CN114570941B - Process for preparing 17-4PH martensitic precipitation stainless steel by electron beam - Google Patents
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- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
- B22F2009/0824—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with a specific atomising fluid
- B22F2009/0828—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with a specific atomising fluid with water
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- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
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Abstract
The invention provides a process for preparing 17-4PH martensitic precipitation stainless steel by an electron beam, belonging to the technical field of metal rapid prototyping. The method comprises the following steps: s1, pretreatment of 17-4PH powder; s2, constructing a three-dimensional model; s3, melting the electron beam selected area of the powder bed; the invention is a innovation of the forming technology of the manufactured 17-4PH material, namely, the additive manufacturing method of the 17-4PH stainless steel material based on electron beam selective melting is that the high-energy electron beam selective melting is formed under the high vacuum condition, and the purity of the manufactured 17-4PH stainless steel material is high; the electron beam high-temperature preheating of the substrate and the rapid scanning preheating powder bed of the electron beam are adopted to realize in-situ stress relief annealing and homogenization of forming tissues, so that cracking, warping and layering of a sample in the manufacturing process are effectively avoided, and the method is particularly suitable for manufacturing parts with high volume fraction particles in complex geometric shapes.
Description
Technical Field
The invention belongs to the technical field of metal rapid prototyping, and particularly relates to a process for preparing 17-4PH martensitic precipitation stainless steel by an electron beam.
Background
The electron beam selective melting technology belongs to one of the main technologies of metal 3D printing, has the advantages of high energy utilization, no reflection, high power density, high scanning speed, no pollution to the vacuum environment, low residual stress and the like, greatly simplifies the manufacturing process, and can manufacture irregularly-shaped parts. The electron beam selective melting of the powder bed is realized by the beam current of high-energy electron beams emitted by an electron gun, and the forming process mainly comprises four parts: the powder bed is preheated, the platform is lowered, the selected area is melted, the substrate is also required to be preheated in the initial layer, and the temperature of the substrate is different due to different materials.
The 17-4PH alloy is a precipitated, quenched, martensitic stainless steel that has good corrosion resistance to both atmospheric and dilute acids or salts, as well as 304 and 430. 17-4pH is commonly used in combination with moderate corrosion resistance or in very high strength applications. 17-4PH is easy to weld and process, and is magnetic. The material is widely applied to aerospace, ships, papermaking, energy, ocean and food industries, and is used for heavy machinery parts, shaft sleeves, turbine blades, couplings, screws, transmission shafts, nuts and measuring equipment.
The casting blank is processed by a machine tool, and serious cracks are generated in the rough drawing process, the drawing process and the pressing process, so that the production cannot be normally carried out.
The 17-4PH stainless steel material prepared by the electron beam selective metal melting technology is used as the most novel and foremost forming means, has the unique technological advantages of micro-zone melting, cyclic heat treatment, rapid solidification and the like, and solves the problems of coarse structure, loose solidification structure and the like of casting, ingot metallurgy and powder metallurgy. In the prior art, there is a few processes for preparing 17-4PH stainless steel materials by using electron beam selective zone melting metal technology, so a process for preparing 17-4PH martensitic precipitation stainless steel by using electron beams is needed.
Disclosure of Invention
In order to solve the defects of the 17-4PH material manufactured and formed crack and the defect of long production time, the invention provides a process for preparing 17-4PH martensitic precipitation stainless steel by using an electron beam.
