Vermicular graphite iron-based alloy material based on additive manufacturing technology and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of high-performance vermicular graphite iron-based alloy materials, and relates to a vermicular graphite iron-based alloy material based on an additive manufacturing technology and a preparation method thereof.The preparation method comprises the steps that iron-based alloy powder and an alterant are subjected to ball-milling mixing and homogenization treatment to obtain mixed powder, the alterant comprises 0.5%-0.7% of a vermiculizer and 0.5%-0.7% of a nucleating agent, and the nucleating agent is added into the mixed powder; the vermicular graphite iron-based alloy material based on the additive manufacturing technology is prepared by the following steps of: drying the mixed powder, putting the dried mixed powder into additive manufacturing equipment, melting and spreading the powder layer by layer through laser cladding to form a single-layer vermicular graphite iron-based alloy, and repeatedly cladding layer by layer to obtain the vermicular graphite iron-based alloy material based on the additive manufacturing technology. According to the method, the vermicular graphite rate is controlled by adjusting the proportion of the modificator, the product meeting the design requirement is obtained, the prepared vermicular graphite iron-based alloy material is small in grain, the vermicular graphite structure is regular in shape and small in size, the plasticity and tensile strength of the material are improved, and the subsequent product machining efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing high-performance compacted graphite iron-based alloy materials, and relates to a compacted graphite iron-based alloy material based on additive manufacturing technology and a preparation method thereof. Background Art

[0002] Vermicular iron-based alloy is a material with better performance between ductile iron and gray cast iron. The tensile strength of vermicular iron-based alloy is higher than that of gray cast iron. The microstructure of vermicular iron-based alloy leads to its good wear resistance, better thermal conductivity and shock absorption performance than ductile iron. Therefore, vermicular iron-based alloy materials are gradually replacing gray cast iron materials.

[0003] In the existing preparation of vermicular graphite iron-based alloy materials, the commonly used production method is to add a vermicularizer and an inoculant to the molten iron when tapping. The amount of vermicularizer and inoculant added has a significant effect on the creep rate, resulting in large fluctuations in the creep rate of each batch of products, thereby reducing the product qualification rate. In addition, in the existing preparation of vermicular graphite iron-based alloy materials, due to the complex product structure and uneven wall thickness, different parts have different requirements for the creep rate, which will also increase the spheroidization rate of key parts and reduce the creep rate. Summary of the Invention

[0004] In order to address the deficiencies in the above-mentioned prior art, the present invention provides a vermicular iron-based alloy material based on additive manufacturing technology and a preparation method thereof. The present invention reduces the high-temperature oxidation loss of the vermicular agent and the inoculant by layer-by-layer stacking, thereby improving the utilization rate.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology comprises the following steps: The iron-based alloy powder and the modifier are ball-milled and mixed, and then homogenized to obtain a mixed powder, wherein the modifier includes a vermicularizer and an inoculant, the content of the vermicularizer is 0.5% to 0.7%, and the content of the inoculant is 0.4% to 0.6%.

[0006] The mixed powder is dried and placed in an additive manufacturing device, and the powder is melted and laid layer by layer by laser cladding to form a single layer of compacted graphite iron-based alloy. The cladding is then repeated layer by layer to obtain a compacted graphite iron-based alloy material based on additive manufacturing technology.

[0007] The method for preparing a vermicular graphite iron-based alloy material of the present invention comprises the following steps: mixing iron-based alloy powder and a modifier by ball milling, and performing a homogenization treatment. The creep rate can be controlled by adjusting the ratio of the modifier to obtain a product that meets the design requirements. After screening, a mixed powder with uniform particle size is obtained, which has a uniform morphology, a stable creep rate, and consistent laser cladding conditions at various locations. The powder is melted and spread layer by layer by additive manufacturing equipment to form a single layer of vermicular graphite iron-based alloy, and the vermicular graphite iron-based alloy material based on the additive manufacturing technology is obtained by repeated cladding layer by layer. Therefore, the printed material has small grains, and the vermicular graphite structure has a regular shape and a small size, thereby increasing the plasticity and tensile strength of the material and improving the machining efficiency of subsequent products.

