CN110586936A - Preparation method of 3D printing low-cost high-strength titanium alloy part - Google Patents

Abstract

The invention discloses a preparation method of a 3D printing low-cost high-strength titanium alloy part, which is implemented by the following steps: step 1, firstly, modifying pure titanium powder; step 2, mixing the pure titanium powder modified in the step 1 with spherical pure titanium powder to obtain mixed powder; step 3, preparing the mixed powder obtained in the step 2 into a deposition state part by adopting a selective laser melting technology; the preparation method provided by the invention solves the problems of overhigh cost and overlow performance of raw material powder for cheap medical and automobile parts for 3D printing.

Description

A preparation method of 3D printing low-cost high-strength titanium alloy parts

technical field

The invention belongs to the technical field of 3D printing, and in particular relates to a method for preparing 3D printing low-cost high-strength titanium alloy parts.

Background technique

The raw materials used in metal powder bed 3D printing technology require high purity, good fluidity, uniform particle size distribution, and high sphericity. At present, the plasma rotating electrode method, gas atomization method, and radio frequency plasma spheroidization method are mainly used to produce powders suitable for 3D printing, but the cost of the powders produced is expensive, as high as 4,000 yuan/kg. High-purity spherical pure titanium powder can be used to form expensive parts such as aerospace, but for high-performance inexpensive parts, the cost of using spherical powder is too high. The price of pure titanium powder prepared by hydrodehydrogenation is about 300-500 yuan/kg, but the powder is irregular in shape and has poor fluidity, so it cannot be directly used for metal powder bed 3D printing. Therefore, for high-performance and cheap parts, It is particularly important to develop a technology that meets the requirements of low-cost high-strength titanium alloy parts for 3D printing.

Contents of the invention

The purpose of the present invention is to provide a method for preparing 3D printing low-cost high-strength titanium alloy parts, which solves the problems of high cost and low performance of raw material powder for 3D printing cheap parts.

The technical solution adopted in the present invention is a method for preparing 3D printing low-cost high-strength titanium alloy parts, which is specifically implemented according to the following steps:

Step 1, first modifying the pure titanium powder;

Step 2, mixing the pure titanium powder modified in step 1 with spherical pure titanium powder to obtain a mixed powder;

Step 3, using the mixed powder obtained in step 2 to prepare deposited parts by laser selective melting technology;

The present invention is also characterized in that:

Wherein step 1 adopts high-speed ball milling process to modify the irregularly shaped pure titanium powder prepared by hydrodehydrogenation;

The high-speed ball milling process specifically includes: using a high-speed vibrating ball mill with a speed of 1200r/min to mill the pure titanium powder prepared by hydrogenation dehydrogenation, the ball-to-material ratio is 5:1, and adding 1.5-5% of the total mass during the ball milling process. Fatty acid;

Wherein, before mixing in step 2, the pure titanium powder modified in step 1 is sieved, and the particle size of the pure titanium powder after screening is not greater than 53 μm;

Wherein in the step 2, the pure titanium powder and the spherical pure titanium powder after the modification treatment in the step 1 are mixed in an omnidirectional planetary ball mill;

The mixing ratio of spherical pure titanium powder and modified pure titanium powder is 8:2 or 7:3;

Among them, the motion frequency of the omnidirectional planetary ball mill is 23Hz-30Hz, and the mixing time is 1h-1.5h;

Among them, after the omnidirectional planetary ball mill is mixed, put the mixed powder into the drying box for drying for 1h~1.5h, and the temperature of the drying box is 110℃~120℃;

The process parameters of the laser selective melting technology in step 3 are: the laser beam spot size is 45 μm ~ 50 μm, the laser power is 80w ~ 100w, the scanning speed is 500mm·s ^-1 ~ 650mm·s ^-1 , and the preheating temperature is 180°C ~200℃, the thickness of each layer of powder coating is 25μm;

Among them, before the laser selective melting technology works, the laser selective melting equipment is flushed with argon until the oxygen content of the air in the equipment is not more than 0.2% to 0.5%.

