阅读说明：本技术 一种中温抗氧化镍基耐蚀合金及其制备工艺 (Medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy and preparation process thereof ) 是由 马颖澈 查向东 李昊泽 高明 梁田 刘奎 于 2020-09-29 设计创作，主要内容包括：本发明公开了一种中温抗氧化镍基耐蚀合金及其制备工艺,属于耐蚀合金技术领域。按重量百分含量计,该合金化学成分为：C≤0.02,Cr 16-24％,Mo 4-9％,Ti≤1.2％,Fe 6-15％,B≤0.006％,Ni余量。本发明合金属于固溶强化型镍基耐蚀合金,具有优异的高温抗氧化性能。在以PO-(4)～(3-)为主,SO-(4)～(2-)、NO～(3-)、H～(+)、OH～(-)等多离子共存,温度为350-600℃范围内,压强为20-30MPa的超临界条件下使用时,本发明合金的耐蚀性明显优于Inconel671、Inconel625、Hastelloy C-276,可作为超临界水氧化环境条件下处理废水、城市污泥装备反应器材料。(The invention discloses a medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy and a preparation process thereof, belonging to the technical field of corrosion-resistant alloys. The alloy comprises the following chemical components in percentage by weight: less than or equal to 0.02 percent of C, 16 to 24 percent of Cr, 4 to 9 percent of Mo, less than or equal to 1.2 percent of Ti, 6 to 15 percent of Fe, less than or equal to 0.006 percent of B, and the balance of Ni. The alloy belongs to solid solution strengthening type nickel-based corrosion resistant alloy and has excellent high-temperature oxidation resistance. In the presence of PO 4 3‑ Mainly, SO 4 2‑ 、NO 3‑ 、H + 、OH ‑ When the alloy is used under the supercritical conditions of 350-600 ℃ temperature and 20-30MPa pressure, the corrosion resistance of the alloy is obviously superior to that of Inconel671, Inconel625 and Hastelloy C-276, and the alloy can be used as equipment for treating wastewater and municipal sludge under the supercritical water oxidation environment conditionReactor materials.)

1. The medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy is characterized in that: the alloy comprises the following chemical components in percentage by weight:

less than or equal to 0.02 percent of C, 16 to 24 percent of Cr, 4 to 9 percent of Mo, less than or equal to 1.2 percent of Ti, 6 to 15 percent of Fe, less than or equal to 0.006 percent of B, and the balance of Ni.

2. The medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy according to claim 1, wherein: in the nickel-based corrosion-resistant alloy, the content of Ti is 0.1-1.2 wt.%.

3. The medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy according to claim 1, wherein: in the nickel-based corrosion-resistant alloy, the content of C is 0.002-0.2 wt.%.

4. The medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy according to claim 1, wherein: in the nickel-based corrosion-resistant alloy, the content of S is less than or equal to 10ppm.wt, and the content of O is less than or equal to 10 ppm.wt.

5. The preparation process of the medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy according to claim 1, which is characterized in that: the process comprises the following steps:

(1) preparing materials according to alloy components, and smelting in a vacuum induction smelting furnace to prepare an alloy ingot;

(2) the alloy ingot is sequentially forged and hot rolled to prepare an alloy rod with the diameter of 14-16 mm;

(3) in order to ensure that the alloy has good strength and plasticity matching at the temperature of 350-600 ℃, carrying out heat treatment on the alloy bar, wherein the heat treatment system is as follows: 1100-1150 deg.c for 0.5-2 hr, and water quenching.

6. The preparation process of the medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy according to claim 4, which is characterized in that: in order to improve the component uniformity of the alloy, the alloy ingot prepared in the step (1) can be remelted by adopting an electroslag remelting or vacuum consumable remelting method, and then forged.

7. The preparation process of the medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy according to claim 4, which is characterized in that: in the step (2), the initial deformation temperature of forging and hot rolling is 1150-1170 ℃, and the final deformation temperature is not lower than 950 ℃.

Technical Field

The invention relates to the technical field of corrosion-resistant alloys, in particular to a medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy and a preparation process thereof.

