Preparation method of SKH-9 high-speed steel part through binder injection additive manufacturing

Abstract

The invention discloses a method for manufacturing an SKH-9 high-speed steel part through binder injection additive manufacturing, the SKH-9 high-speed steel part is obtained through binder injection additive manufacturing, low-temperature baking curing, heat preservation degreasing and high-temperature sintering, and the SKH-9 high-speed steel part is obtained under the conditions that the low-temperature curing temperature of a green body is 180-200 DEG C and the highest sintering temperature is 1250-1270 DEG C; the high-performance SKH-9 high-speed steel part can be obtained, the structure of the high-performance SKH-9 high-speed steel part is integrally compact, the roundness is high The microhardness is gt; 540HV30, the performance is good; and the process scheme is simple and convenient, easy to implement, low in comprehensive cost and easy to popularize, and has great application prospects.

Description

Technical Field

[0001] The invention relates to a method for preparing a SKH-9 high-speed steel part, and in particular to a method for preparing a SKH-9 high-speed steel part by binder jetting additive manufacturing. Background Art

[0002] Additive manufacturing, commonly known as 3D printing, is an advanced green manufacturing technology that has many advantages over traditional machining methods. For example, it does not require the manufacture of tooling and molds, can form complex parts, has a short processing cycle, and saves raw materials. It has been applied in many fields including aerospace, automotive parts, medical, art design, etc.

[0003] There are many branches of additive manufacturing technology, and binder jetting is one of the fastest growing technologies in recent years. Compared with other additive manufacturing technologies, binder jetting additive manufacturing technology has the advantages of wide material adaptability, low equipment cost, fast forming speed, low thermal stress, and low overall cost. It is expected to achieve low-cost and efficient mass production of complex parts, and has broad development prospects. However, there are still problems such as few developed material systems, process parameters to be optimized, and low performance of formed parts. In-depth research is needed to lay the foundation for the promotion and application of this process.

[0004] In the operation of preparing steel parts by binder jetting in the prior art, the 420 stainless steel parts manufactured by binder jetting have good performance when sintered at a temperature of 1350°C. When the sintering temperature is lower (1300°C), the density decreases accordingly; when the sintering temperature is higher, the tensile strength is greatly reduced. There are many reasons why the performance of metal parts manufactured by binder jetting is not high at present. On the one hand, the forming-densification mechanism of this manufacturing method needs to be further clarified, especially the decomposition of the binder, the influence of the escape process on the densification of the parts, and the formation of sintering necks between metal powder particles, the growth process, etc.; on the other hand, the process parameters in the forming process need to be optimized. Such as the best combination of powder particle size distribution, layer thickness of the powder spreading process, and sintering temperature. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to disclose a method for preparing SKH-9 high-speed steel parts with high density and hardness by binder jet additive manufacturing.

[0006] Technical solution: The present invention discloses a method for preparing SKH-9 high-speed steel parts by binder jet additive manufacturing, comprising the following steps:

[0007] (1) SKH-9 fine powder with a particle size of less than 17 μm is taken and layered by layer by a binder jetting additive manufacturing method to obtain a green part;

[0008] (2) taking the part obtained in step (1), baking and curing it in an oven at low temperature to obtain a cured SKH-9 high-speed steel part body, thereby improving the green strength;

[0009] (3) The green body obtained in step (2) is heat-insulated and degreased in a sintering furnace, and sintered at a high temperature of 1250-1270° C. to obtain a SKH-9 high-speed steel part.

[0010] In step (1), the parameters of the binder jet forming equipment used are: the maximum forming size range is 200 mm × 60 mm × 70 mm, the number of nozzles is 1024, and the total amount of ink jetting each time is 30 × 10 -12 L, the sintering furnace model used is Tianjin Zhonghuan SK-Q06163 electric furnace.

[0011] Among them, in step (1), the binder jetting additive manufacturing adopts the following forming parameters: layer thickness 55-65μm, binder resolution 800×800dpi, jetting voltage 55-60V, leveling time 5000ms (expanded to range value); its forming parameters are further preferably layer thickness 60μm, binder resolution 800×800dpi, jetting voltage 58V, leveling time 5000ms.

[0012] Wherein, in step (2), the low-temperature baking curing has a temperature of 180-200° C. and a curing time of 2-3 hours.

[0013] Among them, in step (3), the thermal degreasing process parameters are: heating from room temperature to 550-650°C at a rate of 2-3°C / min, and thermally maintaining the temperature for 6.5-7.5h for degreasing; the process parameters are further preferably: heating from room temperature to 600°C at a rate of 2°C / min, and thermally maintaining the temperature for 7h for degreasing.

