Multistage heterostructure titanium alloy with improved strength and toughness, preparation method and application

Abstract

The invention relates to a multistage heterostructure titanium alloy with improved strength and toughness, and a preparation method and application thereof, and belongs to the technical field of titanium alloys. Any longitudinal section of the titanium alloy contains an alpha phase and a beta phase, wherein the alpha phase has three sizes and forms of a micron equiaxial structure with the length of 1-30 microns, a short rod-shaped structure with the length of 10-20 microns and the width of 1-3 microns, and a slender structure with the length of 100-150 microns and the width of 1-10 microns; wherein the beta phase is composed of two sizes and forms of a nanometer equiaxed structure of 100-200 nm and a micron lamellar structure of 5-20 [mu] m in length and 0.5-2 [mu] m in width, the nanometer beta phase is distributed in all the alpha phase, and the micron-scale beta phase is located at the alpha phase interface; and an FCC phase with the width of 100-180nm is mingled between the alpha phase and the micron beta phase. The mechanical property of the titanium alloy prepared through the method is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloys, and particularly relates to a titanium alloy with a multi-level heterogeneous structure for improving strength and toughness, a preparation method and an application thereof. Background Art

[0002] Ti-6Al-4V belongs to the α+β type titanium alloy, which has excellent comprehensive mechanical properties and is the most widely used alloy among commercial titanium alloys, and is widely used in the fields of aviation, marine, biomedical, etc. At present, after being processed by traditional processes, the microstructure of commercial titanium alloys usually presents four typical morphologies, including lamellar structure, duplex structure, basket weave structure and equiaxed structure. The strength and plasticity of traditional commercial TC4 alloy are usually in the range of 900-1000 MPa and 8%-10% respectively. With the continuous expansion of the application range of titanium alloys, higher requirements are placed on the strength and toughness of the materials. By reasonably adjusting the microstructure, it is the most common way to achieve the preparation of high-strength and high-toughness titanium alloys. However, most methods lead to the deterioration of plasticity while increasing the strength of the material.

[0003] Heterogeneous structure engineering is an important idea in the development of new materials in recent years. Microscopically, the heterogeneous structure presents the coexistence of grains of different scales (from micrometers to millimeters), and the region formed by grains of the same scale connected together is called a "domain". This microstructure can break the inverse relationship between strength and toughness because, during the deformation process, a large strain gradient is generated at the interface of the "domain", triggering high back stress work hardening to obtain excellent ductility. The design of this heterogeneous structure aims to overcome the local non-uniformity of the material during deformation, thereby improving the overall performance. Research shows that a TC4 alloy with a dual-scale heterogeneous structure can achieve the preparation of a titanium alloy at the 1100 MPa level. On the other hand, the multi-level structure refers to the existence of multiple levels or levels of organizational structures inside a system or material. Recent research has confirmed that the multi-level structure can also effectively improve the performance of materials. By adjusting the microstructure at different levels, key performance indicators such as the strength and toughness of the material can be optimized. This makes the multi-level structure a promising material design strategy, providing the possibility for further improvement of the performance of TC4 alloy.

[0004] Traditional Ti-6Al-4V obtains an ingot through melting, and the required microstructure is obtained through plastic deformation and heat treatment. It is difficult to ensure the compositional uniformity of the entire ingot during the melting process, while powder metallurgy can effectively solve the problem of compositional non-uniformity. This enables the material to have a uniform composition after plastic deformation, providing the possibility for the generation of a multi-level microstructure. However, the billets produced by powder metallurgy have more pores, resulting in unsatisfactory mechanical properties. In summary, in the prior art, it is impossible to simultaneously improve the strength and toughness of titanium alloys. Summary of the Invention

[0005] The present invention provides a titanium alloy with a high-strength and tough multi-level heterogeneous structure. On any longitudinal section of the titanium alloy, it contains α-phase and β-phase, and also contains a multi-level structure. First, powder metallurgy is carried out, and plastic deformation is performed after sintering. Powder metallurgy enables the material to have a uniform composition after plastic deformation. Plastic deformation generates dynamic recrystallization, and then air cooling is used to make some recrystallization grow slightly, forming a dual-scale heterogeneous structure. At the same time, dislocation defects generated by high-temperature deformation are utilized to induce the segregation of elements such as V at the defect positions, and nano-scale β-phase is stably formed in the α-phase, forming a multi-level heterogeneous structure. Thereby, the strength and toughness of the titanium alloy are improved as a whole. Thus, the technical problem that the strength and toughness of the titanium alloy in the prior art cannot be improved simultaneously is solved.