The technical scheme of the invention is as follows: a process for preparing 17-4PH martensitic precipitation stainless steel by electron beams comprises the following steps:
s1-1, preparing 17-4PH powder by adopting a water atomization method, enabling the particle size of the powder to be 45-150 mu m, and then sieving the prepared 17-4PH powder with a 160-mesh sieve and collecting the powder for later use;
s1-2, drying the sieved 17-4PH powder for 30-40min at the temperature of 60 ℃;
s1-3, adding the 17-4PH powder processed in the step S1-2 into a powder cylinder of an EBSM device, setting the powder taking amount to be 100-110 mu m, and setting the pre-paving powder thickness to be 50-55 mu m;
s2, construction of three-dimensional model
S2-1, constructing a three-dimensional model of a machined workpiece through Materialise Magic, and constructing the three-dimensional model according to the thickness of the pre-laid powder, the splashing degree of the powder and the particle size of the powder;
s2-2, slicing the constructed three-dimensional model through SL-EBMBuild preparation to obtain a slice data structure, planning a scanning path of the obtained slice data, and guiding the slice data into powder bed electron beam selective melting equipment;
s2-3, setting parameters of the imported entity model;
s3, electron beam selective melting of powder bed
S3-1, vacuumizing a chamber of the powder bed electron beam selective melting equipment to enable the chamber to be in a medium vacuum degree environment, and then filling protective gas, wherein the vacuum degree environment and the protective gas exist to enable the chamber to be rapidly cooled, so that an oxidation phenomenon caused by overhigh temperature of a formed part in a forming process is effectively prevented;
s3-2, preheating the substrate before printing, wherein the specific preheating process is divided into three stages, the first stage is divided into two heating gradients to heat the bottom plate to 200-350 ℃, then preserving heat for 10min, the second stage is divided into two heating gradients to heat the bottom plate to 400-650 ℃, then preserving heat for 10min, the third stage is used for heating the substrate to 700-800 ℃, preserving heat for 10min, then subsequently heating to 950 ℃, then carrying out powder bed selective melting to obtain a single-layer metal thin layer, carrying out powder spreading pre-thermal compensation on the formed metal thin layer and the substrate, repeating the processes until the single-layer metal thin layer is stacked layer by layer, finally obtaining a target workpiece of 17-4PH martensitic precipitation stainless steel, carrying out annealing heat treatment on the previous layer after printing, so that the formed 17-4PH stainless steel has uniform and stable components, and fine microstructure, and the powder has good bonding effect in the preheating process, so that the splash generation of the powder is reduced, and better bonding powder is used for printing samples;
s3-3, dividing the obtained target workpiece and the substrate by using a linear cutting machine.
Further, the components of the 17-4PH powder in the step S1-1 include: 15.5 to 17.5 percent of Cr, 3.0 to 5.0 percent of Ni, less than or equal to 0.07 percent of C, 3.0 to 5.0 percent of Cu, 0.15 to 0.45 percent of Nb, less than or equal to 1.0 percent of Mn, less than or equal to 1 percent of Si, less than or equal to 0.03 percent of S, less than or equal to 0.04 percent of P, less than or equal to 0.40 percent of O, and the balance of Fe, and the effects of difficult cracking and strong corrosion resistance are realized by selecting the components of the 17-4PH stainless steel metal powder material and reasonably proportioning the components.
Further, in the step S1-1, particle size distribution of 17-4PH powder: the content of 150-325 meshes is 98wt%, and the content of less than 325 meshes is 2wt%.
Further, in the step S1-3, before the 17-4PH powder is added into the powder cylinder of the EBSM equipment, the powder bed is subjected to preheating treatment, and the specific treatment process is as follows: after the base plate is paved with powder, the rated power current of presintering is 40-45mA, the presintering time is 12.00-15.00s, the defocusing amount of beam spots is 0.300V, the maximum current is set to 40.00-48.00mA by preheating parameters, the average current is 13.50-16.00mA, the minimum presintering time is 8.000-18.000s, the maximum presintering time is 16.000-25.000s, the maximum preheating time of the preheating is greater than or equal to the sum of the minimum presintering time and the maximum presintering time, and the 17-4PH powder is well bonded in the preheating process by preheating a powder bed, so that the generation of splashing is reduced, and better bonding powder is used for printing samples.
Further, the model fusion forming parameters in the step S2-3 are as follows: the current power is 12.0-15.0mA, the scanning speed is 2.600-2.900m/s, the defocusing amount of the beam spot is-0.500V, and the size of the beam spot is 0.100mm.
