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Austenite heat-resisting steel and heat treatment technology thereof

A technology of austenitic heat-resistant steel and heat-resistant steel, applied in the field of high-temperature alloy steel, can solve the problems of adverse effects on corrosion resistance and reduction of Si content, achieve excellent anti-oxidation and corrosion resistance, and improve brittleness , good corrosion resistance

Active Publication Date: 2017-02-15
CHINA HUANENG GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the reduction of Si content will also have an adverse effect on the corrosion resistance of materials at higher temperatures or in water vapor environments.

Method used

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  • Austenite heat-resisting steel and heat treatment technology thereof
  • Austenite heat-resisting steel and heat treatment technology thereof
  • Austenite heat-resisting steel and heat treatment technology thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] On the basis of the composition of Incoloy 800 alloy, the contents of Nb, Ti, Si, C and other elements are adjusted, and the alloy is smelted in a vacuum induction furnace. The obtained alloy includes: C: 0.08%, Cr: 22%, Mo: 0.5%, W: 2.5%, Nb: 0.4%, Mn: 0.5%, Si: 1.5%, Ni: 32%, B: 0.003%, and the balance is Fe.

[0033] figure 1 It is a photo of the as-cast structure of the alloy. The alloy structure is composed of austenite and grain boundary rod-shaped NbC. Alloy in 750℃ air, water vapor oxidation and boiler flue gas environment (N 2 -15%CO 2 -3.5%O 2 -0.1%SO 2 ) under the weight gain of 3.7g / m 2 , 5.4g / m 2 with 21g / m 2 .

Embodiment 2

[0035] On the basis of the composition of Incoloy 800 alloy, the contents of Nb, Ti, Si, C and other elements are adjusted, and the alloy is smelted in a vacuum induction furnace. The obtained alloy includes: C: 0.09%, Cr: 22%, Mo: 0.5%, W: 2.5%, Nb: 0.4%, Mn: 0.5%, Si: 2.0%, Ni: 32%, B: 0.003%, Al: 0.5%, Ti: 0.2%, and the balance is Fe.

[0036] figure 2It is a photo of the as-cast structure of the alloy. The alloy structure is composed of austenite and grain boundary rod-shaped NbC. Alloy oxidation at 750℃ and boiler flue gas environment (N 2 -15%CO 2 -3.5%O 2 -0.1%SO 2 ) under the weight gain of 3.2g / m 2 , 4.9g / m 2 with 19g / m 2 .

Embodiment 3

[0038] The alloy in Example 1 was solution treated at 1200° C. for 2 hours, then air-cooled to room temperature, and then aged at 750° C. for 30 hours.

[0039] image 3 It is the structure photo of the alloy after solid solution treatment. At this time, the alloy is mainly composed of austenite and NbC at the grain boundary.

[0040] Figure 4 This is the photo of the microstructure of the alloy after aging. NbC has no obvious growth phenomenon, and film-like Cr is formed at the grain boundary. 23 C 6 . There is Cr in the grain boundary of the alloy 23 C 6 Obvious precipitation, and its size is not larger than 5 microns.

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Abstract

The invention discloses austenite heat-resisting steel and a heat treatment technology of the steel. Through adjustment of the content of Si, Ti and C, a small amount of Nb is added into an alloy, particular NbC distributed along the grain boundary is obtained, and through heat treatment, the size of the NbC is limited within the low range; according to the steel and the technology, the obtained material carbide accounts for more than 90% of the grain boundary, the NbC is mainly distributed along the grain boundary, and the size of the NbC does not exceed 5 micrometers; the alloy prepared through the technology has the good structure stability, the room temperature hardness is above 180 HV, the good oxidation resistance performance and the good corrosion resistance performance are achieved, weight increasing of 500h oxidation at the temperature of 750 DEG C does not exceed 4.0g / m<2>, weight increasing of 1000h water steam oxidization at the temperature of 750 DEG C does not exceed 6.0g / m<2>, and corrosion weight increasing of 500 h is lower than 25g / m<2> in the 750 DEG C smoke environment (N2-15%CO2-3.5%O2-0.1%SO2).

Description

technical field [0001] The invention belongs to the field of high-temperature alloy steel, and specifically relates to an austenitic heat-resistant steel and its heat treatment process, which is especially suitable for long-term use of components under high-temperature and low-stress conditions, such as ultra-supercritical unit reheaters, ethylene cracking production The hydrogen production reformer tubes, etc., can also be applied to some lower temperature components, such as nuclear power unit pressurized water reactor steam generator tubes, heat pipes, etc. Background technique [0002] Incoloy 800 alloy has high Cr content and good oxidation resistance and corrosion resistance, so it is widely used in various industries, for example, it is used as a heat exchange tube in the petrochemical industry and has high requirements for stress corrosion cracking The components are used as steam generator tubes in nuclear power units, and used as air cooling heat exchange tubes in ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C30/00C22F1/00
CPCC21D6/004C22C30/00C22C38/02C22C38/04C22C38/06C22C38/34C22C38/44C22C38/48C22C38/50C22C38/54C22F1/00
Inventor 严靖博谷月峰赵新宝鲁金涛周永莉黄锦阳杨征张醒兴张桐朱传志
Owner CHINA HUANENG GRP CO LTD