[0008] In a preferred embodiment of the present invention, the iron-based alloy powder and the modifier are present, and the content of the modifier is 0.9%-1.3% of the iron-based alloy powder.

[0009] In a preferred embodiment of the present invention, the vermicular agent is a rare earth magnesium vermicular agent, and the inoculant is a silicon zirconium inoculant.

[0010] Rare earth magnesium vermicularizers inhibit graphite spheroidization, forming a vermicular structure. Deoxidation and desulfurization improve strength and elongation, enhancing thermal conductivity and thermal fatigue resistance. Silicon zirconium inoculants use zirconium to form a high-melting-point core, refining vermicular graphite and reducing white cast iron tendencies. Silicon promotes graphitization, enhancing recession resistance and improving the mechanical properties of thick castings, synergistically optimizing the microstructure with the vermicularizer.

[0011] In a preferred embodiment of the present invention, the rare earth magnesium vermicular agent comprises, by mass percentage, Mg: 8% to 10%, RE: 18% to 22%, Ca: 2% to 4%, Si: 40% to 45%, and Fe as the remainder, which totals 100%. The silicon zirconium inoculant comprises, by mass percentage, Si: 65% to 70%, Zr: 2% to 3.5%, Ca: 1% to 1.5%, Al<1%, and Fe as the remainder, which totals 100%.

[0012] In a preferred embodiment of the present invention, the laser cladding parameters are: laser power of 500W to 3500W, scanning speed of 1mm / s to 10mm / s, spot diameter of 1mm to 5mm, and powder thickness of 0.5mm to 1mm.

[0013] In a preferred embodiment of the present invention, the chemical components of the iron-based alloy powder are as follows by mass percentage: C: 3.6% to 3.8%, Si: 1.8% to 2.2%, Ni: 2.5% to 5.4%, Cr: 5.3% to 7.2%, and Mn < 0.3%.

[0014] In a preferred embodiment of the present invention, the ball milling time is 2.5-4 hours, and the ball milling speed is 300-450 rpm.

[0015] In a preferred embodiment of the present invention, the particle size that meets the requirements is screened out through a sieve, and the particle size is 100-200 mesh.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention ball-mills an iron-based alloy powder, a vermicularizing agent, and an inoculant, homogenizes the mixture, and obtains a mixed powder. The mixed powder is dried and placed in an additive manufacturing device. Laser cladding is performed layer by layer to melt and spread the powder to form a single layer of vermicular graphite iron-based alloy. The cladding is then repeated layer by layer to obtain a vermicular graphite iron-based alloy material based on additive manufacturing technology. The vermicular graphite iron-based alloy material prepared by the present invention has small grains, regular vermicular graphite structure, and small size, which increases the material's plasticity and tensile strength, and improves the machining efficiency of subsequent products. The method for preparing a vermicular graphite iron-based alloy material of the present invention controls the creep rate by adjusting the ratio of modifiers (vermicularizing agent and inoculant) during powder mixing to obtain a product that meets design requirements. The powder particle size is uniformed by ball milling, and the powder is melted and spread layer by layer by laser cladding to form a single layer of vermicular graphite iron-based alloy. The cladding is then repeated layer by layer. The laser cladding conditions of each part are consistent, so the overall creep rate of the formed part is relatively stable and is not affected by the structure and wall thickness of the formed part. The additive manufacturing technology used in the present invention does not cause cold shut, incomplete filling, and the like, thereby achieving a high yield.

[0017] 2. The present invention obtains a mixed powder with uniform particle size after screening, which has uniform morphology and stable creep rate. The laser cladding conditions of each part are consistent. By precisely controlling the addition amount of the creep entrant and inoculant, a homogenization treatment is performed to ensure their uniform distribution in the material, thereby optimizing the microstructure of the vermicular graphite iron-based alloy. By optimizing the laser cladding optimization parameters, the cooling rate and solidification process are controlled to reduce defects, thereby ensuring that the creep entrant and inoculant can fully play their role. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and examples.

