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Method for forming gradient nano-structure surface layer on austenitic stainless steel and controlling content of martensite in gradient nano-structure surface layer

An austenitic stainless steel and nanostructure technology, which is applied in heat treatment process control, manufacturing tools, heat treatment equipment, etc., can solve the problems of difficult to control martensite, large surface roughness, gradient nano-layer and thin hardened layer, etc. The effect of strengthening layer thickness, high surface quality and large plastic deformation

Active Publication Date: 2017-01-11
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The object of the present invention is to provide a method for forming a gradient nanostructure surface layer on austenitic stainless steel and controlling the content of martensite phase therein. This method not only overcomes the disadvantage that it is difficult to control the formation of martensite phase in traditional methods, but also It can solve the problems of large surface roughness, gradient nano-layer and thin hardened layer

Method used

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  • Method for forming gradient nano-structure surface layer on austenitic stainless steel and controlling content of martensite in gradient nano-structure surface layer
  • Method for forming gradient nano-structure surface layer on austenitic stainless steel and controlling content of martensite in gradient nano-structure surface layer
  • Method for forming gradient nano-structure surface layer on austenitic stainless steel and controlling content of martensite in gradient nano-structure surface layer

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Experimental program
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Effect test

Embodiment 1

[0054] Process 316L austenitic stainless steel cylindrical workpiece with a diameter of 10mm, its chemical composition is (mass percentage): C 0.03%, Si 0.03%, Cr 16.72%, Ni 10.7%, Mn 1.01%, Mo 2.12%, S0.016 %, P 0.042%, Fe is the balance;

[0055] 316L stainless steel stacking fault energy: about 40mJ / m 2 ;

[0056] Original grain size before processing: about 100μm;

[0057] Structure before processing: pure austenite structure;

[0058] Equipment: CNC lathe;

[0059] Spindle (processed workpiece) speed V 1 : 360r / min;

[0060] Spherical rolling tool diameter: 8mm;

[0061] Processing passes: 6 times;

[0062] The amount of pressing a p : 40μm;

[0063] Axial feed speed V 2 : 9mm / min;

[0064] Processing temperature: 22°C.

[0065] The surface smoothness of the processed sample in this embodiment is better than that of the finish turning state (such as figure 2 ). The cross-sectional morphology of 316L austenitic stainless steel after 6-pass treatment is as foll...

Embodiment 2

[0067] Heat treatment 316L austenitic stainless steel cylindrical workpiece, its chemical composition and initial state are the same as embodiment 1.

[0068] Equipment: CNC lathe;

[0069] Spindle (processed workpiece) speed V 1 : 360r / min;

[0070] Spherical rolling tool diameter: 8mm;

[0071] Processing passes: 5 times;

[0072] The amount of pressing a p : 40μm;

[0073] Axial feed speed V 2 : 9mm / min;

[0074] Heating device: hot air blower (heatable range 0 ~ 600 ℃);

[0075] Temperature measuring device: K-type thermocouple, digital display thermometer;

[0076] Processing temperature: 85°C;

[0077] After the 316L austenitic stainless steel shaft workpiece is treated by SMRT surface nano-treatment at a temperature of 85 °C, the surface finish of the treated state is better than that of the fine-turned state (such as Figure 7 ). The cross-sectional morphology of the 5-pass treatment was characterized under the scanning electron microscope as follows: Figu...

Embodiment 3

[0079] Heat treatment 316L austenitic stainless steel cylindrical workpiece, its chemical composition and initial state are the same as embodiment 1.

[0080] Equipment: CNC lathe;

[0081] Spindle (processed workpiece) speed V 1 : 360r / min;

[0082] Spherical rolling tool diameter: 8mm;

[0083] Processing passes: 4 times;

[0084] The amount of pressing a p : 40μm;

[0085] Axial feed speed V 2 : 9mm / min;

[0086] Heating device: hot air blower (heatable range 0 ~ 600 ℃);

[0087] Temperature measuring device: K-type thermocouple, digital display thermometer;

[0088] Processing temperature: 175°C;

[0089] The cross-sectional morphology of the 316L austenitic stainless steel shaft workpiece after 4-pass SMRT treatment at a temperature of 175 ° C is characterized under the scanning electron microscope as follows Figure 10 As shown, the thickness of the 316L stainless steel gradient refinement layer exceeds 700 μm, and the entire gradient structure includes: deform...

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Abstract

The invention discloses a method for forming a gradient nano-structure surface layer on austenitic stainless steel and controlling the content of martensite in the gradient nano-structure surface layer and belongs to the technical field of metal material surface nanocrystallization. According to the method, the austenitic stainless steel is treated through the temperature control SMRT technology; because an SMRT machining tool conducts high-speed rolling on the surface of the austenitic stainless steel to be treated, serious plastic deformation occurs to a surface structure of a steel part, and an original open-grain structure is changed into a gradient structure comprising nanocrystals, submicron crystals and micron crystals from the surface to the center; besides, the environmental temperature is controlled through combination with the SMRT process, transformation of austenite to deformation martensite phases is affected, and accordingly the content of the martensite in the gradient structure surface layer can be controlled. After temperature control SMRT machining, a gradient hardened layer with the thickness up to 1 mm can be formed on the austenitic stainless steel, the thickness of a nano layer can reach up to 50 microns, and the content of the martensite is controlled within 0-90%.

Description

technical field [0001] The invention relates to the surface strengthening method of austenitic stainless steel and the technical field of temperature-controlled surface plastic deformation, in particular to a method for forming a gradient nanostructure surface layer on austenitic stainless steel and controlling the content of martensite in it, which can be used in austenitic stainless steel Gradient nanostructures with different martensite content are prepared on the surface of the tentensitic stainless steel, and the microstructure size gradually increases from the surface to the inside, and the order is nanometer size, submicrometer size and micrometer size. Background technique [0002] Nanostructured materials have attracted extensive research due to their excellent properties, and the plastic deformation method is one of the most effective methods for preparing such materials. As we all know, the instability of most materials starts from the surface, so as long as a cer...

Claims

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Application Information

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IPC IPC(8): C21D7/00C21D11/00
Inventor 王镇波卢柯许久凌斯晓
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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