KR102434520B1 - High strength and high formability titanium alloy using molybdenum and ferrochrome and method of manufacturing the same - Google Patents

Abstract

Disclosed are a high-strength, highly-formable titanium alloy using molybdenum and ferrochrome and a method for manufacturing the same.
Titanium alloy manufacturing method according to the present invention (a) adding ferrochrome containing chromium (Cr), iron (Fe), silicon (Si) and carbon (C) to an alloy or mixture of titanium (Ti) and molybdenum to do; (b) dissolving the resultant of step (a) and then cooling to form a titanium alloy base material; And (c) the step of hot forming the titanium alloy base material; including, characterized in that the molybdenum 1 to 15% by weight, the ferrochrome is added to less than 4% by weight based on the total weight of the titanium alloy.

Description

HIGH STRENGTH AND HIGH FORMABILITY TITANIUM ALLOY USING MOLYBDENUM AND FERROCHROME AND METHOD OF MANUFACTURING THE SAME

The present invention relates to titanium and a method for producing the same. More specifically, the present invention relates to a titanium alloy having high strength and high formability using molybdenum and ferrochrome and a method for manufacturing the same.

Due to its high strength, high corrosion resistance and high biocompatibility, titanium and its alloys are widely used in a wide range of industrial fields such as aerospace, national defense, energy industry, medical care and consumer goods.

In general, types of titanium alloys are classified into pure titanium, alpha (α) alloys, alpha-beta (α-β) alloys, and beta (β) alloys based on the stable phase at room temperature. Among them, the alpha alloy is known to have excellent creep strength and weldability, and the beta alloy is known to increase machinability.

In the case of titanium alloys, pure titanium for general industry and Ti-6Al-4V alloy, which is an alpha-beta alloy for aviation and defense, have been mainly used, and some Ti-Zr alloys that can obtain low modulus and high strength in medical and consumer products , Ti-Nb alloy, and Ti-Mo alloy are used, and research to improve low modulus of elasticity and high strength is continuously being made. However, due to the limitations of the properties of these alloys, their use has not been expanded.

Pure titanium is cheaper than other titanium alloys in terms of price, and has excellent formability, weldability, workability, and corrosion resistance, but its low strength has limitations in application fields. On the other hand, it has a high price and tends to have inferior properties except for strength compared to pure titanium. In addition, the beta alloy can implement desired properties through control of alloying elements, but has a disadvantage in that the price is considerably higher than that of pure titanium as well as Ti-6Al-4V alloy. In particular, medical implants and eyeglass frames require excellent biocompatibility, low modulus of elasticity, and high strength. is causing

Therefore, it is required to develop a titanium alloy composed of relatively inexpensive elements that can control properties such as excellent strength, formability, weldability, workability, corrosion resistance, biocompatibility, and low modulus of elasticity while minimizing price increase and a method for manufacturing the same. do.

Registered Patent Publication No. 10-1835408 (published on May 16, 2012)

The problem to be solved by the present invention is to provide a high-strength, highly moldable titanium alloy using molybdenum and ferrochrome.

In addition, the problem to be solved by the present invention is to use ferrochrome as an alloy additive to not only lower the manufacturing cost of the titanium alloy, but also provide a method of manufacturing a high strength and highly formable titanium alloy advantageous in terms of securing strength and elongation.

The problems of the present invention are not limited to the problems mentioned above, and other problems and advantages of the present invention that are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. will be. Further, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

A titanium alloy according to an embodiment of the present invention for solving the above problems is molybdenum (Mo): 1.0 to 15.0 wt%, chromium (Cr): 0.1 to 3.0 wt%, iron (Fe): 0.1 to 1.0 wt%, silicon (Si): 0.01 to 0.1 wt%, Oxygen (O): 0.4 wt% or less, and the remaining titanium (Ti) and inevitable impurities.

The titanium alloy may have a molybdenum equivalent ([Mo]eq.) of 5.5 to 20 expressed by Equation 1 below, and a beta transformation point of 670 to 815 °C.

[Equation 1]

[Mo]eq. = [Mo] + 0.2 [Ta] + 0.28 [Nb] + 0.4 [W] + 0.67 [V] + 1.25 [Cr] + 1.25 [Ni] + 1.7 [Mn] + 1.7 [Co] + 2.5 [Fe]

The titanium alloy may have a tensile strength of 750 to 1510 MPa, a yield strength of 545 to 1420 MPa, and a Young's modulus of 80 to 110 GPa.