[0006] According to the first aspect of the present invention, there is provided a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness. On any longitudinal section of the titanium alloy, it contains α-phase and β-phase. The α-phase includes a micron equiaxed structure of 1-30 μm, a short rod-shaped structure with a length of 10-20 μm and a width of 1-3 μm, and an elongated structure with a length of 100-150 μm and a width of 1-10 μm. The β-phase has a nano equiaxed structure of 100-200 nm and a micron lamellar structure with a length of 5-20 μm and a width of 0.5-2 μm. The β-phase of the nano equiaxed structure is distributed within all the α-phase, and the β-phase of the micron lamellar structure is at the interfaces of all the α-phase. And an FCC phase with a width of 100-180 nm is interposed between all the α-phase and the β-phase of the micron lamellar structure.

[0007] According to another aspect of the present invention, there is provided a preparation method of the titanium alloy with the multi-level heterogeneous structure having improved strength and toughness, including the following steps:

[0008] (1) Press the Ti-6Al-4V alloy powder into a cylinder.

[0009] (2) Sinter the cylinder in step (1) into a bar blank in a vacuum sintering furnace, and then wrap it with a steel sleeve.

[0010] (3) Perform plastic deformation on the bar blank in step (2). The plastic deformation is to first heat the bar blank under a protective atmosphere condition. The heating temperature is 1000°C - 1050°C, and the holding time is 15 min - 35 min. Then, perform hot extrusion under a protective atmosphere condition, and after air cooling, a titanium alloy with a multi-level heterogeneous structure is obtained.

[0011] Preferably, in step (3), the extrusion ratio of the hot extrusion is 6.25 - 25, and the extrusion speed is 2 mm / s - 3 mm / s.

[0012] Preferably, the hot extrusion is carried out in a hot extrusion die at a temperature of 400°C - 500°C.

[0013] Preferably, the heating rate is 5 s / °C - 15 s / °C.

[0014] Preferably, in step (2), the sintering temperature is 1100°C - 1350°C, and the heat preservation time is 1 h - 3 h.

[0015] Preferably, in step (1), the particle size of the alloy powder is 40 μm - 80 μm.

[0016] Preferably, cold isostatic pressing process is adopted for pressing.

[0017] Preferably, the pressing force of the cold isostatic pressing process is 250 MPa - 350 MPa, and the pressure holding time is 0.5 h - 1.5 h.

[0018] According to another aspect of the present invention, there is provided an application of the titanium alloy with improved strength and toughness and multi-level heterogeneous structure in high-strength structural members and / or impact-resistant structural members.

[0019] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following technical advantages are mainly possessed:

[0020] (1) The present invention first adopts powder metallurgy method to solve the problem of non-uniform composition, so that after plastic deformation, the material can have uniform composition; after sintering, hot extrusion is carried out. The hot extrusion process can effectively improve the material density, and the material is in a triaxial compression state during processing, which can improve the plastic processing ability of the material. That is, a blank is first prepared by powder metallurgy, and hot extrusion is carried out at an appropriate temperature to generate dynamic recrystallization, and then air cooling is used to make part of the recrystallization grow slightly to form a double-scale heterogeneous structure. At the same time, dislocation defects generated by high-temperature deformation are utilized to induce the segregation of elements such as V at the defect positions, and nano-scale β phase is stably formed in the α phase to form a multi-level heterogeneous structure. Thereby, the strength and toughness of the titanium alloy are improved as a whole.