Further, the specific preparation process of the 17-4PH powder by the water atomization method in the step S1-1 is as follows:
(1) Determining the components of the raw material water atomized 17-4PH metal powder according to the component requirements of the target workpiece to be processed, and preparing materials;
(2) Putting ingredients into a smelting furnace for smelting;
(3) The 17-4PH stainless steel melted in the step (2) flows out from a nozzle leakage hole, is atomized by high-pressure water, water is condensed to obtain water atomized 17-4PH powder, and then the water atomized 17-4PH powder is dehydrated, dried and graded;
(4) Zinc stearate with the mass of 0.03-0.1% of the intermediate powder is mixed into the 17-4PH powder obtained in the step (3), and then the powder is crushed into 17-4PH powder with the average particle size of 45-150 mu m by air flow grinding, and the powder obtained by water atomization is basically in an irregular shape, so that the problems of poor fluidity, low apparent density, poor usability and the like are caused, and the two methods of water atomization and air flow grinding are effectively combined, so that the requirement of the particle size can be met, and the irregular powder can be prepared into 17-4PH powder with uniform particle shape distribution by air flow grinding, so that the powder meets the use requirement.
Further, in the step (4), during the airflow grinding, multiple airflows are introduced into the air grinding chamber at different heights equidistantly, so that the water atomized 17-4PH powder can receive unattenuated airflow impact at different height positions during the movement of the air grinding chamber, wherein the airflow pressure is 0.4-0.6MPa, the crushing strength of the 17-4PH powder is not affected basically, and the prepared 17-4PH powder has a more uniform specification.
Further, in the step S3-3, a heat treatment is performed before the target workpiece is separated from the substrate, and the specific treatment process is as follows: firstly, removing residual metal powder on the surface of a target workpiece, placing the metal powder into a sintering furnace, vacuumizing, heating to 1100-1200 ℃, maintaining the temperature for 1-2h, and then air-cooling to 45-50 ℃; then, putting the processed target workpiece and the substrate into a sintering furnace again, and repeating the steps for 2-3 times; finally, the target workpiece and the substrate are segmented, the target workpiece is ground and polished to be a finished product, the target workpiece and the substrate are subjected to heat treatment together, deformation caused by thermal stress in the heat treatment is overcome by using the support of the substrate, and meanwhile, the final heat treatment temperature of 1100-1200 ℃ is selected to avoid the temperature range of material intergranular corrosion, so that the intergranular corrosion in the stainless steel can be effectively eliminated, and the corrosion resistance of the stainless steel is further improved.
Further, the temperature rising rate of the sintering furnace is 300-400 ℃/h.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention is a innovation of the forming technology of the manufactured 17-4PH material, namely a 17-4PH stainless steel material additive manufacturing method based on electron beam selective melting, which is to melt and shape the manufactured 17-4PH stainless steel material with high purity under high vacuum condition by high energy electron beam selective melting.
(2) The production process provided by the invention adopts the electron beam high-temperature preheating of the substrate and the rapid scanning preheating powder bed of the electron beam to realize in-situ destressing annealing and homogenization of the forming structure, effectively avoids cracking, warping and layering of the sample in the manufacturing process, and is particularly suitable for manufacturing parts with high volume fraction particles in complex geometric shapes.
(3) The invention overcomes the problems of poor fluidity, low apparent density, poor usability and the like of the powder obtained by water atomization powder preparation basically in an irregular shape through the effective combination of water atomization and air flow powder preparation, and can not only meet the requirement of particle size, but also prepare the irregular powder into 17-4PH powder with uniform particle shape distribution through air flow powder preparation, so that the powder meets the use requirement.
Drawings
FIG. 1 is a structural view of a 17-4PH martensitic precipitation stainless steel obtained by an orthogonal test in test example 1 according to the present invention;
FIG. 2 is a structural view of a 17-4PH martensitic precipitation stainless steel obtained by an orthogonal test in test example 2 according to the present invention;
FIG. 3 is a structural diagram of a 17-4PH martensitic precipitation stainless steel obtained by an orthogonal test in test example 3 according to the present invention.
Detailed Description
The present invention will be described in detail with reference to examples.