The beneficial effects of the present invention are:

The cost of raw materials required for traditional 3D-prepared titanium alloy parts is too high. The present invention proposes a preparation method for 3D printing low-cost high-strength titanium alloy parts, which reduces the cost from raw materials and changes the performance of parts from raw materials. , the titanium alloy parts are prepared by selective laser melting, and its hardness and strength are significantly higher than those of traditional preparation methods;

Description of drawings

Fig. 1 is the SEM figure before the modification of the pure titanium powder generated by hydrogenation dehydrogenation in a kind of preparation method of 3D printing low-cost high-strength titanium alloy parts of the present invention;

Fig. 2 is the SEM diagram of the modified pure titanium powder generated by hydrogenation dehydrogenation in a kind of preparation method of 3D printing low-cost high-strength titanium alloy parts of the present invention;

Fig. 3 is the SEM figure of spherical pure titanium powder in the preparation method of a kind of 3D printing low-cost high-strength titanium alloy part of the present invention;

Fig. 4 is the SEM diagram of the powder formed after mixing in a kind of preparation method of 3D printing low-cost high-strength titanium alloy parts of the present invention;

Fig. 5 is a forming part diagram of different powder ratios in a preparation method of a 3D printing low-cost high-strength titanium alloy part of the present invention;

Fig. 6 is a graph of compressive stress-strain curves of different powder ratios in a preparation method of 3D printing low-cost high-strength titanium alloy parts of the present invention;

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The invention provides a method for preparing 3D printing low-cost high-strength titanium alloy parts, which is specifically implemented according to the following steps:

Step 1, using a high-speed ball milling process to modify the irregularly shaped pure titanium powder (as shown in Figure 1) prepared by the hydrodehydrogenation method: the high-speed ball milling process specifically includes using a high-speed vibrating ball mill with a speed of 1200r/min to hydrogenate The pure titanium powder prepared by dehydrogenation is ball milled, the ball to material ratio is 5:1, the material of the tank and the ball are all stainless steel, and stearic acid accounting for 1.5-5% of the total mass is added during the ball milling process;

Among them, the process of high-speed ball milling can make the powder with irregular shape undergo shape modification and phase modification at the same time. The modification of shape is mainly reflected in the passivation of the corners of the irregular powder, partial crushing, and the decrease of particle size distribution. Appearance and morphology are nearly spherical; phase modification is to use the frictional heat generated in the ball milling process to generate high temperature, so that the excess stearic acid is decomposed and in situ with pure titanium powder to form non-stoichiometric titanium hydride and titanium carbide, in the powder A dispersed second phase is formed in

Among them, stearic acid is a low-cost 18-carbon chain saturated fatty acid, and its decomposition temperature is 63°C, so the excess stearic acid will be decomposed into carbon, hydrogen and other elements during the high-energy ball milling process, which is the phase modification of the powder provide elements;

Step 2, mixing the pure titanium powder modified in step 1 (as shown in Figure 2) with spherical pure titanium powder to obtain a mixed powder: first, sieve the pure titanium powder modified in step 1, and after screening The particle size of pure titanium powder is not more than 53 μm, and then the modified pure titanium powder and spherical pure titanium powder are mixed in an omnidirectional planetary ball mill, as shown in Figure 3, the D ₅₀ of spherical pure titanium powder is 100 μm, Different from the previous laser selective melting, the average particle size of the spherical powder is 15 μm to 53 μm, and the gap between the spherical powder with larger particle size increases. The mixing ratio of spherical pure titanium powder and modified titanium powder is 8:2 Or 7:3, the motion frequency of the omnidirectional planetary ball mill is 23Hz~30Hz, the mixing time is 1h~1.5h, after the mixing is completed, put the mixed powder into the drying oven for 1h~1.5h, and the temperature of the drying oven is 110 ℃～120℃, drying is mainly to remove the moisture absorbed by the mixed powder;