[0021] (2) The titanium alloy with a multi-level heterogeneous structure composed of micron equiaxed crystals, long strip crystals, ultrafine equiaxed α-phase and ultrafine β-phase can be prepared by the method of the present invention. Both α-phase and β-phase are contained in any longitudinal section of the titanium alloy, wherein the α-phase includes a micron equiaxed structure with a size of 1-30 μm, a short rod-like structure with a length of 10-20 μm and a width of 1-3 μm, and an elongated structure with a length of 100-150 μm and a width of 1-10 μm; the β-phase has a nano equiaxed structure with a size of 100-200 nm and a micron lamellar structure with a length of 5-20 μm and a width of 0.5-2 μm; the nano β-phase exists in all α-phases, and the micron lamellar β-phase forms at the α-phase interface; and an FCC phase with a width of 100-180 nm is interspersed between the α-phase and the micron lamellar β-phase. The present invention combines powder metallurgy and hot extrusion in order to eliminate the pores in the powder metallurgy billet during the hot extrusion process, improve the material density, thereby effectively reducing the crack propagation sources and improving the strength and toughness of the material; heating the billet to the α+β phase region, and at the same time, there is enough temperature during the hot extrusion process to cause dynamic recrystallization of the billet, and not all grains undergo recrystallization, thereby forming a multi-level heterogeneous structure composed of micron equiaxed crystals, long strip crystals, ultrafine equiaxed α-phase and ultrafine β-phase.

[0022] (3) The titanium alloy with improved strength and toughness in the present invention has a yield strength of 1105±42 MPa, an ultimate tensile strength of 1148±18, and an elongation of 14.8±3.2%.

[0023] (4) The multi-level heterogeneous structure titanium alloy of the present invention has excellent mechanical properties and can be applied to high-strength or impact-resistant structural parts in the fields of aerospace, shipbuilding, automobiles, etc. Description of the Drawings

[0024] Figure 1 SEM image of the multi-level heterogeneous structure titanium alloy obtained in Example 1.

[0025] Figure 2 TEM image of the multi-level heterogeneous structure titanium alloy obtained in Example 1.

[0026] Figure 3 SEM image of the multi-level heterogeneous structure titanium alloy obtained in Example 2.

[0027] Figure 4 Mechanical property curves of Example 1, Example 2 and Example 3. Detailed Description of the Invention

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The specific test method of the embodiment of the present invention is as follows: The microstructure of the specimen is observed by a scanning electron microscope; the yield strength, tensile strength and fracture strain of the specimen are tested for tensile properties according to the international standard (Chinese GB / T228-2002).

[0030] A titanium alloy with a high-strength and high-toughness multi-level heterogeneous structure is composed of two phases, α + β. Among them, the α phase has three sizes and morphologies: a micron equiaxed structure with a size of 1-30 μm, a short rod-shaped structure with a length of 10-20 μm and a width of 1-3 μm, and an elongated structure with a length of 100-150 μm and a width of 1-10 μm; the β phase is composed of two sizes and morphologies: a nano equiaxed structure with a size of 100-200 nm and a micron lamellar structure. Among them, the nano-β phase is distributed in all α phases, and the micron-scale β phase is at the α-phase interface; and an FCC phase with a width of 100-180 nm is interspersed in the α and micron lamellar β phases.

[0031] A preparation method of a titanium alloy with a high-strength and high-toughness multi-level heterogeneous structure according to the present invention includes the following steps:

[0032] (1) Press the Ti-6Al-4V alloy powder into a cylinder;

[0033] (2) Sinter the cylinder in step (1) into a bar blank in a vacuum sintering furnace and wrap it with a steel sleeve;

[0034] (3) Subject the bar blank in step (2) to plastic deformation. The plastic deformation is first heated under a protective atmosphere condition. The heating temperature is 1000°C - 1050°C (near the α / β transformation zone), and the holding time is 15 min - 35 min. Then, hot extrusion is carried out under a protective atmosphere condition, and after air cooling, a titanium alloy with a multi-level heterogeneous structure is obtained.

