TWI667358B - Method of producing titanium alloy wire rod - Google Patents

Abstract

The invention provides a method for manufacturing a titanium alloy disk element, which first heats a titanium-15 vanadium-3 chromium-3 aluminum-3 tin alloy to a temperature higher than a β phase transition temperature, and then uses a tandem rolling mill to continuously carry out the titanium alloy. The rolling step, and by controlling the rolling rate, obtains a large number of titanium alloy discs having an equiaxed β phase microstructure in a single process.

Description

Method for manufacturing titanium alloy disk element

The present invention relates to a method for producing a titanium alloy disk, and more particularly to a method for producing a titanium alloy plate of titanium-15 vanadium-3 chromium-3 aluminum-3 tin.

Titanium alloys are often used in industrial, people's livelihood, biomedical and aerospace industries due to their light weight, high strength and corrosion resistance, especially for high value and lightweight products such as screws and springs for steam locomotives. , medical bone nails and fasteners for aircraft.

The structure and structure of the titanium alloy are susceptible to the rolling temperature of the process and the subsequent cooling rate. Further, the titanium alloy can be classified into an α type, an (α + β) type, and a β type depending on the content of the added β stabilizing element (for example, vanadium, molybdenum, chromium, iron, or the like). For example, a common α-type titanium alloy wire is Ti.3 (Grade 9) titanium-3 aluminum-2.5 vanadium (Ti-3Al-2.5V), (α+β) type Gr.5 titanium-6 Aluminum-4 vanadium (Ti-6Al-4V), and β-type titanium-15 vanadium-3chromium-3 aluminum-3 tin (Ti-15V-3Cr-3Al-3Sn, Ti-15-3). In addition to the characteristics of the above titanium alloy, the titanium-15 vanadium-3 chromium-3 aluminum-3 tin alloy also has excellent cold working characteristics and heat treatable strengthening properties.

The production of the conventional titanium-15 vanadium-3 chromium-3 aluminum-3 tin disk unit adopts a segmented process method, which uses a forging machine and a reciprocating rolling after heating the alloy billet at a high temperature. In order to make the alloy have a sufficient amount of plastic deformation, it is formed into a disk of a specific size and the cast structure is eliminated. However, when the reciprocating rolling is performed to plastically deform the alloy, since the alloy embryos are all passed through the rolls, they can be turned to pass the rolls again. Therefore, the waiting time will lower the alloy temperature, and the deformation resistance of the alloy will be greatly improved. When the impedance is too high to continue the rolling delay, the workpiece must be warmed up and then rolled again. This conventional method results in high energy consumption and small weight of single-production discs due to multiple fire operations, resulting in high process cost and low efficiency. In addition, for a single-phase β-type titanium alloy, the prepared disk element needs to be subjected to heat treatment to eliminate the long-axis microstructure caused by the rolling.

In view of this, it is not necessary to provide a method for manufacturing a titanium alloy disk unit, so that the process of the titanium-15 vanadium-3 chromium-3 aluminum-3 tin alloy can reduce the process steps and have high production efficiency.

An aspect of the present invention provides a method for manufacturing a titanium alloy disk unit, which is obtained by controlling the temperature of a high temperature titanium alloy billet and the rolling rate of a continuous rolling step to obtain an equiaxed β phase microscope. Organized titanium-15 vanadium-3 chromium-3 aluminum-3 tin (Ti-15V-3Cr-3Al-3Sn) alloy disk.

According to an aspect of the present invention, a method of manufacturing a titanium alloy disk element comprising providing a titanium alloy billet, a heating step, and a continuous rolling step is provided. Titanium alloy billet is titanium-15 vanadium-3 chromium-3 aluminum-3 tin, and titanium alloy billet Has a beta phase transition temperature. The titanium alloy billet is subjected to a heating step to obtain a high-temperature titanium alloy billet, wherein the temperature of the high-temperature titanium alloy billet is greater than the β phase transition temperature. Then, the high temperature titanium alloy billet is subjected to a continuous rolling step using a tandem rolling mill to obtain a titanium alloy disk. The rolling rate of the continuous rolling step is from 30 m/s to 70 m/s. The microstructure of the obtained titanium alloy disk element is an equiaxed β phase microstructure.