Titanium alloy manufacturing method according to an embodiment of the present invention for solving the above problems is (a) in an alloy or mixture of titanium (Ti) and molybdenum, chromium (Cr), iron (Fe), silicon (Si) and carbon ( C) adding ferrochrome containing; (b) dissolving the resultant of step (a) and then cooling to form a titanium alloy base material; And (c) hot forming the titanium alloy base material; including, characterized in that the molybdenum 1 to 15% by weight, the ferrochrome is added in an amount of less than 4% by weight based on the total weight of the titanium alloy.

It is more preferable to add 0.5 to 2 wt% of the ferrochrome based on the total weight of the titanium alloy.

Oxygen (O) may be included in an amount of 0.4 wt% or less based on the total weight of the titanium alloy.

The ferrochrome includes iron (Fe): 20 to 35% by weight, silicon (Si): 1 to 4% by weight, carbon (C): 0.15% by weight or less, and may be composed of the remaining chromium (Cr) and unavoidable impurities. have.

The hot forming may be performed at a forming rate of 90% or less at 800 to 850 °C.

According to the method for manufacturing a high-strength, high-formability titanium alloy according to the present invention, low-carbon ferrochrome composed of elements (Cr, Fe, Si, etc.) harmless to the human body is used as an additive of the titanium-molybdenum alloy material by using Cr, Fe Compared to adding as individual elements such as , Si, etc., costs can be lowered in terms of raw material price and process.

In addition, the high strength and high formability titanium alloy according to the present invention can provide excellent formability as well as excellent strength through control of the ferrochrome content.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

Figure 1a shows the phase fraction of a specimen in which 5 wt% of molybdenum is added to titanium.
Figure 1b shows the phase fraction of a specimen in which 5 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium.
Figure 1c shows the phase fraction of a specimen in which 5 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium.
Figure 2a shows the phase fraction of a specimen in which 9.5 wt% of molybdenum is added to titanium.
Figure 2b shows the phase fraction of a specimen in which 9.5 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium.
Figure 2c shows the phase fraction of a specimen in which 9.5 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium.
Figure 3a shows the phase fraction of a specimen in which 15 wt% of molybdenum is added to titanium.
Figure 3b shows the phase fraction of a specimen in which 15 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium.
Figure 3c shows the phase fraction of a specimen in which 15 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium.
Figure 4a shows the mechanical properties of Comparative Examples Specimens 1 and 4 and Examples Specimens 1-4.
Figure 4b shows the mechanical properties of Comparative Example specimens 2, 5, and Examples 5-8.
Figure 4c shows the mechanical properties of Comparative Example specimens 3 and 6 and Example specimens 9 to 12.

The above-described objects, features and advantages will be described in detail below, and accordingly, those skilled in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, a high-strength and highly formable titanium alloy using molybdenum and ferrochrome and a method for manufacturing the same according to some embodiments of the present invention will be described.

As a method of increasing the strength of pure titanium, there are a method of increasing the strength by adding an alloying element, and a method of increasing the strength by reducing the internal crystal grains through plastic working and heat treatment. However, this method causes a price increase because an alloy element is added and a separate grain refinement process is added. In addition, in the case of the method of refining crystal grains through plastic working and heat treatment, the mechanical properties of the titanium alloy manufactured according to the process are greatly changed, and a process that is difficult to directly apply to the actual production process can be derived. have.

Therefore, it can be seen that the method of adding an alloying element is more advantageous than the method of refining the crystal grains through plastic working and heat treatment. In particular, alloying by selecting inexpensive alloying elements can be seen as the most desirable method for minimizing price increase and increasing strength. Furthermore, in order to ensure biostability, it is preferable not to add Co, Cu, Ni, V, etc., which are toxic elements, and these elements are not included in the titanium alloy according to the present invention, and are exceptionally included inevitably as impurities. can be

As a result of long-term research, the present inventors have selected Mo, which is inexpensive and non-toxic, among the elements (Mo, V, Nb, etc.) that form a solid solution with titanium (a system showing complete solubility in each other in the liquid and solid phases). Mo alloy was selected as the base, and Fe and Cr were selected as alloying elements that had a greater effect (Mo equivalent greater than 1) on Mo equivalent than Mo, were relatively inexpensive, and were non-toxic. In addition, in order to overcome the disadvantage that it is difficult to achieve a uniform composition due to volatilization during dissolution when separately adding alloying elements such as Fe, Cr, etc., a method of alloying by adding ferrochrome containing Fe, Cr, Si, etc. has been developed. In particular, in the case of Si, which is an element included in ferrochrome, a feature of refining the crystal grains of the molten ingot by providing a nucleation site during dissolution can be expected additionally. Through this, the present inventors developed a new Ti-Mo-Cr-Fe-Si alloy based on a titanium-moly (Ti-Mo) alloy.

