A method of needleless warm mixing of additive components

Abstract

The present application relates to a kind of needleless temperature stirring additive component method.The present application is deposited on substrate according to preset path to complete a layer, then uses continuous laser to heat deposition layer to dynamic recrystallization temperature, and uses needleless stirring head to carry out stir-frying processing to deposition layer in loading state, so that component generates plastic deformation at dynamic recrystallization temperature, realizes grain refinement, makes component internal form cyclic microstructure of equiaxial crystal or columnar crystal-equiaxial crystal, significantly improves the mechanical properties of component, reduces the tensile stress in additive process, produces highly nanocrystalline surface, obtains relatively deep surface gradient nanolayer.

Description

TECHNICAL FIELD

[0001] The present application relates to a needleless temperature stirring additive component method, in particular to a needleless temperature stirring additive method for laser additive manufacturing interlayer columnar crystal and thermal stress regulation, which can refine the columnar crystal of the additive at the dynamic recrystallization temperature while improving the surface quality. BACKGROUND

[0002] Laser directed energy deposition (DED) technology is widely used in emerging rapid prototyping technology for large components in aerospace and other fields. After computer slicing, the super high energy source melts the metal powder, and realizes the layer-by-layer manufacturing of large components under the computer path planning. Its manufacturing process is not limited by the complex structure of metal parts, and does not require any tooling, which can realize the rapid manufacturing of metal parts and reduce costs.

[0003] Laser shock peening (LSP) technology is a new type of surface strengthening technology derived from friction stir welding, which mainly realizes the physical breaking of the surface layer grains of the component by stirring the component with a stirring head, so as to achieve ultra-fine grains. Compared with conventional surface strengthening methods, friction stir processing has the characteristics of large stirring depth and large grain refinement degree. At the same time, the shoulder pressure of friction stir welding can cause plastic deformation of the surface layer of the component, which can induce grain refinement and significantly improve the surface quality of the component and produce residual compressive stress.

[0004] In recent years, although the laser directed deposition process has made breakthrough progress, but since the laser directed energy deposition is a near rapid solidification non-equilibrium process, it is easy to produce thermal stress, and columnar crystals are produced under the driving of the temperature gradient of the molten pool, which seriously affects the mechanical properties of the component. Therefore, using surface strengthening treatment can significantly improve the columnar crystal caused by additive and regulate the thermal stress caused by laser thermal effect. However, due to the defects of conventional surface strengthening methods such as shallow strengthening and refining layer and insufficient processing flexibility, the performance of laser directed energy deposition components cannot be further improved. SUMMARY

[0005] In view of the above problems, the present application provides a needleless temperature stirring additive component method, which can realize the friction stir processing of the formed part during the laser directed energy deposition process, effectively solve the problem of columnar crystal and thermal stress caused by temperature gradient in deposition manufacturing, and further heat the deposited component by using continuous laser before stirring processing, so that the component reaches the dynamic recrystallization temperature, which is beneficial to promote grain refinement and improve the strengthening effect, and effectively improve the mechanical properties of the additive component.

[0006] The present application provides a needle-free temperature stirring method for additive components, characterized in that: a layer of deposition is completed on a substrate according to a preset path, then a continuous laser is used to heat the deposition layer to a dynamic recrystallization temperature, and a needle-free stirring head is used to perform a stirring friction treatment on the deposition layer in a loaded state, so that the component produces plastic deformation at the dynamic recrystallization temperature, grain refinement is realized, a cyclic microstructure structure of equiaxed crystals or columnar crystals-equiaxed crystals is formed in the component, the mechanical properties of the component are significantly improved, the tensile stress in the additive process is reduced, a highly nanometerized surface is produced, and a deep surface gradient nanometer layer is obtained.

[0007] The specific steps are as follows:

[0008] (1) A layer of laser deposition is completed on the substrate by using a laser deposition process, and the laser deposition process parameters are as follows: the laser power is 1000-2000W, the spot diameter is 2-4mm, the scanning speed is 600mm / min, and the additive layer thickness is 0.5-1.5mm.

[0009] (2) After the deposition layer is cooled to room temperature, a continuous laser is used to perform laser heating treatment on the deposition layer, and the continuous laser is reciprocally scanned and heated at a laser power of 500-1000W, a spot diameter of 2-4mm, and a scanning speed of 1000-1200mm / min, until the temperature monitoring system displays that the temperature of the deposition layer is heated to the dynamic recrystallization temperature T DRX , and then the scanning is stopped and kept in the dynamic recrystallization temperature range. Wherein, T DRX =aT m (K), wherein T DRX is the dynamic recrystallization temperature of the metal, a is usually 0.35-0.4, and T m is the melting point of the metal.

[0010] (3) Then, a needle-free stirring head is used to perform a stirring friction treatment on the surface of the additive, i.e., the deposition layer, in a loaded state, and the stirring head shoulder pressure is 200-400N and the stirring speed is 200r / min.

[0011] (4) After the stirring friction treatment is completed, the next layer of deposition is deposited by using the laser directional energy deposition process, the continuous laser is used to heat the next layer of deposition to the dynamic recrystallization temperature range, and then the next layer of deposition is subjected to the stirring friction treatment in a loaded state, and the process is repeated to complete the stirring friction additive treatment of the entire component.

[0012] The present application has the following advantages:

[0013] (1) The stirring friction strengthening process is introduced in the process of laser directional energy deposition, which significantly controls the columnar crystals introduced by the laser directional energy deposition.

