SLM preparation process method of TC4 powder with wide particle size distribution

Abstract

The invention provides an SLM preparation process method for TC4 powder with wide particle size distribution. The SLM preparation process method comprises the following steps that firstly, a first layer of titanium alloy powder is laid on a forming substrate at the powder laying speed of 100 mm / s-200 mm / s; secondly, according to the particle size and particle size distribution characteristics of the current layer of titanium alloy powder, corresponding laser heating melting parameters are selected for laser heating melting, and cooling solidification is conducted; thirdly, the thickness of the formed substrate is reduced by 90-120 micrometers, and a next layer of titanium alloy powder is laid on the basis of the current layer of titanium alloy powder; fourthly, the first step to the third step are repeated, and layer-by-layer stacking is conducted till the titanium alloy part is formed; according to the method, the problems of high porosity, poor forming quality and low performance of wide-size-distribution TC4 powder in SLM forming can be effectively solved, meanwhile, the advantages of low cost and short period of a wide-size-distribution scheme are fully played, and high-quality forming of high-cost-performance TC4 alloy components is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the field of titanium alloy preparation, in particular to an SLM preparation process method of TC4 powder with wide particle size distribution. BACKGROUND

[0002] In the high-end manufacturing field of aerospace, medical devices and the like, TC4 titanium alloy is widely used due to excellent specific strength, corrosion resistance and biocompatibility, and laser selective melting (SLM) technology is a core means for forming complex components of the TC4 titanium alloy. At present, the TC4 powder used for SLM forming is mostly powder with narrow particle size distribution. Although such powder has good flowability and uniformity of powder laying, the powder yield is low, the cost of raw materials is high, and generally small layer thickness is used for printing, so that the production cycle is long, thereby restricting the large-scale application of the SLM component of the TC4 alloy.

[0003] The TC4 powder with wide particle size distribution has a significant cost advantage because it does not need to be finely sieved, but pores and other defects are prone to occur in the forming process. The core reason is that the particle size span of the wide particle size powder is large, the gradation between particles is unreasonable, the temperature field and flow field of the molten pool are unstable under the action of the laser, and pores and un-melted defects are easily formed in the solidification process, so that the density and mechanical properties of the formed part are difficult to guarantee. Therefore, the existing SLM process cannot meet the forming requirements of the TC4 powder with wide particle size distribution. SUMMARY

[0004] The purpose of the present application is to provide an SLM preparation process method of TC4 powder with wide particle size distribution, which can effectively overcome the problems of high porosity, poor forming quality and low performance of the TC4 powder with wide particle size distribution in SLM forming, fully exert the advantages of low cost and short cycle of the wide particle size distribution scheme, and realize high-quality forming of high-performance TC4 alloy components.

[0005] To solve the above technical problems, the present application provides an SLM preparation process method of TC4 powder with wide particle size distribution, comprising the following steps: Step one, laying the first layer of titanium alloy powder on the forming substrate at a powder laying speed of 100-200 mm / s; Step two, selecting corresponding laser heating and melting parameters according to the particle size and particle size distribution characteristics of the current layer of titanium alloy powder, and performing laser heating and melting, and cooling and solidification; Step three, lowering the forming substrate by 90-120 microns in layer thickness, and laying the next layer of titanium alloy powder on the basis of the current layer of titanium alloy powder; Step four, repeating steps one to three, layer by layer until the titanium alloy part is formed.

[0006] Further, the particle size of the titanium alloy powder is 15-110 microns.

[0007] Further, the titanium alloy powder particle size distribution is 10 μm≤D10≤30 μm, 60 μm≤D50≤80 μm, and 100 μm≤D90≤120 μm.

[0008] Further, the laser heating and melting parameters are laser power 180 W-450 W, laser scanning speed 600 mm / s-1500 mm / s, spot diameter 0.07 mm-0.1 mm, and scanning interval 0.07 mm-0.2 mm.

[0009] Further, in step two, when laser heating and melting is performed, each layer is rotated by 67° for scanning and printing.

[0010] The beneficial effects of the present application are: 1. By the particle size distribution mode of 10 μm≤D10≤30 μm, 60 μm≤D50≤80 μm, and 100 μm≤D90≤120 μm, and the particle size distribution interval of 15 μm-110 μm, compared with the SLM process of the conventional particle size TC4 powder of 15 μm-53 μm, the material cost is reduced, the forming efficiency is improved, and it is suitable for low-cost and efficient additive manufacturing of large TC4 structural parts.

[0011] 2. By the laser heating and melting parameter setting of laser power 180 W-450 W, laser scanning speed 600 mm / s-1500 mm / s, spot diameter 0.07 mm-0.1 mm, and scanning interval 0.07 mm-0.2 mm, the physical properties of the wide particle size distribution TC4 powder are adapted, the uniformity and forming density of the molten pool are ensured, and the generation of pores is effectively inhibited. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a schematic diagram of the internal organizational structure displayed according to the particle size distribution interval of the present application.