[0035] In some embodiments, the plastic deformation method is heating - holding - extrusion; among them, the heating rate is 5 - 15 s / °C, the heating temperature is 1000 - 1050°C, the holding time is 15 - 45 min, the extrusion ratio is 6.25 - 25 (the extrusion ratio is the cross-sectional area of the material before extrusion divided by the cross-sectional area after extrusion), the extrusion speed is 2 - 3 mm / s, and after extrusion, it is air cooled to room temperature.

[0036] In some embodiments, the particle size of the alloying powder is 40 - 80 μm.

[0037] In some embodiments, the pressing method uses the cold isostatic pressing process, the pressing force is 250 - 350 MPa, and the pressure holding time is 0.5 - 1.5 h.

[0038] In some embodiments, the vacuum sintering temperature is 1100 - 1350 °C, and the heat preservation time is 1 - 3 h.

[0039] In some embodiments, the heat preservation temperature of the hot extrusion die is 400 - 500 °C, and it reaches the heat preservation temperature 2 - 4 h before hot extrusion and remains until the end of hot extrusion.

[0040] In some embodiments, before heating the vacuum atmosphere furnace, the air in the furnace is pumped out and filled with argon, and during the hot extrusion process, argon is continuously kept flowing in the furnace throughout the process.

[0041] The titanium alloy with high strength and toughness and multi - level heterogeneous structure of the present invention can be used in high - strength structural parts or anti - impact structural parts in the fields of aerospace, ships, automobiles, etc.

[0042] The following are specific embodiments

[0043] Example 1

[0044] A preparation method of a titanium alloy with high strength and toughness and multi - level heterogeneous structure includes the following steps:

[0045] The raw materials used in this example are as follows: Ti - 6Al - 4V alloy powder (79.21 μm).

[0046] (1) Alloy powder treatment: The target alloy composition of this example is Ti - 6Al - 4V alloy. First, the alloy powder is pressed by cold isostatic pressing with a pressing force of 300 MPa for 1 h. It is pressed into a billet with a diameter of 50 mm and a height of 100 mm;

[0047] (2) Billet sintering: The billet pressed in step (1) is put into a vacuum sintering furnace and sintered at 1300 °C for 2 h;

[0048] (3) Billet encapsulation: The billet sintered in step (2) is machined into two cylinders with a diameter of 47.5 mm and a height of 48, and put into a jacket made of 45 steel. The diameter of the part with the jacket is 49.5 mm and the height is 50 mm;

[0049] (4) Billet heating: The jacketed billet in step (3) is put into a vacuum atmosphere furnace and kept at 1000 °C for 30 min. Among them, the vacuum atmosphere furnace needs to be filled with argon in advance, and argon is introduced into the furnace throughout the heat preservation process;

[0050] (5) Hot extrusion forming: Take out the billet after heat preservation in step (4) from the vacuum atmosphere furnace, quickly put it into the preheated extrusion die, extrude the sample with an extrusion ratio of 9.76 and an extrusion speed of 20 mm / s, and obtain a multi-level heterogeneous structure titanium alloy after air cooling.

[0051] Figure 1 It is the scanning electron microscope image of the multi-level heterogeneous structure titanium alloy obtained in Example 1. From Figure 1 it can be seen that for the multi-level heterogeneous structure titanium alloy prepared in this example, its matrix is composed of equiaxed α-phase with a size of 15 - 25 μm, short rod-shaped α-phase with a length of 10 - 20 μm and a width of 1 - 3 μm, and slender α-phase with a length of 100 μm and a width of 1 - 10 μm. The β-phase with a nano-equiaxed structure exists in all α-phases, and the β-phase with a micron lamellar structure forms at the interfaces of all α-phases.

[0052] Figure 2 It is the transmission electron microscope image of the multi-level heterogeneous structure titanium alloy obtained in Example 1. From Figure 2 it can be known that there is also an FCC phase with a width of 100 - 180 nm existing between the α-phase and the β-phase with a micron lamellar structure.

