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Gradient nanostructure with excellent comprehensive high cycle and low cycle fatigue performance

A nano-structure, low-cycle fatigue technology, applied in the field of fatigue performance enhancement of metal materials, can solve the problems of high-cycle fatigue performance limitations, low strength, and inability to guarantee fatigue resistance, and achieve the effect of improving comprehensive performance and simultaneously optimizing fatigue performance

Active Publication Date: 2018-11-30
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the low strength and high cycle fatigue performance of traditional engineering coarse-grained metals severely limit their application in more severe working conditions.
[0005] Under the premise of not changing the material composition, refining the grain size of polycrystalline materials to the nanometer level can greatly improve its strength and hardness, but it cannot guarantee the improvement of its fatigue resistance

Method used

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  • Gradient nanostructure with excellent comprehensive high cycle and low cycle fatigue performance
  • Gradient nanostructure with excellent comprehensive high cycle and low cycle fatigue performance
  • Gradient nanostructure with excellent comprehensive high cycle and low cycle fatigue performance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The Cu#1 sample with gradient nanostructure on the surface was obtained by mechanically treating the surface of the sample with a common lathe. The process parameters of the surface mechanical treatment are selected as follows: the diameter of the copper rod material is 6mm, and the rotating speed is 600r / min; In the pass, the indentation depth of the cemented carbide ball cutter head on the material surface is 40 μm, and the processing pass is 8. The treatment temperature is liquid nitrogen temperature ~ 173K.

[0032] As the depth from the surface increases, the grain size in this material presents a gradient trend of monotonous increase, and the average grain size gradually increases from 42nm in the outermost layer to 21μm in the core, such as figure 1 shown. The thicknesses of nanocrystalline and ultrafine crystalline layers on the surface are 20 μm and 200 μm, respectively.

[0033] In this embodiment, as the depth from the surface of the material increases, th...

Embodiment 2

[0037] The difference from Example 1 is:

[0038] Surface gradient nanostructured Cu#2 samples were obtained by surface mechanical treatment. The process parameters of the surface mechanical treatment are selected as follows: the diameter of the copper rod material is 6mm, and the rotating speed is 400r / min; In the pass, the indentation depth of the cemented carbide ball cutter head on the surface of the material is 40 μm, and the processing pass is 3 passes. The treatment temperature is liquid nitrogen temperature ~ 173K.

[0039] As the depth from the surface increases, the grain size in this material presents a monotonically increasing gradient trend, with the average grain size gradually increasing from 58nm to 21μm, as figure 2 shown. The thickness of surface nanocrystalline and ultrafine crystalline layer is 5 μm and 60 μm, which is smaller than that of surface gradient nanostructure Cu#1 sample.

[0040] In this embodiment, as the depth from the surface of the mate...

Embodiment 3

[0044] The difference from Example 1 is:

[0045] Gradient nanostructures were obtained on the surface of 304 stainless steel by surface mechanical treatment. The process parameters of the surface mechanical treatment are selected as follows: the diameter of the 304 stainless steel material is 6mm, and the rotating speed is 300r / min; In one treatment pass, the indentation depth of the cemented carbide ball cutter head on the surface of the material is 20 μm, and the treatment pass is 6 passes. The treatment temperature is room temperature.

[0046] As the depth from the surface increases, the grain size in this material presents a monotonically increasing gradient trend, and the average grain size changes from 30nm in the outermost layer ( Figure 8 ) gradually increases to 46 μm in the core. The thickness of the surface gradient nanostructure is 400 μm.

[0047] In this embodiment, as the distance from the surface of the material increases, the microhardness of the 304 st...

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Abstract

The invention discloses a gradient nanostructure with excellent comprehensive high cycle and low cycle fatigue performance, and belongs to the technical field of metal material fatigue performance enhancement. Specifically, surface plastic processing is conducted, a gradient nanostructure is introduced to the surface of a metal material, and microstructures of the metal material are an surface layer nanocrystalline structure, a subsurface superfine / deformed twin structure and a core original coarse crystal structure, wherein the overall thickness of a gradient nanostructure layer is greater than 50 microns and is within 50-300 microns. Compared with uniform coarse grain structures of the same compositions, the stress control high cycle fatigue limit of a pure-Cu sample with the surface gradient nanostructure is improved by two times, and high cycle fatigue life is prolonged by 15 times; and the strain control low cycle fatigue life is doubled compared with common coarse grain samples.According to the surface layer gradient nanostructured metal material, both the high cycle and low cycle fatigue properties of the metal material are improved.

Description

technical field [0001] The invention relates to the technical field of fatigue performance enhancement of metal materials, in particular to a gradient nanostructure with excellent comprehensive high-cycle and low-cycle fatigue performance. Background technique [0002] In practical applications, most metal engineering components serve under alternating loads (the stress amplitude is much smaller than the yield strength of the material), that is, they are in the high-cycle fatigue stage (the fatigue life is higher than 104 cycles), and the local engineering components such as holes or notches or cross-sections Shaft and connecting rod parts with changing shapes are in the low cycle fatigue stage (fatigue life is less than 104 cycles) due to stress / strain concentration. Statistics show that fatigue failure accounts for about 90% of failure failure accidents, causing huge social and economic losses and a large number of personal casualties. Therefore, it is very important to h...

Claims

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Application Information

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IPC IPC(8): C21D7/04C22F1/02C22F1/08
CPCC21D7/04C21D2201/03C22F1/02C22F1/08
Inventor 卢磊龙建周潘庆松陶乃镕
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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