JP3481428B2 - Method for producing Ti-Fe-ON-based high-strength titanium alloy sheet with small in-plane anisotropy - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a Ti—Fe—O—N based high strength titanium alloy sheet containing iron, oxygen and nitrogen as main alloying elements.

[0002]

2. Description of the Related Art High strength α + β type titanium alloys represented by Ti-6Al-4V are lightweight, high strength and high corrosion resistance.
Since it has various processing characteristics such as weldability, superplasticity, and diffusion bondability, it has been widely used mainly in the aircraft industry. In order to further utilize these characteristics, in recent years, it has come to be used for sports equipment such as golf equipment, automobile parts, civil engineering building materials, various tools, deep sea and energy development applications. The expansion of application to the so-called consumer products field is also underway. However, the remarkably high production cost of α + β type titanium alloys slows down the progress speed thereof, and development of inexpensive titanium alloys is required to promote expansion of application to these consumer products fields.

The reasons for the high production cost of these high strength α + β type titanium alloys are that i) the use of expensive β phase stabilizing elements such as V, ii) α phase stabilizing elements and solid solution strengthening elements The Al used as is significantly increased in deformation resistance during hot work and impairs hot workability, which makes it difficult to work and easily causes defects such as cracks. In particular, iii) is a large cost factor when manufacturing the plate, which is the main product, and there are problems such as the need for reheating during rolling and the cracking of the plate edge to reduce the material yield. there were.

Under these circumstances, various low-cost titanium alloys have been proposed in recent years, and among them, Ti-Fe-O has been proposed.
-N-based high-strength titanium alloy employs inexpensive Fe as a β-phase stabilizing element, and further, Al that reduces hot workability.
Instead of, it uses oxygen and nitrogen as α-phase stabilizing elements that are inexpensive and do not impair hot workability.
Compared with the conventional α + β type titanium alloy, it is expected that the cost will be considerably reduced.

However, when this Ti-Fe-O-N-based titanium alloy is manufactured by ordinary unidirectional rolling, extreme in-plane material anisotropy occurs and the characteristics of the plate in the longitudinal direction are excellent. However, there is a problem that ductility in the width direction is extremely poor. Therefore, the birth of a Ti-Fe-O-N-based high strength titanium alloy plate having small in-plane anisotropy and high strength and ductility in both the length direction and the width direction of the plate has been strongly desired.

[0006]

Such in-plane anisotropy is present in Japanese Examined Patent Publication No. Sho 62 in the existing α type and α + β type titanium alloys.
It is known that it can be reduced by repeatedly performing cross rolling, as disclosed in Japanese Patent Publication No. 24498. However, this method is a complicated process such as breaking down the ingot, and repeating the process of rolling in different directions and annealing,
High cost. That is, Ti-
When applied to a Fe-O-N type titanium alloy, there is a problem in that the characteristic of the alloy, that is, the low cost of bending is ruined.

In view of these problems, the present invention makes the most of the features of the Ti-Fe-O-N high strength alloy, which is low cost, has a small in-plane anisotropy, and has a plate length. It is an object of the present invention to provide a practical plate product having high strength and high ductility in both the width direction and the width direction, and further to provide a method for manufacturing the product.

[0008]

