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A high-niobium austenitic heat-resistant steel with high structural stability at 700°C and its preparation method

An austenitic heat-resistant steel and stability technology, applied in the field of high-temperature metal structural materials, can solve problems such as poor organizational stability, increased unit construction costs, and inability to meet service performance requirements

Active Publication Date: 2021-05-04
HUANENG POWER INT INC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Austenitic heat-resistant steel has poor microstructure stability during long-term service, and the σ phase and M 23 C 6 The large amount of phase precipitation in the grain boundary and in the grain has caused the high temperature strength and toughness of the austenitic heat-resistant steel to drop significantly, which will pose a huge threat to the safety of the unit and personnel
Since austenitic heat-resistant steel cannot meet the service performance requirements of the unit parameters above 650 °C, the use of more nickel-based superalloys will undoubtedly greatly increase the construction cost of the unit

Method used

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  • A high-niobium austenitic heat-resistant steel with high structural stability at 700°C and its preparation method
  • A high-niobium austenitic heat-resistant steel with high structural stability at 700°C and its preparation method
  • A high-niobium austenitic heat-resistant steel with high structural stability at 700°C and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] 1) Alloy preparation.

[0044] The specific chemical composition (unit: mass percentage) of the above alloy at the time of preparation is Cr: 21.5%, Ni: 18%, Nb: 1.7%, C: 0.04%, N: 0.1%, Co: 0.9%, Si: 0.4% , Mn:

[0045] 0.03%, B: 0.002%, Zr: 0.002%, and the balance is Fe.

[0046] After considering the burning loss, the batching is completed, argon gas is introduced into the vacuum arc melting furnace as a protective gas, and a 150g button ingot with uniform alloy composition is obtained by electromagnetic stirring and turning. In order to eliminate macroscopic and microscopic segregation, a homogenization annealing treatment is carried out at 1100-1260°C for 20-35 hours, so that the alloy elements can be diffused as fully and uniformly as possible. After the homogenization annealing treatment, in order to make a large amount of Nb, C and N elements in the primary MX phase dissolve back into the matrix as much as possible, the alloy is subjected to solution treatment...

Embodiment 2-7

[0056] Table 2 shows the specific chemical composition of the alloys of Examples 2-7 of the present invention. Through the preparation and analysis of these alloys, it is found that the corresponding microstructure stability and mechanical properties are in line with the conditions and requirements applied to the steam pipeline of the 650 ℃ ultra-supercritical supercritical super / reheater.

[0057] Table 2 Chemical composition of Examples 2-7 of the present invention (unit is mass percent, balance is Fe)

[0058] alloy 2# 3# 4# 5# 6# 7# Cr 18 18.5 19 20 21 22 Ni 17 17.5 19 19.5 21 22 Nb 1.1 1.6 1.2 1.5 2 1 C 0.01 0.02 0.05 0.06 0.07 0.08 N 0.01 0.05 0.08 0.10 0.12 0.15 co 0.1 0.3 0.5 0.75 0.8 1 Si 0.3 0.34 0.4 0.43 0.52 0.75 mn 0.1 0.15 0.2 0.25 0.3 0.5 B 0.001 0.002 0.002 0.002 0.003 0.003 Zr 0.001 0.002 0.002 0.002 0.002 0.003

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Abstract

A high-niobium austenitic heat-resistant steel with high structural stability at 700°C and a preparation method thereof, the composition design is reasonable, the processing performance is good and the cost performance is high, and the precipitated phase of the long-term aging structure at 700°C is stable, and no σ phase is found , to avoid the embrittlement of the alloy during high-temperature service due to it, and through the secondary MX phase and Z phase dispersion strengthening. The heat-resistant steel includes, by mass percentage, 18-22% of Cr, 17-22% of Ni, 1-2% of Nb, 0.01-0.08% of C, 0.01-0.15% of N, 0.1-1% of Co, 0.4% ≤(Si+Mn+B+Zr)≤1%, the balance is Fe. The preparation method includes smelting into alloy ingots; homogenizing and annealing the alloy ingots; and solid solution treating the alloy ingots after homogenizing annealing at 1200-1280°C for 20-120 minutes.

Description

technical field [0001] The invention relates to the technical field of high-temperature metal structural materials, in particular to a high-niobium austenitic heat-resistant steel with high structural stability at 700°C and a preparation method thereof. Background technique [0002] Energy and environmental issues are undoubtedly major global issues in the 21st century and play a decisive role in the economic development of various countries. Since my country's reform and opening up, the demand for electricity has increased dramatically year by year along with economic development. my country's annual newly installed capacity has steadily increased, and coal-fired thermal power generation still occupies an important position, accounting for about 70% of the total power generation. As we all know, thermal power generation usually uses steam to drive the rotation of the steam turbine to obtain electrical energy, so higher steam parameters are the key to improving the efficienc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C33/04C22C38/02C22C38/04C22C38/48C22C38/50C22C38/52C22C38/54C21D1/26C21D6/00
Inventor 白佳铭袁勇朱传志张鹏尹宏飞党莹樱严靖博杨珍鲁金涛周永莉黄锦阳谷月峰
Owner HUANENG POWER INT INC
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