A high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel and a rapid preparation method thereof

Abstract

The application belongs to the field of metal material processing, and discloses a high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel and a rapid preparation method thereof. The target components of the strengthened steel are mainly Fe elements, and further include Cr 9.0-14.0%, W 1.0-2.0%, Mn 0.2-1.0%, Si 1.0-3.0%, Y 0.4-1.0%, O 0.11-0.27%, and C≤0.0016%. The strengthened steel is prepared by the following method: (1) forming multiple pre-alloy powders by using a gas atomization method; simultaneously preparing pre-oxidized Si powder SiO x ; (2) mixing and ball-milling the powders, and obtaining a cored wire by using a steel belt method; and (3) printing the cored wire by using an electric arc wire additive manufacturing process, so that the strengthened steel is obtained. The application improves the actual use rate of Y elements by improving the process flow of the preparation method, forms a high-number-density Y-Si-O nano-dispersion phase in the matrix, and improves the mechanical strength and high-temperature-resistant and corrosion-resistant performance of the ODS steel.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal material processing, and more particularly relates to a high-temperature-resistant and corrosion-resistant silicon-containing nanometer oxide dispersion strengthened steel and a rapid preparation method thereof. BACKGROUND

[0002] Oxide dispersion strengthened (ODS) steel is considered as one of the key candidate materials for fusion reactor blanket structure due to its excellent high-temperature mechanical properties, radiation resistance, and low sensitivity to hydrogen embrittlement and helium embrittlement. The excellent high-temperature performance of ODS steel is attributed to the dispersion of fine nanometer oxide particles in the matrix. Currently, ODS steel is usually prepared by powder metallurgy, which is time-consuming, low in efficiency, and high in cost, limiting its large-scale application. Although the traditional smelting and casting method has high preparation efficiency and can realize large-scale production, the wettability between the oxide particles and the steel liquid is poor, and the oxide particles are prone to coarsening and agglomeration during the smelting process, resulting in deterioration of the performance of the ODS steel.

[0003] In addition, the dispersion strengthening phase is generally introduced into the ODS steel by directly adding nanometer / micron oxide powder, decomposing the oxide particles during mechanical alloying, and precipitating during subsequent high-temperature sintering. However, due to the good thermal stability of the oxide powder, it is difficult to dissolve during preparation, and the actual content in the steel is much less than the added amount, which also leads to waste of resources.

[0004] Therefore, it is of great significance to develop a production and preparation process with fast preparation rate, low process cost, and the ability to prepare large-scale complex components, which can effectively introduce high number density of nanometer oxide particles into the matrix for the wide application of ODS steel. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide a high-temperature-resistant and corrosion-resistant silicon-containing nanometer oxide dispersion strengthened steel and a rapid preparation method thereof. By improving the process flow of the preparation method, the composite pre-alloy powder and the pre-oxidized Si powder SiO x (x<2), on the one hand, avoids the poor dissolution of directly added yttrium oxide in the matrix, improves the actual use rate of Y element, and on the other hand, improves the number density of Y-Si-O nanometer dispersion phase, forms a high number density of Y-Si-O nanometer dispersion phase in the matrix, and improves the mechanical strength and high-temperature-resistant and corrosion-resistant performance of the ODS steel. Moreover, the present application is based on the electric arc wire additive manufacturing process, which is suitable for the rapid preparation of fusion reactor blanket structure materials and large-scale complex components.

[0006] To achieve the above objectives, according to one aspect of the present invention, a high-temperature and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel is provided, characterized in that the target component of the strengthened steel is mainly Fe element, and the target component further comprises, by mass percentage: Cr 9.0-14.0%, W 1.0-2.0%, Mn 0.2-1.0%, Si 1.0-3.0%, Y 0.4-1.0%, O 0.11-0.27%, and C ≤ 0.0016%;

[0007] The reinforced steel is prepared according to a preparation method comprising the following steps:

[0008] (1) According to the target composition, each metal element except Fe, Si and O is respectively mixed with Fe to form a plurality of corresponding pre-alloyed powders by gas atomization;

[0009] Si and O elements are prepared according to the component ratio of Si and O in the target component to form pre-oxidized Si powder SiO x , x<2;

[0010] (2) Various pre-alloyed powders are mixed with the pre-oxidized Si powder SiO x The components of the target component, excluding Fe, are mixed according to the component ratio, and then mechanically alloyed by ball milling under a protective atmosphere to obtain a uniform composite alloy powder; the composite alloy powder is then wrapped in a steel strip and drawn and reduced to obtain a cored wire; wherein the steel strip is used to additionally introduce Fe to ensure that the cored wire meets the target component;

[0011] (3) The flux-cored wire is printed and formed by an arc-fused wire additive manufacturing process, and the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel is obtained by heat treatment.

[0012] As a further preferred embodiment of the present invention, the target components of the strengthened steel specifically include, by mass percentage: Cr 9.0-14.0%, W 1.0-2.0%, Mn 0.2-1.0%, Si 1.0-3.0%, Y 0.4-1.0%, O 0.11-0.27%, C≤0.0016%, and the rest are Fe and unavoidable impurities.