[0053] The micron equiaxed grains, long strip crystal α-phase, ultrafine equiaxed crystal α-phase, and the FCC phase between the α-phase and the β-phase together constitute the multi-level heterogeneous structure. The room temperature tensile yield strength, tensile strength and elongation are 1123 MPa, 1148 MPa and 14.8% respectively (as Figure 4 shown). The strength of the Ti-6Al-4V alloy prepared in this example is much higher than that of the Ti-6Al-4V prepared by traditional sintering and commercial Ti-6Al-4V alloys.

[0054] Example 2

[0055] A preparation method of a high-strength and tough multi-level heterogeneous structure titanium alloy, comprising the following steps:

[0056] The raw materials used in this example are as follows: Ti-6Al-4V alloy powder (43.86 μm).

[0057] (1) Alloy powder treatment: The target alloy composition of this example is Ti-6Al-4V alloy. First, the alloy powder is pressed by cold isostatic pressing with a pressing force of 300 MPa for 1 h. It is pressed into a rod blank with a diameter of 50 mm and a height of 100 mm;

[0058] (2) Rod blank sintering: Put the pressed rod blank in step (1) into a vacuum sintering furnace and sinter it at 1300 °C for 2 h;

[0059] (3) Billet sheathing: The sintered billets in step (2) are machined into two cylinders with a diameter of 47.5 mm and a height of 48, and placed into a sheathing made of 45 steel. The diameter of the part with the sheathing is 49.5 mm and the height is 50 mm;

[0060] (4) Billet heating: The sheathed billet in step (3) is placed into a vacuum atmosphere furnace and held at 1000 °C for 30 min. Among them, the vacuum atmosphere furnace needs to be filled with argon in advance, and argon is introduced into the furnace throughout the holding process;

[0061] (5) Hot extrusion forming: The billet after holding in step (4) is taken out from the vacuum atmosphere furnace and quickly placed into a preheated extrusion die, and a sample is extruded with an extrusion ratio of 9.76 and an extrusion speed of 20 mm / s. After air cooling, a multi-level heterogeneous structure titanium alloy is obtained.

[0062] Figure 3 This is the scanning electron microscope image of the multi-level heterogeneous structure titanium alloy obtained in this example. As can be seen from Figure 3 it, for the multi-level heterogeneous structure titanium alloy prepared in this example, its matrix is composed of equiaxed α phases with a size of 1 - 5 μm, short rod-shaped phases with a length of 20 - 40 μm and a width of 10 - 25 μm, and slender α phases with a length of 100 - 150 μm and a width of 1 - 10 μm. The nano-equiaxed structured β phase exists in all α phases, and the micron lamellar structured β phase forms at the interfaces of all α phases; and there is a 100 - 180 nm wide FCC phase between all α phases and the micron lamellar structured β phase.

[0063] The micron equiaxed grains, long strip α phases, ultra-fine equiaxed α phases, and the FCC phase between α and β phases together constitute the multi-level heterogeneous structure. Its room temperature tensile yield strength, tensile strength and elongation are 1047 MPa, 1126 MPa and 18.7% respectively (as Figure 4 shown). The strength of the Ti-6Al-4V alloy prepared in this example is much higher than that of the Ti-6Al-4V prepared by traditional sintering and commercial Ti-6Al-4V alloys.

[0064] Example 3

[0065] A preparation method of a high-strength and tough multi-level heterogeneous structure titanium alloy, comprising the following steps:

[0066] The raw materials used in this example are as follows: Ti-6Al-4V alloy powder (79.21 μm).

[0067] (1) Alloy powder treatment: The target alloy composition in this example is Ti-6Al-4V alloy. First, the alloy powder is cold isostatically pressed with a pressing force of 300 MPa for 1 h. It is pressed into a billet with a diameter of 50 mm and a height of 100 mm;

[0068] (2) Sintering of the billet: The billet pressed in step (1) is placed in a vacuum sintering furnace and sintered at 1300 °C for 2 h;

[0069] (3) Billet encapsulation: The billet sintered in step (2) is machined into two cylinders with a diameter of 47.5 mm and a height of 48, and placed in a jacket made of 45 steel. The diameter of the part with the jacket is 49.5 mm and the height is 50 mm;

[0070] (4) Billet heating: The jacket billet in step (3) is placed in a vacuum atmosphere furnace and kept at 1000 °C for 30 min. Among them, the vacuum atmosphere furnace needs to be filled with argon in advance, and argon is introduced into the furnace throughout the holding process;

[0071] (5) Hot extrusion forming: The billet after holding in step (4) is taken out of the vacuum atmosphere furnace and quickly placed into a preheated extrusion die, and a sample is extruded with an extrusion ratio of 6.25 and an extrusion speed of 20 mm / s, and a multi-level heterogeneous structure titanium alloy is obtained after air cooling.