In order to achieve the above object, the inventor diligently studied the cause of the anisotropy of a Ti--Fe--O--N type high strength alloy, and as a result, a direction orthogonal to the initial rolling direction was obtained. By rolling only once with an appropriate reduction ratio, it was found that the in-plane anisotropy of strength and ductility is significantly reduced without repeating complicated cross rolling, and the present invention has been completed. The present invention has the following structures. ( 1 ) % by mass , Fe: 0.8 to 2.3%, N: 0.
Containing less than 05%, the balance consisting essentially of Ti , and oxygen equivalent value: Q = [ % O 2 ] +2.77 [ % N 2 ] +0.1
A titanium alloy ingot or slab whose [ % Fe ] is in the range of 0.35 to 1.00 is heated to a temperature range not higher than the β transformation point of the alloy, and slab rolling is performed. A slab
In the method for producing a titanium alloy sheet by heating in a temperature range below the β transformation point, tenter rolling and sequentially rolling in the length direction, and then annealing, the slab rolling direction and tenter rolling direction are the same direction. , The direction orthogonal to it is the length rolling direction,
Slabbing and tentering against the rolling reduction of lengthwise rolling
The ratio of total rolling reduction is 0.70 to 1.43, the total rolling reduction of slabbing, tenter rolling, and lengthwise rolling is 80% or more, and further the rolled sheet 600 ℃ ~ β
Temperature below the transformation point at annealed over 10 minutes, the length direction of the plate
And tensile strength in the width direction are both 700 MPa or more.
And in the plate length direction relative to the tensile strength in the plate width direction.
The ratio of tensile strength is 0.95 to 1.05 times,
In addition, the tensile elongations in the length direction and the width direction are both 15
Plane, characterized in that to obtain a titanium alloy plate is at least%
A method for producing a Ti-Fe-O-N-based high-strength titanium alloy plate having small anisotropy . ( 2 ) % by mass , Fe: 0.8 to 2.3%, N: 0.0.
Containing less than 05%, the balance consisting essentially of Ti , and oxygen equivalent value: Q = [ % O 2 ] +2.77 [ % N 2 ] +0.1
A titanium alloy ingot or slab whose [ % Fe ] is in the range of 0.68 to 1.00 is heated to a temperature range equal to or lower than the β transformation point of the alloy, and slabbing is performed. A slab
In the method for producing a titanium alloy sheet by heating in a temperature range below the β transformation point, tenter rolling and sequentially rolling in the length direction, and then annealing, the slab rolling direction and tenter rolling direction are the same direction. , The direction orthogonal to it is the length rolling direction,
For rolling reduction in the length direction rolling out slabbing and width
The ratio of total rolling reduction is 0.70 to 1.43, the total rolling reduction of slabbing, tenter rolling, and lengthwise rolling is 80% or more, and further the rolled sheet 600 ℃ ~ β
Temperature below the transformation point at annealed over 10 minutes, the length direction of the plate
And the tensile strength in the width direction is 900 MPa or more.
And in the plate length direction relative to the tensile strength in the plate width direction.
The ratio of tensile strength is 0.95 to 1.05 times,
In addition, the tensile elongations in the length direction and the width direction are both 15
Plane, characterized in that to obtain a titanium alloy plate is at least%
A method for producing a Ti-Fe-O-N-based high-strength titanium alloy plate having small anisotropy .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Generally, α type and α type containing Al
It is well known that when a + β type titanium alloy is hot worked, a strong texture is formed. Among them, when rolled in one direction, a texture called a transverse texture is formed, compared with the length direction of the plate, the strength in the plate width direction becomes high, and the ductility in this direction reciprocally Markedly reduced. On the other hand, a plate having this transverse texture is
Rolling in a direction orthogonal to the initial rolling direction reduces the transverse texture and strengthens the texture called basal texture. As this basal texture develops, the in-plane anisotropy decreases.

The present inventor has conducted extensive studies on the texture of a Ti—Fe—O—N type high strength titanium alloy, and as a result,
The following new findings were obtained. That is, (a) when an alloy system to which oxygen and nitrogen are added like this alloy is rolled, Ti
Compared with existing Al-containing α + β type titanium alloys such as -6Al-4V, the transverse texture is significantly more likely to develop, and as a result, in-plane anisotropy is significantly stronger than existing Al-containing α + β type titanium alloys. (B) On the contrary, Ti
The transverse texture of the —Fe—O—N system titanium alloy can be easily basalized by repeating rolling once in a direction orthogonal to the initial rolling direction at an appropriate reduction rate without repeating complicated cross rolling. It was found that the structure can be converted into a structure and the degree of accumulation is significantly higher than that of the existing Al-containing α + β type titanium alloy such as Ti-6Al-4V, and the in-plane anisotropy of strength and ductility is significantly reduced.