Example 1
A process for preparing 17-4PH martensitic precipitation stainless steel by electron beams comprises the following steps:
pretreatment of S1, 17-4PH powder
S1-1, preparing 17-4PH powder by adopting a water atomization method, and then sieving the prepared 17-4PH powder with a 160-mesh sieve and collecting for later use;
s1-2, drying the sieved 17-4PH powder for 30min at the temperature of 60 ℃;
s1-3, adding the 17-4PH powder processed in the step S1-2 into a powder cylinder of an EBSM device, setting the powder taking amount to be 100 mu m, and setting the pre-paving powder thickness to be 50 mu m;
s2, construction of three-dimensional model
S2-1, constructing a three-dimensional model of a machined workpiece through Materialise Magic, and constructing the three-dimensional model according to the thickness of the pre-laid powder, the splashing degree of the powder and the particle size of the powder;
s2-2, slicing the constructed three-dimensional model through SL-EBMBuild preparation to obtain a slice data structure, planning a scanning path of the obtained slice data, and guiding the slice data into powder bed electron beam selective melting equipment;
s2-3, setting parameters of the imported entity model;
s3, electron beam selective melting of powder bed
S3-1, vacuumizing a chamber of the powder bed electron beam selective melting equipment to enable the chamber to be in a medium vacuum degree environment, and then filling protective gas, wherein the vacuum degree environment and the protective gas exist to enable the chamber to be rapidly cooled, so that an oxidation phenomenon caused by overhigh temperature of a formed part in a forming process is effectively prevented;
s3-2, preheating the substrate before printing, wherein the specific preheating process is divided into three stages, the first stage is divided into two heating gradients to heat the bottom plate to 200 ℃, then preserving heat for 10min, the second stage is divided into two heating gradients to heat the bottom plate to 400 ℃, then preserving heat for 10min, the third stage is divided into two heating gradients to heat the substrate to 700 ℃, preserving heat for 10min, then preserving heat to 950 ℃, then carrying out powder bed selective melting to obtain a single-layer metal thin layer, carrying out thermal compensation before powder laying on the formed metal thin layer and the substrate, repeating the processes until the single-layer metal thin layer is stacked layer by layer, and finally obtaining the target workpiece of the 17-4PH martensitic precipitation stainless steel; the method comprises the steps of carrying out a first treatment on the surface of the
S3-3, dividing the obtained target workpiece and the substrate by using a linear cutting machine.
Example 2
A process for preparing 17-4PH martensitic precipitation stainless steel by electron beams comprises the following steps:
s1-1, preparing 17-4PH powder by adopting a water atomization method, and then sieving the prepared 17-4PH powder with a 160-mesh sieve and collecting for later use;
s1-2, drying the sieved 17-4PH powder for 35min at the temperature of 60 ℃;
s1-3, adding the 17-4PH powder processed in the step S1-2 into a powder cylinder of an EBSM device, setting the powder taking amount to be 105 mu m, and setting the pre-paving powder thickness to be 53 mu m;
s2, construction of three-dimensional model
S2-1, constructing a three-dimensional model of a machined workpiece through Materialise Magic, and constructing the three-dimensional model according to the thickness of the pre-laid powder, the splashing degree of the powder and the particle size of the powder;
s2-2, slicing the constructed three-dimensional model through SL-EBMBuild preparation to obtain a slice data structure, planning a scanning path of the obtained slice data, and guiding the slice data into powder bed electron beam selective melting equipment;
s2-3, setting parameters of the imported entity model;
s3, electron beam selective melting of powder bed
S3-1, vacuumizing a chamber of the powder bed electron beam selective melting equipment to enable the chamber to be in a medium vacuum degree environment, and then filling protective gas, wherein the vacuum degree environment and the protective gas exist to enable the chamber to be rapidly cooled, so that an oxidation phenomenon caused by overhigh temperature of a formed part in a forming process is effectively prevented;
s3-2, preheating the substrate before printing, wherein the specific preheating process is divided into three stages, the first stage is divided into two heating gradients to heat the bottom plate to 300 ℃, then preserving heat for 10min, the second stage is divided into two heating gradients to heat the bottom plate to 500 ℃, then preserving heat for 10min, the third stage is divided into two heating gradients to heat the substrate to 750 ℃, preserving heat for 10min, then preserving heat to 950 ℃, then carrying out powder bed selective melting to obtain a single-layer metal thin layer, carrying out thermal compensation before powder laying on the formed metal thin layer and the substrate, repeating the processes until the single-layer metal thin layer is stacked layer by layer, and finally obtaining the target workpiece of the 17-4PH martensitic precipitation stainless steel;
s3-3, dividing the obtained target workpiece and the substrate by using a linear cutting machine.