[0014] (2) Before the friction stir strengthening, the deposited component is heated to a dynamic recrystallization temperature by a continuous laser, which is beneficial to improve the strengthening efficiency and promote grain refinement. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings used in the examples or the prior art are briefly introduced as follows.

[0016] Figure 1 A flow chart of a method for needleless temperature stirring additive component

[0017] Figure 2 Microstructure of the component strengthened in Example 1

[0018] Figure 3 Microstructure of the component added in Example 2 DETAILED DESCRIPTION

[0019] The specific embodiments of the present application will be described in detail below with reference to the drawings and examples, but the present application should not be limited to the examples.

[0020] In Example 1, the laser directional energy deposition metal powder is Ti6Al4V titanium alloy powder, the particle size of the powder is 53-150 μm, and the melting point of the Ti6Al4V titanium alloy is 1800℃.

[0021] The specific steps are as follows:

[0022] (1) A layer of laser deposition is completed on the Ti6Al4V substrate by using the laser directional deposition process, and the laser deposition process parameters are as follows: the laser power is 1500W, the spot diameter is 3mm, the scanning speed is 600mm / min, and the additive layer thickness is 0.7mm.

[0023] (2) After the deposition layer is cooled to room temperature, the deposition layer N is subjected to laser heating treatment by using a continuous laser, the continuous laser is circularly reciprocating scanned for 3 times at a laser power of 500W, a spot diameter of 3mm and a scanning speed of 1500mm / min, and the temperature monitoring system displays that the heating is stopped after the deposition layer is heated to a dynamic recrystallization temperature of 720℃ and kept in the dynamic recrystallization temperature range.

[0024] (3) Then, the surface deposition after the addition is subjected to friction stir processing by using a needleless stirring head, the shoulder of the stirring head is pressed at a pressure of 300N, and the stirring speed is 200r / min.

[0025] (4) After the friction stir processing is completed, the next layer is deposited using the laser directed energy deposition process and heated using the continuous laser before the next layer is friction stir processed, repeating steps (1)-(3) to complete the friction stir additive processing of the entire component.

[0026] In Example 2, the metal powder for the laser directed energy deposition is Ti6AI4V titanium alloy powder with a particle size of 53-150 pm.

[0027] Unlike Example 1, Example 2 is a direct continuous laser deposition manufacturing of Ti6AI4V titanium alloy powder with the same process parameters as Example 1, a laser power of 1500 W, a spot diameter of 3 mm, a scanning speed of 600 mm / min, and an additive layer thickness of 0.7 mm per layer, for a total of two layers.

[0028] As shown in Table 1, the titanium alloy microstructure of Example 1 has a reduced columnar grain and significantly refined grains compared to Example 2, while the tensile strength of the additive component of Example 1 is significantly improved.

[0029] Table 1

[0030]

Claims

1. A method of needleless warm mixing of an additive member, characterized by, The method comprises the following steps: a layer of deposition is completed on a substrate along a preset path, then the deposition layer is heated to a dynamic recrystallization temperature by continuous laser, and the deposition layer is subjected to a stirring friction treatment in a loaded state by using a needleless stirring head, so that the component is plastically deformed at the dynamic recrystallization temperature, the grain refinement is realized, the isometric crystal or the cyclic microstructure of columnar crystal-isometric crystal is formed in the component, the mechanical properties of the component are improved, the tensile stress in the additive process is reduced, the highly nanometer surface is generated, the deep surface gradient nanometer layer is obtained, and the specific steps are as follows: (1) a layer of laser deposition is completed on the substrate by using a laser deposition process; (2) after the deposited layer is cooled to room temperature, the deposited layer is subjected to laser heating treatment using continuous laser until the temperature monitoring system shows heating to the dynamic recrystallization temperature T DRX of the deposited layer; and (3) after the deposited layer is cooled to room temperature, the deposited layer is subjected to laser heating treatment using continuous laser until the temperature monitoring system shows heating to the dynamic recrystallization temperature T DRX of the deposited layer; and (4) after the deposited layer is cooled to room temperature, the deposited layer is subjected to laser heating treatment using continuous laser until the temperature monitoring system shows heating to the (3) then the surface after the additive, i.e. the deposition layer, is subjected to a stirring friction treatment in a loaded state by using a needleless stirring head; (4) after the stirring friction treatment is completed, the next layer of deposition is deposited by using the laser directional energy deposition process, the temperature of the next layer of deposition is heated to and kept in the dynamic recrystallization temperature range by using the continuous laser, then the next layer of deposition is subjected to the stirring friction treatment in the loaded state, and the stirring friction additive treatment of the whole component is completed by repeating the above steps.

2. A method of needleless warm mixing of additive components as claimed in claim 1 wherein, The laser deposition process parameters are as follows: the laser power is 1000-2000 W, the spot diameter is 2-4 mm, the scanning speed is 600 mm / min, and the additive layer thickness is 0.5-1.5 mm.

3. A method of needleless warm mixing of additive components as claimed in claim 1 wherein, The continuous laser is repeatedly scanned and heated at the laser power of 500-1000 W, the spot diameter of 2-4 mm, and the scanning speed of 1000-1200 mm / min.

4. A method of needleless warm mixing of additive components as claimed in claim 1 wherein, TDRX=aTm (K), wherein TDRX is the dynamic recrystallization temperature of the metal, a is usually 0.35-0.4, and Tm is the melting point of the metal.

5. A method of needleless warm mixing of additive components as claimed in claim 1 wherein, The process parameters of the stirring friction treatment are as follows: the shoulder pressure of the stirring head is 200-400 N, and the stirring speed is 200 r / min.

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