JPWO2020149787A5 - - Google Patents

Description

The present invention relates to 3D printed products of iron-based alloys with high hardness. 3D printed products are cured using a furnace in which the products resulting from 3D printing are treated during Hot Isostatic Pressure (HIP) and hardened.

Several different approaches exist today for making powder metallurgy materials. One of the main methods is PM-HIP (Powder Metallurgy Isostatic Pressing). The above method involves spraying (granulating) a metal powder, placing the powder in a container, sealing the container, and converting the sealed container for HIP, for example, from 1120 to The exposure is typically 3 hours at 1150° C. and 100 MPa. The result is typically a block of consolidated material that needs to be further processed.

The container can have different shapes, largely depending on the material and shape required for the final part. It can also be a standard cylindrical shape, if the material is a rod for further manufacture.

In the latter case, for example for the production of PM-HSS (powder metallurgy high speed steel), the material block is then typically forged and rolled to the final bar dimensions. These bars are then typically softened and tempered before being transported to inventory. They are then transported to the workshop where soft machining is carried out for the shape of the necessary details, such as gear hobs. However, after soft machining, the gear hob blank is hardened in a vacuum furnace and then tempered in another furnace. And finally, the hardened blank can serve as a basis for achieving the desired surface tolerances.

Typically, machining of the softened and tempered steel bar is followed by hardening of the material. One of the most common curing processes for PM-HSS is heating to 1180 °C, remaining at that temperature during the holding time, and then cooling to 25-50 °C, with a minimum cooling rate of 1000 °C. This guarantees a rate of 7°C/s between 800°C and 800°C. In this case, hardening is followed by tempering, and the material is repeatedly heated to 560° C. with holding times of more than 1 hour (h) and cooled to less than 25° C. between repetitions.

The temperature will of course depend on the type of alloy and the hardness goal. In addition, if high-precision soft machining is being performed, a stress relaxation step (typically 600-700°C for 2 hours (h) and slow cooling to 500°C, followed by cooling to 25°C) is added. Is possible.

The result of the PM-HIP process, besides powder quality, composition, forging and rolling, is therefore an effect of temperature, pressure and time.

The HIP process can also be utilized for 3D printed (additively manufactured) metal alloys. The process may then serve as a means to close the holes resulting from the 3D printing process. The process then serves to guarantee the total density component. After the HIP process of the 3D printed product, a conventional curing process may subsequently be used.

The outcome of 3D printing, HIP and curing processes is then a result of powder quality, composition and 3D printing parameters, as well as of temperature, pressure and time. Nevertheless, this multi-step process is time consuming.

The aim of the invention is to overcome the drawbacks of the prior art. The present invention therefore provides a method in which HIP and curing are integrated and the resulting material unexpectedly has improved mechanical properties compared to materials HIPed and cured by conventional methods. . The present invention also aims to provide a material or product with a more uniform carbide size or carbide area distribution. For example, the hardness of the material was improved by 12%, and wear studies revealed a 7.5% lower wear rate. Furthermore, even though the hardness increased, the toughness remained similar to the conventionally processed samples. This is more pronounced for alloys with higher carbon content.

In a first aspect, the invention relates to a 3D printed product according to claim 1.

In a preferred embodiment, the invention is a 3D printed article formed of a ferrous alloy comprising a metal matrix and carbide particles incorporated into the metal matrix;
Carbon: 1.0 or more and 5.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Iron: Balance;
including;
The above alloy is
Tungsten: 2 or more and 13 or less weight %;
Cobalt: 7 or more and 18 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
further comprising at least two of the elements;
The above alloy contains unavoidable trace impurities;
the maximum carbide area is less than 8 μm ² and the average carbide area is less than 2 μm ² ;
and/or the carbide area distribution has a difference between the d90 value and the d10 value of 1.90 μm ² or less;
and/or the carbide area distribution has a d90 value of 2.20 μm ² or less.

In a second aspect, the invention provides a method of making a 3D printed product, comprising:
a. providing a powder of an iron-based alloy, the iron-based alloy further comprising carbon and an unavoidable amount of impurities;
b. 3D printing a product from a ferrous alloy in a free-forming device having a chamber, the 3D printing being performed in a vacuum;
c. The product obtained in step b,
i. placing the product in the oven;
ii. heating the product to a first temperature of at least 850° C., increasing the pressure in the furnace to a first pressure of at least 80 MPa, and holding the product at the first temperature and first pressure during a first holding time; step;
iii. heating the product to a second temperature of at least 950°C and maintaining the product at the second temperature and at a second pressure for a second holding time;
iv. quenching the product to a third temperature, reducing the pressure in the furnace to the third pressure, and holding the product at the third temperature and the third pressure for a third holding time;
v. by heating the product to a fourth temperature, increasing the pressure in the furnace to the fourth pressure, and holding the product at the fourth temperature and the fourth pressure for a fourth holding time; The present invention relates to a method of making a 3D printed product, the method comprising: temperature cycling the product by reducing the temperature of the product to a fifth temperature.

In a third aspect, the invention relates to a product obtainable by the method of the invention.

In one embodiment, the product obtained by the method of the invention is obtained by a method in which the first temperature is between 1120 and 1150° C. and the first pressure is about 100 MPa. Preferably, the first holding time is preferably 3 hours (h).

In another embodiment, the product obtained according to the invention has a 2 kg It has a hardness measured using a Vickers indenter.

An advantage of the present invention is that the resulting product has at least 5% higher hardness (HV2kg), preferably 7% higher hardness, more preferably has 10% higher hardness.

All embodiments described herein are applicable to all aspects unless expressly stated otherwise. Preferred embodiments of the invention are defined in the dependent claims.

Wear rate for material 280 with different heat treatments. The figure shows the unexpectedly low wear volume of the integrated HIP and hardened material 280-5 compared to the conventional HIP and heat treated material 280-4. Both use a curing temperature of 1180°C followed by a 3 x 1 hour (h) temper at 560°C. At the final sliding distance in the test (31 m), the measured wear rates were 0.0055 mm ³ for 280-4 and 0.0051 mm ³ for 280-5, respectively. This corresponds to a wear rate reduction of 7.5%. a) after conventional HIP and curing (WD=7.6mm, EHT=10.00kV, magnification 10.00KX) and b) integrated HIP and curing according to the invention (WD=6.7mm, EHT=10 SEM image of material 150 after .00 kV and 10.00 KX magnification. SEM images of material 150 with carbide edges marked a) after conventional HIP and curing and b) after integrated HIP and curing according to the present invention. a) after conventional HIP and curing (WD=7.5mm, EHT=10.00kV, magnification 10.00KX) and b) integrated HIP and curing according to the invention (WD=5.9mm, EHT=10 SEM image of material 280 after .00 kV and 10.00 KX magnification. SEM images of material 280 with carbide edges marked a) after conventional HIP and curing, and b) after integrated HIP and curing according to the present invention. a) after conventional HIP and curing (WD=6.3mm, EHT=10.00kV, magnification 10.00KX) and b) integrated HIP and curing according to the invention (WD=4.5mm, EHT=10 SEM image of material 290 after .00 kV and 10.00 KX magnification. SEM images of material 290 with carbide edges marked a) after conventional HIP and curing, and b) after integrated HIP and curing according to the present invention. a) after conventional HIP and curing (WD=4.6mm, EHT=10.00kV, magnification 10.00KX) and b) integrated HIP and curing according to the invention (WD=4.5mm, EHT=10 SEM image of material 350 after .00 kV and 10.00 KX magnification. The larger gray areas are of the (Cr,V)C carbide type and the smaller circular, whiter particles are of the V,N enriched carbide/nitride type. SEM images of material 350 with carbide edges marked a) after conventional HIP and curing and b) after integrated HIP and curing according to the present invention. Schematic illustration of the effect of the present invention (dotted line) on carbide area distribution compared to conventional HIP and curing (solid line). FIG. 2 is a schematic diagram of the method according to the invention. 2 is a graph showing the reduction in d90 and d10 values of carbide area distribution in percentage when using the present invention. Graph showing carbide area distribution for samples made using conventional HIP and heat treatment and samples made using the present invention (URQ). The graph shows the difference in d90 and d10 values for white and gray carbides and the average value of the differences. Graph showing carbide area distribution for samples made using conventional HIP and heat treatment and samples made using the present invention (URQ). Max represents the maximum carbide area and SD represents the standard deviation.