Hereinafter, a method for manufacturing a high-strength titanium alloy using molybdenum and ferrochrome will be described in more detail.

High-strength titanium alloy manufacturing method according to the present invention by adding ferrochrome containing chromium (Cr), iron (Fe), silicon (Si) and carbon (C) to an alloy or mixture of titanium (Ti) and molybdenum (Mo) and dissolving titanium and ferrochrome and then cooling to form a titanium alloy base material, and hot forming the titanium alloy base material.

For dissolution of titanium, molybdenum and ferrochrome, various known methods such as vacuum melting, electron beam melting, plasma arc melting, non-consumable electrode arc melting, or induction skull melting can be used. Hot forming may be performed in a manner such as hot rolling, hot forging, or the like. Hot forming may be performed at 800 to 850 °C with a forming ratio of 90% or less. The forming rate may be expressed as a reduction rate in the case of rolling. In the case of the present invention, as described below, 1 to 15% by weight of molybdenum and less than 4% by weight of ferrochrome are added. can provide

For cooling after hot forming, various methods such as water cooling, air cooling, and furnace cooling may be used. The cooling method may be determined depending on whether or not there is an additional hot process after hot forming. For example, if there is no additional hot process, water cooling may be performed after hot forming. After hot forming, heat treatment such as homogenization treatment, solution treatment treatment, and aging treatment may be additionally performed.

One characteristic with respect to dissolution of ferrochrome is that the temperature when dissolving ferrochrome is significantly lower than when dissolving chromium, iron, silicon, etc. individually, and is similar to the melting point of titanium. Through this, ferrochrome can be dissolved together with titanium at a relatively low temperature, thereby reducing the cost of manufacturing a titanium alloy.

In the present invention, it is preferable that the addition amount of ferrochrome is less than 4% by weight based on the total weight of the titanium alloy. More preferably, it is 3 wt% or less, and most preferably 0.5 to 2 wt%. When ferrochrome is added, strength may be increased compared to a titanium alloy to which ferrochrome is not added. However, when the addition amount of ferrochrome is 4% by weight or more, the elongation is very low, and there is a risk of cracking.

Ferrochrome includes iron (Fe): 20 to 35 wt%, silicon (Si): 1 to 4 wt%, carbon (C): 0.15 wt% or less, and may be composed of the remaining chromium (Cr) and unavoidable impurities. .

When the content of ferrochrome is less than 4% by weight, it is possible to satisfy the preferred content ranges of chromium, iron, and silicon as described above in the titanium alloy.

Through the above method, the present invention is molybdenum (Mo): 1.0 to 15.0 wt%, chromium (Cr): 0.1 to 3.0 wt%, iron (Fe): 0.1 to 1.0 wt%, silicon (Si): 0.01 to 0.1 wt %, oxygen (O): 0.4 wt % or less, and the remaining titanium (Ti) and unavoidable impurities may be provided.

Molybdenum (Mo) is a non-toxic beta-phase stabilizing element. Molybdenum serves to increase strength due to the solid solution strengthening effect. However, when molybdenum is added in excess of 15% by weight, there is a problem in that the elastic modulus of the alloy is greatly increased.

Chromium (Cr) is a non-toxic element and is a higher beta-phase stabilizing element than molybdenum (Mo) in a titanium alloy. When chromium is added to titanium, the strength can be increased due to the solid solution strengthening effect. However, if chromium is added in excess of 3.0% by weight, the possibility of fracture in the molding process is high due to the formation of the Laves Phase (TiCr ₂ ) phase.

Iron (Fe) is non-toxic like chromium (Cr) and is a higher beta-phase stabilizing element than molybdenum. When iron is added to titanium, the strength can be increased due to the solid solution strengthening effect. However, when the iron is added in excess of 1.0% by weight when the titanium alloy is dissolved, macro or micro segregation can be induced, and when heat-treated at a certain temperature, a TiFe phase, which is a fairly fragile phase, can be formed.