Background

At present, with the enlargement of urban scale and the rapid development of industrial enterprises in China, the service conditions of corrosion-resistant materials become more and more rigorous, people always pursue to develop superalloys with more outstanding performance, and hope to obtain larger universality, but the requirement is a contradiction, and no universal alloy exists at present, so that the development of the corrosion-resistant alloy with performance and cost taken into consideration is a hotspot and inevitable trend of the development of the corrosion-resistant alloy at home and abroad at present according to the requirement of the use environment. At present, the municipal wastewater and sludge treatment equipment in China faces the technical problem in the aspect of material use when treating solid-liquid emissions in cities and towns, and is mainly embodied in corrosion-resistant materials of equipment preheaters and superheater tubes. Some experimental devices are designed to be made of corrosion-resistant alloys such as Inconel671, Inconel625 and Hastelloy C-276, but more or less of the materials have the problems of poor cold and hot processability, difficulty in welding, poor corrosion resistance, high manufacturing cost and the like, and the application is severely restricted. Therefore, the corrosion resistant material which completely meets the requirements of urban wastewater and sludge treatment equipment and has lower cost is urgently needed to be developed, and the corrosion resistant material has important scientific significance and application value.

Disclosure of Invention

The invention aims to provide a medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy and a preparation process thereof. .

The medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy comprises the following chemical components in percentage by weight:

less than or equal to 0.02 percent of C, 16 to 24 percent of Cr, 4 to 9 percent of Mo, less than or equal to 1.2 percent of Ti, 6 to 15 percent of Fe, less than or equal to 0.006 percent of B, and the balance of Ni.

In the nickel-based corrosion-resistant alloy, the content of Ti is preferably 0.1-1.2 wt.%.

In the nickel-based corrosion-resistant alloy, the content of C is preferably 0.002-0.2 wt.%. (

In the nickel-based corrosion-resistant alloy, the content of S is less than or equal to 10ppm.wt, and the content of O is less than or equal to 10 ppm.wt.

The preparation process of the medium-temperature oxidation-resistant nickel-based corrosion-resistant alloy comprises the following steps:

(1) preparing materials according to alloy components, and smelting in a vacuum induction smelting furnace to prepare an alloy ingot;

(2) the alloy ingot is sequentially forged and hot rolled to prepare an alloy rod with the diameter of 14-16 mm;

(3) in order to ensure that the alloy has good strength and plasticity matching at the temperature of 350-600 ℃, carrying out heat treatment on the alloy bar, wherein the heat treatment system is as follows: 1100-1150 deg.c for 0.5-2 hr, and water quenching.

In order to improve the component uniformity of the alloy, the alloy ingot prepared in the step (1) can be remelted by adopting an electroslag remelting or vacuum consumable remelting method, and then forged.

In the step (2), the initial deformation temperature of forging and hot rolling is 1150-1170 ℃, and the final deformation temperature is not lower than 950 ℃.

The alloy of the invention has the following design mechanism:

the alloy belongs to a solid solution strengthening type nickel-based corrosion resistant alloy, and realizes solid solution strengthening by adding Cr, Mo and Fe for synergistic action, so that the medium-high temperature oxidation resistance is improved; the addition of a small amount of Ti improves the precipitation amount of carbide in the grain boundary of the alloy, and reduces the intergranular corrosion tendency of the alloy.

In order to ensure that the alloy has good cold and hot processability, the alloy S, B, O and the like are strictly controlled, wherein the S content is less than or equal to 10ppm.

In order to ensure that the alloy has excellent oxidation resistance within the range of 350-600 ℃, the alloy element Cr is added to realize oxidation resistance under the synergistic effect with other elements. In order to ensure that the alloy has good strength and plasticity matching at 350-600 ℃, the heat treatment system is as follows: 1100-1150 deg.c for 0.5-2 hr, and water quenching.

The invention has the advantages that:

1. the alloy components of the invention can be accurately controlled, the domestic scarce resources of the precious alloy element Co are greatly saved, the production cost is relatively low, the production process has strong practicability, and the material can be produced in large batch.

2. The alloy belongs to a nickel-based corrosion-resistant alloy strengthened by solid solution and aging, is particularly suitable for being used at 350-600 ℃, and has stable alloy structure and no brittle phase precipitation in the long-term aging process.

3. The alloy of the invention contains high Cr element and a certain content of Ti element, ensures that the alloy has excellent corrosion resistance at high temperature, and is used as a reactor material for treating urban wastewater sludge under supercritical conditions. In the presence of PO₄ ^3-Mainly, SO₄ ^2-、NO^3-、H⁺、OH^-When the alloy is used under the supercritical conditions of the temperature of 350-600 ℃ and the pressure of 20-30MPa, the corrosion resistance of the alloy is superior to that of foreign alloys such as Inconel625, Inconel671 and Hastelloy C-276.

