Patent Grant
11629394
The invention relates to the field of gradient hardened materials, in particularly to a method for preparing a gradient hardened titanium alloy.
A gradient material is a heterogeneous composite material whose structure and properties vary continuously or quasi-continuously in its thickness-wise or lengthwise direction of the material. Gradient materials are widely used in various fields such as aerospace, machinery, electromagnetism, biology, nuclear energy and electrical engineering, for example are applied in various equipment such as in aerospace engines, bearings in mechanical engineering, magnetic disks and oscillators in electromagnetic engineering, teeth, bones and joints in biological engineering, and thermoelectric converters in nuclear and electrical engineering. Titanium alloys are one kind of materials with highest specific strength in the materials currently used. The titanium alloys have characteristics of high specific strength, good corrosion resistance and good heat resistance, and are widely used in aviation, aerospace, petroleum, chemical industry, shipbuilding and other fields. However, due to low hardness, high friction coefficient and poor wear resistance, service life and application scope of the titanium alloy are affected to a certain extent. It is an effective way to improve the surface wear resistance and service life of the titanium alloy by using appropriate surface hardening technology to improve surface hardness of the titanium alloy without reducing mechanical properties of a matrix, which can expand the application scope of high-strength titanium alloys.
At present, a method for preparing a gradient hardened titanium alloy is usually to prepare a composite film structure with hardness gradient change on a surface of a titanium alloy, and the method is complicated in process, high in equipment cost, unstable in process, low in utilization rate, and high in rejection rate, so that the development of the gradient-hardened titanium alloy is limited.
Accordingly, an objective of the invention is to provide a method for preparing a gradient hardened titanium alloy.
In order to achieve the above objective, the invention proposes technical solutions as follows.
Specifically, a method for preparing a gradient hardened titanium alloy, may include the following steps of:
putting a steel momentum block and a cleaned titanium alloy plate in a steel base with a through hole sequentially from bottom to top, wherein a size of a cross section of the through hole is matched with sizes of cross sections of the steel momentum block and the titanium alloy plate, and a height of the through hole is matched with a total thickness of the steel momentum block and the titanium alloy plate;
fixing an explosive frame on an edge of a top surface of the steel base;
placing high explosion velocity explosive with an explosion velocity of equal to or greater than 7000 m/s and pressed into a plate-shaped structure in the explosive frame; and
detonating from an end of a top surface of the explosive to perform impact treatment on the titanium alloy plate to thereby obtain the gradient hardened titanium alloy.
In a preferred embodiment, the impact treatment is performed with twice or three times.
In a preferred embodiment, a ratio of a thickness of the titanium alloy plate:a thickness of the steel momentum block:a thickness of the high explosion velocity explosive:a horizontal distance between a side of the steel base close to an explosive detonation position and the titanium alloy plate:a distance between a side of the steel base far away from the explosive detonation position and the titanium alloy plate is 10-50:5-10:3-5:50-80:10-20.
In a preferred embodiment, a top surface and a bottom surface of the titanium alloy plate both are coated with grease, the top surface is a detonation surface, and the bottom surface is a contact surface of the titanium alloy plate with the steel momentum block. More preferably, a coating thickness of the grease is in a range of 0.5 mm to 1 mm. The bottom surface of the titanium alloy plate is coated with the grease to prevent an air gap between the titanium alloy plate and the steel momentum block from affecting a pressure relief effect of the steel momentum block; and the top surface of the titanium alloy plate is coated with the grease to prevent detonation energy after the explosive is detonated from burning the surface of titanium alloy plate.
In a preferred embodiment, a material of each of the steel base and the steel momentum block is 45# steel or stainless steel.
In a preferred embodiment, a material of the explosive frame is an organic glass.
In a preferred embodiment, the high explosion velocity explosive is castable powder explosive, plastic plate-shaped explosive or rubber plate-shaped explosive. More preferably, the high explosion velocity explosive is composition 4 (C4) explosive.
In a preferred embodiment, the explosive is fixed with the steel base together before the explosive is detonated.