[0014] Wherein, in step (3), the high temperature sintering has the following process parameters: heating to 950-1000°C at a rate of 5-6°C / min, keeping warm for 1.5-2h for initial sintering; then heating to 1250-1270°C at a rate of 5-6°C / min, keeping warm for 4-5h; finally cooling to room temperature at a rate of 9-11°C / min; the process parameters are further preferably: heating to 1000°C at a rate of 5°C / min, keeping warm for 1.5h for initial sintering; then heating to 1250-1270°C at a rate of 5°C / min, keeping warm for 4h; finally cooling to room temperature at a rate of 10°C / min.

[0015] The present invention also discloses a SKH-9 high-speed steel part obtained by the above preparation method, wherein the part has a density higher than 95% and a hardness higher than 540HV. 30 .

[0016] Principle of the invention: The preparation method of SKH-9 high-speed steel parts by binder jet additive manufacturing of the present invention obtains formed parts with excellent performance by optimizing the process parameters; this is mainly due to the following points: (1) The method uses fine powder with a powder particle size distribution range of 0-17μm. Finer powder has a large specific surface area, high surface activity during sintering, and is easier to densify; (2) The forming parameters of binder jet additive manufacturing have been repeatedly optimized, and the formed blank is made dense and uniform under the condition of using as little adhesive as possible, laying the foundation for subsequent sintering; (3) The method strictly limits the sintering process, especially the maximum sintering temperature. The sintering process fully considers the influencing factors such as material composition, melting point, and sintering atmosphere. It is a sintering process specially formulated for SKH-9 materials. Under a specific process, SKH-9 fine powder with a special particle size is effectively activated, and synergistically enhanced to produce high-speed steel parts with excellent performance.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The binder jet additive manufacturing method for SKH-9 high-speed steel parts has a simple process scheme, is easy to implement, has a low overall cost, is easy to promote, and the prepared SKH-9 high-speed steel parts have excellent performance, dense overall structure, high roundness, and a density of more than 95%; the hardness is greater than 540HV 30 , which has great application prospects in actual manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The surface morphology of the SKH-9 high-speed steel sample after low-temperature baking and curing (bottom) and high-temperature sintering at 1250°C (top) in Example 1;

[0019] Figure 2 The metallographic structure of the sample of SKH-9 high speed steel after sintering at 1250°C in Example 1;

[0020] Figure 3 This is the surface morphology of the deformed sample in Comparative Example 1 when the sintering temperature is 1350°C. DETAILED DESCRIPTION

[0021] The technical scheme of the present invention is further described below in conjunction with the examples. The test materials used in the examples can all be purchased through conventional channels.

[0022] Example 1

[0023] The preparation method of SKH-9 high-speed steel parts by binder jet additive manufacturing of the present invention comprises the following steps:

[0024] (1) SKH-9 fine powder with a particle size range of 0 to 17 μm was used to obtain green parts by layer-by-layer accumulation through binder jetting additive manufacturing. The forming parameters used in binder jetting additive manufacturing are: layer thickness 65 μm, binder resolution 800×800 dpi, jet voltage 55 V, and leveling time 5000 ms.

[0025] (2) baking and curing in an oven at a low temperature of 180°C for 2 hours to improve the green body strength;

[0026] (3) The solidified SKH-9 high-speed steel part blank is kept in a sintering furnace for degreasing and high-temperature sintering. The specific process parameters of high-temperature sintering are: heating from room temperature to 600℃ at a rate of 2℃ / min, keeping it for 7h for degreasing; then heating to 1000℃ at a rate of 5℃ / min, keeping it for 1.5h for initial sintering; then heating to 1250℃ at a rate of 5℃ / min, keeping it for 4h; finally cooling to room temperature at a rate of 10℃ / min to obtain SKH-9 high-speed steel parts.

[0027] In this embodiment, the appearance of the sample of SKH-9 high speed steel after curing at 180°C and sintering at 1250°C is shown in the figure. Figure 1 As shown in the figure, the sintered sample has a bright metallic luster. Compared with the green body, its three-dimensional dimensions have shrunk and no major deformation has occurred. Figure 2 As shown, the structure is dense as a whole, with a small amount of pores and high roundness. After testing, its density is 95.68% and its microhardness is 542HV 30 The results show that the forming, curing and sintering process are appropriate and the obtained material has good performance.

[0028] Example 2

[0029] The preparation method of SKH-9 high-speed steel parts by binder jet additive manufacturing of the present invention comprises the following steps:

[0030] (1) SKH-9 fine powder with a particle size range of 0 to 17 μm was used to obtain green parts by layer-by-layer accumulation through binder jetting additive manufacturing. The forming parameters used in binder jetting additive manufacturing are: layer thickness 55 μm, binder resolution 800×800 dpi, jet voltage 60 V, and leveling time 5000 ms.