[0013] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned high temperature resistant and corrosion resistant silicon-containing nano-oxide dispersion strengthened steel, characterized in that it comprises the following steps:

[0014] (1) According to the target composition, each metal element except Fe, Si and O is respectively mixed with Fe to form a plurality of corresponding pre-alloyed powders by gas atomization;

[0015] Si element and O element are formed into pre-oxidized Si powder SiO according to the component allocation ratio of Si element and O element in the target component x x<2

[0016] (2) mixing various pre-alloyed powders with the pre-oxidized Si powder SiO x according to the component allocation ratio of other elements except Fe element in the target component, and then realizing mechanical alloying under a protective atmosphere to obtain a uniform composite alloy powder; then, the composite alloy powder is wrapped in a steel belt, and a core-in-sheath wire is obtained by drawing and reducing the diameter; wherein the steel belt is used to additionally introduce Fe element, so that the core-in-sheath wire meets the target component;

[0017] (3) printing the core-in-sheath wire by using an electric arc melting wire additive manufacturing process, and obtaining the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel by heat treatment.

[0018] According to another aspect of the present application, the present application provides a preparation method of the above-mentioned high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel, characterized in that it comprises the following steps:

[0019] (1) according to the target component, using a gas atomization method to form Cr-Fe, W-Fe, Mn-Fe, Y-Fe multiple pre-alloyed powders;

[0020] Si element and O element are formed into pre-oxidized Si powder SiO according to the component allocation ratio of Si element and O element in the target component x x<2

[0021] (2) mixing various pre-alloyed powders with the pre-oxidized Si powder SiO x according to the component allocation ratio of other elements except Fe element in the target component, and then realizing mechanical alloying under a protective atmosphere to obtain a uniform composite alloy powder; then, the composite alloy powder is wrapped in a steel belt, and a core-in-sheath wire is obtained by drawing and reducing the diameter; wherein the steel belt is used to additionally introduce Fe element, so that the core-in-sheath wire meets the target component;

[0022] (3) printing the core-in-sheath wire by using an electric arc melting wire additive manufacturing process, and obtaining the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel by heat treatment.

[0023] As a further preferred embodiment of the present application, in step (1), the pre-oxidized Si powder SiO x has an oxygen content of 0.11-0.27wt% of the total mass of the core-in-sheath wire;

[0024] The pre-oxidized Si powder SiO xThe method comprises soaking Si powder in hydrofluoric acid to remove the surface oxide layer, and then ultrasonically cleaning with acetone; then quickly placing the cleaned Si powder into a reaction bottle pre-filled with dry oxygen, and continuously introducing dry oxygen; the reaction bottle is always placed on a balance until the Si powder increases to the target oxygen content, then stopping the oxygen input and transferring the powder to a vacuum drying oven for drying.

[0025] As a further preferred embodiment of the present invention, in step (2), the composite pre-alloyed powder and the pre-oxidized Si powder SiO x During mixing, NaF was additionally added as an arc stabilizer;

[0026] Preferably, the amount of NaF added is 0.2 to 0.5 wt% of the total mass of the core wire;

[0027] More preferably, the composite pre-alloyed powder and the pre-oxidized Si powder SiO x During mixing, reduced iron powder is additionally added.

[0028] As a further preference of the present invention, in step (2), the ball milling is wet ball milling, and ethanol is used as a process control agent.

[0029] As a further preference of the present invention, in step (2), the ball milling is carried out in a planetary ball mill;

[0030] Preferably, the ball milling is to first evacuate the ball mill jar and then fill it with argon as a protective gas, the ball mill speed is 350r / min, the ball milling time is 5h to 20h, the ball milling medium is stainless steel grinding balls, the diameters of the large and small balls are 10mm and 6mm respectively, and the ball-to-material mass ratio is 15:1.

[0031] As a further preferred embodiment of the present invention, in step (2), the mass of the composite alloy powder accounts for 15% to 40% of the mass of the core wire;

[0032] Preferably, the diameter of the core wire obtained by drawing and reducing the diameter is 3 to 4 mm.

[0033] As a further preference of the present invention, in step (3), the arc fuse additive manufacturing process uses argon as the shielding gas with a gas flow rate of 20 L / min; the deposition voltage is 20 to 40 V, the deposition current is 100 to 300 A, the wire feeding speed is 3 to 8.5 m / min, and the deposition speed is 0.2 to 0.5 m / min.

[0034] Compared with the prior art, the above technical solutions proposed by the present invention can achieve the following:

[0035] Beneficial effects:

[0036] 1. The application uses the characteristics of electric arc wire additive manufacturing to realize high preparation rate and low process cost of ODS steel, and can quickly prepare large complex components.

[0037] 2. The application uses composite pre-alloy powder prepared by gas atomization method, and simultaneously introduces oxygen into the ODS steel through pre-oxidized Si powder SiO x (x<2) to quantitatively control the oxygen content introduced in the ODS steel, realize the separate introduction of rare earth elements and oxygen elements in the ODS steel, avoid the problem of difficult dissolution of directly added oxide particles, and improve the raw material utilization rate.