The present invention is based on the above findings, and is an invention that makes full use of the metallurgical features of Ti-Fe-O-N alloys. Now, according to the present invention, a practical Ti-Fe-O- which is low in cost, has small in-plane anisotropy of the plate, and has high strength and high ductility in both the length direction and the width direction of the plate.
The N-based titanium alloy plate has the characteristics as described in (1) above. That is, in mass% , Fe: 0.8 to 2.3%, N
: 0.05% or less, the balance being substantially Ti, and oxygen equivalent value: Q = [ % O 2 ] +2.77 [ % N 2 ] +
In a titanium alloy plate in which 0.1 [ % Fe ] is in the range of 0.35 to 1.00, the tensile strengths in the length direction and the width direction of the plate are both 700 MPa or more, and the plate width is Person
The ratio of the tensile strength in the plate length direction to the tensile strength in the
Ti-Fe-O-N with small in - plane anisotropy, which is 0.95 to 1.05 times , and further has tensile elongations in the length direction and the width direction of 15% or more. System high strength titanium alloy plate.

The strength level with a tensile strength of less than 700 MPa is achieved by, for example, JIS Class 4 pure titanium, and is not within the range covered by high strength titanium alloys. Further, if the tensile elongation of 15% or more is not ensured in both the length direction and the width direction of the plate, it is insufficient for a high load application such as using a high strength alloy. In addition, with respect to the tensile strength in the plate width direction,
If the ratio of tensile strength is not 0.95 to 1.05 times , unevenness may occur during processing such as bending and the shape may not be stable. The Ti-Fe-O-N-based titanium alloy plate having the characteristics of strength and ductility as described above is inexpensive, and at the same time, it is processed into the final product shape, from the practical viewpoint of stability in actual use, It is a very useful product.

In the Ti—Fe—O—N high strength titanium alloy, the Fe content is limited to 0.8 to 2.3% for the following reason. In other words, Fe is an element that is added to enhance strength and ductility because it causes a β phase to promote the refinement of the structure, but it is an element that easily solidifies and segregates, and in an alloy containing more than 2.3% Fe. However, the solidification segregation becomes very remarkable, and the ductility decreases at that portion, so that the effect of the present invention cannot be sufficiently achieved. Also, 0.8
In an alloy containing only Fe of less than 10%, the effect of refining the structure is insufficient, and as a result, the strength and ductility are also insufficient.

The reason for setting the Q value to 0.35 to 1.00 is as follows. That is, Q = [ % O ] +2.77
[ % N ] +0.1 [ % Fe ] is an index showing the strength of the alloy, and the degree of contribution to the strength of Fe, O, and N, which are alloying elements, is O: N: Fe = 1: 2. This is a formula devised based on the fact that it is 77: 0.1. And Q is 0.3
Alloys such as 5 to 1.00 are 700 MPa to 12
It is a high strength alloy having a tensile strength of about 00 MPa .
That is, alloys with a Q of less than 0.35 have low strength, and ultra-high-strength alloys with a Q of more than 1.00 originally have low ductility. Since it is difficult to secure a tensile elongation of 15% or more in both directions, it is outside the scope of the present invention.

Further, the content of N is set to 0.05% or less, because if it is added over this amount, a compound with Ti precipitates and ductility decreases, so that the length direction and the width direction of the plate are reduced. In both cases, it is difficult to secure a tensile elongation of 15% or more. The plate having a small in-plane anisotropy and high strength and high ductility in both the length direction and the width direction can be manufactured by the method described in ( 1 ) above.

[0016] Generally, the sheet is manufactured by using a continuous rolling mill such as a hot strip rolling mill or a reverse type rolling mill such as a thick plate rolling mill. Of these, when a hot strip rolling mill is used, since the rolling direction is constant, strong rolling in one direction is unavoidable, resulting in extreme in-plane material anisotropy. Although it has excellent properties in the length direction, the ductility in the plate width direction becomes extremely poor. Therefore, this method cannot be applied. On the other hand, when a plate is manufactured by the reverse type rolling mill, the rolling direction can be changed on the way so that complicated cross rolling is actually repeated. Therefore, this manufacturing method
The use of the latter reverse type rolling mill is a prerequisite.

This manufacturing method uses a Ti--Fe--O--N system
Ingot or slab of high strength titanium alloy is
Heating to a temperature range below the freezing point, slab rolling, and
Heat the slab to a temperature range below the β transformation point and
The plate is manufactured by sequentially rolling and rolling in the length direction. here,
1) Ingot or slab heating temperature before slab rolling, slab rolling
The heating temperature of the subsequent agglomerate slab is the β transformation point of the alloy.
It is necessary to be the following, 2) lump rolling direction and width
The rolling direction is the same, and the length rolling direction is orthogonal to these.
It must be the direction to do 3)Rolling reduction of lengthwise rolling
To the ratio of total rolling reduction of slabbing and tenter rolling
Must be in the range 0.70 to 1.43. Well
4) Total reduction of slabbing, tenter rolling, and longitudinal rolling
The rate must be above 80%. About the reason
This will be described below.