Silicon (Si) is a non-toxic element and forms many nucleation sites when dissolving a titanium alloy, leading to grain refinement. Silicon also contributes to increasing the static strength of the titanium alloy. However, when the content of silicon exceeds 0.1% by weight, cracking may be promoted due to the formation of silicide having strong brittleness.

The content of Cr, Fe and Si in the titanium alloy according to the present invention is determined according to the amount of ferrochrome added, and the amount of ferrochrome added is less than 4% by weight, more preferably not more than 3.0% by weight, and most preferably 0.5 to 2.0% by weight. Optionally, the Cr, Fe and Si contents as described above may be satisfied.

In the titanium alloy according to the present invention, oxygen (O) may be included in an amount of 0.4 wt% or less based on the total weight of the titanium alloy. Oxygen is an interstitial element and is a solid solution strengthening alloy element that strengthens the lattice without significantly affecting corrosion resistance. However, when oxygen is contained in excess of 0.4% by weight, it is possible to rapidly reduce the impact resistance by suppressing twin deformation at low temperature.

The titanium alloy according to the present invention may have a molybdenum equivalent ([Mo]eq.) of 5.5 to 20, as can be seen in Examples to be described later ([A] is the weight % of A ).

[Equation 1]

[Mo]eq. = [Mo] + 0.2 [Ta] + 0.28 [Nb] + 0.4 [W] + 0.67 [V] + 1.25 [Cr] + 1.25 [Ni] + 1.7 [Mn] + 1.7 [Co] + 2.5 [Fe]

In addition, the high-strength titanium alloy according to the present invention may have a beta transformation point of 670 ~ 815 ℃.

Further, as a result of the experiment, the high-strength titanium alloy according to the present invention may have a tensile strength of 750 to 1510 MPa, a yield strength of 545 to 1420 MPa, and a Young's modulus of 80 to 110 GPa.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, these are presented as preferred examples of the present invention and cannot be construed as limiting the present invention in any sense. Content not described in the following embodiments will be omitted because it can be technically inferred sufficiently by those skilled in the art.

1. Ferrochrome analysis

Component analysis was performed as follows for three ferrochrome specimens. EDS analysis was performed three times each for three positions (Left, Center, Right) of each specimen having a size of 10 mm × 10 mm, and the results are shown in Table 1.

[Table 1] (Unit: % by weight)

All three specimens contain about 66% by weight of Cr, about 31% of Fe, and about 3% by weight of Si, and it can be seen that the content difference of the components is not large.

Hereinafter, an experiment was conducted on ferrochrome specimen #1.

After removing the surface oxide layer of the ferrochrome specimen #1, the results of analyzing the contents of O, N, H, and C by EDS are shown in Table 2.

[Table 2]

Ferrochrome is classified into low carbon ferrochrome, medium carbon ferrochrome, and high carbon ferrochrome according to the carbon content, of which low carbon ferrochrome means that the carbon content is 0.2 wt% or less or 0.15 wt% or less. In the case of the previously analyzed ferrochrome specimen #1, the carbon content was about 0.1% by weight and the chromium content was about 67%, which corresponds to low-carbon ferrochrome.

The melting points of Cr, Fe and Si are 1907° C., 1538° C. and 1414° C., respectively, but the melting point of low-carbon ferrochrome having a carbon content of 0.15 wt% or less is known to be about 1620° C. Further, the melting point of titanium is 1668°C.

In titanium, O, N, C, H, etc. are major elements that reduce fracture ductility and require special management. In the titanium alloy, these elements should be controlled in the weight % or less shown in Table 3 (there is a very small difference in the tolerance by country). In particular, H lowers the fracture ductility even when added in a small amount, so special management is required compared to other elements.

[Table 3]

In the case of ferrochrome specimen #1 analyzed above, it is low-carbon ferrochrome, and satisfies the maximum weight % or less with respect to elements such as O, N, C, and H in Table 3.

Preparation of Titanium Alloy Specimens

Titanium (Ti-0.02O) and molybdenum and ferrochrome of the contents described in Table 4 were dissolved in an induction skull melting furnace to form a titanium alloy, and then cooled to prepare ingots having a width of 10mm × length 30mm × thickness 10mm.