[0038] Unlike traditional direct addition of rare earth oxide powder, the application separately prepares composite pre-alloy powder and pre-oxidized Si powder SiO x , i.e. using composite alloy powder prepared by gas atomization method and pre-oxidized Si powder SiO x , and simultaneously quantitatively controlling the oxygen content in the matrix to realize the separate introduction of rare earth elements and oxygen elements in the ODS steel, which not only can improve the raw material utilization rate, but also can significantly improve the high-temperature strength and high-temperature corrosion resistance by the complex of Si with rare earth element atoms and oxygen atoms in the matrix and the formation of high-density dispersed nanometer oxide particles.

[0039] 3. The application uses composite pre-alloy powder prepared by gas atomization method, and simultaneously introduces oxygen into the ODS steel through pre-oxidized Si powder SiO x to quantitatively control the oxygen content introduced in the ODS steel, realize the separate introduction of rare earth elements and oxygen elements in the ODS steel, avoid the problem of uneven distribution of oxide particles in the ODS steel caused by directly adding too much rare earth oxide powder, and easily form large particles to deteriorate the performance of the ODS steel, and at the same time seriously affect its welding performance.

[0040] 4. The application is to mix and ball mill the composite pre-alloy powder and the pre-oxidized Si powder SiO x according to the component allocation ratio of the target strengthened steel, and through the mechanical alloying of ball milling, 1-3% of Si is solid-solved in the iron matrix to form Si-Fe solid solution, which increases the lattice constant of the matrix; after heat treatment, Y and O oversaturated in the matrix are dispersed and precipitated with the participation of Si, Y-Si-O complex oxide nanoparticles are generated in the iron-silicon alloy matrix as a strengthening phase, and the high-density dispersed nanometer oxide particles (in the following example 1 product, the number density is about 5.89x10 23 m -3, the average particle size is 3.7 nm) can effectively pin dislocations, hinder grain growth and grain boundary migration, thereby improving the strength of the ODS steel (compared with the product of Comparative Example 1, the hardness of the alloy is increased from 405 HV to 689 HV in Example 1 hereinafter). The ODS steel matrix prepared by the present application is a martensitic structure. Taking the product of Example 1 hereinafter as an example, the average grain size is 2.31 μm, and the geometric necessary density is 1.49 x 10 14 m -2 .

[0041] 5、The present application can not only promote the formation of a continuous and dense SiO2 oxidation layer during oxidation of the ODS steel, thereby hindering further inward diffusion of O, but also reduce the critical Cr content for forming a continuous Cr2O3 oxidation film, thereby promoting outward diffusion of Cr, which is conducive to the formation of a protective Cr2O3 oxidation film, by adding Si element. Taking Example 1 hereinafter as an example, the oxidation rate of the ODS steel obtained in Example 1 is 0.36 x 10 -3 mg·cm -2 ·h -1 after oxidation in an air environment at 800℃ for 200h, which is much better than most commercial steels (taking commercial T91 steel and SIMP steel as examples, it has been reported in the prior art that the oxidation weight gain rates of T91 steel and SIMP steel are about 0.175 mg·cm -2 ·h -1 and 3.25 x 10 -3 mg·cm -2 ·h -1 after oxidation in an air environment at 800℃ for 200h, respectively).

[0042] In summary, the present application can realize batch production of ODS steel with high raw material utilization rate, high preparation rate and low process cost, and can also realize rapid forming of large-size complex parts. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a flowchart of a rapid preparation method of a high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel provided by the present application.

[0044] Figure 2 is a BSE image and Y element distribution image of the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel prepared in Comparative Example 1 and Example 1 of the present application; wherein, Figure 2 (a) in the figure corresponds to the product of Comparative Example 1, Figure 2 (b) in the figure corresponds to the product of Example 1.

[0045] Figure 3 is a grain boundary image of the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel prepared in Example 1 of the present application.

[0046] Figure 4 TEM image of the high temperature resistant and corrosion resistant silicon-containing nano-oxide dispersion strengthened steel prepared in Example 1 of the present invention, wherein: Figure 4 (a) is the microstructure of heat-treated ODS steel. Figure 4 (b) is a bright field TEM image. Figure 4 (c) in the figure is a high-resolution image of oxide particles.

[0047] Figure 5 The cross-sectional morphology SEM and element line scan results of the oxide layer of the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel prepared in Example 1 of the present invention; wherein, Figure 5 (a) corresponds to the cross-sectional morphology SEM, Figure 5 (b) in the figure corresponds to the element line scan result.

[0048] Figure 6 The optical microscopic observation image of the silicon-containing nano-oxide dispersion-strengthened steel prepared in Comparative Example 2 of the present invention and the high-resolution image of the oxide particles therein are shown; wherein, Figure 6 (a) in the figure corresponds to the image observed by light microscope. Figure 6 (b) corresponds to the high-resolution image of oxide particles. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0050] In the following comparative examples and examples, after the ODS steel was produced, it was subjected to conventional heat treatment to obtain the final samples. The heat treatment used in the comparative examples and examples was an air-cooled heat treatment (1050°C for 1 hour). Of course, other heat treatment temperatures, holding times, and cooling methods may also be used.