The invention may achieve the following beneficial effects.
The invention provides a titanium alloy hardening treatment method which is different from the concept of the prior art. In the method, the titanium alloy is placed in a steel base with a specific structure, so that material damage caused by “boundary effect” in the process of impact treatment of high explosion velocity explosive can be effectively avoided. Through the impact treatment with a specific explosion velocity on the titanium alloy, a phase transformation from α to ω occurs in the hardening process of the titanium alloy, and thereby the gradient hardening of the top surface of the titanium alloy is realized.
Furthermore, the invention can further improve the phase change content of ω by carrying out 2-3 times of impact treatment on the titanium alloy, thereby improving the hardness of the titanium alloy.
In addition, by controlling the sizes of the titanium alloy, the steel momentum block and the steel base, the gradient-hardened titanium alloy may have better sample integrity and hardening uniformity.
The method of the invention may have advantages of low cost, good process stability, good controllability, high preparation efficiency and low rejection rate, and have important theoretical significance and practical value for the development and application of gradient hardened materials.
In order to explain technical solutions of the invention more clearly, drawings used in embodiments of the invention will be briefly introduced below. Apparently, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained according to these illustrated drawings without creative work.
The invention will be described below in further detail in combination with concrete embodiments.
In the following embodiments:
(1) a structure of a device used for explosive impact treatment is illustrated in
A material of the steel base 2 is 45# steel, and a size of the through hole is 200 mm×150 mm×15 mm. A horizontal distance between a side of the steel base 2 close to an explosive detonation position and the titanium alloy 4 is 80 mm, and a horizontal distance between a side of the steel base 2 far away from the explosive detonation position and the titanium alloy 4 is 20 mm.
The titanium alloy 4 employs a TA2 titanium alloy plate with a size of 200 mm×150 mm×10 mm.
A material of the steel momentum block 5 is 45# steel, and a size thereof is 200 mm×150 mm×5 mm.
(2) the high explosion velocity explosive employs the C4 (abbreviation for Composition 4) explosive.
(3) hardness test: a micro Vickers hardness tester with a model of FM-700 is used, and test conditions are: a pressure of 2.4 newtons (N), and a pressure holding time of 15 seconds (s).
A method for preparing a gradient hardened titanium alloy may include steps as follows.
Step 1, polishing a surface of a titanium alloy by using a handheld electric grinding wheel to remove an oxide layer and cleaning the surface by using absolute ethyl alcohol to remove grease, to thereby obtain a cleaned titanium alloy.
Step 2, placing the steel base on a pre-paved sandpile, putting the steel momentum block and the titanium alloy into the through hole of the steel base sequentially from bottom to top, ensuring that a bottom surface of the steel base is flush with a bottom surface of the momentum block, and applying a layer of grease with a thickness of 0.5 mm on a contact interface between the steel base and the momentum block.
Step 3, evenly applying a layer of grease with a thickness of 0.5 mm on a detonation surface of the titanium alloy, and then fixing the explosive frame on an edge of the top surface of the steel base.
Step 4, putting the C4 explosive pressed into plate-shape in the explosive frame, wherein a thickness of the explosive is 5 mm, and an explosion velocity of the explosive is 7746 minute per second (m/s)/
Step 5, inserting the detonator into one end of the top surface of the explosive, fixing the detonator on the explosive by using an adhesive tape, and packing and compacting the explosive and the steel base.
Step 6, connecting the detonator with the initiator, and detonating to perform impact treatment on the titanium alloy to thereby obtain the gradient hardened titanium alloy.
A Vickers hardness distribution of the obtained gradient-hardened titanium alloy is shown in
An X-ray diffraction (XRD) test of the gradient hardened titanium alloy is shown in
In this embodiment, the impact treatment is performed twice, and the rest are the same as in the embodiment 1.
A Vickers hardness distribution of the obtained gradient hardened titanium alloy is shown in
An XRD test of the gradient hardened titanium alloy is shown in
A method for preparing a gradient hardened titanium alloy may include steps as follows.