The ingots were formed at 830 ° C ± 20 ° C at a forming ratio of about 90% described in Table 4 and then cooled with water to prepare titanium alloy specimens according to Comparative Examples 1 to 3 and Examples 1 to 12.

Table 4 shows the Mo equivalent and beta transformation point according to the ferrochrome content in the titanium alloy specimens prepared according to Comparative Examples 1 to 3 and Examples 1 to 12. And, Table 5 shows the contents of Cr, Fe and Si according to the ferrochrome added in the titanium alloy specimens according to Examples 1 to 12.

[Table 4]

[Table 5]

Figure 1a shows the phase fraction of a specimen in which 5 wt% of molybdenum is added to titanium. Figure 1b shows the phase fraction of a specimen in which 5 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium. Figure 1c shows the phase fraction of a specimen in which 5 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium.

1a to 1c, in the case of a specimen in which 5% by weight of molybdenum is added to titanium and a specimen in which 5% by weight of molybdenum and 0.5% by weight of ferrochrome are added to titanium, TiCr ₂ hardly showing a precipitation phase On the other hand, in the case of a specimen in which 5 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium, it can be seen that the TiCr ₂ precipitated phase of about 5.63 wt% is exhibited. As described above, when TiCr ₂ is excessive, there is a possibility of breakage in the molding process, ferrochrome needs to be added in an amount of less than 4.0% by weight, more preferably 3.0% by weight or less, more preferably 0.5 to 2.0% by weight. .

Figure 2a shows the phase fraction of a specimen in which 9.5 wt% of molybdenum is added to titanium. Figure 2b shows the phase fraction of a specimen in which 9.5 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium. Figure 2c shows the phase fraction of a specimen in which 9.5 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium.

2a to 2c, in the case of a specimen in which 9.5% by weight of molybdenum is added to titanium and a specimen in which 9.5% by weight of molybdenum and 0.5% by weight of ferrochrome are added to titanium, TiCr2 precipitation phase is hardly exhibited, whereas , it can be seen that in the case of a specimen in which 9.5 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium, about 5.63 wt% of TiCr ₂ precipitated phase can be seen.

Figure 3a shows the phase fraction of a specimen in which 15 wt% of molybdenum is added to titanium. Figure 3b shows the phase fraction of a specimen in which 15 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium. Figure 3c shows the phase fraction of a specimen in which 15 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium.

3a to 3c, in the case of a specimen in which 15 wt% of molybdenum is added to titanium and a specimen in which 15 wt% of molybdenum and 0.5 wt% of ferrochrome are added to titanium, TiCr ₂ hardly showing a precipitation phase On the other hand, in the case of a specimen in which 15 wt% of molybdenum and 4.0 wt% of ferrochrome are added to titanium, it can be seen that about 5.63 wt% of TiCr ₂ precipitated phase is exhibited.

4a to 4c show the mechanical properties of the comparative example specimens 1 to 6 and the example specimens 1 to 12. Specifically, Figure 4a shows the mechanical properties of Comparative Example Specimens 1 and 4 and Example Specimens 1 to 4 having a molybdenum content of 5.0% by weight, and Figure 4b is a Molybdenum content of 9.5% by weight Comparative Example Specimens 2 and 5 and Example specimens 5 to 8, and FIG. 4c shows mechanical properties of Comparative Examples Specimens 3 and 6 and Example Specimens 9 to 12 having a molybdenum content of 15 wt%.

The specimen according to Comparative Example 4 is a titanium alloy specimen prepared by adding 5.0% by weight of molybdenum and 4% by weight of ferrochrome, and the specimen according to Comparative Example 5 is titanium prepared by adding 9.5% by weight of molybdenum and 4% by weight of ferrochrome. It is an alloy specimen, and is a titanium alloy specimen prepared by adding 15% by weight of molybdenum and 4% by weight of ferrochrome.

Mechanical properties were obtained by performing a tensile test for each titanium alloy specimen at a strain rate of 1.5 mm/min at room temperature.

Table 6 shows the mechanical properties of Comparative Example Specimens 1 to 3 and Example Specimens 1 to 12.

[Table 6]

Referring to Table 6, in the case of the titanium-molybdenum alloy specimens according to Comparative Examples 1 to 3 to which ferrochrome is not added, it can be seen that the tensile strength of 786 ~ 1064 MPa and the yield strength of 712 ~ 855 MPa. On the other hand, in the case of titanium alloy specimens prepared by adding ferrochrome in an amount of 3.0 wt % or less to a titanium-molybdenum alloy, it can be seen that the tensile strength is increased to a maximum of 1510 MPa and the yield strength to a maximum of 1420 MPa. That is, in the case of a titanium alloy manufactured by adding ferrochrome, it can be seen that the strength is increased compared to that of a titanium alloy that is not.

