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Method for controlling grain boundary characteristics of austenitic stainless steel

A technology of austenitic stainless steel and grain boundary, which is applied in the field of controlling the surface structure of austenitic stainless steel to achieve the effect of improving the resistance to intergranular corrosion

Inactive Publication Date: 2011-04-27
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This technology has been widely used to improve the hardness, fatigue strength and wear resistance of materials, but the existing reports are all from the perspective of changes in stress distribution on the surface of materials caused by laser shock and the refinement of material grains, and have not yet been adopted. A report on controlling the distribution of grain boundary features in materials by laser shock combined with high temperature heat treatment

Method used

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  • Method for controlling grain boundary characteristics of austenitic stainless steel
  • Method for controlling grain boundary characteristics of austenitic stainless steel

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Experimental program
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Effect test

Embodiment 1

[0013] A Q-switched neodymium glass laser was used to perform surface impact treatment on austenitic stainless steel. The specific process parameters are shown in Table 1. Subsequently, the impacted sample was annealed at 927°C, 947°C and 967°C for 24 hours respectively, so that the ratio of low-energy CSL (heavy site lattice) grain boundaries (Σ≤29) in the treated layer can reach more than 74%. , the specific test results are shown in Table 2.

[0014]

Embodiment 2

[0016] At room temperature in 0.5 M H 2 SO 4 Electrochemical corrosion experiments were carried out on the treated materials in +0.01M KSCN solution. The reactivation current ratio varied with the sensitization temperature and time. The reactivation current ratio measured at 650°C for 2 hours is listed in Table 2.

Embodiment 3

[0018] Table 2 lists the corrosion rate of the treated material after being sensitized at 650°C for 2 hours and corroded in boiling sulfuric acid-ferric sulfate solution for 72 hours.

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Abstract

The invention relates to a method for controlling grain boundary characteristics of austenitic stainless steel. The method comprises the following steps of: pre-processing the austenitic stainless steel, cutting the austenitic stainless steel into square blocks of the size of 40*40mm, and polishing the blocks with sand paper gradually to obtain No.800; then placing the pre-processed material on a laser processing workbench, regulating the output power, pulse width, light spot size and overlap ratio of a laser device, and carrying out laser impact processing on the surface of the material; and finally placing the material processed by laser impact in a heat treatment furnace, taking the material out of the furnace after warm preservation for water quenching so as to realize the control over the grain boundary characteristics of the austenitic stainless steel. The method can increase the intergranular corrosion resistance of the austenitic stainless steel, and can perform in-situ repair on an austenitic stainless steel member.

Description

technical field [0001] The invention belongs to the technique of controlling the surface structure of austenitic stainless steel, in particular to a method for controlling the grain boundary characteristics of austenitic stainless steel. Background technique [0002] One of the main factors causing the low intergranular corrosion resistance of austenitic stainless steel is that austenitic stainless steel is very easy to sensitize. The sensitization will lead to the appearance of intergranular corrosion and intergranular stress corrosion, which will eventually lead to the failure of components. As an important structural feature of polycrystalline materials, grain boundaries have an important impact on the properties of materials. The study found that many phenomena (grain boundary diffusion, precipitation, corrosion) are closely related to the structure of the grain boundary. Low-energy CSL grain boundaries (especially ∑3) exhibit strong inhibitory effects on slip, fractur...

Claims

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Application Information

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IPC IPC(8): C21D1/09C21D1/18
Inventor 杨森
Owner NANJING UNIV OF SCI & TECH
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