[0051] Example 1

[0052] A rapid preparation method for high-temperature resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel comprises the following steps:

[0053] Step 1: Cr-Fe, W-Fe, Mn-Fe, and Y-Fe pre-alloyed powders are prepared respectively by gas atomization. Similar to the conventional gas atomization method, this embodiment uses argon as the atomizing gas, the gas pressure is 6 MPa, the gas flow rate is 300 L / min, and the collected powder particle size range is 5 to 20 μm.

[0054] Step 2: Prepare pre-oxidized Si powder. The specific preparation steps are as follows: soak 75g of Si powder with a particle size of 5 to 20μm in hydrofluoric acid to remove the surface oxide layer, and then ultrasonically clean it with acetone; then quickly place the cleaned Si powder into a reaction bottle that has been pre-aerated with dry high-purity oxygen for 10 minutes, and continue to aerate with dry oxygen; keep the reaction bottle on a balance until the Si powder increases to 83.25g (that is, the oxygen content is 8.25g, and the oxygen content is 0.11wt.% of the total mass of the designed core wire), stop the oxygen input, and transfer the powder to a vacuum drying oven for drying.

[0055] Step 3: Weigh the prepared pre-alloyed powders of each element, 964.3 g of Cr-Fe alloy powder (70% Cr; i.e., the mass percentage of Cr in the Cr-Fe alloy powder is 70%; the following expressions are similar), 160.7 g of W-Fe alloy powder (70% W), 80 g of Mn-Fe alloy powder (75% Mn), 500 g of Y-Fe alloy powder (6% Y), 86.75 g of reduced iron powder and 83.25 g of pre-oxidized Si powder, and add 18.8 g of NaF as an arc stabilizer.

[0056] All powders were mechanically alloyed in a planetary ball mill. The mill was evacuated and then filled with high-purity argon as a protective gas to reduce oxidation of the alloy powder during milling. The mill speed was 350 rpm for 10 hours. Stainless steel balls were used as the milling medium, with diameters of 10 mm and 6 mm, respectively, for a ball-to-batch ratio of 15:1. Ethanol was used as a process control agent during the mechanical alloying process. After milling, the powders were dried at 80°C in a vacuum for 10 hours and sealed in vacuum-sealed bags for storage.

[0057] In step 4, the composite alloy powder is placed in a steel strip and drawn and reduced to produce a 4 mm diameter flux-cored wire. The fill factor is 25% (mass percentage; the same applies below). The target composition of the flux-cored wire is (by mass content): Fe-9Cr-1.5W-0.8Mn-1Si-0.4Y-0.11O. (In this expression, except for Fe, the Arabic numerals preceding each element represent the target mass percentage of that element in the flux-cored wire. For example, Cr has a mass percentage of 9% in the flux-cored wire; the remainder is Fe and unavoidable impurities; the same applies below.) Of course, if the flux-cored wire is not used immediately, it can be stored in a vacuum dry environment to prevent oxidation.

[0058] Step five, the above core wire is prepared into ODS steel by using electric arc wire additive manufacturing technology. In the electric arc wire additive manufacturing process, high-purity argon is used as the protective gas, the gas flow is 20 L / min; the deposition voltage is 25.8 V, the deposition current is 170 A, the wire feeding speed is 5.5 m / min, and the deposition speed is 0.36 m / min.

[0059] The prepared sample is tested by EPMA for element analysis, and the results are shown in (b) of Figure 2 , it is found that the actual Y content in the sample matrix is about 0.31wt.%, and the actual introduction rate of rare earth elements is greatly improved compared with Comparative Example 1. The grain boundaries of the sample are characterized by EBSD, and the geometric dislocation density is measured and calculated, and the results are shown in Figure 3 , it is found that the matrix of the sample is martensite structure, the average grain size is 2.31μm, and the geometric necessary density is 1.49×10 14 m -2 . Further, the matrix of the sample and the nano-oxide particles therein are characterized and analyzed by TEM, as shown in Figure 4 , dispersed distribution of high number density of nano Y2SiO5 oxide particles (number density about 5.89×10 23 m -3 , average particle size 3.7nm) is precipitated in the martensite matrix. As can be seen from (b) of Figure 4 , the precipitated nano-oxide particles can inhibit the movement and annihilation of dislocations, can hinder the grain growth and grain boundary migration, so as to maintain the high dislocation density of the matrix. The hardness of the sample is tested by Vickers hardness tester, and it is found that the hardness of the prepared sample is increased to 689HV compared with Comparative Example 1. The sample is subjected to 800℃ oxidation experiment for 200 hours in a muffle furnace, and the oxidation section is observed as shown in Figure 5 , it is found that the sample forms a three-layer structure of Cr 1.5 Mn 1.5 O4 / Cr2O3 / SiO2 oxidation layer with a total thickness of about 2.19μm. The addition of Si element not only promotes the formation of continuous and dense SiO2 oxidation layer during the oxidation of ODS steel, but also reduces the critical Cr content for the formation of continuous Cr2O3 oxidation film, promotes the outward diffusion of Cr, and is beneficial to the formation of protective Cr2O3 oxidation film. The oxidation rate of ODS steel in 800℃ air environment for 200h is 0.36×10 -3 mg·cm -2 ·h -1 , which is much better than most of the current commercial steels (for example, commercial T91 steel and SIMP steel, it has been reported in the prior art that the oxidation weight gain rate of T91 steel and SIMP steel in 800℃ air environment for 200h is about 0.175mg·cm-2 ·h -1 and 3.25 x 10 -3 mg·cm -2 ·h -1 ).