Step 3, use the mixed powder obtained in step 2 (as shown in Figure 4) to prepare deposited parts by laser selective melting technology: use the Concept Laser MLABcusing R-type laser metal additive manufacturing processing system produced by CONCEPT to process the mixed powder For printing, first use Solidworks software, Pro/Engineer software or Unigraphic software to establish a three-dimensional solid model, and then use Magics software to layer and slice the three-dimensional model to obtain layered information at different heights; then the processed The mixed powder is poured into the argon gas in the glove box of the laser additive manufacturing machine. After the oxygen content of the air in the printing room is reduced to below 0.2-0.5%, the mixed powder is loaded into the silo, and then the powder spreading roller is evenly spread. The thickness of each layer of powder is 25 μm. When each layer of powder is laid, the scanning system starts to print according to the obtained layered information under the control of the computer. After laser scanning, melting and forming processes, the scanning is repeated until the forming process. Until the three-dimensional parts are manufactured, the process parameters of the laser selective melting technology are: the laser beam spot size is 45 μm ~ 50 μm, the laser power is 80w ~ 100w, the scanning speed is 500mm·s ^-1 ~ 650mm·s ^-1 , the preheating temperature It is 180°C to 200°C.

The advantages of the preparation method of a 3D printing low-cost high-strength titanium alloy parts of the present invention are explained from the raw material preparation and forming process: the traditional 3D printing powder raw material costs are high, and the low-cost hydrogenated dehydrogenated titanium powder is mixed with stearic acid Afterwards, high-energy ball milling is carried out to improve the fluidity of the powder, and the decomposition of stearic acid is used to provide solid solution elements such as carbon and hydrogen to form a non-stoichiometric second phase of titanium hydride and titanium carbide in situ with the pure titanium powder. Ball milling will The modified powder is mixed with the spherical powder to improve the fluidity and bulk density of the printing material. This invention proposes to use laser selective melting technology to form high-performance titanium alloy parts, which uses the solid solution strengthening and dispersion strengthening of interstitial elements and titanium. Improve the strength and hardness of formed parts, significantly higher than traditional preparation methods;

Example 1

Step 1, put the hydrodehydrogenated pure titanium powder into a high-speed vibrating ball mill with a rotating speed of 1200r/min for ball milling with the ball milling time being 15min, 30min, 45min and 60min respectively, the addition of stearic acid is 5%, and the modified powder SEM The morphology is shown in Figure 1. It is found that the sharp edges and corners of the pure titanium powder are passivated when the ball milling time is 15min and 30min, and the morphology is nearly spherical. The pure titanium powder with a time of 30 minutes also has a slight agglomeration phenomenon, so the performance of the pure titanium powder with a ball milling time of 15 minutes is further characterized: the maximum particle size of the pure titanium powder after ball milling for 15 minutes is 45.2 μm, the minimum particle size is 12.1 μm, and the average particle size is 23.2μm, the angle of repose before ball milling is 38.7°, and the angle of repose of the modified pure titanium powder is 34.3°. Ball milling at high speed and short time can meet the requirements of powder fluidity and reduce the cost of raw materials, which further shows that pure titanium powder Powder modification uses high-speed conditions to input high energy, which can achieve pure titanium powder crushing and sharp corner passivation, and improve the fluidity of the modified powder, but the ball milling time should be strictly controlled. The longer the time, the higher the temperature in the ball milling tank , when the decomposition temperature of stearic acid is above 63°C, the qualitative control of the phase of pure titanium powder can be realized by controlling the amount of stearic acid added;

Step 2: Mix the spherical pure titanium powder with a particle size distribution of 325 mesh to 100 mesh (45 μm to 150 μm) and the modified pure titanium powder at a ratio of 8:2 and 7:3, and in the omnidirectional planetary ball mill, Run at a frequency of 23Hz for 1h to mix evenly, and finally dry in a drying oven at 120°C for 1h. The SEM morphology of the mixed powder is shown in Figure 2;

Step 3, adjust the laser energy density by changing the forming process parameters, use Pro/Engineer layering software to slice and discretize the 3D solid model in step 1, use Magics software to layer, scan the path in a zigzag grid format, and build The connection rate is 50%, and the cross-sectional data of each layer are obtained, and then the cross-sectional data of each layer are imported into the laser selective melting forming equipment as the laser scanning path, and then the processing parameters are set on the laser selective melting equipment, and the processing parameters include the metal powder layer. Thickness, beam spot diameter, lap rate, laser power, scanning speed; metal powder layer thickness is 25 μm; beam spot diameter is 45 μm; the laser power is 100w; laser scanning speed is 550mm/s, and the preheating temperature is 200°C ;

