CN-122007438-A - SLM preparation method and part of weak anisotropy strengthening and toughening titanium-aluminum alloy micro-laminated structure

CN122007438ACN 122007438 ACN122007438 ACN 122007438ACN-122007438-A

Abstract

The invention discloses a preparation method of an SLM (selective laser melting) with a weak anisotropy strengthening and toughening titanium-aluminum alloy micro-laminated structure and a product. The method is characterized by comprising the following steps of S1, forming a flexible layer on a substrate by an SLM method, forming a space interconnection lattice structure on the flexible layer, forming a brittle layer on the flexible layer, repeating lamination steps of the flexible layer, the space interconnection lattice structure and the brittle layer to obtain a laminated structure part, S2, carrying out two-stage three-dimensional in-situ gradient heat treatment on the substrate and surrounding wall plates of an inner cavity of the SLM device according to the stress accumulation condition in the printing process in the lamination process, and then cooling to the preheating temperature of the substrate. According to the invention, through the design of the three-dimensional interconnected lattice structure of the toughness space penetrating through the TiAl4722 matrix, the structure has the mechanical locking and metallurgical bonding strengthening effects, the interlayer fracture toughness is increased, the anisotropy is weakened, and the fracture toughness of the laminated structure is improved by more than 50%.

Inventors

SUN JING
Yin yuhuan
JIN YANG
WANG JIE
LI SONGBIN
JIANG XIAO
WANG CHAOYUE
CHEN HAI
ZHANG YING
YIN YING

Assignees

上海航天设备制造总厂有限公司

Dates

Publication Date: 20260512
Application Date: 20260205

Claims (8)

1. The preparation method of the SLM with the weak anisotropy strengthening titanium-aluminum alloy micro-lamination structure is characterized by comprising the following steps of: S1, forming a ductile layer on a substrate by adopting an SLM method, forming a space interconnection lattice structure on the ductile layer, forming a brittle layer on the ductile layer, repeating lamination steps of the ductile layer, the space interconnection lattice structure and the brittle layer to obtain a part with a laminated structure, S2, in the lamination process, according to the stress accumulation condition in the printing process, printing a section of height, performing two-stage three-dimensional in-situ gradient heat treatment on a substrate of the SLM device and surrounding wall plates of an inner cavity, and then cooling to the preheating temperature of the substrate until the preparation of the workpiece is completed, and finally obtaining the structural-toughened titanium-aluminum micro-lamination structure composite structural workpiece; the three-dimensional in-situ gradient heat treatment is that the substrate, the left cavity wall and the rear cavity wall are respectively provided with a heat source in the XYZ direction of the forming cavity; the temperature of the two-stage three-dimensional in-situ gradient heat treatment is controlled to be 400-550 ℃; the frequency of the two-stage three-dimensional in-situ gradient heat treatment is that in-situ heat treatment is carried out once every 30-60 mm of height is printed; The two-stage three-dimensional in-situ gradient heat treatment time is increased in a gradient manner according to the total thickness of the current accumulated formed part and the formed breadth area; The time of the two-stage three-dimensional in-situ gradient heat treatment is T min, the numerical relation between the total printing thickness in the current stage and the average forming breadth area in the current stage is that the heat preservation time of the cavity wall heat treatment is T q , and the heat preservation time T j of the substrate heat treatment is (T q +3-5) min: The heat preservation treatment time of the cavity wall meets the formula: Wherein the specific heat capacity of the laminated structure is C d J/(g DEG C), the density of the laminated structure is ρ d g/cm 3 , the total printing thickness of the current stage is t d mm, the thermal conductivity of the laminated structure is k d W/(mm DEG C), the average forming area of the current stage is A mm 2 , and C d 、ρ d 、k d is measured according to the proportion of laminated materials, and C is a constant of 48.9 s/mm.
2. The method for manufacturing an SLM with a weak anisotropic and tough titanium-aluminum alloy micro-laminated structure according to claim 1, wherein in step S1, the micro-laminated structure means that the minimum thickness of a single layer is controlled to be less than 0.5 mm.
3. The method for manufacturing the SLM with the weak anisotropic and tough titanium-aluminum alloy micro-laminated structure according to claim 1, wherein in the step S1, the brittle layer is made of TiAl4722; And/or the material of the toughness layer is TC4; And/or the material of the space interconnection lattice structure is TC4.
4. The method for manufacturing the SLM with the weak anisotropic and tough titanium-aluminum alloy micro-laminated structure according to claim 1, wherein in the manufacturing process of the laminated structure part in the step S1, a substrate is preheated, and the preheating temperature is 200-250 ℃.
5. The preparation method of the SLM with the weak anisotropy and toughness titanium-aluminum alloy micro-laminated structure, which is characterized in that in the step S1, the preparation parameters of a toughness layer are that the laser power is 350-400 w, the scanning speed is 950-105mm/S, and the scanning interval is 0.10-0.20 mm; And/or the preparation parameters of the brittle layer, wherein the laser power is 100-1000 w, the laser power is related to the forming thickness of the brittle layer, the scanning speed is 200-400 mm/s, and the scanning interval is 0.15-0.25 m; And/or the preparation parameters of the space interconnection lattice structure are that the laser power is 350-400 w, the scanning speed is 950-105mm/s, and the scanning interval is 0.10-0.20 mm; and/or the thickness of the powder spreading of the ductile layer, the brittle layer and the space interconnection lattice structure is 0.03-0.60 mm.
6. The method for manufacturing the SLM with the weak anisotropic and tough titanium-aluminum alloy micro-laminated structure according to claim 1, wherein in the step S1, the space interconnection lattice structure refers to a space continuous lattice structure formed by topological optimization; and/or the height of the space interconnection lattice structure is equal to the height of the brittle layer where the space interconnection lattice structure is located.
7. The method for preparing the SLM with the weak anisotropy and toughness titanium-aluminum alloy micro-laminated structure, which is characterized in that in the two-stage three-dimensional in-situ gradient heat treatment, a cavity wall enters a cooling stage before a substrate, the substrate is cooled after the cavity wall is cooled for 3-5 min, and the cooling rate is 5-10 ℃ per min.
8. A weak anisotropic and tough titanium-aluminum alloy micro-laminated structure product, which is characterized by being prepared by the SLM preparation method of the weak anisotropic and tough titanium-aluminum alloy micro-laminated structure according to any one of claims 1-7.