As described above, this alloy has a feature that extremely strong in-plane anisotropy develops in rolling in one direction, but when rolling in a direction orthogonal to this, a complicated cross is produced. It also has a metallurgical feature that the in-plane anisotropy can be easily reduced without repeating rolling. Therefore, it is necessary to change the rolling direction only once during the manufacturing process, but the rolling reduction ratio in rolling in the two directions must be close to 1. In other words, it is necessary that the reduction rate in rolling in a certain direction and the reduction rate in rolling in a direction orthogonal to this direction do not differ significantly. When a plate is manufactured using a reverse type rolling mill, it is unavoidable that the rolling reduction of the last lengthwise rolling becomes high.Therefore, tenter rolling before that and further slab rolling prior to this By making the directions equal and bringing the total reduction rate of both to approach the reduction rate of the lengthwise rolling, the ratio of the reduction rates in rolling in the two directions can be brought close to 1 for the first time. This is the technical explanation of 2) above. Regarding the above 3), the fact that the in-plane anisotropy disappears or becomes slight is
Slabbing and tentering against the rolling reduction of lengthwise rolling
In the case where the ratio of the total rolling reduction ratio is in the range of 0.70 to 1.43, if the ratio deviates from this range, the in-plane anisotropy becomes strong, and in particular the ductility in the length direction or width direction of the plate. Becomes scarce. As described above, in the present invention, the slabbing is an essential step, and it cannot be replaced by forging. However, the material used for the slabbing may be an ingot or a slab manufactured by forging.

Technically, regarding the above 1),
When heated to a temperature above the β transformation point, the structure coarsens and the texture generated by rolling disappears, and ductility decreases in both the length direction and the width direction. It must be carried out below the β transformation point. Regarding 4), unless structural refinement is also achieved, sufficient ductility cannot be ensured. Therefore, the total rolling reduction after slabbing must be a high value of 80% or more. If it is less than the above range, sufficient microstructure refinement due to work recrystallization cannot be achieved, resulting in insufficient ductility.

The process sequence described above is the same as a general metal sheet manufacturing method using a reverse rolling mill, although there are restrictions on heating temperature, rolling reduction, rolling direction, etc. No additional steps are added. That is, there are no extra steps such as repeated cross rolling, which have large dimensional constraints and increase costs, and the low cost of the Ti-Fe-O-N titanium alloy is sufficiently maintained. ing.

Next, the rolled sheet has a temperature of 600 ° C. to β.
Annealing is performed for 10 minutes or more at a temperature below the transformation point. As a result, excess processing strain is removed, and a product having excellent strength and ductility in both the width direction and the length direction can be manufactured. here,
The reason why the annealing condition is 600 ° C. to less than the β transformation point is 600.
If the temperature is lower than ℃, the diffusion is insufficient, the strain is not completely removed, and high ductility cannot be achieved. Also, when heated to a temperature higher than the β transformation point, the structure becomes coarse, which also reduces ductility. Because. Further, the annealing time is set to 10 minutes or more because the diffusion is insufficient and the strain is not completely removed at any plate thickness or plate width, if the time is shorter than this.
This is because high ductility cannot be achieved. In the present invention, the upper limit of the annealing time was not particularly limited, but this may be appropriately adjusted according to the dimensions such as the plate thickness and the plate width, and may be completed when the strain is sufficiently released, and belongs to the prior art. Therefore, the present invention does not specifically limit this. In addition,
This annealing can also be performed in combination with hot straightening treatment such as creep straightening.

The titanium alloy described in (2) above is particularly a Ti-Fe-O-N high strength titanium alloy having a higher strength such that the oxygen equivalent value Q is 0.68 to 1.00. The present invention is applied. An alloy having an oxygen equivalent value in this range has particularly high strength among Ti—Fe—O—N titanium alloys and has a tensile strength of 900 MPa or more, but the material anisotropy is The effect of applying the present invention is particularly remarkable because it is likely to appear very strongly. This Ti—Fe—O—N high strength titanium alloy also has the above ( 2 )
As described, it can be manufactured by the same rolling and annealing method as the above (1) except that the Q value is set to 0.68 to 1.00.