In this application, the terms three-dimensional printing or 3D printing or free-forming or additive manufacturing refer to the same thing and are used interchangeably.

In this application, the term "carbide size" refers to the widest part of the cross-sectional area of a carbide or carbide cluster.

In this application, the term "carbide area" refers to the cross-sectional area of carbides.

In this application, the term "carbide cluster area" refers to the cross-sectional area of a carbide cluster. Carbide clusters are individual carbides placed close together to function as one large carbide.

In this application, the term "average carbide area" refers to the average cross-sectional area of carbides.

In this application, the term "average carbide cluster area" refers to the average cross-sectional area of carbide clusters.

In this application, the term "maximum carbide area" means that a maximum of 10%, preferably a maximum of 5%, more preferably a maximum of 1% of the carbides have this area or more. represent.

In this application, the term "maximum carbide size" means that a maximum of 10%, preferably a maximum of 5%, more preferably a maximum of 1%, of the carbides have this size or more. represent.

3D Printed Product It is an object of the present invention to provide a three-dimensional (3D) printed product made of or comprising a ferrous alloy with high hardness and good high temperature properties. The alloy includes a metal matrix and carbide particles embedded within the metal matrix. The alloy is iron (balance Fe) based and includes carbon and chromium, and may also include tungsten, cobalt, vanadium, molybdenum, and carbon. Preferably, the alloy has a very low oxygen content, preferably less than 100 ppm by weight, more preferably less than 50 ppm by weight.

The alloys of the present invention include carbon, chromium, and (balance) iron, and at least two of tungsten, cobalt, molybdenum, and vanadium. In a preferred embodiment, the alloy includes tungsten, molybdenum, and vanadium. In another preferred embodiment, the alloy includes tungsten, cobalt, molybdenum, and vanadium.

The chromium (Cr) content is greater than or equal to 2.0 and less than or equal to 22% by weight. In one preferred embodiment, the content is between 3 and 10, preferably between 3.5 and 4.5% by weight. In another preferred embodiment, the chromium content is between 18 and 22% by weight, more preferably about 20% by weight.

The tungsten (W) content is greater than or equal to 2 and less than or equal to 13% by weight. In one preferred embodiment, the tungsten content is between 4 and 12% by weight. In one preferred embodiment, the content is preferably 6-11% by weight.

The cobalt (Co) content is greater than or equal to 9 and less than or equal to 18% by weight. In one embodiment, the content is preferably 10-17% by weight.

The vanadium (V) content is greater than or equal to 3 and less than or equal to 8% by weight. In one embodiment, said content is preferably 4-7% by weight.

The molybdenum (Mo) content is greater than or equal to 1 and less than or equal to 10% by weight. In one embodiment, the content is preferably 2-8% by weight, more preferably 5-7% by weight.

The carbon (C) content is greater than or equal to 1.0 and less than or equal to 5.0% by weight. In one embodiment, the content is preferably 1.4 to 3.0% by weight, more preferably 2.20 to 2.60% by weight, more preferably 2.30 to 2% by weight. .50% by weight.

Besides the inevitable impurities, the remainder of the alloy is iron, or Fe balance. The amount of iron in the balance depends on the amounts of other ingredients. Usually the amount of iron is 50-70% by weight, preferably 60-65% by weight. Oxygen content in 3D printed products should be as low as possible. In the present invention, the oxygen content is preferably 30 ppm or less or 20 ppm or less.

The alloy may further contain unavoidable amounts of impurities of other elements, or trace impurities. These elements can be, but are not limited to, niobium, nickel, manganese, silicon, boron, tantalum, or combinations thereof. The total amount of the other elements or impurities is preferably less than 1% by weight, less than 0.5% by weight, or less than 0.05% by weight.

In a preferred embodiment, the alloy comprises:
Carbon: 1.0 or more and 5.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Iron: balance;
including;
The above alloy is
Tungsten: 2 or more and 13 or less weight %;
Cobalt: 7 or more and 18 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
further comprising at least two of the elements;
The above alloy contains unavoidable trace amounts of impurities.

One advantage of the present invention is that it does not require the use of any organic binders or adhesives, and therefore 3D printed products typically contain more than 95% by weight of iron, vanadium, molybdenum, carbon, tungsten, with a combined content of chromium and cobalt. In one embodiment of the invention, the mixed content of iron, vanadium, molybdenum, carbon, tungsten, chromium, and cobalt is greater than or equal to 97% by weight. Preferably, the mixed content of iron, vanadium, molybdenum, carbon, tungsten, chromium and cobalt is greater than or equal to 98% by weight. More preferably, the mixed content of iron, vanadium, molybdenum, carbon, tungsten, chromium, and cobalt is greater than or equal to 99% by weight. Most preferably, the mixed content of iron, vanadium, molybdenum, carbon, tungsten, chromium, and cobalt is greater than or equal to 99.9% by weight. In one embodiment of the invention, the amount of organic compounds in the 3D printed product is 0.1% by weight or less. Preferably, the amount of organic compounds in the 3D printed product is 0.05% by weight or less. In one embodiment of the invention, the product is essentially free of any organic compounds. Carbon in the product is primarily present in the form of carbides such as tungsten and chromium carbides, although elemental carbon and elemental tungsten may also be present in the matrix.

