 632HV. After the thermal diffusion treatment, the hardness of the matrix changes in steps. ,like Figure 4 shown.

Embodiment 3

[0068] The difference between Example 3 and Example 1 is that the deformation amount of cold forming is 40%, and the nitriding time is 18h.

[0069] The nitrided workpiece obtained after low-temperature nitriding in Example 3 and the nitrided workpiece obtained after thermal diffusion treatment were tested. The results showed that the thickness of the nitrided workpiece after low-temperature nitridation in Example 3 was 3 mm, and the surface N concentration was 26.9%; after the thermal diffusion treatment, the surface N concentration of the TC4 alloy is 25%, the core concentration is 22.3%, the thickness of the infiltrated layer is 4.4mm, the friction coefficient is 0.24, and the surface hardness reaches 661HV. like Figure 5 shown.

[0070] The comprehensive properties of the products of Examples 1 to 3 are far superior to those of the incoming TC4 titanium alloy (the hardness is 310HV and the friction coefficient is 0.69). It can be seen that the hardness and wear resistanc...

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Abstract

The invention relates to the technical field of titanium alloy nitriding, in particular to an alpha+beta type titanium alloy based on cold forming composite low-temperature nitriding treatment and a nitriding layer forming method thereof. The nitriding layer forming method comprises the following steps that quenching, cold forming and low-temperature nitriding are sequentially conducted on the alpha+beta type titanium alloy, and a nitriding layer is formed on the surface of the alpha+beta type titanium alloy, wherein the accumulated deformation amount of cold forming is 10%-65%; and the temperature of the low-temperature nitriding is 400-600 DEG C. By the adoption of the method, the millimeter-scale super-thick nitriding layer can be formed on the surface of the alpha+beta type titanium alloy, the hardness gradient can be adjusted and controlled, the plasticity and toughness of an alloy matrix structure and the abrasion resistance of the titanium alloy can be remarkably improved, the fatigue damage resistance of the nitriding layer is improved, and the service life of a product is prolonged.

Description

technical field [0001] The invention relates to the technical field of titanium alloy nitriding, in particular to an α+β type titanium alloy based on cold forming compound low temperature nitriding treatment and a method for forming a nitrided layer thereof. Background technique [0002] As one of the most abundant metals in the crustal resources, titanium metal has experienced more than 200 years of development history, and has been used more and more in the defense industry, chemical industry, energy and other fields. At present, hundreds of titanium alloys with different compositions and properties have been developed. [0003] Among them, there is a class of titanium alloys with dual-phase (α+β) characteristics, such as TC4, TC11, TC17 and TC21. The biggest constraints on the application of this type of titanium alloys are relatively low strength and poor surface wear resistance. Most of the improvement methods currently studied are to use surface treatment technology t...

Claims

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Application Information

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IPC IPC(8): C23C8/24C23C8/02C22F1/18
CPCC23C8/24C23C8/02C22F1/002C22F1/183
Inventor 傅宇东刘国潭朱小硕冷科闫牧夫
Owner HARBIN ENG UNIV
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