The present invention has been described in detail above.
In Ti-Fe-O-N-based high-strength titanium alloy of the present invention, Fe, O, in addition to N, purpose 0.3 or mass% or less of the platinum group elements are added in improving corrosion resistance, Ni, Cr an impurity element such as, no influence on the characteristics also contain long each 0.3 mass% or less.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples. <Example 1> 250 mm thick by electron beam melting method
Ti-1.5% Fe-0.5% O- with a width of 1000 mm
0.04% N (Q = 0.76, β transformation point = 960 ° C.) ingot was produced, from which slabs of various dimensions were cut and sampled, and rolled into a plate under the conditions shown in Table 1, 750 ° C-1h
Was annealed and air cooled. Then, tensile test pieces in the length direction and the plate width direction of this plate were cut out and subjected to a tensile test. The test results are shown in Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

In Table 1, test number 1 is 90 m.
This is an example in which a slab having a thickness of m is directly subjected to lengthwise rolling (unidirectional rolling) without slabbing and tentering rolling. As shown in Table 2, although high strength and high ductility are achieved in the length direction of the plate, there is almost no ductility in the width direction of the plate, and the tensile elongation is only 3.2%. Before reaching, it broke during the test and the tensile strength could not be measured. Test No. 2 did not perform slabbing (reduction rate of slabbing = 0
%), And tenter rolling and longitudinal rolling only. In this case, total rolling reduction (a) of slabbing and tenter rolling
Since the ratio (a / b) of the reduction ratio (b) in the rolling direction and the rolling direction in the lengthwise direction was smaller than the range of 0.70 to 1.43 specified in the method described in the second aspect of the invention, the tensile force in the width direction of the sheet was obtained. The elongation is insufficient, and the ratio (c / d) of the tensile strength (c) in the length direction of the plate and the tensile strength (d) in the width direction of the plate is 0.95 described in the first invention. It deviates from the range of 1.05 and the in-plane anisotropy of the plate becomes strong. Test No. 3 is an example in which slabbing rolling, tenter rolling, and lengthwise rolling were carried out in order, but the effect of the present invention was achieved because the directions of slabbing and lengthwise rolling were the same. However, although the strength and ductility of the plate in the length direction were excellent, the in-plane anisotropy was strong, and the ductility in the plate width direction was particularly poor. In Test No. 5, the heating temperature of the slabbing was not less than the β transformation point and was out of the temperature range specified by the method of the present invention 2 , so that the structure became coarse and the ductility became poor in both directions. In addition, test number 8
Since the total reduction ratio after the slabbing was less than 80% specified by the method described in the second aspect of the present invention, sufficient microstructure refinement was not achieved and ductility was lowered in both directions.

In contrast to the above comparative examples, all of the test numbers 4, 6 and 7 of the present invention have tensile strengths of 900 MPa or more in both the length direction and the width direction of the plate and their ratios. Is 0.95 or more and 1.05 or less, the tensile elongation in both the length direction and the width direction of the plate is 15% or more, the in-plane anisotropy is small, and high strength and high ductility Ti-in both directions is obtained. F
An e-ON type high strength titanium alloy plate has been obtained. <Example 2> Ti-1.5% by the vacuum arc twice melting method
Fe-0.5% O-0.04% N ingot is manufactured and
It is made into a slab with a thickness of 250 mm and a width of 1000 mm by forging at 0 ° C., heated to 850 ° C., and slab-rolled to 90 m.
m thickness-1000 mm width. This was subdivided into pieces each having a length of 900 mm, and rolled and annealed under the conditions shown in Table 3. At this time, the rolling direction was the same as the slab rolling direction and the tenter rolling direction, and the lengthwise rolling was performed so as to be orthogonal thereto. That is, the width and length direction of the slab are
It corresponds to the length and width of the product plate. Then, cut out a tensile test piece from the length direction and the plate width direction of this plate,
A tensile test was conducted. The test results are shown in Table 4.