Description

SLM preparation method and part of weak anisotropy strengthening and toughening titanium-aluminum alloy micro-laminated structure Technical Field The invention relates to the technical field of metal composite structure laser selective melting additive manufacturing, in particular to an SLM preparation method and a workpiece of a weak anisotropic tough titanium aluminum alloy micro-laminated structure. Background Recoverable carrier rockets with the characteristic of point-to-point rapid transportation in a deep space exploration mode and a sub-orbit mode become a trend of sustainable development of future spaceflight in China, and stricter requirements are put forward on engine performance. At present, the common high-temperature resistant material of the engine is nickel-based superalloy, the density is high, the weight gain of the engine is obvious, and the light requirement in the aerospace field is difficult to meet. The TiAl system alloy represented by TiAl4722 (TiAl 4722) has excellent high-temperature performance and corrosion resistance, becomes one of the most potential materials capable of replacing the nickel-based superalloy, particularly has the density of about 1/3 of that of the nickel-based superalloy, and further enhances the application potential in the field of aerospace engines. However, the inherent brittleness of the TiAl series alloy makes it difficult to form and the processing cost is extremely high. The cooling rate of the laser additive manufacturing process can reach 10 -7 K/s due to the characteristics of rapid cooling and rapid heating, and the extremely high cooling rate brings extremely high residual stress and anisotropy caused by directional heat conduction while bringing fine grains. The above factors determine that it is almost impossible to form a crack-free pure TiAl4722 mass using laser selective melting (SELECTIVE LASER MELTING, SLM). The idea of the ductile-brittle composite laminated structure provides possibility for the additive forming of the ductile TiAl4722, but the interlayer bonding force is extremely poor due to the difference of thermal physical properties among ductile-brittle dissimilar materials, and the interlayer cracking phenomenon is extremely easy to generate due to the problem of inconsistent thermal expansion coefficients. Therefore, improvement is still needed on the basis of the micro-lamination design, and the interlayer bonding performance is increased by adopting a mode of prefabricating a convex structure between tough and brittle layers in the patent application CN202511013735.2, but the interlayer strength improving effect of the material is limited because the convex structure cannot realize the strengthening effect in the height direction. In addition, in the patent application CN202511013735.2, the substrate is subjected to in-situ heat treatment, so that the heat treatment efficiency is low, the stress relief effect caused by the unidirectional heat source is limited, and in view of the two aspects, the anisotropy of the laminated material is still obvious. Therefore, the invention improves the interlayer toughness structure mode into a space interconnection topological lattice structure, promotes the double strengthening effect of interlayer metallurgical bonding and mechanical locking, adopts a three-dimensional gradient heat treatment mode, increases the efficiency and relieves the anisotropy caused by directional heat dissipation in a single heat source. Disclosure of Invention The invention aims at overcoming the defects in the prior art and provides a design and manufacturing method for preparing a weak anisotropic tough titanium aluminum alloy (TiAl 4722) micro-laminated structure by using an SLM. The method adopts the SLM method to prepare the TiAl4722/TC4 micro-laminated structure with the strengthening structure of the space interconnection three-dimensional lattice structure, and performs three-dimensional in-situ gradient heat treatment on the composite structure in the process of preparing the TiAl4722/TC4 micro-laminated structure product by the SLM. The invention designs a micro-laminated interlayer space interconnection lattice structure, has double reinforcement of mechanical locking and metallurgical bonding, increases the fracture toughness between TiAl4722/TC4 layers, adopts three-dimensional in-situ heat treatment, and realizes the micro-laminated toughening design. The invention aims at realizing the following technical scheme: the preparation method of the SLM with the weak anisotropy strengthening titanium-aluminum alloy micro-lamination structure is characterized by comprising the following steps of: S1, forming a ductile layer on a substrate by adopting an SLM method, forming a space interconnection lattice structure on the ductile layer, forming a brittle layer on the ductile layer, repeating lamination steps of the ductile layer, the space interconnection lattice structure and the brittle layer to obtain a