[0060] Example 2

[0061] A rapid preparation method of a high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel comprises the following steps:

[0062] Step one, Cr-Fe, W-Fe, Mn-Fe and Y-Fe pre-alloy powders are prepared by gas atomization, argon is used as atomization gas, the gas pressure is 6 MPa, the gas flow is 300 L / min, and the collected powder particle size range is 5-20 μm.

[0063] Step two, pre-oxidized Si powder is prepared, and the specific preparation steps are as follows: 150 g of Si powder with a particle size of 5-20 μm is soaked in hydrofluoric acid to remove the surface oxide layer, and then ultrasonic cleaned with acetone; then the cleaned Si powder is quickly placed in a reaction bottle pre-filled with 10 min dry high-purity oxygen, and dry oxygen is continuously introduced; the reaction bottle is always placed on a balance, until the Si powder increases to 159.75 g (that is, the oxygen content is 9.75 g, and the oxygen element content is 0.13 wt.% of the total mass of the designed core wire), stop oxygen input, and transfer to a vacuum drying box for drying.

[0064] Step three, the prepared pre-alloy powders of each element are weighed, 1285.7 g of Cr-Fe alloy powder (70%Cr), 214.3 g of W-Fe alloy powder (70%W), 20 g of Mn-Fe alloy powder (75%Mn), 625 g of Y-Fe alloy powder (6%Y), 95.25 g of reduced iron powder and 159.75 g of pre-oxidized Si powder are mixed, and 24 g of NaF is added as arc stabilizer.

[0065] All powders are mechanically alloyed in a planetary ball mill, the ball mill tank is first evacuated and then filled with high-purity argon as protective gas to reduce the oxidation of alloy powder during ball milling; the rotation speed of the ball mill is 350 r / min, the ball milling time is 10 h, the stainless steel grinding balls are selected as the ball milling medium, the diameters of the large and small balls are 10 mm and 6 mm respectively, and the ball-to-material ratio is 15:1. Ethanol is used as a process control agent during mechanical alloying. After ball milling, the powder is dried at 80℃ in vacuum for 10 h and sealed in a vacuum bag for storage.

[0066] Step 4: The composite alloy powder is placed in a steel strip and drawn and reduced to prepare a cored wire with a diameter of 4 mm. The filling rate is 32%, and the target composition of the cored wire is (by mass content) Fe-12Cr-2W-0.2Mn-1.5Si-0.5Y-0.13O.

[0067] Step 5: Arc-fused wire additive manufacturing (AFM) was used to prepare the ODS steel from the flux-cored wire. During the AFM process, high-purity argon was used as the shielding gas at a flow rate of 20 L / min. The deposition voltage was 25.8 V, the deposition current was 170 A, the wire feed speed was 5.5 m / min, and the deposition rate was 0.36 m / min.

[0068] Example 3

[0069] A rapid preparation method for high-temperature resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel comprises the following steps:

[0070] Step 1: Cr-Fe, W-Fe, Mn-Fe, and Y-Fe pre-alloyed powders were prepared by gas atomization. Argon was used as the atomizing gas, the gas pressure was 6 MPa, the gas flow rate was 300 L / min, and the collected powder particle size range was 5 to 20 μm.

[0071] Step 2: Prepare pre-oxidized Si powder. The specific preparation steps are as follows: soak 150g of Si powder with a particle size of 5 to 20μm in hydrofluoric acid to remove the surface oxide layer, and then ultrasonically clean it with acetone; then quickly place the cleaned Si powder into a reaction bottle that has been pre-aerated with dry high-purity oxygen for 10 minutes, and continue to aerate with dry oxygen; keep the reaction bottle on a balance until the Si powder increases to 159.75g (that is, the oxygen content is 9.75g, and the oxygen content is 0.13wt.% of the total mass of the designed core wire), stop the oxygen input, and transfer the powder to a vacuum drying oven for drying.

[0072] Step 3: Weigh the prepared pre-alloyed powders of each element, 1500g Cr-Fe alloy powder (70% Cr), 214.3g W-Fe alloy powder (70% W), 20g Mn-Fe alloy powder (75% Mn), 625g Y-Fe alloy powder (6% Y), 105.95g reduced iron powder and 159.75g pre-oxidized Si powder, and add 25g of NaF as an arc stabilizer.

[0073] All powders were mechanically alloyed in a planetary ball mill. The ball mill jar was first evacuated and then filled with high purity argon as a protective gas to reduce the oxidation of the alloy powders during the milling process. The rotation speed of the ball mill was 350 r / min, the milling time was 10 h, the milling media were stainless steel balls with diameters of 10 mm and 6 mm, and the ball-to-powder ratio was 15:1. Ethanol was used as a process control agent during the mechanical alloying process. After milling, the powders were dried at 80 °C for 10 h in vacuum and stored in vacuum-sealed bags.