Table 7 shows the elongation measurement results and crack occurrence observation results of the specimens according to Comparative Examples 4 to 6 and the specimens according to Examples 1 to 12.

[Table 7]

Referring to FIGS. 4a to 4c and Table 7, in the case of Comparative Examples 4 to 6, when ferrochrome is added in an amount of 4.0% by weight in a titanium alloy in which 5-15% by weight of molybdenum is added to titanium, the elongation is 1.4 to 2.3%. It can be seen that the elongation decreased sharply. On the other hand, in the case of Examples 1 to 12, when less than 4.0% by weight of ferrochrome is added to the titanium alloy in which 5 to 15% by weight of molybdenum is added to titanium, the elongation range is 2.4 to 49% without a sharp decrease in elongation. can see. Furthermore, when the amount of ferrochrome added is 0.5 to 2.0 wt%, it can be seen that the added amount of ferrochrome is 0.5 to 2.0 wt%, which is the most preferable bar, indicating a higher elongation, considering both strength and elongation.

In addition, referring to Table 7, it can be seen that cracks occurred in the titanium alloy specimens according to Comparative Examples 4 and 6, but no cracks occurred in the titanium alloy specimens according to Examples 1 to 12.

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in the present specification. It is obvious that variations can be made. In addition, although the effects according to the configuration of the present invention are not explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Claims (8)

Molybdenum (Mo): 1.0 to 15.0 wt%, Chromium (Cr): 0.1 to 1.98 wt%, Iron (Fe): 0.1 to 0.93 wt%, Silicon (Si): 0.01 to 0.09 wt%, Oxygen (O): 0.4 Including weight % or less, but the content of chromium (Cr) is greater than the content of iron (Fe), and consists of the remaining titanium (Ti) and unavoidable impurities,
Titanium alloy, characterized in that it has a tensile strength of 1109 to 1510 MPa.
According to claim 1,
The titanium alloy has a molybdenum equivalent ([Mo]eq.) expressed by the following formula 1 of 5.5 to 20, and a titanium alloy, characterized in that it has a beta transformation point of 670 to 815 °C.
[Equation 1]
[Mo]eq. = [Mo] + 0.2 [Ta] + 0.28 [Nb] + 0.4 [W] + 0.67 [V] + 1.25 [Cr] + 1.25 [Ni] + 1.7 [Mn] + 1.7 [Co] + 2.5 [Fe]
According to claim 1,
The titanium alloy is a titanium alloy, characterized in that it has a yield strength of 545 to 1420 MPa and a Young's modulus of 80 to 110 GPa.
(a) adding ferrochrome including chromium (Cr), iron (Fe), silicon (Si) and carbon (C) to an alloy or mixture of titanium (Ti) and molybdenum;
(b) dissolving the resultant of step (a) and then cooling to form a titanium alloy base material; and
(c) hot forming a titanium alloy base material;
The ferrochrome includes iron (Fe): 20 to 35% by weight, silicon (Si): 1 to 4% by weight, carbon (C): 0.15% by weight or less, and consists of the remaining chromium (Cr) and unavoidable impurities, ,
Based on the total weight of the titanium alloy, 1 to 15% by weight of molybdenum and less than 4% by weight of ferrochrome are added,
The produced titanium alloy is molybdenum (Mo): 1.0 to 15.0 wt%, chromium (Cr): 0.1 to 1.98 wt%, iron (Fe): 0.1 to 0.93 wt%, silicon (Si): 0.01 to 0.09 wt%, oxygen (O): A method for producing a high-strength titanium alloy, characterized in that it contains 0.4 wt% or less, and consists of the remaining titanium (Ti) and unavoidable impurities, and has a tensile strength of 1109 to 1510 MPa.
5. The method of claim 4,
A method for producing a titanium alloy, characterized in that 0.5 to 2% by weight of the ferrochrome is added based on the total weight of the titanium alloy.
5. The method of claim 4,
The hot forming is a titanium alloy manufacturing method, characterized in that performed at a forming rate of 90% or less at 800 ~ 850 ℃. delete delete

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