[0031] (2) baking and curing in an oven at a low temperature of 200°C for 3 hours to improve the green body strength;

[0032] (3) The solidified SKH-9 high-speed steel part blank is kept in a sintering furnace for degreasing and high-temperature sintering. The specific process parameters of high-temperature sintering are: heating from room temperature to 600℃ at a rate of 2℃ / min, keeping it for 7h for degreasing; then heating to 1000℃ at a rate of 5℃ / min, keeping it for 1.5h for initial sintering; then heating to 1270℃ at a rate of 5℃ / min, keeping it for 4h; finally cooling to room temperature at a rate of 10℃ / min to obtain SKH-9 high-speed steel parts.

[0033] After testing, the density of the sample of SKH-9 high-speed steel in this embodiment after curing at 200°C and sintering at 1270°C is 96.73%, and the microhardness is 568HV 30 The performance is good, which shows that the forming, curing and sintering process is appropriate.

[0034] Comparative Example 1

[0035] A method for preparing a SKH-9 high-speed steel part, compared with Example 2, wherein the maximum sintering temperature of step (3) is changed in Comparative Example 1, comprising the following steps:

[0036] (1) SKH-9 fine powder with a particle size range of 0 to 17 μm was used to obtain green parts by layer-by-layer accumulation through binder jetting additive manufacturing. The forming parameters used in binder jetting additive manufacturing are: layer thickness 60 μm, binder resolution 800×800 dpi, jet voltage 58 V, and leveling time 5000 ms.

[0037] (2) baking and curing in an oven at a low temperature of 200°C to improve the green body strength;

[0038] (3) The solidified SKH-9 high-speed steel part blank is kept in a sintering furnace for degreasing and high-temperature sintering. The specific process parameters for high-temperature sintering are: heating from room temperature to 600°C at a rate of 2°C / min, keeping it for 7 hours for degreasing; then heating to 1000°C at a rate of 5°C / min, keeping it for 1.5 hours for initial sintering; then heating to 1350°C at a rate of 5°C / min, keeping it for 4 hours; finally cooling to room temperature at a rate of 10°C / min to obtain the formed part.

[0039] like Figure 3 As shown in the figure, after sintering, the surface brightness of the sample is higher, but it has obvious deformation, from square to drum-like and spherical. This shows that too high sintering temperature will have a significant adverse effect on the morphology of the sample, destroying the morphology of the parts and making them unable to be put into normal use.

[0040] By comparing the embodiments with the comparative examples, the preparation method of the binder jet additive manufacturing SKH-9 high-speed steel parts of the present invention can obtain high-performance SKH-9 high-speed steel parts with a density of >95% and a microhardness of >540HV under the conditions of a green body low-temperature curing temperature of 180-200°C and a maximum sintering temperature of 1250-1270°C. 30 , good performance, and the process scheme is simple, easy to implement, low in comprehensive cost, easy to promote, and has great application prospects.

Claims

1. A method for preparing SKH-9 high-speed steel parts by binder jetting additive manufacturing, characterized in that: The steps include: (1) SKH-9 fine powder with a particle size of less than 17 μm was used to obtain green parts by binder jetting additive manufacturing; (2) taking the part obtained in step (1), baking and curing it in an oven at low temperature to obtain a cured SKH-9 high-speed steel part blank; (3) The green body obtained in step (2) is heat-insulated and degreased in a sintering furnace, and sintered at a high temperature of 1250-1270° C. to obtain a SKH-9 high-speed steel part.

2. The preparation method according to claim 1, characterized in that: In step (1), the binder jetting additive manufacturing adopts the following forming parameters: layer thickness 55-65 μm, binder resolution 800×800 dpi, jetting voltage 55-60 V, and leveling time 5000 ms.

3. The preparation method according to claim 1, characterized in that: In step (1), the parameters of the binder jet forming equipment used are: the maximum forming size range is 200mm×60mm×70mm, the total amount of ink jetting each time is 30×10 -12 L.

4. The preparation method according to claim 1, characterized in that: In step (2), the low-temperature baking and curing is carried out at a temperature of 180-200° C. and a time of 2-3 hours.

5. The preparation method according to claim 1, characterized in that: In step (3), the thermal degreasing process has the following process parameters: heating from room temperature to 550-650°C at a rate of 2-3°C / min, and thermal degreasing for 6.5-7.5h.

6. The preparation method according to claim 1, characterized in that: In step (3), the high temperature sintering has the following process parameters: heating to 950-1000°C at a rate of 5-6°C / min, keeping warm for 1.5-2h for initial sintering; then heating to 1250-1270°C at a rate of 5-6°C / min, keeping warm for 4-5h; and finally cooling to room temperature at a rate of 9-11°C / min.

7. A SKH-9 high speed steel part obtained by the preparation method of claim 1, characterized in that: The parts have a density higher than 95% and a hardness higher than 540HV 30 .

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