Multiphase alloys primarily include a matrix of iron, carbon, and chromium, but may also include cobalt, tungsten, and/or molybdenum. There are carbides of chromium, vanadium, molybdenum, and tungsten, ie of the CrC type, VC and WC, or W/Mo ₆ C, present in the matrix. Depending on the alloy composition, the carbides of the present invention may be mainly W/Mo ₆ C and VC, the total amount of said carbides being 20-30% by volume, preferably 22-28% by volume. The carbides of the 3D printed product are uniformly distributed (well dispersed) and the size distribution is narrow as seen in Table 3, schematically shown in Figure 10 and shown in Figures 12-14. The matrix may further include vanadium or nitrogen enriched carbides/nitrides. The maximum carbide size of the 3D printed and cured product is 10 μm or less. In one embodiment, the maximum carbide size is 8 μm or less, 5 μm or less, preferably 3 μm or less. The average carbide size is usually 5 μm or less, or 3 μm or less, or 1 μm or less. The average carbide area is preferably 5 μm ² or less, more preferably 2 μm ² or less, even more preferably 1 μm ² or less. In one embodiment, the average carbide area is greater than or equal to 0.025 μm ² , preferably greater than or equal to 0.25 μm ² . This indicates that a narrow carbide size distribution is found in the products of the invention. The maximum carbide area is preferably 10 μm ² or less, preferably 8 μm ² or less, or 5 μm ² or less, or 4 μm ² or less. The small carbide size, carbide area, and maximum carbide area of the products according to the invention are, in part, a result of the method according to the invention. The carbide area distribution preferably has a d90 value of 2.20 μm ² or less, preferably 2.0 μm ² or less, more preferably 1.8 μm ² or less, more preferably 1.6 μm ^{2 or} less. In one embodiment, the difference between the d90 and d10 values is 1.90 μm ² or less, preferably 1.70 μm ² or less, more preferably 1.50 μm ² or less.

Metal compounds containing carbides can cause the carbides to form clusters, stringers, dendritic or network structures that make the material more brittle. Typically, in these types of alloys, especially those with high chromium and carbon, the chromium has carbides (such as Cr ₇ C ₃ and Cr ₂₃ C ₆ , but also other stoichiometric types). Form. These carbides typically grow rapidly during the solidification stage, resulting in large and long stringers with dimensions of 100-1000 μm in size. These large carbides reduce macrofracture toughness and fatigue resistance in the material. Thus, one of the advantages of the present invention is that the 3D article contains carbide or carbide particles that are generally smaller and better dispersed in the matrix than those found in the prior art. This is the result of the method according to the invention.

One advantage of the present invention is the realization of improved mechanical properties of 3D printed products. Hardness of the cured product (austenitized at 1180°C, followed by 3 times tempering at 560°C for 1 hour (h), and then air cooled with temperature between temperature steps less than 25°) can be at least 1050 HV2 kg (HV2), such as at least 1075 HV2 kg, or at least 1100 HV2 kg, or at least 1125 HV2 kg. In some embodiments, the hardness is 1075-1175 HV2 kg or 1100-1150 HV2 kg. Hardness is determined using a 2 kg Vickers indentation (HV2).

Without wishing to be bound by theory, it is believed that the mechanical properties of the present invention are a result of the product's microstructure. 3D printed products are essentially free of carbide dendritic structures. The carbides are small in size and they are evenly distributed within the matrix as can be seen. The alloys of 3D printed and hardened products usually have no or very few carbides with a size of 15 μm or more. Instead, the average size of the carbides is less than 10 μm or less than 5 μm.

The present invention not only facilitates the creation of products and components with improved mechanical properties, but also allows the creation of products with highly or complex three-dimensional shapes and morphologies. The product may include cavities, channels, or holes, and the product may have curved sections or a helical configuration. These shapes or forms are made without any removal of the alloy other than any optional post-treatment. The cavities, holes, or channels may be curved, ie, their surfaces may be curved, helical, spiral, etc. In some embodiments, the article includes a cavity where the cavity is sealed or has an opening where the diameter or width of the opening is less than the diameter or width of the underlying cavity. The products include cutting tools such as milling cutters, shaper cutters, power skiving cutters, drills, milling tools, etc., forming tools such as extrusion heads, wire drawing dies, hot rolling rolls, etc., or pump or valve components, It may be a wearing component such as a sliding or rolling bearing ring or the like.

Method The method is illustrated schematically in FIG.
The invention also relates to a method of making 3D printed products from alloy powders, including a combined HIP and hardening process. The alloy is an iron-based alloy (Fe balance) further containing carbon and an unavoidable amount of impurities. The alloy may further include at least one of chromium, tungsten, cobalt, vanadium, and molybdenum. In one preferred embodiment, the iron-based alloy includes carbon, chromium, vanadium, and molybdenum. In another preferred embodiment, the iron-based alloy includes carbon, tungsten, chromium, cobalt, vanadium, and molybdenum. In yet another preferred embodiment, the iron-based alloy includes carbon, tungsten, chromium, vanadium, and molybdenum.

In yet another preferred embodiment, the alloy is as defined above. The alloy is iron-based (Fe balance), comprises carbon and chromium, and may further comprise tungsten, cobalt, vanadium, molybdenum, and carbon. In one embodiment, the alloy is iron-based (Fe balance) and comprises carbon and chromium, and the alloy further comprises at least two of the following elements: tungsten, cobalt, vanadium, and molybdenum. Preferably, the alloy has a very low oxygen content, preferably less than 100 ppm by weight, more preferably less than 50 ppm by weight.

The carbon content of the iron-based alloy may be greater than or equal to 0.2 and less than or equal to 5% by weight. In one embodiment, the carbon content is 2.20 or more and 2.60 or less by weight. In one preferred embodiment, the content is between 2.30 and 2.50% by weight. In one embodiment, the carbon (C) content is 1.0 or more and 5.0 or less by weight. In one embodiment, the content is preferably 1.4 or more and 3.0 or less, more preferably 2.20 to 2.60% by weight, more preferably 2.30 to 2.50% by weight. be.

The chromium content can be greater than or equal to 2 and less than or equal to 30% by weight. In one embodiment, the chromium (Cr) content is greater than or equal to 2.0 and less than or equal to 22% by weight. In one preferred embodiment, the content is between 3.8 and 4.4% by weight, preferably between 3.9 and 4.3% by weight. In one preferred embodiment, the content is between 3 and 10% by weight, preferably between 3.5 and 4.5% by weight. In another preferred embodiment, the chromium content is between 18 and 22% by weight, more preferably about 20% by weight.

The tungsten (W) content can be greater than or equal to 2 and less than or equal to 25% by weight. In one preferred embodiment, the content is 5 or more and 13 or less weight %. In one preferred embodiment, the tungsten content is between 4 and 12% by weight. In a more preferred embodiment, the content is 6-11% by weight. In one embodiment, the tungsten (W) content is 2 or more and 13 or less by weight. In one preferred embodiment, the content is preferably 6-11% by weight.

The cobalt (Co) content can be greater than or equal to 5 and less than or equal to 25% by weight. In one embodiment, the content is greater than or equal to 9 and less than or equal to 18% by weight. In a more preferred embodiment, the content is 10 to 17% by weight. In one embodiment, the cobalt (Co) content is greater than or equal to 7 and less than or equal to 18% by weight. In one preferred embodiment, the content is 9 or more and 18 or less. In one embodiment, the content is preferably 10-17% by weight.

The vanadium (V) content can be greater than or equal to 2 and less than or equal to 15% by weight. In one preferred embodiment, the content is greater than or equal to 5 and less than or equal to 8% by weight. In a more preferred embodiment, the content is 6-7% by weight. In one embodiment, the vanadium (V) content is greater than or equal to 3 and less than or equal to 8% by weight. In one embodiment, said content is preferably greater than or equal to 4 and less than or equal to 7% by weight.