[0013] Figure 2 is a schematic diagram of the mechanical property detection of the control group of multiple groups of tests.

[0014] Figure 3 is a schematic diagram of the printing path rotation angle of the titanium alloy powder. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0016] Those skilled in the art should understand that in the disclosure of the present application, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the above terms cannot be understood as a limitation of the present application.

[0017] It can be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of one element can be one, and in another embodiment, the number of the element can be multiple, and the term "one" cannot be understood as a limitation on the number.

[0018] As Figures 1-3 The present application provides an SLM preparation process method of wide particle size distribution TC4 powder, comprising the following steps: Step one, laying the first layer of titanium alloy powder on the forming substrate at a powder laying speed of 100-200 mm / s; Step two, according to the particle size of 15-110 μm and the particle size distribution of 10 μm≤D10≤30 μm, 60 μm≤D50≤80 μm, 100 μm≤D90≤120 μm of the current layer of titanium alloy powder, selecting the corresponding laser heating and melting parameters, i.e. laser power 180-450 W, laser scanning speed 600-1500 mm / s, spot diameter 0.07-0.1 mm, scanning pitch 0.07-0.2 mm, and performing laser heating and melting, and during the laser heating and melting, rotating 67° for scanning printing and cooling and solidification of each layer; Wherein, the laser scanning adopts energy density laser adapted to the wide particle size powder to ensure the homogenization and densification of the molten pool; the rotation printing angle of each layer of titanium alloy powder refers to the spatial projection included angle between the current layer printing path and the previous layer printing path, and the first layer can set the printing path along the placing direction of the forming substrate, as shown in Figure 3 .

[0019] Specifically, according to the particle grading characteristics of the wide particle size distribution TC4 powder, the laser power is set to the interval of 180-450 W, which can ensure the full melting of large particle TC4 powder and avoid spheroidization defects; at the same time, through the regulation of the above laser heating and melting parameters, the precise control of the molten pool dynamics and solidification behavior can be realized, and the forming adaptability of the wide particle size powder can be improved, as shown in Figure 2 According to the regulation of the above laser heating and melting parameters, three horizontal and three vertical samples are taken for mechanical property analysis to ensure the reliability of the test results.

[0020] Step three, the forming substrate is lowered by 90-120 mu m layer thickness, and the next layer of titanium alloy powder is laid on the basis of the current layer of titanium alloy powder; Specifically, the forming substrate is lowered by 90-120 mu m layer thickness, that is, the single layer titanium alloy layer thickness is set to 90-120 mu m, and the powder laying speed of 100-200 mm / s is matched, so as to ensure the powder laying effect of the titanium alloy powder, and the higher layer thickness also improves the printing efficiency.

[0021] Step four, repeat steps one to three, and stack layer by layer until the titanium alloy part is formed.

[0022] The present application is not limited to the above best embodiment, anyone can derive other various forms of products under the inspiration of the present application, but regardless of any changes in shape or structure, any technical solution with the same or similar to the present application falls within the scope of the present application.

Claims

1. A process method for SLM preparation of a wide particle size distribution TC4 powder, characterized in that, The method comprises the following steps: Step 1: laying the first layer of titanium alloy powder on the forming substrate at a powder laying speed of 100-200 mm / s; Step 2: selecting corresponding laser heating and melting parameters according to the particle size and particle size distribution characteristics of the current layer of titanium alloy powder to perform laser heating and melting, and then cooling and solidifying; Step 3: lowering the forming substrate by 90-120 μm in layer thickness, and laying the next layer of titanium alloy powder on the basis of the current layer of titanium alloy powder; Step 4: repeating steps 1-3 until the titanium alloy part is formed.

2. The SLM process method for preparing a wide particle size distribution TC4 powder according to claim 1, characterized in that: The titanium alloy powder has a particle size of 15-110 μm.

3. The SLM process method for preparing a wide particle size distribution TC4 powder according to claim 1, characterized in that: The titanium alloy powder has a particle size distribution of 10 μm≤D10≤30 μm, 60 μm≤D50≤80 μm, and 100 μm≤D90≤120 μm. 4.The SLM process method for preparing a wide particle size distribution TC4 powder according to claim 1, characterized in that: The laser heating and melting parameters are as follows: laser power 180-450 W, laser scanning speed 600-1500 mm / s, spot diameter 0.07-0.1 mm, and scanning pitch 0.07-0.2 mm.

5. The SLM process method for preparing the wide particle size distribution TC4 powder according to claim 1, characterized in that: In step 2, the laser heating and melting is performed by rotating 67° for scanning and printing each layer.

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