[0074] Step four, the composite alloy powder was put into a steel belt to prepare a diameter of 4 mm core wire by drawing reduction, the filling rate was 35%, and the target composition of the core wire was (by mass content) Fe-14Cr-2W-0.2Mn-1.5Si-0.5Y-0.13O.

[0075] Step five, the core wire was prepared into an ODS steel by using an electric arc wire additive manufacturing technology. In the electric arc wire additive manufacturing process, high purity argon was used as a protective gas, the gas flow was 20 L / min; the deposition voltage was 25.8 V, the deposition current was 170 A, the wire feeding speed was 5.5 m / min, and the deposition speed was 0.36 m / min.

[0076] Example 4

[0077] A rapid preparation method of a high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion strengthened steel includes the following steps:

[0078] Step one, Cr-Fe, W-Fe, Mn-Fe, and Y-Fe pre-alloy powders were prepared by using a gas atomization method. Argon was used as the atomizing gas, the gas pressure was 6 MPa, the gas flow was 300 L / min, and the collected powder particle size range was 5-20 μm.

[0079] Step two, pre-oxidized Si powder was prepared. The specific preparation steps were as follows: 300 g of Si powder with a particle size of 5-20 μm was soaked in hydrofluoric acid to remove the surface oxide layer, and then ultrasonic cleaned with acetone; then the cleaned Si powder was quickly put into a reaction bottle pre-filled with 10 min dry high-purity oxygen, and dry oxygen was continuously input; the reaction bottle was always placed on a balance, until the Si powder increased to 320.25 g (that is, the oxygen content was 20.25 g, and the oxygen element content was 0.27 wt.% of the total mass of the designed core wire), the oxygen input was stopped, and the vacuum drying box was transferred for drying.

[0080] Step 3: Weigh the prepared pre-alloyed powders of each element, 964.3g Cr-Fe alloy powder (70% Cr), 107.1g W-Fe alloy powder (70% W), 100g Mn-Fe alloy powder (75% Mn), 1250g Y-Fe alloy powder (6% Y), 108.35g reduced iron powder and 320.25g pre-oxidized Si powder, and add 28.5g NaF as an arc stabilizer.

[0081] All powders were mechanically alloyed in a planetary ball mill. The mill was evacuated and then filled with high-purity argon as a shielding gas to minimize oxidation during milling. The mill speed was 350 rpm for 10 hours. Stainless steel balls were used as the milling medium, with diameters of 10 mm for the larger and 6 mm for the smaller balls, resulting in a ball-to-batch ratio of 15:1. Ethanol was used as a process control agent during the mechanical alloying process. After milling, the powders were dried under vacuum at 80°C for 10 hours and sealed in vacuum-sealed bags for storage.

[0082] Step 4: The composite alloy powder is placed in a steel strip and drawn and reduced to prepare a cored wire with a diameter of 4 mm. The filling rate is 38%, and the target composition of the cored wire is (by mass content) Fe-9Cr-1W-1Mn-3Si-1Y-0.27O.

[0083] Step 5: Arc-fused wire additive manufacturing (AFM) was used to prepare the ODS steel from the flux-cored wire. During the AFM process, high-purity argon was used as the shielding gas at a flow rate of 20 L / min. The deposition voltage was 25.8 V, the deposition current was 170 A, the wire feed speed was 5.5 m / min, and the deposition rate was 0.36 m / min.

[0084] Comparative Example 1

[0085] This comparative example adopts the conventional method of directly adding rare earth oxide powder, which specifically includes the following steps:

[0086] Step 1: All elements except Y are prepared by gas atomization method. Cr-Fe, W-Fe, Mn-Fe, and Si-Fe pre-alloyed powders are used. Argon is used as the atomizing gas, the gas pressure is 6 MPa, the gas flow rate is 300 L / min, and the collected powder particle size range is 5 to 20 μm.

[0087] Step 2: Weigh the prepared pre-alloyed powders of each element, 964.3g Cr-Fe alloy powder (70% Cr), 160.7g W-Fe alloy powder (70% W), 80g Mn-Fe alloy powder (75% Mn), 100g Si-Fe (75% Si), 180g reduced iron powder and 15g nano Y2O3 powder, and add 15g NaF as an arc stabilizer.

[0088] All powders were mechanically alloyed in a planetary ball mill. The mill was evacuated and then filled with high-purity argon as a shielding gas to minimize oxidation of the alloy powder during milling. The mill speed was 350 rpm for 10 hours. Stainless steel balls were used as the milling medium, with diameters of 10 mm for the larger and 6 mm for the smaller balls, resulting in a ball-to-batch ratio of 15:1. Ethanol was used as a process control agent during the mechanical alloying process. After milling, the composite alloy powder was dried at 80°C in a vacuum for 10 hours and sealed in vacuum-sealed bags for storage.

[0089] Step 3: The composite alloy powder is placed in a steel strip and drawn and reduced to produce a 4 mm diameter flux-cored wire with a filling ratio of 20%. The target composition of the flux-cored wire is (by mass): Fe-9Cr-1.5W-0.8Mn-1Si-0.2Y2O3.