Step 1, polishing a surface of a titanium alloy by using a handheld electric grinding wheel to remove an oxide layer and cleaning the surface by using absolute ethyl alcohol to remove grease, to thereby obtain a cleaned titanium alloy.
Step 2, placing the steel base on a pre-paved sandpile, putting the steel momentum block and the titanium alloy into the through hole of the steel base sequentially from bottom to top, ensuring that a bottom surface of the steel base is flush with a bottom surface of the momentum block, and applying a layer of grease with a thickness of 0.5 mm on a contact interface between the steel base and the momentum block.
Step 3, evenly applying a layer of grease with a thickness of 0.5 mm on a detonation surface of the titanium alloy, and then fixing the explosive frame on an edge of the top surface of the steel base.
Step 4, putting the C4 explosive pressed into plate shape in the explosive frame, wherein a thickness of the explosive is 3 mm, and an explosion velocity of the explosive is 7746 minute per second (m/s)/
Step 5, inserting the detonator into one end of the top surface of the explosive, fixing the detonator on the explosive by using an adhesive tape, and packing and compacting the explosive and the steel base.
Step 6, connecting the detonator with the initiator and detonating to perform impact treatment on the titanium alloy, to thereby obtain the gradient hardened titanium alloy.
A result of a Vickers hardness distribution of the obtained gradient-hardened titanium alloy shows that the hardness of the gradient-hardened titanium alloy is distributed in a gradient manner from the top surface in the thickness-wise direction.
A XRD test result of the gradient hardened titanium alloy shows that the phase transformation from α to ω occurs during the hardening process of the titanium alloy.
In this embodiment, the explosion velocity of the explosive is 7300 m/s, and the rest are the same as in the embodiment 3.
A result of a Vickers hardness distribution of the obtained gradient-hardened titanium alloy shows that the hardness of the gradient-hardened titanium alloy is distributed in a gradient manner from the top surface in the thickness-wise direction.
A XRD test result of the gradient hardened titanium alloy shows that the phase transformation from α to ω occurs during the hardening process of the titanium alloy.
In this embodiment, the explosion velocity of the explosive is 7000 m/s, and the rest are the same as in the embodiment 3.
A result of a Vickers hardness distribution of the obtained gradient-hardened titanium alloy shows that the hardness of the gradient-hardened titanium alloy is distributed in a gradient manner from the top surface in the thickness-wise direction.
A XRD test result of the gradient hardened titanium alloy shows that the phase transformation from α to ω occurs during the hardening process of the titanium alloy.
In summary, the invention includes but is not limited to the above embodiments, and any equivalent substitution or partial improvement under the spirit and principle of the invention shall be deemed to be within the scope of protection of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110998042.9 | Aug 2021 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3608490 | O'Keefe | Sep 1971 | A |
| 3615921 | Delgrosso | Oct 1971 | A |
| 20090142586 | Otsuka | Jun 2009 | A1 |
| 20160186536 | Dai | Jun 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 20190107917 | Sep 2019 | KR |
| Entry |
|---|
| Jaw et al.; “Thermal Behaviors of PETN Base Polymer Bonded Explosives”; Journal of Thermal Analysis and Calorimetry, vol. 93, 2008, pp. 953-957 (Year: 2008). |
| Wikipedia; “Table of explosive detonation velocities”, https://web.archive.org/web/20200229042716/https://en.wikipedia.org/wiki/Table_of_explosive_detonation_velocities, webpage snapshot from Feb. 2020 (Year: 2020). |
| KR20190107917A: Espacenet English machine translation (Year: 2019). |
| CNIPA, Notification of a First Office Action for CN202110998042.9, dated Dec. 1, 2021. |
| Beijing Institute of Technology (Applicant), Reply to Notification of a First Office Action for CN202110998042.9, w/allowed replacement claims, dated Dec. 6, 2021. |
| CNIPA, Notification to grant patent right for invention in CN202110998042.9, dated Jan. 17, 2022. |
| Number | Date | Country | |
|---|---|---|---|
| 20230068869 A1 | Mar 2023 | US |