Example 3
A process for preparing 17-4PH martensitic precipitation stainless steel by electron beams comprises the following steps:
pretreatment of S1, 17-4PH powder
S1-1, preparing 17-4PH powder by adopting a water atomization method, and then sieving the prepared 17-4PH powder with a 160-mesh sieve and collecting for later use;
s1-2, drying the sieved 17-4PH powder for 40min at the temperature of 60 ℃;
s1-3, adding the 17-4PH powder processed in the step S1-2 into a powder cylinder of an EBSM device, setting the powder taking amount to be 110 mu m, and setting the pre-paving powder thickness to be 55 mu m;
s2, construction of three-dimensional model
S2-1, constructing a three-dimensional model of a machined workpiece through Materialise Magic, and constructing the three-dimensional model according to the thickness of the pre-laid powder, the splashing degree of the powder and the particle size of the powder;
s2-2, slicing the constructed three-dimensional model through SL-EBMBuild preparation to obtain a slice data structure, planning a scanning path of the obtained slice data, and guiding the slice data into powder bed electron beam selective melting equipment;
s2-3, setting parameters of the imported entity model;
s3, electron beam selective melting of powder bed
S3-1, vacuumizing a chamber of the powder bed electron beam selective melting equipment to enable the chamber to be in a medium vacuum degree environment, and then filling protective gas, wherein the vacuum degree environment and the protective gas exist to enable the chamber to be rapidly cooled, so that an oxidation phenomenon caused by overhigh temperature of a formed part in a forming process is effectively prevented;
s3-3, dividing the obtained target workpiece and the substrate by using a linear cutting machine.
Example 4
This embodiment is substantially the same as embodiment 3 except that:
the components of the 17-4PH powder in the step S1-1 mainly comprise: 15.5% of Cr, 3.0% of Ni, 0.07% of C, 3.0% of Cu, 0.15% of Nb, 1.0% of Mn, 1% of Si, 0.03% of S, 0.04% of P, 0.40% of O and 75.81% of Fe;
in step S1-1, particle size distribution of 17-4PH powder: the content of 150-325 meshes is 98wt%, and the content of less than 325 meshes is 2wt%;
in the step S1-3, before 17-4PH powder is added into a powder cylinder of the EBSM equipment, preheating treatment is carried out on the powder bed, and the specific treatment process is as follows: after the base plate is paved with powder, presintering rated power current is 43mA, presintering time is 14s, beam spot defocusing amount is 0.300V, preheating parameter setting maximum current is 45.00mA, average current is 15.00mA, presintering minimum time is 13.000s, presintering maximum time is 20.000s, and the maximum preheating time of the presintering is more than or equal to the sum of presintering minimum time and presintering maximum time;
the model fusion forming parameters in the step S2-3 are as follows: the current power is 14.0mA, the scanning speed is 2.800m/s, the defocusing amount of the beam spot is-0.500V, and the size of the beam spot is 0.100mm.
Example 5
This embodiment is substantially the same as embodiment 4 except that:
the specific preparation process of the 17-4PH powder prepared by the water atomization method in the step S1-1 is as follows:
(1) Determining the components of the raw material water atomized 17-4PH metal powder according to the component requirements of the target workpiece to be processed, and preparing materials;
(2) Putting ingredients into a smelting furnace for smelting;
(3) The 17-4PH stainless steel melted in the step (2) flows out from a nozzle leakage hole, is atomized by high-pressure water, water is condensed to obtain water atomized 17-4PH powder, and then the water atomized 17-4PH powder is dehydrated, dried and graded;
(4) Mixing zinc stearate with the mass of 0.08% of the intermediate powder into the 17-4PH powder obtained in the step (3), grinding the powder into 17-4PH powder with the average particle size of 110 mu m by using jet milling, and introducing a plurality of air streams at different heights in an air grinding chamber in the air grinding process, so that the water atomized 17-4PH powder can receive unattenuated air stream impact at different height positions in the air grinding chamber moving process, wherein the air stream pressure is 0.5MPa.