[0029]

[Table 3]

[0030]

[Table 4]

Now, in Table 3, test numbers 10 and 1
1, 12, 13, 16 and 18 are all examples of the present invention, and as shown in Table 4, all have a tensile strength of 900 MPa or more in both the length direction and the width direction of the plate and the ratio thereof. Is 0.95 or more and 1.05 or less, the tensile elongation in both the length direction and the width direction of the plate is 15% or more, the in-plane anisotropy is small, and high strength and high ductility Ti-in both directions is obtained. F
An e-ON type high strength titanium alloy plate has been obtained. Test No. 16 is an example of performing both annealing and creep correction, and in this case also, a plate having excellent characteristics was obtained. In Test No. 12, the rolling reduction of the tenter rolling was set to 1%, but this was performed to adjust the shape of the plate, and substantially tenter rolling was not performed.

For the above examples, test numbers 9, 14,
15, 17, 19 both in the length direction and the width direction of the plate
Direction elongation is small, or ductility in one direction is small
In-plane anisotropy with high strength appeared. Exam number 9
Indicates that the slab heating temperature before sheet rolling is at or above the β transformation point,
inventionTwoSince the temperature is outside the temperature range specified in
Became coarse and the ductility became poor in both directions. Exam number 1
4 is the total rolling reduction (a) and length of slab rolling and tenter rolling
The ratio (a / b) of the reduction ratio (b) of the direction rolling is the present invention.TwoIn
Than the range of 0.70 to 1.43 specified in the method
Large, insufficient tensile elongation in the longitudinal direction, and
Tensile strength in the length direction (c) and tensile strength in the width direction (d)
The ratio (c / d) of1Described in 0.95
It deviates from the range of 1.05 and the in-plane anisotropy becomes strong.
I ended up. Test No. 15 has an annealing temperature of the present invention.TwoRecord
Since the temperature was lower than the lower limit temperature specified in the mounting method, diffusion
Is insufficient and strain removal is insufficient, resulting in high ductility in both directions.
Was not achieved. Test No. 17 shows that the annealing time is
inventionTwoIt was less than the lower limit time specified in the described method.
Therefore, the diffusion is insufficient and the strain is not removed sufficiently in both directions.
High ductility was not achieved. Test No. 19 is the annealing temperature
Degree of the inventionTwoAbove the maximum temperature specified in the described method
Since it was above the β transformation point, the structure became coarse and this also
The ductility of the direction has deteriorated. <Example 3> The composition shown in Table 5 and the β
Ti-Fe-O-N system titanium alloy is melted, 1000 ° C
By heat forging, the thickness of 250mm-1000mm width
And heat to 850 ° C, which is a temperature below the β transformation point,
Slab rolling was performed to obtain a thickness of 90 mm and a width of 1000 mm. This
Slab of 900mmCut to length and re-heat to 850 ° C
A plate with a thickness of 6 mm that is heated, tentering and lengthwise rolled
Was manufactured. The rolling direction at this time is the rolling direction of the slab.
The direction of tenter rolling is the same as that of tenter rolling.
I went to meet each other. That is, slab width and length direction
Corresponds to the length and width of the product plate, respectively. Also this
Total rolling reduction of slabbing and tenter rolling(A)
And the rolling reduction of the longitudinal rolling(B)ratio(A / b)Is
1.00, slab rolling, tenter rolling, longitudinal rolling
The total rolling reduction is 97.6%. Then rolled plate
Was annealed at 750 ° C. for 1 hour and air-cooled. And this
Cut out tensile test pieces in the length and width directions of the plate,
A tensile test was conducted. The test results are also shown in Table 5.

[0033]

[Table 5]

Now, in Table 5, test numbers 21 and 2
Nos. 3, 26, 27, 29, and 30 are examples of the present invention, and all have tensile strengths of 700 MPa or more in both the length direction and the width direction of the plate and a ratio of 0.95 or more and 1.0 or more.
5 or less, the tensile elongation in both the length direction and the width direction of the plate is 15% or more, the in-plane anisotropy is small, and the Ti-Fe-O-N-based high strength in both directions is high. A strong titanium alloy plate has been obtained. Test numbers 29 and 30 are
Pd and Ni are contained by 0.3% or less for improving corrosion resistance or as impurities, but the effect of the present invention is sufficiently achieved.