The molybdenum (Mo) content can be 2 or more and 20 or less by weight. In a preferred embodiment, said content is greater than or equal to 3 and less than or equal to 10% by weight. In a more preferred embodiment, the content is between 4 and 8% by weight, more preferably between 5 and 7% by weight. In one embodiment, the molybdenum (Mo) content is greater than or equal to 1 and less than or equal to 10% by weight. In one embodiment, the content is preferably 2-8% by weight, more preferably 5-7% by weight.

Besides the inevitable impurities, the remainder of the alloy is iron, or Fe balance. The amount of iron in the balance depends on the amounts of other ingredients. Usually the amount of iron is 50-70% by weight, preferably 60-65% by weight. Oxygen content in 3D printed products should be as low as possible. In the present invention, the oxygen content is preferably 30 ppm or less, or 20 ppm or less.

The alloy may further comprise unavoidable amounts of impurities of other elements, or trace impurities. These elements can be, but are not limited to, niobium, nickel, manganese, silicon, boron, tantalum, or combinations thereof. The total amount of the other plurality of elements or impurities is preferably less than 1% by weight, less than 0.5% by weight, or less than 0.05% by weight.

In a preferred embodiment, the alloy comprises:
Carbon: 1.0 or more and 5.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Iron: Balance;
including;
The above alloy is
Tungsten: 2 or more and 13 or less weight %;
Cobalt: 7 or more and 18 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
further comprising at least two of the elements;
The above alloy contains unavoidable trace amounts of impurities.

Oxygen content in 3D printed products should be as low as possible. Preferably the oxygen content is 30 ppm or less or 20 ppm or less.

3D Printing Next, refer to FIG. 11. The method uses a freeform device (3D printer) with a chamber in which the powder is placed. The free-forming method comprises the steps of obtaining a powder of iron-based alloy (step 10) and 3D printing the powder (step 12). This is done by forming a layer of alloy powder in a low oxygen environment within a chamber, as defined below. The method of 3D printing may be performed as described in WO 2018/169477 or based on the method described in WO 2018/169477, which is incorporated herein by reference. One suitable freeform device is an electron beam machine (EBM) by Arcam, such as the ARCAM A2X. The alloy contains carbon, tungsten, molybdenum, chromium, vanadium, and cobalt in the above amounts, and the selection of alloy depends on the desired properties of the final product. The content of oxygen and other impurities in the reactor should be as low as possible, such as below 10 ppm (corresponding to gas purity grade 5) or below 1 ppm (corresponding to gas purity grade 6). , and the environment in the reactor may include an inert gas such as argon or helium. The vacuum pressure in the reactor may be below 1.5 x ^10-3 mBar, preferably below 1.5 x ^10-4 mBar. In one embodiment, the initial pressure in the reactor is about 1.10 x 10 ^-5 mBar (1.10 x 10 ^-3 Pa), after which the pressure decreases to 1.5 x 10 ^-3 mBar or less. Or preferably an inert gas such as helium or argon is added to increase the pressure below 1.5×10 ⁻⁴ mBar. The powder is then locally melted by exposing it to an energy beam for a period sufficient to melt it. The energy beam can be a laser beam or an electron beam. The beam is swept across the powder in an arbitrary pattern. The duration of the sweep can range from a few milliseconds to a few minutes depending on the size of the particles in the alloy and powder. The molten powder can then be at least partially solidified into a multilayer metal alloy. Another layer of powder may then be added on top of the solidified alloy.

In order to avoid crack formation in the product and to improve the properties of the product, the product is maintained at an elevated temperature (first elevated temperature) during printing or forming of the 3D printed product. . Crack formation may be due to a combination of increased internal stress and increased material brittleness at lower temperatures. The increase in internal stress is caused by volume changes during phase transitions and also by normal thermal expansion. To avoid crack formation, the elevated temperature can be 300°C or higher, 400°C or higher, 500°C or higher, 550°C or higher, 600°C or higher, 700°C or higher, 800°C or higher, or 900°C or higher, but typically , 1100°C or less. For example, the base plate or workbench on which the product is based may be equipped with a heating device. Thus, 3D printed products may exhibit temperature gradients therein during construction of the product. Heating the product is such that the temperature of the built product during the construction process is preferably 600°C or higher, 700°C or higher, or 750°C or higher, but typically 900°C or lower, 850°C or lower, or 800°C or lower. should be controlled so that In one embodiment, the temperature is between 720°C and 790°C, such as 780°C. The temperature should of course be low enough for the molten powder layer to at least partially solidify before adding a new powder layer. This allows the method to not only be cheaper, but also to have a more positive influence on the microstructure.

In one embodiment, 3D printing includes:
A. forming a layer of iron-based alloy powder on a bedplate in the chamber, the iron-based alloy further comprising carbon and an unavoidable amount of impurities, the powder comprising generally spherical particles and/or approximately spherical particles; forming a layer of iron-based alloy powder including spherical particles;
B. locally melting the powder by exposing the powder to an energy beam for a period of time sufficient to form a molten pool;
C. solidifying the molten powder into a multiphase alloy in a melt pool;
D. optionally creating a further layer of powder on the previous layer by repeating steps i-iii, step ii comprising disposing the powder on the previous layer; arbitrarily producing step;
including;
The product being constructed is heated and maintained at an elevated temperature during the method.

The advantages of using EBM compared to lasers are that thicker powder layers can be made and powders with larger particles can be used. Carbide growth occurs during solidification of the molten material and growth time should be limited to limit carbide size. Solidification time is primarily influenced by thermal diffusion rate, heat of solidification, and thermal diffusion distance. The rate of solidification in conventional casting techniques is determined by cooling the molten material using any suitable technique, such as casting in quenched refractory molds or casting details. , can be improved. Furthermore, in existing prior art cladding approaches, the cooling rate, while still high, is not high enough to prevent carbide growth or obtain a fully dense material.

Novel Integrated HIP and Curing The resulting 3D printed product is then processed in an integrated HIP and curing process. This can preferably be done using a Quintus machine equipped with a uniform rapid quench (URQ®). In this integrated process, the 3D printed product is placed in a suitable oven or furnace (step 14). The print is heated to a first temperature of at least 850<0>C and the pressure is increased to a first pressure of at least 80 MPa. The product is maintained at this temperature and pressure for a first hold time (step 16), after which the temperature is further increased to a second temperature of at least 950<0>C. At the second temperature, the product is maintained for a second holding time (step 18) and then rapidly quenched (cooled) to a third temperature and the pressure is further reduced to a third pressure. (step 20). Hardening can be performed using any suitable means, for example using a gas such as an inert gas. In order to obtain better mechanical properties and microstructure, the quenching is at least 10°C/s, more preferably 20°C/s, more preferably 30°C/s, more preferably at least 40°C/s, and more. Preferably, the cooling is carried out at a high speed of up to 50° C./s. The product is maintained at a third temperature and pressure for a third holding time. After quenching and pressure reduction, a temperature cycle (tempering) is performed in which the temperature is increased to a fourth temperature and the pressure is increased to a fourth pressure. The product may be maintained at a fourth temperature and pressure for a fourth hold time, after which the temperature may be decreased to a fifth temperature. The pressure may be further reduced to a fifth pressure. The temperature cycle may be repeated at least once, preferably twice.