According to an embodiment of the present invention, the titanium alloy billet comprises 69.5 wt% to 82.5 wt% of titanium, 13 wt% to 17 wt% of vanadium, 1.5 wt% to 4.5 wt%, based on the titanium alloy billet being 100 wt%. Chromium, 1.5 wt% to 4.5 wt% aluminum, 1.5 wt% to 4.5 wt% tin, and less than 0.4 wt% oxygen.

According to an embodiment of the invention, the length of the titanium alloy billet is greater than or equal to 5 meters.

According to an embodiment of the present invention, the high temperature titanium alloy billet has a temperature of from 750 ° C to 1200 ° C.

According to an embodiment of the present invention, the rolling temperature of the continuous rolling step is 800 ° C to 1300 ° C.

According to an embodiment of the invention, the titanium alloy disk element is not subjected to an annealing treatment.

According to an embodiment of the present invention, the method for manufacturing a titanium alloy disk unit further comprises a wire drawing step, a stripping step or a pickling step on the titanium alloy disk.

According to an embodiment of the present invention, the titanium alloy disk has a single production weight of 600 kg to 1250 kg.

According to an embodiment of the present invention, the titanium alloy disk has a wire diameter of 6 mm to 20 mm.

A method for manufacturing a titanium alloy disk element according to the present invention, which first heats a titanium-15 vanadium-3 chromium-3 aluminum-3 tin alloy to a temperature higher than its β phase transition temperature, and then uses a tandem rolling mill for continuous rolling The steps, and by controlling the rolling rate, produce a titanium alloy disk having an equiaxed β phase microstructure.

100‧‧‧ method

110‧‧‧ Providing titanium alloy billets

120‧‧‧heating the titanium billet to obtain high temperature titanium billets

130‧‧‧Continuous rolling step for superalloy billets to obtain titanium alloy discs

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; A flow chart of manufacturing method 100.

Fig. 2 is an optical micrograph showing a titanium alloy disk unit produced in Example 1 of the present invention.

3A and 3B show optical micrographs of titanium alloy discs obtained in Comparative Example 1 and Comparative Example 2 of the present invention, respectively.

In view of the above, the present invention provides a method for manufacturing a titanium alloy disk element by controlling the temperature of the high temperature titanium alloy billet and the rolling rate of the continuous rolling step to obtain an equiaxed β phase microscope. Organized titanium-15 vanadium-3 chromium-3 aluminum-3 tin (Ti-15V-3Cr-3Al-3Sn) alloy disk.

Please refer to FIG. 1 , which is a flow chart of a method 100 for fabricating a titanium alloy disk according to an embodiment of the invention. First, proceed to step 110, A titanium alloy billet is provided. The titanium alloy billet is titanium-15 vanadium-3chromium-3 aluminum-3 tin (Ti-15V-3Cr-3Al-3Sn, Ti-15-3) and has a β phase transition temperature. It is additionally noted that the titanium alloy billet has both an α phase and a β phase at a temperature lower than the β phase transition temperature, and only has a β phase at a temperature higher than the β phase transition temperature. In one embodiment, the titanium alloy billet has a beta phase transition temperature of from about 750 °C to 770 °C. In one embodiment, the length of the titanium alloy blank is greater than or equal to 5 meters to operate a large number of blanks in a single process. In another embodiment, the titanium alloy blank has a weight of from 600 kg to 1250 kg.

Next, in step 120, the titanium alloy billet is subjected to a heating step to obtain a high-temperature titanium alloy billet. In one embodiment, the temperature of the high temperature titanium alloy billet is greater than its beta phase transition temperature such that the superalloy billet has only the beta phase. In another embodiment, the superalloy billet has a temperature of from 750 ° C to 1200 ° C, preferably from 900 ° C to 1100 ° C. If the temperature of the superalloy billet is too low (for example, below 750 ° C), the subsequent rolling step may be due to the high resistance of the superalloy billet, which is not conducive to rolling, which may cause damage to the mill. . However, if the temperature of the superalloy billet is too high (for example, higher than 1200 ° C), it may cause defects and oxides on the surface of the superalloy billet to affect the properties of the titanium alloy.