On the other hand, in Test No. 20, since the Fe content was less than 0.8%, the structure refining effect was insufficient, and as a result, high strength (tensile strength) commensurate with the oxygen equivalent value was obtained. 900 MPa or more) and high ductility (tensile elongation 1
5% or more) was not achieved. Test No. 22 has a low strength (700 MPa or less in tensile strength) because the oxygen equivalent value is less than 0.35 which is the target of the present invention, and is not applicable to the present invention. Test No. 24 has a nitrogen content of 0.0
Since it was added in excess of 5%, a compound of Ti and nitrogen was precipitated and ductility was lowered. Test number 25 is Fe
Content of more than 2.3%, solidification segregation occurred, and the ductility decreased in that portion. In Test No. 28, the oxygen equivalent value exceeded 1.00, so the ductility decreased in both the width direction and the length direction.

[0036]

As described above, according to the present invention, a practical Ti-Fe-O having a small in-plane anisotropy and a high strength and a high ductility in both the width direction and the length direction of the plate.
It is possible to provide a —N titanium alloy plate and a method for producing the same, and to maximize the characteristics of the Ti—Fe—O—N high strength alloy, which is low cost. Therefore, it can be said that the present invention has an extremely high industrial value.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 684 C22F 1/00 684C 691 691B 691C 694 694A (58) Fields investigated (Int.Cl. ⁷ , DB name) C22F 1/00-3/02 C22C 14/00

Claims (2)

(57) [Claims] 1. In mass% , Fe: 0.8 to 2.3%, N
: 0.05% or less, the balance being substantially of Ti
, Oxygen equivalent value: Q = [ % O ] +2.77 [ % N ] +
A titanium alloy ingot or slab having a content of 0.1 [ % Fe ] in the range of 0.35 to 1.00 is heated to a temperature range below the β transformation point of the alloy, slab rolling is performed, and The slab after agglomeration is heated to a temperature range below the β-transformation point, and subjected to tenter rolling and lengthwise rolling in order and then annealed, in the method for producing a titanium alloy sheet, in the slab rolling direction and tentering. The rolling direction is the same direction, and the direction orthogonal to it is the length rolling direction.
The ratio of the total rolling reduction of the tenter rolling is in the range of 0.70 to 1.43, the total rolling reduction of the slab rolling , tenter rolling, and length rolling is 80% or more, and further, after rolling. Plate of 600
℃ annealed at a temperature below ~β transformation point or more 10 minutes, the length of the plate
Tensile strength in both depth and width directions is 700MP
Plate length that is a or more and the tensile strength in the plate width direction
The ratio of tensile strength in the direction is 0.95 to 1.05 times,
Furthermore, the tensile elongation in the length direction and the width direction are both
Characterized by obtaining a titanium alloy plate of 15% or more
A method for producing a Ti-Fe-O-N-based high strength titanium alloy plate having a small in - plane anisotropy . 2. Fe: 0.8 to 2.3%, N in mass%
: 0.05% or less, the balance being substantially of Ti
, Oxygen equivalent value: Q = [ % O ] +2.77 [ % N ] +
A titanium alloy ingot or slab in which 0.1 [ % Fe ] is in the range of 0.68 to 1.00 is heated to a temperature range equal to or lower than the β transformation point of the alloy, slab rolling is performed, and The slab after agglomeration is heated to a temperature range below the β-transformation point, and subjected to tenter rolling and lengthwise rolling in order and then annealed, in the method for producing a titanium alloy sheet, in the slab rolling direction and tentering. The rolling direction is the same direction, and the direction orthogonal to it is the length rolling direction.
The ratio of the total rolling reduction of the tenter rolling is in the range of 0.70 to 1.43, the total rolling reduction of the slab rolling , tenter rolling, and length rolling is 80% or more, and further, after rolling. Plate of 600
℃ annealed at a temperature below ~β transformation point or more 10 minutes, the length of the plate
Tensile strength in both depth and width directions is 900MP
Plate length that is a or more and the tensile strength in the plate width direction
The ratio of tensile strength in the direction is 0.95 to 1.05 times,
Furthermore, tensile elongation in the longitudinal and transverse directions are both
Characterized by obtaining a titanium alloy plate of 15% or more
A method for producing a Ti-Fe-O-N-based high strength titanium alloy plate having a small in - plane anisotropy .