In one embodiment, the first temperature is at least 1000°C, but preferably below 1200°C, preferably within the range 1100°C to 1200°C, more preferably within the range 1120°C to 1150°C. It is.

In one embodiment, the second temperature is at least 1050°C, preferably within the range of 1100°C to 1200°C, more preferably within the range of 1180°C to 1200°C. The second temperature is higher than the first temperature.

In one embodiment, the third temperature is 75°C or less. In the quenching step (step 20), the temperature is rapidly cooled in one embodiment from the second temperature to a third temperature of 50° C. or less, and the third pressure is preferably 65 MPa or less.

In one embodiment, the first pressure is less than 210 MPa, preferably in the range 90-120 MPa.

In one embodiment, the second pressure is at least 80 MPa, preferably at least 90 MPa, or preferably at least 100 MPa, preferably less than 210 MPa, more preferably less than 150 MPa. In a preferred embodiment, the first and second pressures are the same, ie, the pressures are not changed in step 18.

In one embodiment, the third pressure is in the range 30-70 MPa, preferably 55-65 MPa.

In one embodiment, the fourth pressure is at least 70 MPa, preferably in the range 70-80 MPa, more preferably about 75 MPa.

In one embodiment, the fourth temperature is in the range of 500-600°C, preferably 550-580°C, more preferably about 560°C.

In one embodiment, the fifth temperature is below 50°C, preferably within the range of 20-25°C.

Holding time depends on the alloy composition and thickness of the product. In a preferred embodiment, each hold time is sufficient for the product to reach the set or target temperature or oven temperature. In one preferred embodiment, the first holding time is in the range of 1 to 4 hours, preferably 3 hours. In one embodiment, the second holding time is within the range of 10 minutes to 60 minutes, preferably 30 minutes. In one embodiment, the third retention time is within the range of 1 second to 1 hour, or 30 seconds to 30 minutes. In another embodiment, the fourth holding time is in the range of 30 minutes to 3 hours, preferably 1 hour.

As can be seen in the examples, the products according to the invention or obtained by the method according to the invention unexpectedly have high hardness and often remain brittle. This is unexpected compared to conventional curing processes. This is because alloys processed by conventional hardening are already hardened to their "full hardening temperature" according to conventional wisdom. This effect is realized for different types of steel, further considering the results from PM-HSS material (M42, materials 150, 280 and 290) and highly alloyed martensitic stainless steel (material 350). The comparison is clear.

Without being bound by theory, it is believed that integrated HIP and heat treatment reduces the amount of large carbides. This is shown for example in FIG. 12, where the decrease in d90 value is higher than the decrease in d10 value. Figures 12-14 clearly show that the present method results in a product with a narrower carbide area distribution, where the amount of large carbides is reduced in favor of smaller carbides. Since the white carbide is, for example, a W carbide, the effect of the reduction in area distribution on the white carbide, as seen in FIG. 13, is even more interesting.

All embodiments disclosed herein are to be understood as some exemplary examples of the invention. It will be appreciated that various modifications, combinations, and changes can be made to the embodiments and aspects without departing from the scope of the invention. In particular, different partial solutions in different embodiments can be combined in other configurations, if technically possible.

Example 1
The Quintus QIH 21 URQ machine was used to compare separate HIP and hardening and integrated HIP and hardening for 3D printed highly alloyed materials with compositions as shown in Table 1. has been done. Four 3D printed Fe alloys are compared: three high speed steels and one martensitic stainless steel. 3D printing is basically performed as described in WO 2018/169477, which is incorporated herein by reference. All four materials were first conventionally consolidated by HIP, conventionally hardened, and tempered. Samples from just the same 3D printing batch are then processed through a novel integrated HIP, cure, and temper process with the same cure and temper time and temperature settings as before. See Table 1.

Conventional HIP parameters were heating to 1120-1150° C. with a holding time of 3 h (hours) and HIP pressure of 100 MPa, then cooling to room temperature and then pressure release.

The test detail was heated to 1180 °C with a holding time of about 30 minutes, followed by a high-speed quenching in the interval 970 °C to 800 °C with a cooling rate of more than 7 °C/s, followed by 25 to 50 °C. Conventional curing was performed in a conventional vacuum oven with cooling in air to .degree. The test detail was then tempered three times by heating the detail to 560°C with a holding time of 1 hour (h) and then cooling to 25°C between three temperature cycles.

Conventional HIP parameters and hardening and tempering are all standard procedures performed at large scale suppliers.

The novel integrated HIP, hardening and tempering process according to the present invention uses the following parameters: First, the detail or product is heated to 1120-1150°C while the pressure is increased up to 100 Ma. Ta. At this stage, a holding time of 3 hours (h) is maintained, after which the temperature is increased to 1180° C. with a new holding time of 30 minutes. From this stage, a rapid temperature quenching up to 20° C. (with pressure also dropping to 60 MPa) takes place. Three temperature increases to 560° C. (followed by increased pressure to 75 MPa) are then carried out, which is a tempering cycle. The holding time at 560°C was 1 hour (h) each, and the temperature between temperature cycles was 20°C.

The material samples are then compared in hardness and in microstructure. Hardness measurements were carried out by using a 2 kg Vickers indenter on ground and polished samples according to the standard material analysis method by finish grinding with SiC P4000 according to SS-EN ISO 6507. Ta. At this stage, hardness was measured at several points from multiple pieces with the same results.

After cutting the sample from the treated piece of material, the sample is further processed to facilitate carbide measurements. This fabrication was performed using 1 μm diamond for 5 min followed by Struers OP-S solution (40 μm SiO2 at pH 9.8), a well-known method to facilitate carbide structure analysis. It was further polishing.

Results The hardness of all samples is shown in Table 2. Overall, the hardness after integrated HIP, hardening and tempering is unexpectedly much higher than traditional HIP and heat treatment processes. Material 150 is 12% more expensive, Material 280 is 11.8% more expensive, Material 290 is 5% more expensive, and Material 350 is 12% more expensive.

Abrasion resistance was analyzed for conventional HIP and heat treated material 280 and the same grade with the new integrated HIP and heat treatment.

The test used to analyze the abrasion resistance is a commercially available dimple grinder (Gatan) with a grinding wheel rotating on a horizontal axis, pressed onto the sample rotating on a vertical axis. A diamond slurry with an average particle size of 2.5 μm was introduced into the contact before each run. A fixed load of 20 g was applied to the grinding wheel when it contacted the sample. Each test had a duration of 500 wheel revolutions, totaling a total sliding distance of approximately 31 m. For statistical purposes, the test was repeated three times for each sample.

Three cubes of test material were prepared with approximately 6×6 mm test surfaces ground and polished to a surface roughness of Ra ˜3 μm. The wear rate was given by measuring the volume of material removed (abraded) by white light optical profilometry.

As a result, the integrated HIP and heat treated grades had a 7.5% lower wear rate even though they were cured at the same maximum temperature of 1180°C (see Figure 1). ).