[0072] The titanium alloy with a multi-level heterogeneous structure prepared in this embodiment has a matrix composed of equiaxed α phases with a size of 15 - 25 μm, short rod-shaped α phases with a length of 10 - 20 μm and a width of 1 - 3 μm, and slender α phases with a length of 100 μm and a width of 1 - 10 μm. The nano-equiaxed structured β phase exists in all α phases, and the micron lamellar structured β phase forms at the interfaces of all α phases; and there is an FCC phase with a width of 100 - 180 nm between all α phases and the micron lamellar structured β phase.

[0073] The micron equiaxed crystals, long strip crystal α phases, ultrafine equiaxed crystal α phases, and the FCC phase between α and β phases together constitute a multi-level heterogeneous structure. Its room temperature tensile yield strength, tensile strength and elongation are 1145 MPa, 1171 MPa and 10.8% respectively (as Figure 4 shown). The strength of the Ti-6Al-4V alloy prepared in this embodiment is much higher than that of the Ti-6Al-4V prepared by traditional sintering and commercial Ti-6Al-4V alloys.

[0074] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A titanium alloy with a multi-level heterogeneous structure having improved strength and toughness, characterized in that: The titanium alloy contains α phase and β phase on any longitudinal section, wherein the α phase includes a micron equiaxed structure of 1-30 μm, a short rod-like structure of 10-20 μm in length and 1-3 μm in width, and a slender structure of 100-150 μm in length and 1-10 μm in width; the β phase has a nano equiaxed structure of 100-200 nm and a micron lamellar structure of 5-20 μm in length and 0.5-2 μm in width; the β phase with nano equiaxed structure is distributed in all α phases, and the β phase with micron lamellar structure is at all α phase interfaces; and a 100-180 nm wide FCC phase is interspersed between all α phases and the β phase with micron lamellar structure.

2. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 1, characterized in that: The following steps are involved: (1) Pressing Ti-6Al-4V alloy powder into a cylinder; (2) sintering the cylinder in step (1) into a rod blank in a vacuum sintering furnace, and then enclosing it in a steel sleeve; (3) plastically deforming the rod blank in step (2), wherein the plastic deformation is firstly heating the rod blank under protective atmosphere conditions, wherein the heating temperature is 1000° C.-1050° C., and the holding time is 15 min-35 min, and then hot extruding is performed under protective atmosphere conditions, and after air cooling, a titanium alloy with a multi-level heterogeneous structure is obtained.

3. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 2, characterized in that: In step (3), the extrusion ratio of the hot extrusion is 6.25-25, and the extrusion speed is 2mm / s-3mm / s.

4. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 2 or 3, characterized in that: The hot extrusion is carried out in a hot extrusion die at a temperature of 400°C-500°C.

5. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 2, characterized in that: The heating rate is 5s / °C-15s / °C.

6. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 2, characterized in that: In step (2), the sintering temperature is 1100°C-1350°C, and the holding time is 1h-3h.

7. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 2, characterized in that: In step (1), the particle size of the alloy powder is 40 μm-80 μm.

8. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 2, characterized in that: The pressing adopts a cold isostatic pressing process.

9. The method for preparing a titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 8, characterized in that: The pressing force of the cold isostatic pressing process is 250 MPa-350 MPa, and the holding time is 0.5 h-1.5 h.

10. Use of the titanium alloy with a multi-level heterogeneous structure having improved strength and toughness as claimed in claim 1 in high-strength structural parts and / or impact-resistant structural parts.

Images