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Pretreatment method for improving lead-bismuth corrosion resistance of ferrite-martensite steel

A technology for martensitic steel and corrosion performance, applied in heat treatment furnaces, heat treatment equipment, coatings, etc., can solve problems such as the decline in mechanical properties and lead-bismuth corrosion resistance, the decline in the stability of fine-grained structures, and the limitation of Al additions , to achieve the effect of facilitating industrialization, convenient operation, and improving the corrosion resistance of lead and bismuth

Active Publication Date: 2021-04-13
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

In order to solve the above problems, the researchers proposed that the addition of Si can promote the formation of Si-rich oxides in the oxide layer and improve the corrosion resistance of liquid lead and bismuth, but too high Si content will promote the formation of δ-ferrite and Laves phase, Reduce mechanical properties
Although the addition of Al has a more obvious effect on improving the compactness of the oxide layer, Al has a strong role in promoting the formation of ferrite, which limits the amount of Al addition.
In addition, some researchers have proposed the method of grain refinement to improve the corrosion resistance of liquid lead and bismuth, but after long-term service at high temperature, the stability of the fine grain structure gradually decreases, resulting in the decline of mechanical properties and corrosion resistance of lead and bismuth.

Method used

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  • Pretreatment method for improving lead-bismuth corrosion resistance of ferrite-martensite steel
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  • Pretreatment method for improving lead-bismuth corrosion resistance of ferrite-martensite steel

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Effect test

Embodiment 1

[0032] This embodiment provides 9Cr2WVTa ferrite-martensitic steel plate, chemical composition (wt.%) is: C: 0.11%, Cr: 8.86%, W: 1.62%, V: 0.24%, Ta: 0.11%, Mn : 0.45%, Si: 0.05%, S: 0.005%, P: 0.005%, and the balance is Fe. The pretreatment process steps of the plate are as follows:

[0033] 1) Heat treatment: Quenching and tempering heat treatment of ferritic-martensitic steel plate. The quenching treatment is 1020°C for 60 minutes and then water cooling, and the tempering treatment is 750°C for 2 hours and then air cooling.

[0034] 2) Surface treatment: Mechanical polishing is carried out on the surface of the plate to completely remove the surface oxide skin, so that the surface reveals a metallic luster, and the surface roughness is required to be less than 1 μm.

[0035] 3) Cold deformation: cold rolling deformation treatment is carried out at room temperature, and the cold rolling deformation is 20%.

[0036] 4) High-temperature oxidation: the cold-rolled plate is s...

Embodiment 2

[0039] The same ferritic-martensitic steel sheet as in Example 1 was used and subjected to the same quenching and tempering heat treatment, but no pretreatment of cold deformation and high temperature oxidation was performed. The sample is placed in the same liquid lead-bismuth environment as in Example 1, and the cross-sectional appearance of the corrosion layer is as follows: Figure 5 shown. It can be seen that a corrosion layer with a thickness of about 23 μm is formed on the surface of ferrite-martensitic steel. It can be seen that the ferritic-martensitic steel without pretreatment by the method of the present invention will undergo obvious oxidation corrosion.

Embodiment 3

[0041] The same ferritic-martensitic steel sheet as in Example 1 was used and subjected to the same quenching and tempering heat treatment and high-temperature oxidation treatment, but no cold deformation pretreatment was performed before the oxidation treatment. The sample is placed in the same liquid lead-bismuth environment as in Example 1, and the cross-sectional appearance of the corrosion layer is as follows: Image 6 shown. It can be seen that a corrosion layer with a thickness of about 9 μm is formed on the surface of ferrite-martensitic steel. It can be seen that the ferritic-martensitic steel without cold deformation pretreatment cannot effectively resist the corrosion of liquid lead and bismuth even if it is subjected to high temperature oxidation treatment.

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Abstract

The invention discloses a pretreatment method for improving lead-bismuth corrosion resistance of ferrite-martensite steel and belongs to the technical field of corrosion protection of nuclear materials. The pretreatment method comprises the following steps: firstly, carrying out quenched-tempered heat treatment for quenching and tempering ferrite-martensite steel, then carrying out surface treatment, enabling the surface of the ferrite-martensite steel to expose metallic luster, and requiring the surface roughness to be smaller than 1 micron; secondly, carrying out cold deformation treatment at room temperature, wherein the accumulated deformation amount is 10-40%; and finally, carrying out high-temperature oxidation treatment, wherein the oxidation temperature is 500-650 DEG C, and the oxidation time is 5-50 hours. Through the pretreatment method with combination of cold deformation and high-temperature oxidation, generation of a compact oxidation film on the surface of the ferrite-martensite steel can be accelerated so as to improve the lead-bismuth corrosion resistance; and meanwhile, the mechanical property of a base body cannot be damaged due to reasonable control of the deformation amount and the high-temperature oxidation system. The method is convenient to operate and lower in cost, and is not limited by sizes and shapes of workpieces, and industrial popularization of the method is facilitated.

Description

technical field [0001] The invention relates to the technical field of corrosion protection of nuclear materials, in particular to a pretreatment method for improving the lead-bismuth corrosion resistance of ferrite-martensitic steel. Background technique [0002] Lead-bismuth eutectic alloys have been used as coolants for fourth-generation lead-bismuth cooled fast reactors and accelerator-driven subcritical systems (ADS) due to their weak neutron absorption and moderation capabilities, low melting point, high boiling point, and good chemical stability. ) coolant and spallation target candidate materials. However, the high-temperature, flowing liquid lead-bismuth alloy will have a strong corrosion effect on structural materials, which will endanger the safe operation of the reactor. How to improve the compatibility of structural materials with liquid lead-bismuth alloys has become an urgent problem to be solved. [0003] 9-12% Cr ferritic-martensitic steel has good thermop...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/25C21D6/00C21D9/00C22C38/02C22C38/04C22C38/22C22C38/24C22C38/26C23C8/02C23C8/10
CPCC21D1/25C21D6/002C21D6/005C21D6/008C21D9/0081C22C38/22C22C38/24C22C38/26C22C38/04C22C38/02C22C38/002C23C8/02C23C8/10C21D2211/005C21D2211/008
Inventor 陈胜虎戎利建姜海昌闫德胜赵明久王本贤胡小峰宋元元赵帅张洋鹏
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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