Carbide calculations For carbide size analysis, a comprehensive microstructure analysis was performed, and the corresponding representative microstructures are shown here.

The most important microstructural changes are a decrease in carbide (and/or carbide cluster) area and a narrowing of the carbide area distribution, as shown in Table 3. A general trend is revealed where the maximum carbide/cluster is much smaller and at the same time the average carbide area is larger. This suggests that the carbide area distribution is very narrow. This indicates that the toughness of the alloy is improved, or at least not degraded. This is because the toughness of these types of hard and highly alloyed materials is set by the "maximum imperfection" in the material. These imperfections are usually some kind of impurity, oxide, large carbide or carbide cluster, but can also be a grinding error, ie a white layer due to grinding at too high a temperature. Furthermore, the material becomes more uniform and isotropic, with a narrower carbide distribution.

The microstructure was analyzed in a scanning electron microscope (SEM) as shown in the figure. The SEM was a Zeiss Ultra 55 FEG-SEM using secondary electron imaging mode. The primary electron energies (EHT, ultra-high tension voltage) were 3, 5, and 10 keV, and the apertures used were 30 (standard) or 60 μm. The microstructure of the material showed an unexpectedly high carbide content and very fine carbides (Figs. 2, 4, 6 and 8).

Carbides were calculated, for example, by utilizing the microstructure seen in FIG. 2, marking the boundaries of single carbides or clusters of carbides, and using suitable software.

The results can be seen in FIGS. 3, 5, 7, and 9. The results of carbide area and ratio calculations can be found in Table 3.

Example 2
A series of tests were performed on samples to see how toughness (impact resistance) was affected by this method compared to conventional HIP and heat treatment.

Toughness measurements were performed by 3D printing 10 Charpy toughness bars in each direction, horizontally and vertically. After the different heat treatments tested, the bars were ground to the final test bar measurements: L x W x H = 7 x 10 x 55, +/- 0.025 mm. The surface roughness is set by the last surface grinding step, grit 4000. No notches are used on the test bar. The toughness is then measured at room temperature in a 300J Charpy tester with an egg radius of 2 mm. Toughness results are expressed in Joules and as an average of 10 samples.

As mentioned above, the hardness of the samples was significantly increased when the samples were prepared by using integrated HIP and heat treatment according to the present invention. What was unexpected was that the toughness of the samples was somewhat the same; an increase in hardness is usually accompanied by a decrease in toughness. Figures 12-14 show the effect on the carbide area distribution for these samples, with white and gray carbides representing how they appear in the SEM, with white carbides typically associated with heavy metal elements such as W. Gray carbides are usually formed with lighter metallic elements such as Cr or V in several different stoichiometric amounts. Carbide area analysis was performed as described above. Two products of each alloy were printed, one in the horizontal orientation and one in the vertical upright orientation, and the values shown are the average values of the two products.

As seen in FIG. 12, both d90 and d10 values are lower using the present method compared to conventional HIP and heat treatment. Furthermore, FIG. 12 shows that the decrease in d90 value is greater than the decrease in d10, indicating that the method has a more pronounced effect on the reduction of large carbides than on small carbides. ing.

Figure 13 shows that the carbide area analysis is narrower for samples made using the present method (URQ) than conventional HIP and heat treatments. Furthermore, the carbide area distributions of white and gray carbides are also more similar.

Figure 14 shows that preparing samples using the present invention (URQ) results in smaller carbides (mean), smaller maximum carbides (maximum), and narrower distribution (SD, standard deviation). .

Example 3
Here, printing tests of alloy M42 were performed using two heat treatment methods: conventional 3 hour (h) HIP and hardening in a separate vacuum furnace at 1180 °C, tempering at 3 x 560 °C and conventional A comparison was made between integrated HIP and heat treatment according to the present invention using the same temperature and time settings as the method, but at different pressures.

The powder used is gas atomized with a size fraction of 53 to 150 μm, with a composition in accordance with the specifications in % by weight.

M42 is an ultra-high Mo steel, typically a conventional non-PM high speed steel material, conforming to standards HS2-9-1-8, AISIS M42, or EN 1.3247.

Integrated HIP and heat treatment, as described above, requires the following conditions:
HIP for 3 hours (h) at 1120°C and 1000 Bar
Temperature increased to 1180° C. Quenching/hardening was carried out at 560° C. with tempering for 3×1 hour (h) at approximately 500 bar.

Conventional HIP and heat treatment:
HIPed for 3 hours (h) at 1120-1150°C and 1000 bar in a separate HIP oven;
cooled to room temperature,
Transported to a curing company,
Cured at 1180℃,
Tempered at 560° C. for 3×1 hour (h).

The material specification for this material (as a conventional bar) allows it to be cured from 61HRC to 68HRC (Rockwell), the latter for 3 x 1 hour (h) at a curing temperature of 1190°C + 560°C. It is realized by When cured at 1180°C, the hardness is approximately 67.6 HRC. Austenitization occurs between 1050 and 1090°C (Erasteel material specification data).

Hardness and toughness were determined as described above.

Results The conventionally cured sample had a hardness of 945+/-68 HV2kg, while the sample obtained by integrated HIP and heat treatment had a hardness of 1020+/-69 HV2kg.

This means that the method increases the hardness by 8%.

Toughness for the integrated HIP and heat treated samples was 13-21% lower than the conventionally treated samples. Without being bound by theory, it is believed that this is a result of the low carbon content, meaning that the effects of the integrated HIP and heat treatment are not fully realized in this case. do.