Pour the processed mixed powder into argon in the glove box of the laser additive manufacturing machine. After the oxygen content in the air in the printing room is reduced to below 0.5%, spread the mixed powder on the bottom plate, and then use a larger The laser spot and high scanning speed are used to preheat the mixed powder on the bottom plate; the laser is used to perform selective melting and scanning on the preheated mixed powder according to the laser scanning path to form a single-layer solid sheet; the lifting platform descends One layer, repeating the process of flat laying the mixed powder and preheating, and performing selective melting and scanning on the preheated mixed powder to form a single-layer solid sheet, until the preparation of each layer of solids is completed, and the laser Melt the molded parts in selected areas; finally use compressed air to remove excess powder in the molded parts, clean them and dry them to obtain compact parts, as shown in Figure 5, it can be seen that the appearance of the molded parts is silvery white with metallic luster, without Overburning or poor fusion, and the forming accuracy is 0.3-0.5mm;

It can be seen through testing that the highest density of the titanium alloy prepared in this embodiment is 98.32%, and the compressive stress-strain curves of formed parts with different raw material ratios are shown in Figure 6, and it can be seen that the powder mixing ratio is 8:2 (line a ) is 1580MPa, the compressive strength is 1040MPa when the powder mixing ratio is 7:3 (line b), and the strength and plasticity of the powder mixing ratio of 8:2 are better than that of 7:3 The reason for the plasticity of the specimen, the strength and plasticity of the 8:2 ratio forming part is the effect obtained by the dispersion distribution of the second phase in the titanium matrix.

Example 2

Step 1, using a high-speed ball milling process of 1200r/min to modify the irregularly shaped pure titanium powder prepared by the hydrodehydrogenation method, the particle size of the pure titanium powder obtained after ball milling is not greater than 53 μm, and the amount of stearic acid added 1.5%;

Step 2, mix the pure titanium powder and spherical pure titanium powder modified in step 1 in the omnidirectional planetary ball mill according to the ratio of 2:8, the motion frequency of the omnidirectional planetary ball mill is 30Hz, and the mixing time is 1.5h , put the mixed powder into the drying oven for drying for 1.5h after the completion, and the temperature of the drying oven is 110°C;

Step 3, use the mixed powder obtained in step 2 to prepare deposited parts by laser selective melting technology: use the Concept Laser MLAB cusing R laser metal additive manufacturing processing system produced by CONCEPT to print the mixed powder, first use Solidworks The software builds a three-dimensional solid model, and then uses the Magics software to slice the three-dimensional model layered to obtain layered information at different heights; then the processed mixed powder is punched in the glove box of the laser additive manufacturing machine. Inject argon gas, and after the oxygen content in the air in the printing room is reduced to below 0.2%, put the mixed powder into the hopper, and then spread the powder evenly with the powder spreading roller. The thickness of each layer of powder is 25 μm. When each layer of powder is laid After that, the scanning system starts to print according to the obtained layered information under the control of the computer. After laser scanning, melting and forming process, the scanning is repeated until the forming process is completed until the three-dimensional parts are manufactured. The process parameters of the laser selective melting technology are: The laser beam spot size is 50 μm, the laser power is 80w, the scanning speed is 650mm·s ^-1 , and the preheating temperature is 180°C.