Example 6
This embodiment is substantially the same as embodiment 5 except that:
in step S3-3, heat treatment is performed before the target workpiece and the substrate are divided, and the specific treatment process is as follows: firstly, removing residual metal powder on the surface of a target workpiece, putting the metal powder into a sintering furnace, vacuumizing, heating to 1150 ℃ at a heating rate of 350 ℃/h, keeping the temperature for 1.5h, and then air-cooling to 48 ℃; then, the processed target workpiece and the substrate are put into a sintering furnace again, and the steps are repeated for 2 times; finally, the target workpiece and the substrate are divided, and the target workpiece is ground and polished to obtain a finished product.
Test example 1
The experimental methods used in the following experimental procedures are conventional experimental methods unless otherwise specified. The materials, reagents, methods and apparatus used, unless otherwise indicated, are commercially available to those skilled in the art.
The process of examples 1-4 was used to prepare 17-4PH martensitic precipitation stainless steel, wherein the printing protocol was run in quadrature with three levels (5 m/s, 4m/s, 3 m/s) of two factors (14 mA and 12 mA), four sets of samples were printed for each parameter, with a print thickness of 1mm, and the obtained surface quality was smoother than the other scan speeds at different power, same scan speed of 3m/s from the experimental procedure and results analysis.
Test example 2
The process of examples 1-4 was used to prepare 17-4PH martensitic precipitation stainless steel, wherein the printed schedule was tested in three-factor (14 mA,13mA,12 m) three-level (3.5 m/s, 3m/s, 2.5 m/s) orthogonal, printing a thickness of 5mm, and as a result of the analytical test, FIG. 2 shows that a scan rate of 2.5m/s at the same power resulted in severe over-melting of the sample, a scan rate of 3m/s resulted in over-melting, and a scan rate of 3.5m/s did not result in over-melting.
Test example 3
17-4PH martensitic precipitation stainless steel was prepared by the process of examples 1-4, wherein the printing protocol used orthogonal experiments at one factor (13 mA) four levels (2.6 m/s, 2.7m/s, 2.8m/s, 2.9 m/s) to obtain samples without excessive melting by observing the surface characteristics of the samples of FIG. 3.
Claims (8)
1. A process for preparing 17-4PH martensitic precipitation stainless steel by electron beam, comprising the steps of:
pretreatment of S1, 17-4PH powder
S1-1, preparing 17-4PH powder by adopting a water atomization method, enabling the particle size of the powder to be 45-150 mu m, and then sieving the prepared 17-4PH powder with a 160-mesh sieve and collecting the powder for later use;
s1-2, drying the sieved 17-4PH powder for 30-40min at the temperature of 60 ℃;
s1-3, adding the 17-4PH powder processed in the step S1-2 into a powder cylinder of an EBSM device, setting the powder taking amount to be 100-110 mu m, and setting the pre-paving powder thickness to be 50-55 mu m;
s2, construction of three-dimensional model
S2-1, constructing a three-dimensional model of a machined workpiece through Materialise Magic, and constructing the three-dimensional model according to the thickness of the pre-laid powder, the splashing degree of the powder and the particle size of the powder;
s2-2, slicing the constructed three-dimensional model through SL-EBMBuild preparation to obtain a slice data structure, planning a scanning path of the obtained slice data, and guiding the slice data into powder bed electron beam selective melting equipment;
s2-3, setting parameters of the imported entity model;
s3, electron beam selective melting of powder bed
S3-1, vacuumizing a chamber of the powder bed electron beam selective melting equipment to enable the chamber to be in a medium vacuum degree environment, and subsequently filling protective gas;
s3-2, preheating the substrate before printing, wherein the specific preheating process is divided into three stages, the first stage is divided into two heating gradients to heat the bottom plate to 200-350 ℃, then preserving heat for 10min, the second stage is divided into two heating gradients to heat the bottom plate to 400-650 ℃, then preserving heat for 10min, the third stage is used for heating the substrate to 700-800 ℃, preserving heat for 10min, then subsequently heating to 950 ℃, then carrying out powder bed selective melting to obtain a single-layer metal thin layer, carrying out powder spreading pre-thermal compensation on the formed metal thin layer and the substrate, repeating the processes until the single-layer metal thin layer is stacked layer by layer, and finally obtaining the target workpiece of the 17-4PH martensitic precipitation stainless steel;