4. Compared with the similar alloy, the alloy has moderate room temperature strength and excellent plasticity after solid solution and aging treatment; alloy in supercritical PO₄ ^3-The complex ionic medium mainly used has good tissue stability and corrosion resistance, and harmful brittle phases are not precipitated after long-term aging at medium temperature; the corrosion resistance of the alloy is superior to that of foreign Inconel671, Inconel625 and Hastelloy C-276 alloy;

5. the alloy of the invention has good cold and hot processing performance and can be prepared into bars, plates, pipes and wires. Can be used as a reactor material for treating wastewater and municipal sludge under the supercritical water oxidation environmental condition.

Drawings

FIG. 1 is a comparison of the thickness of the corrosion layer after four alloy coupons have been held in a mixed salt solution at 450 ℃ for 500 hours; wherein: the upper part, the middle part and the lower part of the alloy hanging piece (vertically placed in the solution) are respectively arranged on the upper part, the middle part and the lower part of the lower part; u26-1 represents the alloy of the present invention.

FIG. 2 is a comparison of the thickness of the corrosion layer after four alloy coupons have been held in a mixed salt solution at 600 ℃ for 500 hours; u26-1 represents the alloy of the present invention.

Detailed Description

The present invention will be described in further detail below with reference to the accompanying drawings.

3 20kg of cast ingots are smelted by a vacuum induction furnace, and the cast ingots are directly forged and hot-rolled into bars with the diameter of 14 mm. The initial deformation temperature of forging and hot rolling is 1150-1170 ℃, and the final deformation temperature is not lower than 950 ℃. The hot rolled bar chemical composition is shown in table 1.

The heat treatment system of the alloy is 1100-1150 ℃ solid solution, the heat preservation time is changed according to the size change of the alloy finished product, and the minimum heat preservation time is 30 min.

Table 1 three alloy chemistries of the present invention (wt.%) smelted using a vacuum induction furnace

No.1, No.2 and No.3 alloys in Table 1 are subjected to solution treatment at 1150 ℃ for 30min, and the instantaneous mechanical properties of the materials at room temperature, 300 ℃ and 600 ℃ are measured, wherein the mechanical properties of the alloys are shown in Table 2. It can be seen that the mechanical properties of the material are well matched, and the requirements of strength and plasticity under supercritical conditions can be met. The alloy has good strength and plasticity at room temperature and medium temperature, is completely suitable for cold rolling and cold drawing processing with large deformation, and is beneficial to preparing sectional materials such as bars, plates, pipes, wires and the like.

TABLE 2 instantaneous tensile Property data of alloys of the invention at different temperatures

The alloy of the invention in a solid solution state and alloy 625 are taken to be welded by different materials, the instantaneous tensile property of the materials at room temperature, 300 ℃ and 600 ℃ is measured, as shown in the table 3, the result shows that the welding coefficient of an alloy welding joint is more than 85% under the same temperature condition, and the use requirement of welding is met.

TABLE 3 instantaneous tensile Property data of welded joints of alloy of the present invention and alloy 625 dissimilar materials at different temperatures

In order to verify the corrosion resistance of the alloy, the No.2 alloy is taken as a test alloy, and is subjected to solution treatment at 1150 ℃ for 30min and then subjected to aging treatment at 760 ℃ for 16h to prepare a round test piece with the thickness of 3mm and the surface polished. The prepared alloy hanging piece of the invention and alloy hanging pieces of 625, 671 and C-276 with the same size specification are divided into an upper layer, a middle layer and a lower layer which are placed into the same reactor, the medium in the reactor is mixed sodium salt solution containing phosphate radical, sulfate radical and chloride ion (the molar ratio is 8:1:1), the pressure is 22MPa, and the temperature is respectively 450 ℃ and 600 ℃. Keeping the temperature for 500h, taking out, and measuring the thicknesses of the corrosion layers of the four materials by adopting an SEM method. As shown in fig. 1 and 2. Clearly, the corrosion layer thickness for the alloy of the invention is the thinnest of the four alloys, the corrosion layer thickness for the alloy 625 is the thickest, and increases with increasing depth of immersion. This phenomenon indicates that the corrosion resistance of the alloy of the present invention is superior to that of several other corrosion resistant alloys, whether 450 c or slightly higher 600 c.