Example 3

Step 1, using a high-speed ball milling process of 1200r/min to modify the irregularly shaped pure titanium powder prepared by the hydrodehydrogenation method, the particle size of the pure titanium powder obtained after ball milling is not greater than 53 μm, and the amount of stearic acid added 3%;

Step 2, mix the pure titanium powder and spherical pure titanium powder modified in step 1 in the omnidirectional planetary ball mill according to the ratio of 2:8, the motion frequency of the omnidirectional planetary ball mill is 30Hz, and the mixing time is 1.2h , put the mixed powder into the drying oven for drying for 1.2 hours after the completion, and the temperature of the drying oven is 115°C;

Step 3, use the mixed powder obtained in step 2 to prepare deposited parts by laser selective melting technology: use the Concept Laser MLAB cusing R laser metal additive manufacturing processing system produced by CONCEPT to print the mixed powder, first use Unigraphic The software software builds a three-dimensional solid model, and then uses the Magics software to slice the three-dimensional model layered to obtain layered information at different heights; then put the processed mixed powder in the glove box of the laser additive manufacturing machine Rush into the argon gas, after the oxygen content in the air in the printing room is reduced to below 0.3%, put the mixed powder into the silo, and then spread the powder evenly with the powder spreading roller, the thickness of each layer of powder is 25 μm, when each layer of powder is spread After finishing, the scanning system starts to print according to the obtained layered information under the control of the computer. After laser scanning, melting and forming process, the scanning is repeated until the forming process is completed until the three-dimensional parts are manufactured. The process parameters of the laser selective melting technology are : The laser beam spot size is 48 μm, the laser power is 90w, the scanning speed is 600mm·s ^-1 , and the preheating temperature is 190°C.

Claims (10)

1. A preparation method of a 3D printing low-cost high-strength titanium alloy part is characterized by comprising the following steps:

step 1, firstly, modifying pure titanium powder;

step 2, mixing the pure titanium powder modified in the step 1 with spherical pure titanium powder to obtain mixed powder;

and 3, preparing the mixed powder obtained in the step 2 into a deposition state part by adopting a selective laser melting technology.

2. The method for preparing the 3D printed low-cost high-strength titanium alloy part as claimed in claim 1, wherein the pure titanium powder with irregular shape prepared by the hydrogenation and dehydrogenation method is modified by a high-speed ball milling process in step 1.

3. The preparation method of the 3D printed low-cost high-strength titanium alloy part as claimed in claim 2, wherein the high-speed ball milling process specifically comprises: and (2) carrying out ball milling on the pure titanium powder prepared by hydrogenation and dehydrogenation by using a high-speed vibration ball mill with the rotating speed of 1200r/min, wherein the ball-to-material ratio is 5:1, and stearic acid accounting for 1.5-5% of the total mass is added in the ball milling process.

4. The method for preparing the 3D printed low-cost high-strength titanium alloy part according to claim 1, wherein the pure titanium powder modified in the step 1 is sieved before mixing in the step 2, and the particle size of the sieved pure titanium powder is not more than 53 μm.

5. The method for preparing the 3D-printed low-cost high-strength titanium alloy part according to claim 1, wherein the pure titanium powder modified in the step 1 and the spherical pure titanium powder are mixed in an all-directional planetary ball mill in the step 2.

6. The preparation method of the 3D printed low-cost high-strength titanium alloy part as claimed in claim 5, wherein the mixing ratio of the spherical pure titanium powder to the modified pure titanium powder is 8: 2.

7. The preparation method of 3D printing low-cost high-strength titanium alloy parts according to claim 5, wherein the movement frequency of the all-directional planetary ball mill is 23Hz to 30Hz, and the mixing time is 1h to 1.5 h.

8. The preparation method of the 3D printed low-cost high-strength titanium alloy part as claimed in claim 5, wherein the mixed powder is placed into a drying oven for drying for 1-1.5 hours after the all-directional planetary ball mill is mixed, and the temperature of the drying oven is 110-120 ℃.

9. The method for preparing the 3D printed low-cost high-strength titanium alloy part according to claim 1, wherein the process parameters of the selective laser melting technology in the step 3 are as follows: the size of the laser beam spot is 45-50 μm, the laser power is 80-100 w, and the scanning speed is 500mm s^-1～650mm·s^-1The preheating temperature is 180-200 ℃, and the powder spreading thickness of each layer is 25 mu m.

10. The method for preparing a 3D printed low-cost high-strength titanium alloy part as claimed in claim 9, wherein before the selective laser melting technique is used, argon is injected into the selective laser melting equipment until the oxygen content in the equipment is not more than 0.2% -0.5%.