Then, in step 130, the superalloy billet is subjected to a continuous rolling step to obtain a titanium alloy disk. In one embodiment, since the prepared titanium alloy disk element has an equiaxed β phase microstructure, the subsequent processing process can be directly performed without annealing the disk element. In one embodiment, the foregoing processing process includes a draw step, a stripping step, or a pickling step to form a titanium alloy disk into the desired product.

The continuous rolling step can be carried out using a tandem rolling mill in which a tandem rolling mill is connected in series, for example, to an eighteen-seat mill. In one embodiment, the rolling rate of the continuous rolling step is from 30 m/s to 70 m/s. It should be understood that the "rolling rate" as used herein refers to the rolling rate of the last rolling mill in the tandem rolling mill. In general, as the number of rolling mills through which the alloy embryo passes, the rolling rate also increases.

In one embodiment, the titanium alloy disk has a wire diameter of 6 mm to 20 mm. This wire diameter can be adjusted according to product requirements. Depending on the rolling rate of the tandem mill and the wire diameter of the titanium alloy disk, the rolling temperature of the continuous rolling step will also vary. If the rolling rate is high or the wire diameter is small, the temperature of the titanium alloy disk may be raised. Therefore, after the continuous rolling step, the rolling temperature of the titanium alloy disk may be greater than, equal to, or less than the temperature of the superalloy billet obtained in step 120. In one embodiment, the finishing temperature of the continuous rolling step is preferably from 800 ° C to 1300 ° C, more preferably from 850 ° C to 1200 ° C. If the rolling temperature is between 800 ° C and 1300 ° C, not only the prepared titanium alloy disk has an equiaxed β phase microstructure, but is more suitable for subsequent processes such as coiling. It should be noted that since the continuous rolling step is carried out by a tandem rolling mill, the above-mentioned finishing rolling temperature refers to the finishing temperature of the titanium alloy disk through the last rolling mill.

According to the above, the wire diameter, the rolling rate, the rolling temperature, and the heating temperature of the titanium alloy disk are related to each other. For example, if a titanium alloy disk with a wire diameter of 8 mm to 12 mm is to be produced, the rolling rate can be 40 m/s to 50 m/s, and the high temperature billet must be heated to 1100 ° C to 1200 ° C, and the continuous rolling is performed. The finishing temperature of the step is from 1000 ° C to 1200 ° C. By The above process control can produce a titanium alloy disk having an equiaxed β phase microstructure and an elongation (EL) of more than 7%. In one embodiment, the titanium alloy disk may have a Yield Strength (YS) greater than 600 MPa, a Tensile Strength (TS) greater than 700 MPa, and an elongation greater than 20%.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention. Those skilled in the art can make various changes without departing from the spirit and scope of the present invention. Retouching.

Embodiment 1

A titanium -15 vanadium-3 chrome-3 aluminum-3 tin alloy billet having a length of 6.5 m was heated to 1100 ° C above the β phase transition temperature. Next, the alloy blank was rolled into a titanium alloy disk having a wire diameter of 8 mm by a tandem rolling mill, wherein the rolling rate was 50 m/s, and the rolling temperature was 1,150 °C. By the process of the first embodiment, a 630 kg titanium alloy disk element can be obtained in a single process.

Referring to FIG. 2, which is an optical micrograph showing the titanium alloy disk obtained in the first embodiment, it can be seen that the first embodiment can produce a titanium alloy disk having an equiaxed β phase microstructure. Further, according to the mechanical property test, the titanium alloy disk of Example 1 had a lodging strength of 657 MPa, a tensile strength of 744 MPa, and an elongation of 21.7%.