[0019] Figure 1 Schematic diagram of the planetary ball mill grinding process of the present invention.

[0020] Figure 2 Schematic diagram of the laser cladding process principle of the present invention.

[0021] Figure 3 Figures a and b are the metallographic structures of the compacted graphite iron-based alloy prepared in Example 1 of the present invention.

[0022] Figure 4 This is the creep rate data diagram of Example 1. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0024] The following is a detailed description of the technical solutions in the embodiments of the present invention, using preferred embodiments and accompanying drawings in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0026] Example 1 A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology comprises the following steps: (1) The vermicular agent and inoculant used in the production of vermicular graphite iron-based alloy are made into powder, and the particle size that meets the requirements is screened out through a sieve, and the particle size is 100-150 mesh.

[0027] (2) Iron-based alloy powder and modifier (vermicularizer powder and inoculant powder) were placed in a planetary ball mill in a certain proportion and uniformly mixed for 2.5 hours at a ball mill speed of 350 rpm. The mixture was then allowed to stand for 7 hours. The grinding balls were made of stainless steel. The content of modifier was 1.0% of the iron-based alloy powder, the content of vermicularizer was 0.5% of the weight of the iron-based alloy powder, and the content of inoculant was 0.5% of the weight of the iron-based alloy powder.

[0028] (3) The uniformly mixed powder described in (2) is dried and placed into the hopper of the additive manufacturing technology equipment.

[0029] (4) The program of the product to be printed is imported into the additive manufacturing technology equipment and the machine is started. The powder spreading scraper of the additive manufacturing technology equipment spreads the mixed powder (iron-based alloy powder, modifier) on the workbench, and the mixed powder is melted by laser cladding. The laser cladding power is 1500W, the scanning speed is 1mm / s, the spot diameter is 1.5mm, and the powder spreading thickness is 0.8mm, obtaining a layer of thick vermicular iron-based alloy material.

[0030] (5) Repeat step (4) to complete a layer of thick vermicular iron-based alloy material layer and descend a layer thickness height, and repeat the stacking method until the entire component is obtained to form a stacked material.

[0031] Example 2 A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology comprises the following steps: (1) The vermicular agent and inoculant used in the production of vermicular graphite iron-based alloy are made into powder, and the particle size that meets the requirements is screened out through a sieve, and the particle size is 100-150 mesh.

[0032] (2) Iron-based alloy powder and modifier (vermicularizer powder, inoculant powder) were placed in a planetary ball mill in a certain proportion and uniformly mixed for 2.5 hours at a ball mill speed of 350 rpm. The mixture was then allowed to stand for 7 hours. The grinding balls were made of stainless steel. The content of modifier was 0.9% of the iron-based alloy powder, the content of vermicularizer was 0.45% of the iron-based alloy powder by weight, and the content of inoculant was 0.45% of the iron-based alloy powder by weight.

[0033] (3) The uniformly mixed powder described in (2) is dried and placed into the hopper of the additive manufacturing technology equipment.

[0034] (4) The program of the product to be printed is imported into the additive manufacturing technology equipment and the machine is started. The powder spreading scraper of the additive manufacturing technology equipment spreads the mixed powder (iron-based alloy powder, modifier) on the workbench, and the mixed powder is melted by laser cladding. The laser cladding power is 2000W, the scanning speed is 3mm / s, the spot diameter is 2.5mm, and the powder spreading thickness is 0.7mm, obtaining a layer of thick vermicular iron-based alloy material.

[0035] (5) Repeat step (4) to complete a layer of thick vermicular iron-based alloy material layer and descend a layer thickness height, and repeat the stacking method until the entire component is obtained to form a stacked material.

[0036] Example 3 A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology comprises the following steps: (1) The vermicular agent and inoculant used in the production of vermicular graphite iron-based alloy are made into powder, and the particle size that meets the requirements is screened out through a sieve, and the particle size is 100-150 mesh.