(1) A 3D printed article formed of an iron-based alloy comprising a metal matrix and carbide particles incorporated into the metal matrix;
The alloy is
Carbon: 1.0 or more and 5.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Iron: balance;
including;
The alloy is
Tungsten: 2 or more and 13 or less weight %;
Cobalt: 7 or more and 18 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
further comprising at least two of the elements;
The alloy contains unavoidable trace impurities;
Maximum carbide area is 8μm ² The average carbide area is less than 2 μm. ² less than;
and/or
Carbide area distribution is 1.90μm ² It has the following difference between d90 value and d10 value;
and/or
The carbide area distribution is 2.20 μm ² having a d90 value of
3D printed products.
(2) the carbon content is 1.4 or more and 3.0 or less by weight;
The 3D printed product described in (1) above.
(3) The alloy is
Tungsten: 2 or more and 13 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
Optionally,
Cobalt: 9 or more and 18 or less weight%
further including,
The 3D printed product described in (1) or (2) above.
(4) The alloy is
Carbon: 1.0 or more and 3.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
Iron: balance;
including;
The alloy contains unavoidable trace impurities,
The 3D printed product described in (1) or (2) above.
(5) The alloy is
Carbon: weight percent of 2.20 or more and 2.60 or less;
Tungsten: 5 or more and 13 or less weight %;
Chromium: 3.5 or more and 4.5 or less weight %;
Cobalt: 9 or more and 18 or less weight %;
Molybdenum: 3 or more and 10 or less weight %;
Vanadium: 5 or more and 8 or less weight %;
Iron: balance;
Unavoidable trace impurities
including,
The 3D printed product described in (1) or (2) above.
(6) The average carbide area is 1 μm ² is less than
The 3D printed product described in (1) above.
(7) The iron-based alloy
Carbon: 2.25 or more and 2.40 or less weight %;
Tungsten: 6 or more and 8 or less weight %;
Chromium: 3.5 or more and 4.5 or less weight %;
Cobalt: 9 or more and 12 or less weight %;
Molybdenum: 5 or more and 8 or less weight %;
Vanadium: 5 or more and 8 or less weight %;
Iron: balance;
The 3D printed product described in (1) above, including:
(8) The iron-based alloy
Carbon: 1.2 or more and 1.8 or less weight %;
Chromium: 3.5 or more and 4.5 or less weight %;
Tungsten: 2.0 or more and 4.0 or less by weight;
Vanadium: 3 or more and 5 or less weight %;
Molybdenum: 1 or more and 4 or less weight %;
Iron: balance;
Unavoidable trace impurities
including,
The 3D printed product described in (1) above.
(9) The iron-based alloy
Carbon: 1.5 or more and 2.3 or less weight %;
Chromium: 17 or more and 22.0 or less weight %;
Vanadium: 3 or more and 5 or less weight %;
Molybdenum: 1 or more and 3 or less weight %;
Iron: Balance;
Unavoidable trace impurities
including,
The 3D printed product described in (1) above.
(10) The iron-based alloy
Carbon: 1.0 or more and 1.20 or less weight %;
Chromium: 2.0 or more and 5.0 or less weight %;
Molybdenum: 7 or more and 10 or less weight %;
Cobalt: 7 or more and 9 or less weight %;
including;
The alloy is
Tungsten: 1.0 or more and 3.0 or less weight %;
Vanadium: 1.0 or more and 3.0 or less weight %;
Iron: balance;
Unavoidable trace impurities
further including,
The 3D printed product described in (1) above.
(11) The maximum carbide area is 4 μm ² or less, preferably 3 μm ² The 3D printed product according to any one of (1) to (10) above, which is as follows.
(12) The 3D printed product according to any one of (1) to (7) above, wherein the product has a hardness of at least 1050 HV2 kg, preferably at least 1100 HV2 kg.
(13) A method of producing a 3D printed product, comprising:
a. providing a powder of an iron-based alloy, said iron-based alloy further comprising carbon and an unavoidable amount of impurities;
b. 3D printing a product from said iron-based alloy in a free-forming device having a chamber, the 3D printing being performed in a vacuum;
c. The product obtained in step b,
i. placing the product in a furnace;
ii. heating the product to a first temperature of at least 850° C.; increasing the pressure in the furnace to a first pressure of at least 80 MPa; and heating the product to a first temperature and the first temperature during a first holding time. holding at a pressure of 1;
iii. heating the product to a second temperature of at least 950° C. and maintaining the product at the second temperature and at a second pressure for a second holding time;
iv. quenching the product to a third temperature, reducing the pressure in the furnace to a third pressure, and holding the product at the third temperature and the third pressure for a third holding time. ;
v. heating the product to a fourth temperature, increasing the pressure in the furnace to a fourth pressure, and holding the product at the fourth temperature and the fourth pressure for a fourth holding time; and then temperature cycling the product by decreasing the temperature of the product to a fifth temperature.
Steps processed by
including,
A method of making 3D printed products.
(14) Vacuum pressure is 1.5×10 ^-3 mBar or less, preferably 1.5×10 ^-Four The method according to (13) above, wherein the energy beam is preferably an electron beam.
(15) the first temperature is at least 1000°C, but preferably 1400°C or less, preferably within the range of 1100 to 1200°C, more preferably within the range of 1120 to 1150°C; The method according to (13) or (14), wherein the second temperature is higher than the first temperature.
(16) the second temperature is at least 1050°C, preferably within the range of 1100 to 1200°C, more preferably within the range of 1180 to 1200°C;
the second temperature is higher than the first temperature,
The method according to any one of (13) to (15) above.
(17) The method according to any one of (13) to (16) above, wherein the third temperature is 50° C. or lower, and the third pressure is preferably 65 MPa or lower.
(18) Any one of (13) to (17) above, wherein the first pressure is at least 90 MPa or less, or preferably at least 100 MPa, preferably less than 210 MPa, and more preferably less than 150 MPa. The method described in.
(19) The fourth temperature is within the range of 500 to 600°C, preferably 550 to 580°C, more preferably about 560°C, according to any of (13) to (18) above. Method described.
(20) The method according to (18) above, wherein the first pressure is within a range of 90 to 120 MPa.
(21) The method according to any one of (13) to (20) above, wherein the third pressure is within a range of 55 to 65 MPa.
(22) The method according to any one of (13) to (21) above, wherein the fourth pressure is at least 70 MPa, preferably in the range of 70 to 80 MPa, and more preferably about 75 MPa.
(23) The method according to any one of (13) to (22) above, wherein the fifth temperature is 50°C or lower, preferably within the range of 20 to 25°C.
(24) The method according to any one of (13) to (23) above, wherein the first holding time is within a range of 1 to 4 hours, preferably 3 hours.
(25) The method according to any one of (13) to (24) above, wherein the second holding time is within a range of 10 to 60 minutes, preferably 30 minutes.
(26) The method according to any one of (13) to (25) above, wherein the third holding time is within a range of 1 second to 30 minutes.
(27) The method according to any one of (13) to (26) above, wherein the fourth holding time is within a range of 30 minutes to 3 hours, preferably 1 hour.
(28) The method according to any one of (13) to (27) above, wherein the alloy further contains at least one of chromium, tungsten, cobalt, vanadium, and molybdenum.
(29) The alloy is
Carbon: 1.0 or more and 5.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Iron: balance;
including;
The alloy is
Tungsten: 2 or more and 13 or less weight %;
Cobalt: 7 or more and 18 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
further comprising at least two of the elements;
The alloy contains unavoidable trace impurities,
The method described in (13) above.
(30) Quenching the product is carried out at a cooling rate of at least 10°C/s, preferably at least 20°C/s, preferably at least 30°C/s, or at least 40°C/s, as described in (13) above. The method according to any one of (27) to (27).
(31) The method described in (13) above, wherein the 3D printing comprises:
A. forming a layer of the iron-based alloy powder on the bedplate in the chamber, the iron-based alloy further comprising carbon and an unavoidable amount of impurities, and the powder substantially comprising: forming a layer of said iron-based alloy powder comprising spherical particles and/or substantially spherical particles;
B. locally melting the powder by exposing the powder to an energy beam for a period of time sufficient to form a molten pool;
C. solidifying the molten powder into a multiphase alloy in the molten pool;
D. optionally creating a further layer of powder on said previous layer by repeating steps i-iii, step ii comprising disposing said powder on said previous layer; optionally creating further layers;
including;
the product being constructed is heated and maintained at an elevated temperature during the method;
The method described in (13) above.
(32) The method according to (13) above, wherein step v, which is a step of performing a temperature cycle, is repeated at least once, preferably twice.
(33) The second pressure is at least 80 MPa, preferably at least 90 MPa, or preferably at least 100 MPa, preferably less than 210 MPa, more preferably less than 150 MPa, (13) to The method according to any one of (32).
(34) A product obtained by the method described in any one of (13) to (33) above.
(35) The resulting product has at least 5% higher hardness (HV2 kg), preferably 7% higher hardness, more preferably, than the corresponding 3D printed product processed using conventional HIP and heat treatment. The product described in (34) above, having 10% higher hardness.
(36) The product according to (34) or (35) above, wherein the first temperature is 1120 to 1150°C and the first pressure is about 100 MPa, preferably with a holding time of 3 hours.
(37) The hardness was measured using a 2 kg Vickers indenter on samples that were ground and polished by the standard material analysis method by finish grinding on SiC P4000 according to SS-EN ISO 6507. The product described in (35) above.
(38) The product described in (1) above is a milling cutter, shaper cutter, power skiving cutter, drill, milling tool, extrusion head, wire drawing die, hot rolling roll, or sliding or rolling bearing ring. The product according to any one of ~(12) or (34) ~ (37).