[0090] Step 4: Arc-fused wire additive manufacturing (AFAM) was used to prepare the ODS steel from the flux-cored wire. During the AFAM process, high-purity argon was used as the shielding gas at a flow rate of 20 L / min. The deposition voltage was 25.8 V, the deposition current was 170 A, the wire feed speed was 5.5 m / min, and the deposition rate was 0.36 m / min.

[0091] EPMA was used to perform elemental analysis on the prepared samples, and the results were as follows: Figure 2 As shown in (a), the actual Y content in the sample matrix is ​​about 0.02 wt.%, which is much lower than the actual addition amount. The hardness of the sample directly added with nano-Y2O3 powder is only 405 HV when tested with a Vickers hardness tester.

[0092] Comparative Example 2

[0093] This comparative example adopts the conventional method of directly adding rare earth oxide powder, which specifically includes the following steps:

[0094] Step 1: All elements except Y are prepared by gas atomization method. Cr-Fe, W-Fe, Mn-Fe, and Si-Fe pre-alloyed powders are used. Argon is used as the atomizing gas, the gas pressure is 6 MPa, the gas flow rate is 300 L / min, and the collected powder particle size range is 5 to 20 μm.

[0095] Step 2: Weigh the prepared pre-alloyed powders of each element, 964.3g Cr-Fe alloy powder (70% Cr), 160.7g W-Fe alloy powder (70% W), 80g Mn-Fe alloy powder (75% Mn), 100g Si-Fe (75% Si), 120g reduced iron powder and 75g nano Y2O3 powder, and add 15g NaF as an arc stabilizer.

[0096] All powders were mechanically alloyed in a planetary ball mill. The mill was evacuated and then filled with high-purity argon as a shielding gas to minimize oxidation of the alloy powder during milling. The mill speed was 350 rpm for 10 hours. Stainless steel balls were used as the milling medium, with diameters of 10 mm for the larger and 6 mm for the smaller balls, resulting in a ball-to-batch ratio of 15:1. Ethanol was used as a process control agent during the mechanical alloying process. After milling, the composite alloy powder was dried at 80°C in a vacuum for 10 hours and sealed in vacuum-sealed bags for storage.

[0097] Step 3: The composite alloy powder is placed in a steel strip and drawn and reduced to produce a 4 mm diameter flux-cored wire with a filling ratio of 20%. The target composition of the flux-cored wire is (by mass): Fe-9Cr-1.5W-0.8Mn-1Si-1Y2O3.

[0098] Step 4: Arc-fused wire additive manufacturing (AFAM) was used to prepare the ODS steel from the flux-cored wire. During the AFAM process, high-purity argon was used as the shielding gas at a flow rate of 20 L / min. The deposition voltage was 25.8 V, the deposition current was 170 A, the wire feed speed was 5.5 m / min, and the deposition rate was 0.36 m / min.

[0099] The obtained samples were observed using a light microscope, and the results were as follows: Figure 6 As shown in (a) of the figure, crack defects are found in the matrix. This is because the excessive addition of Y2O3 deteriorates the welding performance of the sample and produces cracks and other defects during the solidification process of the molten pool. TEM is further used to observe the oxide particles in the sample. The results are shown in Figure 2. Figure 6 As shown in (b), the oxide is Y2O3 particles with a particle size of about 17 nm.

[0100] The high-purity argon and high-purity oxygen used in the above embodiments have a purity of no less than 99.999%.

[0101] The above embodiments are only examples. For example, the high-temperature resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel obtained based on the present invention, in addition to containing Cr, W, Mn, Si, Y, O, C, Fe elements and inevitable impurities, may also contain other non-impurity elements, as long as the components, by mass percentage, are Cr 9.0-14.0%, W 1.0-2.0%, Mn 0.2-1.0%, Si 1.0-3.0%, Y0.4-1.0%, O 0.11-0.27%, C ≤ 0.0016%, and Fe is the main element.

[0102] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high temperature resistant and corrosion resistant silicon nano-oxide dispersion strengthened steel, characterized in that: The target composition of the strengthened steel is mainly composed of Fe element, and the target composition also includes, by mass percentage: Cr 9.0~14.0%, W 1.0~2.0%, Mn 0.2~1.0%, Si 1.0~3.0%, Y 0.4~1.0%, O 0.11~0.27%, C≤0.0016%; The reinforced steel is prepared according to a preparation method comprising the following steps: (1) According to the target composition, each metal element except Fe, Si and O is respectively mixed with Fe to form a plurality of corresponding pre-alloyed powders by gas atomization method; Si and O elements are prepared according to the component ratio of Si and O in the target component to form pre-oxidized Si powder SiO x , x<2; (2) Various pre-alloyed powders are mixed with the pre-oxidized Si powder SiO x The components of the target component, excluding Fe, are mixed according to the composition ratio, and then mechanically alloyed by ball milling under a protective atmosphere to obtain a uniform composite alloy powder; the composite alloy powder is then wrapped in a steel strip and drawn and reduced to obtain a cored wire; wherein the steel strip is used to additionally introduce Fe to ensure that the cored wire meets the target composition; (3) The flux-cored wire is printed and formed by an arc-fused wire additive manufacturing process, and the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel is obtained by heat treatment.