[0037] (2) Iron-based alloy powder and modifier (vermicularizer powder, inoculant powder) were placed in a planetary ball mill in a certain proportion and uniformly mixed for 2.5 hours at a ball mill speed of 350 rpm. The mixture was then allowed to stand for 7 hours. The grinding balls were made of stainless steel. The content of modifier was 1.1% of the iron-based alloy powder, the content of vermicularizer was 0.55% of the weight of the iron-based alloy powder, and the content of inoculant was 0.55% of the weight of the iron-based alloy powder.

[0038] (3) The uniformly mixed powder described in (2) is dried and placed into the hopper of the additive manufacturing technology equipment.

[0039] (4) The program of the product to be printed is imported into the additive manufacturing technology equipment and the machine is started. The powder spreading scraper of the additive manufacturing technology equipment spreads the mixed powder (iron-based alloy powder, modifier) on the workbench, and the mixed powder is melted by laser cladding. The laser cladding power is 2500W, the scanning speed is 5mm / s, the spot diameter is 2.5mm, and the powder thickness is 0.5mm, obtaining a layer of thick vermicular iron-based alloy material.

[0040] (5) Repeat step (4) to complete a layer of thick vermicular iron-based alloy material layer and descend a layer thickness height, and repeat the stacking method until the entire component is obtained to form a stacked material.

[0041] Example 4 A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology comprises the following steps: (1) The vermicular agent and inoculant used in the production of vermicular graphite iron-based alloy are made into powder, and the particle size that meets the requirements is screened out through a sieve, and the particle size is 100-150 mesh.

[0042] (2) Iron-based alloy powder and modifier (vermicularizer powder, inoculant powder) were placed in a planetary ball mill in a certain proportion and uniformly mixed for 2.5 hours at a ball mill speed of 350 rpm. The mixture was then allowed to stand for 7 hours. The grinding balls were made of stainless steel. The content of modifier was 1.2% of the iron-based alloy powder, the content of vermicularizer was 0.6% of the iron-based alloy powder, and the content of inoculant was 0.6% of the iron-based alloy powder.

[0043] (3) The uniformly mixed powder described in (2) is dried and placed into the hopper of the additive manufacturing technology equipment.

[0044] (4) The program of the product to be printed is imported into the additive manufacturing technology equipment and the machine is started. The powder spreading scraper of the additive manufacturing technology equipment spreads the mixed powder (iron-based alloy powder, modifier) on the workbench, and the mixed powder is melted by laser cladding. The laser cladding power is 3500W, the scanning speed is 10mm / s, the spot diameter is 5mm, and the powder spreading thickness is 1mm, obtaining a layer of thick vermicular iron-based alloy material.

[0045] (5) Repeat step (4) to complete a layer of thick vermicular iron-based alloy material layer and descend a layer thickness height, and repeat the stacking method until the entire component is obtained to form a stacked material.

[0046] Example 5 A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology comprises the following steps: (1) The vermicular agent and inoculant used in the production of vermicular graphite iron-based alloy are made into powder, and the particle size that meets the requirements is screened out through a sieve, and the particle size is 100-150 mesh.

[0047] (2) Iron-based alloy powder and modifier (vermicularizer powder, inoculant powder) were placed in a planetary ball mill in a certain proportion and uniformly mixed for 2.5 hours at a ball mill speed of 350 rpm. The mixture was then allowed to stand for 7 hours. The grinding balls were made of stainless steel. The content of modifier was 1.3% of the iron-based alloy powder, the content of vermicularizer was 0.65% of the weight of the iron-based alloy powder, and the content of inoculant was 0.65% of the weight of the iron-based alloy powder.

[0048] (3) The uniformly mixed powder described in (2) is dried and placed into the hopper of the additive manufacturing technology equipment.

[0049] (4) The program of the product to be printed is imported into the additive manufacturing technology equipment and the machine is started. The powder spreading scraper of the additive manufacturing technology equipment spreads the mixed powder (iron-based alloy powder, modifier) on the workbench, and the mixed powder is melted by laser cladding. The laser cladding power is 3000W, the scanning speed is 8mm / s, the spot diameter is 4mm, and the powder thickness is 0.6mm, obtaining a layer of thick vermicular iron-based alloy material.

