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A Method for Improving the Lead-Bismuth Corrosion Resistance of Low-Activation Ferrite/Martensitic Steel

A low-activation ferritic and martensitic steel technology, applied in the field of metal protection, can solve the problems of poor lead-bismuth corrosion resistance, difficult to use for a long time, etc., so as to improve lead-bismuth corrosion resistance and high temperature oxidation resistance. and mechanical properties

Active Publication Date: 2017-12-26
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the problems that the candidate structure material of ADS spallation target—low ​​activation ferrite / martensitic steel has poor lead-bismuth corrosion resistance and is difficult to use in lead-bismuth alloy for a long time, the present invention provides a method to improve its lead-resistant The method of bismuth corrosion performance, through the combination of surface mechanical rolling treatment (SMGT) and high temperature pre-oxidation, forms a layer of dense and uniform manganese-rich and chromium-rich oxide film on the nanocrystalline surface layer of low-activation steel; the oxide film is uniform, Dense and stable, so that it can effectively reduce the corrosion of liquid lead-bismuth alloy to low-activation ferrite / martensitic steel, so that it can meet the requirements of service conditions

Method used

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  • A Method for Improving the Lead-Bismuth Corrosion Resistance of Low-Activation Ferrite/Martensitic Steel
  • A Method for Improving the Lead-Bismuth Corrosion Resistance of Low-Activation Ferrite/Martensitic Steel
  • A Method for Improving the Lead-Bismuth Corrosion Resistance of Low-Activation Ferrite/Martensitic Steel

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Embodiment 1

[0030] 9Cr2WVTa low-activation ferrite / martensitic steel is used as the research material to illustrate the influence of the present invention on the lead-bismuth corrosion resistance of low-activation steel, and its composition is shown in Table 1. The heat treatment system of the material before SMGT is: water quenching at 1050°C for 1 hour, air cooling at 750°C for 2 hours; figure 1 It can be seen that the material after heat treatment is composed of tempered martensite and carbide, and the grain size is about 15 μm. The low-activation steel after heat treatment is subjected to surface mechanical rolling treatment, figure 2 is the cross-sectional morphology of the material after SMGT treatment. It can be seen from the figure that its microstructure refinement layer is about 70 μm; image 3 It is a transmission electron microscope dark field image of the surface structure of the material after SMGT treatment, and it can be seen that nanocrystals with a grain size smaller t...

Embodiment 2

[0034] Using the same material as in Example 1, and through the same heat treatment but without pre-oxidation and nano-processing, the sample is placed in the same corrosion environment as in Example 1, and the corrosion results are as follows Figure 6 As can be seen from the figure, an oxide layer with a thickness of about 20 μm has been formed on the surface of the raw material, which is equivalent to the situation in Example 2. It can be seen that the original state coarse-grained material will undergo obvious oxidation in the environment of lead and bismuth, and does not have the performance of corrosion resistance of lead and bismuth.

Embodiment 3

[0036] The same material, heat treatment, and nanonization method as in Example 1 were used, but no pre-oxidation treatment was performed on the material with a nanocrystalline surface. The material with the nanocrystalline surface is placed in the same corrosion environment as in Example 1 for 500h, and its cross-sectional appearance is as follows: Figure 7 shown. It can be seen from the figure that the material has been oxidized in the lead-bismuth environment, and an oxide layer of about 20 μm is formed on the surface of the material. Therefore, pure nanocrystals cannot avoid the corrosion of 9CrWVTa low-activation steel in lead-bismuth alloy.

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Abstract

The purpose of the present invention is to provide a method for improving the lead-bismuth corrosion resistance of low-activation ferrite / martensitic steel so as to meet the requirements of service conditions. The method first prepares nanocrystalline structures with a grain size of less than 100nm on the surface of the material by Surface Mechanical Grinding (SMGT) technology, and then pre-oxidizes the low-activation steel with nanocrystalline surfaces to form a material with better comprehensive properties. The oxide layer rich in manganese and chromium, which is uniform, dense and stable, can significantly reduce the corrosion damage of lead-bismuth alloy to structural materials. This method can significantly improve the lead-bismuth corrosion resistance of the material, thus providing a feasible way to solve the problem of poor corrosion resistance of low-activation materials.

Description

technical field [0001] The invention relates to metal protection technology, and specifically provides a method for improving the lead-bismuth corrosion resistance of low-activation ferrite / martensitic steel. Background technique [0002] Low activation ferrite / martensitic steel is selected as a candidate structural material for future ADS spallation targets due to its low thermal expansion coefficient, high thermal conductivity, excellent resistance to radiation swelling and resistance to radiation brittleness. Because Pb-Bi alloy has the advantages of good neutronic properties, excellent thermal conductivity and no radiation damage in liquid Pb-Bi, Pb-Bi alloy is selected as the neutron generation target and coolant in the future ADS system. Since the working environment temperature of the ADS system is in the range of 300-700°C, the liquid lead-bismuth alloy will inevitably corrode the structural materials. The main corrosion methods are as follows: 1) The component eleme...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23F17/00C23C8/14
Inventor 戎利建鲁艳红卢柯王镇波宋元元
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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