Comparative Example 1 and Comparative Example 2

The titanium-15 vanadium-3 chromium-3 aluminum-3 tin alloy billet was repeatedly rolled using a reciprocating rolling mill of a conventional method, wherein the titanium alloy billet of Comparative Example 1 was first heated to 1000 ° C, and Comparative Example 2 The titanium alloy billet is first heated to 1100 ° C, and its temperature is higher than the β phase transition temperature of the titanium alloy billet. In comparison In the first and second comparative examples, the rolling rate is from 0.5 m/s to 1.5 m/s, and the finishing temperature is between 600 ° C and 850 ° C. Since the first comparative example and the second comparative example are subjected to reciprocating rolling, only a titanium alloy disk of less than 50 kg can be produced in a single process.

Please refer to FIG. 3A and FIG. 3B , which are optical micrographs of titanium alloy discs prepared in Comparative Example 1 and Comparative Example 2, and it can be seen that the microstructure of the microstructure has a large number of long-axis type grain structures. Due to the reciprocating rolling delay, the temperature of the billet drops rapidly and recrystallization is less likely to occur, so that the titanium alloy disc produced has a large number of long-axis type grain structures. Since the long-axis type grain has poor ductility, the disk element must be annealed to recrystallize the alloy into an equiaxed β structure, and the subsequent processing can be performed. Further, according to the mechanical property test, the titanium alloy disk of Comparative Example 1 had a lodging strength of 761 MPa, a tensile strength of 816 MPa, and an elongation of 18%. The titanium alloy disk of Comparative Example 2 had a lodging strength of 763 MPa, a tensile strength of 821 MPa, and an elongation of 18.5%.

According to the above embodiment, the present invention provides a method for manufacturing a titanium alloy disk element, which first heats a titanium-15 vanadium-3 chromium-3 aluminum-3 tin alloy to a temperature higher than its β phase transition temperature, and then uses a tandem type. The rolling mill performs a continuous rolling step and, by controlling the rolling rate, produces a titanium alloy disk having an equiaxed β phase microstructure, and can have a higher throughput in a single process.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. Change and retouch, so the scope of protection of the present invention is attached to the scope of patent application The definition is final.

Claims (9)

A method for manufacturing a titanium alloy disk element, comprising: providing a titanium alloy billet, wherein the titanium alloy billet is titanium-15 vanadium-3 chromium-3 aluminum-3 tin (Ti-15V-3Cr-3Al-3Sn), And the titanium alloy billet has a β phase transition temperature; the titanium alloy billet is subjected to a heating step to obtain a high temperature titanium alloy billet, wherein a temperature system of the high temperature titanium alloy billet is greater than the β phase transition temperature And using a tandem rolling mill to perform a continuous rolling step on the high temperature titanium alloy blank to obtain the titanium alloy disk, wherein one of the continuous rolling steps has a rolling rate of 30 m/s to 70 m/s, And one of the microstructures of the titanium alloy disk element is an isometric β phase microstructure. The method for producing a titanium alloy disk according to claim 1, wherein the titanium alloy blank comprises 69.5 wt% to 82.5 wt% of titanium, 13 wt% to 17 wt%, based on the titanium alloy billet being 100 wt%. Vanadium, 1.5 wt% to 4.5 wt% chromium, 1.5 wt% to 4.5 wt% aluminum, 1.5 wt% to 4.5 wt% tin, and less than 0.4 wt% oxygen. The method for producing a titanium alloy disk according to claim 1, wherein one of the titanium alloy blanks has a length greater than or equal to 5 meters. The method for manufacturing a titanium alloy disk according to claim 1, wherein the temperature of the high temperature titanium alloy billet is 750 ° C to 1200 ° C. The method for producing a titanium alloy disk according to claim 1, wherein the one of the continuous rolling steps has a finishing temperature of 800 ° C to 1300 ° C. The method for producing a titanium alloy disk according to claim 1, wherein the titanium alloy disk is not subjected to an annealing treatment. The method for manufacturing a titanium alloy disk according to claim 1, further comprising: performing a drawing step, a stripping step or a pickling step on the titanium alloy disk. The method for producing a titanium alloy disk according to claim 1, wherein the titanium alloy disk has a single production weight of 600 kg to 1250 kg. The method for producing a titanium alloy disk according to claim 1, wherein the titanium alloy disk has a wire diameter of 6 mm to 20 mm.