Claims (13)

A 3D printed article formed of an iron-based alloy comprising a metal matrix and carbide particles incorporated into said metal matrix;
The alloy is
(i) Carbon: 1.0 or more and 5.0 or less weight %;
(ii) Chromium: 2.0 or more and 22.0 or less weight percent;
(iii) selected from tungsten: 2 or more and 13 or less weight %, cobalt: 7 or more and 18 or less weight %, molybdenum: 1 or more and 10 or less weight %, and vanadium: 3 or more and 8 or less weight %; at least two;
(iv) unavoidable trace impurities; and
(v) Iron: remainder
consists of
the maximum carbide area is less than 8 μm ² and the average carbide area is less than 2 μm ² ;
and
The carbide area distribution has a difference between the d90 value and the d10 value of 1.90 μm ² or less,
3D printed products. The carbon content is 1.4 or more and 3.0 or less by weight%,
3D printed product according to claim 1. (iii) contains tungsten: 2 or more and 13 or less weight % , molybdenum: 1 or more and 10 or less weight % , vanadium: 3 or more and 8 or less weight %, and optionally cobalt: 9 or more. 3D printed product according to claim 1 or 2 , comprising 18% by weight or less. 3D printed product according to claim 1 or 2, wherein the alloy is:
(a)
Carbon: 1.0 or more and 3.0 or less weight %;
Chromium: 2.0 or more and 22.0 or less weight %;
Molybdenum: 1 or more and 10 or less weight %;
Vanadium: 3 or more and 8 or less weight %;
unavoidable trace impurities; and
Iron: including the remainder;
(b)
Carbon: weight percent of 2.20 or more and 2.60 or less;
Tungsten: 5 or more and 13 or less weight %;
Chromium: 3.5 or more and 4.5 or less weight %;
Cobalt: 9 or more and 18 or less weight %;
Molybdenum: 3 or more and 10 or less weight %;
Vanadium: 5 or more and 8 or less weight %;
unavoidable trace impurities; and
Iron: including the remainder;
(c)
Carbon: 2.25 or more and 2.40 or less weight %;
Tungsten: 6 or more and 8 or less weight %;
Chromium: 3.5 or more and 4.5 or less weight %;
Cobalt: 9 or more and 12 or less weight %;
Molybdenum: 5 or more and 8 or less weight %;
Vanadium: 5 or more and 8 or less weight %; and
Iron: including the remainder;
(d)
Carbon: 1.2 or more and 1.8 or less weight %;
Chromium: 3.5 or more and 4.5 or less weight %;
Tungsten: 2.0 or more and 4.0 or less by weight;
Vanadium: 3 or more and 5 or less weight %;
Molybdenum: 1 or more and 4 or less weight %;
unavoidable trace impurities; and
Iron: including the remainder;
(e)
Carbon: 1.5 or more and 2.3 or less weight %;
Chromium: 17 or more and 22.0 or less weight %;
Vanadium: 3 or more and 5 or less weight %;
Molybdenum: 1 or more and 3 or less weight %;
unavoidable trace impurities; and
Iron: including the remainder;
(f)
Carbon: 1.0 or more and 1.20 or less weight %;
Chromium: 2.0 or more and 5.0 or less weight %;
Molybdenum: 7 or more and 10 or less weight %;
Cobalt: 7 or more and 9 or less weight %;
Tungsten: 1.0 or more and 3.0 or less weight %;
Vanadium: 1.0 or more and 3.0 or less weight %;
unavoidable trace impurities; and
Iron: including remainder
3D printed product according to claim 1 or 2. The average carbide area is less than 1 μm ² .
3D printed product according to claim 1. The maximum carbide area is 4 μm ² or less,
3D printed product according to any one of claims 1 to 4. the product has a hardness of at least 1050 HV2 kg ;
The hardness is measured using a 2 kg Vickers indenter on a sample that is ground and polished according to the standard material analysis method by finish grinding on SiC P4000 according to SS-EN ISO 6507.
3D printed product according to any one of claims 1 to 5. A method of producing a 3D printed product, the method comprising:
a. providing a powder of an iron-based alloy,
The iron-based alloy is
(i) Carbon: 1.0 or more and 5.0 or less weight %;
(ii) Chromium: 2.0 or more and 22.0 or less weight percent;
(iii) selected from tungsten: 2 or more and 13 or less weight %, cobalt: 7 or more and 18 or less weight %, molybdenum: 1 or more and 10 or less weight %, and vanadium: 3 or more and 8 or less weight %; at least two;
(iv) unavoidable trace impurities; and
(v) Iron: remainder
providing a powder of an iron-based alloy consisting of ;
b. 3D printing a product from said iron-based alloy in a free-forming device having a chamber, said 3D printing being performed in a vacuum;
c. The product obtained in step b,
i. placing the product in a furnace;
ii. heating the product to a first temperature of at least 850° C.; increasing the pressure in the furnace to a first pressure of at least 80 MPa; and heating the product to a first temperature and the first temperature during a first holding time. holding the pressure at 1;
iii. heating the product to a second temperature of at least 950° C.; heating the product to the second temperature during a second holding time; and a second pressure, wherein the second pressure is at least 80 MPa; holding at a second pressure;
iv. The product is quenched to a third temperature of 50° C. or less, the pressure in the furnace is reduced to a third pressure of 65 MPa or less, and the product is heated to the third temperature and the third temperature during a third holding time. Holding the pressure at 3;
v. heating the product to a fourth temperature between 500 and 600° C.; increasing the pressure in the furnace to a fourth pressure of at least 70 MPa; and heating the product to a fourth temperature and the temperature during a fourth holding time. holding at a fourth pressure, followed by temperature cycling the product by decreasing the temperature of the product to a fifth temperature of 50° C. or less;
A method of making 3D printed products. the first temperature is at least 1000 °C ;
the second temperature is higher than the first temperature
The method according to claim 8 . 10. A method according to claim 8 or 9 , wherein the first pressure is at least 90 MPa. A method according to any one of claims 8 to 10 , wherein the first holding time is in the range of 1 to 4 hours. A method according to any one of claims 8 to 11 , wherein the step of hardening the product is carried out at a cooling rate of at least 10° C./s. step v, which is a step of performing a temperature cycle, is repeated at least once ;
The method according to claim 8 .