[0050] (5) Repeat step (4) to complete a layer of thick vermicular iron-based alloy material layer and descend a layer thickness height, and repeat the stacking method until the entire component is obtained to form a stacked material.

[0051] Result Analysis Figure 3 In the figure, a and b are the metallographic organization diagrams of the vermicular graphite iron-based alloy of Example 1 of the present invention at different magnifications. It can be seen from the figure that the vermicular graphite is evenly distributed in the organization, and the matrix organization is a mixed organization of ferrite and pearlite. The results show that the preparation method of the present invention can prepare vermicular graphite cast iron with uniform organization; Figure 4 The creep rate data diagram of Example 1 is shown in the horizontal axis, which is the different positions under the microscope, also called different fields of view. Figure 3 Six groups of creep rates were obtained from the six regions. Figure 4 It can be seen that the creep rate is above 90%, and the results show that the present invention has a high creep rate and creep control technology.

[0052] Table 1 Creep rate rating GB 26656 As can be seen from Table 1, fields of view 1 to 6 are Figure 3 Six different positions were selected for testing in part b. The obtained vermicular graphite iron-based alloy has a high creep rate and creep grade, a graphite content of about 8%, and uniform distribution of vermicular graphite.

[0053] The performance of the remaining embodiments is similar to that of embodiment 1 and will not be described in detail.

[0054] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, such changes and modifications are intended to be included.

Claims

1. A method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology, characterized in that: The following steps are involved: The iron-based alloy powder and the modifier are ball-milled and mixed, and then homogenized to obtain a mixed powder, wherein the modifier includes a vermicularizer and an inoculant, the content of the vermicularizer is 0.5% to 0.7% by mass of the iron-based alloy powder, and the content of the inoculant is 0.4% to 0.6% by mass of the iron-based alloy powder; The mixed powder is dried and placed in an additive manufacturing device, and the powder is melted and laid layer by layer by laser cladding to form a single layer of compacted graphite iron-based alloy. The cladding is then repeated layer by layer to obtain a compacted graphite iron-based alloy material based on additive manufacturing technology.

2. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 1, characterized in that: The total content of the vermicular agent and the inoculant is 0.9% to 1.3% of the mass of the iron-based alloy powder.

3. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 1, characterized in that: The vermicular agent is a rare earth magnesium vermicular agent, and the inoculant is a silicon zirconium inoculant.

4. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 3, characterized in that: The rare earth magnesium vermicular agent comprises, by mass percentage, Mg: 8% to 10%, RE: 18% to 22%, Ca: 2% to 4%, Si: 40% to 45%, and Fe as the remainder, which totals 100%; the silicon zirconium inoculant comprises, by mass percentage, Si: 65% to 70%, Zr: 2% to 3.5%, Ca: 1% to 1.5%, Al<1%, and Fe as the remainder, which totals 100%.

5. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 1, characterized in that: The laser cladding parameters are: laser power of 500W to 3500W, scanning speed of 1mm / s to 10mm / s, spot diameter of 1mm to 5mm, and powder thickness of 0.5mm to 1mm.

6. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 1, characterized in that: The chemical components of the iron-based alloy powder are as follows by mass percentage: C: 3.6-3.8%, Si: 1.8-2.2%, Ni: 2.5%-5.4%, Cr: 5.3%-7.2%, Mn<0.3%, and Fe as the remainder, which totals 100%.

7. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 1, characterized in that: The ball milling time is 2.5h-4h, and the ball milling speed is 300-450 rpm.

8. The method for preparing a compacted graphite iron-based alloy material based on additive manufacturing technology according to claim 1, characterized in that: The particles that meet the requirements are screened out through a sieve with a particle size of 100-200 mesh.

9. The compacted graphite iron-based alloy material obtained by the preparation method according to any one of claims 1 to 8 using additive manufacturing technology.

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