Method for improving strength and plasticity of high-nitrogen duplex stainless steel

A duplex stainless steel and high-nitrogen technology, applied in the field of steel alloy materials, can solve the problems of deterioration of plastic toughness and corrosion resistance of materials, affecting the safety of materials in service, and large residual stress of materials, so as to improve the comprehensive service performance and facilitate industrialization Effect of application, reduction of adverse effects

Active Publication Date: 2021-08-24
CHINA WEAPON SCI ACADEMY NINGBO BRANCH
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

However, the use of incomplete recrystallization annealing will leave a large residual stress in the material, reduce its corrosion resistance, and affect the service safety of the material in a corrosive environment
In addition, there is also the use of "cold rolling + low temperature annealing" to obtain a non-uniform layered structure, and to achieve performance improvement through grain refinement and back stress strengthening, but the strength and plasticity obtained by the above method are low, and due to the With more elements such as Cr, Mo, N, etc., it is easy to cause the precipitation of brittle phases such as nitrides and σ during low temperature (900-1000°C) annealing treatment, thereby deteriorating the plasticity, toughness and corrosion resistance of the material

Method used

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  • Method for improving strength and plasticity of high-nitrogen duplex stainless steel
  • Method for improving strength and plasticity of high-nitrogen duplex stainless steel
  • Method for improving strength and plasticity of high-nitrogen duplex stainless steel

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Embodiment 1

[0027] Such as Figure 1 to Figure 4 Shown is the first preferred embodiment of the present invention. The composition of the high-nitrogen duplex stainless steel in this embodiment is: C=0.02%, Cr=19.20%, Mo=0.01%, Ni=0.05%, Mn=6.13%, N=0.37%; the balance is iron and other unavoidable impurities.

[0028] The components according to the above content are placed in a vacuum induction melting furnace, and cast and melted under the protection of a nitrogen atmosphere to obtain an ingot of high nitrogen stainless steel.

[0029] Such as figure 1 As shown, the method for improving the strong plasticity of the above-mentioned high-nitrogen duplex stainless steel includes the following steps in turn:

[0030] 1) The ingot of duplex stainless steel is hot-rolled, the initial temperature of hot rolling is 1200°C, and the final rolling temperature is 980°C. After hot rolling, it is water-cooled to inhibit the precipitation of brittle phases such as carbonitrides;

[0031]2) Homogen...

Embodiment 2

[0037] The difference between this embodiment and the above-mentioned embodiment 1 is only that: the process parameters in the method for improving the strong plasticity of the above-mentioned high-nitrogen duplex stainless steel are different, specifically, the annealing time in step 4) is 30s.

[0038] The high-nitrogen duplex stainless steel in this embodiment has a tensile strength of 1000 MPa, a yield strength of 700 MPa, and an elongation after fracture of 58% after high-temperature rapid annealing. Due to the long annealing time, the crystal grain grows, the elongation increases, and the strength-plasticity product is 58GPa%. Compared with conventional solution treatment (1050°C, heat preservation for 300s, water cooling), the tensile strength is basically the same, but the yield strength is significantly improved, and the strength and plasticity product are slightly improved.

Embodiment 3

[0040] The difference between this embodiment and above-mentioned embodiment 1 is only:

[0041] The content of each component of the high-nitrogen duplex stainless steel is different. Specifically, according to the mass percentage, the high-nitrogen duplex stainless steel includes the following components: C=0.04%, Cr=22.8%, Mo=0.01%, Ni=1.5 %, Mn=7.8%, N=0.24%, and the balance is iron and other unavoidable impurities.

[0042] The process parameters in the method for improving the strong plasticity of the above-mentioned high-nitrogen duplex stainless steel are different. Specifically, the initial temperature of hot rolling in step 1) is 1250° C., and the final rolling temperature is 1000° C.; the annealing temperature in step 2) is 1050° C. ℃; the total reduction rate in step 3) is 65%.

[0043] Using conventional solution treatment (1050°C, heat preservation for 300s, water cooling), the tensile strength of the high-nitrogen duplex stainless steel is 950MPa, the yield str...

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Abstract

The invention relates to a method for improving the strength and plasticity of high-nitrogen duplex stainless steel. The steel is characterized by sequentially comprising the following steps that 1, hot rolling is carried out on a cast ingot of the duplex stainless steel, and water-cooling treatment is carried out after hot rolling; 2, the hot-rolled duplex stainless steel is subjected to homogenization solution annealing treatment, the annealing temperature ranges from 1050 DEG C to 1200 DEG C, and the heat preservation time ranges from 1 hour to 4 hours; 3, the duplex stainless steel treated in the step 2 is subjected to cold rolling treatment, and the total reduction rate ranges from 60% to 80%; and 4, the duplex stainless steel obtained after cold rolling is subjected to high-temperature rapid annealing treatment, the annealing temperature ranges from 1100 DEG C to 1200 DEG C, the annealing time ranges from 10 seconds to 90 seconds, and then water cooling is conducted. By means of TRIP effect strengthening, fine grain strengthening and back stress strengthening, the strength and plasticity matching problem of the high-nitrogen duplex stainless steel is effectively solved, and the yield strength, the tensile strength and the ductility of the high-nitrogen duplex stainless steel are improved.

Description

technical field [0001] The invention belongs to the technical field of iron and steel alloy materials, and in particular relates to a method for improving the strong plasticity of high-nitrogen duplex stainless steel. Background technique [0002] Duplex stainless steel has multiple advantages such as excellent mechanical properties, corrosion resistance and low alloy cost, and plays an important role in the construction of the national economy. Industry and other fields have broad application prospects, and have become one of the main trends in the future development of the stainless steel industry. Traditional duplex stainless steel contains more Ni elements, but my country is a country with a relative shortage of Ni resources. The massive consumption of Ni resources has caused sharp price fluctuations, leading to high cost of stainless steel alloys, which has affected the popularization and application of duplex stainless steel. Therefore, resource-saving duplex stainle...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D8/00C21D1/26
CPCC21D8/0273C21D8/0226C21D8/0236C21D1/26C21D2211/001C21D2211/005
Inventor 赵岩高永亮陈巍陈达宇宗铎
Owner CHINA WEAPON SCI ACADEMY NINGBO BRANCH
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