s3-3, dividing the obtained target workpiece and the substrate by using a linear cutting machine;
in the step S1-3, before 17-4PH powder is added into a powder cylinder of the EBSM equipment, preheating treatment is carried out on the powder bed, and the specific treatment process is as follows: after laying powder on a substrate, presintering rated power current is 40-45mA, presintering time is 12.00-15.00s, beam spot defocusing amount is 0.300V, preheating parameters are set to maximum current of 40.00-48.00mA, average current is 13.50-16.00mA, presintering minimum time is 8.000-18.000s, presintering maximum time is 16.000-25.000s, and the maximum preheating time of the presintering is more than or equal to the sum of presintering minimum time and presintering maximum time;
the specific preparation process of the 17-4PH powder by the water atomization method in the step S1-1 is as follows:
(1) Determining the components of the raw material water atomized 17-4PH metal powder according to the component requirements of the target workpiece to be processed, and preparing materials;
(2) Putting ingredients into a smelting furnace for smelting;
(3) The 17-4PH stainless steel melted in the step (2) flows out from a nozzle leakage hole, is atomized by high-pressure water, water is condensed to obtain water atomized 17-4PH powder, and then the water atomized 17-4PH powder is dehydrated, dried and graded;
zinc stearate with an intermediate powder mass of 0.03-0.1% is mixed into the 17-4PH powder obtained in the step (3), and then the mixture is pulverized into the 17-4PH powder with an average particle size of 45-150 mu m by jet milling.
2. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 1, wherein the composition of 17-4PH powder in step S1-1 comprises: 15.5 to 17.5 percent of Cr, 3.0 to 5.0 percent of Ni, less than or equal to 0.07 percent of C, 3.0 to 5.0 percent of Cu, 0.15 to 0.45 percent of Nb, less than or equal to 1.0 percent of Mn, less than or equal to 1 percent of Si, less than or equal to 0.03 percent of S, less than or equal to 0.04 percent of P, less than or equal to 0.40 percent of O and the balance of Fe.
3. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 1, wherein in said step S1-1, the particle size distribution of the 17-4PH powder is: the content of 150-325 meshes is 98wt%, and the content of less than 325 meshes is 2wt%.
4. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 1, wherein said step S2-3 is characterized in that the model fusion forming parameters are: the current power is 12.0-15.0mA, the scanning speed is 2.600-2.900m/s, the defocusing amount of the beam spot is-0.500V, and the size of the beam spot is 0.100mm.
5. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 1, wherein in the step (4), a plurality of air flows are introduced into the air grinding chamber at different heights in an equidistant manner during the air grinding process, so that the water atomized 17-4PH powder can receive unattenuated air flow impact at different height positions during the movement of the water atomized 17-4PH powder in the air grinding chamber, wherein the air flow pressure is 0.4-0.6MPa.
6. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 1, wherein in the step S3-3, a heat treatment is performed before the target workpiece is separated from the substrate, and the specific treatment process is as follows: firstly, removing residual metal powder on the surface of a target workpiece, placing the metal powder into a sintering furnace, vacuumizing, heating to 1100-1200 ℃, maintaining the temperature for 1-2h, and then air-cooling to 45-50 ℃; then, putting the processed target workpiece and the substrate into a sintering furnace again, and repeating the steps for 2-3 times; finally, the target workpiece and the substrate are divided, and the target workpiece is ground and polished to obtain a finished product.
7. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 6, wherein the temperature rising rate of the sintering furnace is 300-400 ℃/h.
8. The process for preparing 17-4PH martensitic precipitation stainless steel by electron beam according to claim 6, wherein the temperature of said sintering furnace is 800-900 ℃.
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| EP1992709A1 (en) * | 2007-05-14 | 2008-11-19 | EOS GmbH Electro Optical Systems | Metal powder for use in additive method for the production of three-dimensional objects and method using such metal powder |
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| EP1992709A1 (en) * | 2007-05-14 | 2008-11-19 | EOS GmbH Electro Optical Systems | Metal powder for use in additive method for the production of three-dimensional objects and method using such metal powder |
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