2. The high temperature resistant and corrosion resistant silicon-containing nano-oxide dispersion strengthened steel according to claim 1, characterized in that: The target components of the strengthened steel specifically include, by mass percentage, Cr 9.0-14.0%, W 1.0-2.0%, Mn 0.2-1.0%, Si 1.0-3.0%, Y 0.4-1.0%, O 0.11-0.27%, C≤0.0016%, and the remainder is Fe and unavoidable impurities.

3. The method for preparing high temperature resistant and corrosion resistant silicon-containing nano-oxide dispersion strengthened steel according to claim 1 or 2, characterized in that: The following steps are involved: (1) According to the target composition, each metal element except Fe, Si and O is respectively mixed with Fe to form a plurality of corresponding pre-alloyed powders by gas atomization method; Si and O elements are prepared according to the component ratio of Si and O in the target component to form pre-oxidized Si powder SiO x , x<2; (2) Various pre-alloyed powders are mixed with the pre-oxidized Si powder SiO x The components of the target component, excluding Fe, are mixed according to the composition ratio, and then mechanically alloyed by ball milling under a protective atmosphere to obtain a uniform composite alloy powder; the composite alloy powder is then wrapped in a steel strip and drawn and reduced to obtain a cored wire; wherein the steel strip is used to additionally introduce Fe to ensure that the cored wire meets the target composition; (3) The flux-cored wire is printed and formed by an arc-fused wire additive manufacturing process, and the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel is obtained by heat treatment.

4. The method for preparing high temperature resistant and corrosion resistant silicon-containing nano-oxide dispersion strengthened steel according to claim 2, characterized in that: The following steps are involved: (1) According to the target composition, a variety of pre-alloyed powders such as Cr-Fe, W-Fe, Mn-Fe, and Y-Fe are formed by gas atomization; Si and O elements are prepared according to the component ratio of Si and O in the target component to form pre-oxidized Si powder SiO x , x<2; (2) Various pre-alloyed powders are mixed with the pre-oxidized Si powder SiO x The components of the target component, excluding Fe, are mixed according to the composition ratio, and then mechanically alloyed by ball milling under a protective atmosphere to obtain a uniform composite alloy powder; the composite alloy powder is then wrapped in a steel strip and drawn and reduced to obtain a cored wire; wherein the steel strip is used to additionally introduce Fe to ensure that the cored wire meets the target composition; (3) The flux-cored wire is printed and formed by an arc-fused wire additive manufacturing process, and the high-temperature-resistant and corrosion-resistant silicon-containing nano-oxide dispersion-strengthened steel is obtained by heat treatment.

5. The preparation method according to claim 3 or 4, characterized in that: In step (1), the pre-oxidized Si powder SiO x The oxygen content is 0.11-0.27 wt% of the total mass of the core wire; The pre-oxidized Si powder SiO x The method comprises soaking Si powder in hydrofluoric acid to remove the surface oxide layer, and then ultrasonically cleaning with acetone; then quickly placing the cleaned Si powder into a reaction bottle pre-filled with dry oxygen, and continuously introducing dry oxygen; the reaction bottle is always placed on a balance until the Si powder increases to the target oxygen content, then stopping the oxygen input and transferring the powder to a vacuum drying oven for drying.

6. The preparation method according to claim 3 or 4, characterized in that: In step (2), various pre-alloyed powders are mixed with the pre-oxidized Si powder SiO x During mixing, NaF is additionally added as an arc stabilizer.

7. The preparation method according to claim 6, characterized in that: The amount of NaF added is 0.2-0.5 wt% of the total mass of the core wire.

8. The preparation method according to claim 6, characterized in that: In step (2), various pre-alloyed powders are mixed with the pre-oxidized Si powder SiO x When the reduced iron powder is added, additional reduced iron powder is added.

9. The preparation method according to claim 3 or 4, characterized in that: In step (2), the ball milling is wet ball milling, and ethanol is used as a process control agent.

10. The preparation method according to claim 3 or 4, characterized in that: In step (2), the ball milling is carried out in a planetary ball mill.

11. The preparation method according to claim 10, characterized in that: In step (2), the ball milling is performed by first evacuating the ball mill jar and then filling it with argon as a protective gas. The ball mill speed is 350 r / min, the ball milling time is 5h~20h, and the ball milling medium is stainless steel grinding balls. The diameters of the large and small balls are 10 mm and 6 mm respectively, and the ball-to-material mass ratio is 15:

1.

12. The preparation method according to claim 3 or 4, characterized in that: In step (2), the mass of the composite alloy powder accounts for 15% to 40% of the mass of the core wire.

13. The preparation method according to claim 12, characterized in that: In step (2), the diameter of the core wire obtained by drawing and reducing the diameter is 3 to 4 mm.

14. The preparation method according to claim 3 or 4, characterized in that: In step (3), the arc fuse additive manufacturing process uses argon as the shielding gas with a gas flow rate of 20 L / min; the deposition voltage is 20~40 V, the deposition current is 100~300 A, the wire feeding speed is 3~8.5 m / min, and the deposition speed is 0.2~0.5 m / min.

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