JP2871292B2 - Manufacturing method of α + β type titanium alloy sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an .alpha. +. Beta. Type titanium alloy sheet, and more particularly to a method of manufacturing an .alpha. +. Beta. Type titanium alloy sheet capable of easily and reliably improving anisotropy of mechanical properties such as tensile strength. It is about the method.

[0002]

2. Description of the Related Art It is known that when an α + β type titanium alloy sheet is rolled in the same direction, a large anisotropy occurs in the mechanical properties of the titanium alloy sheet.

Conventionally, as a method of improving only the anisotropy of the yield strength of an α + β type titanium alloy sheet having the above-mentioned properties, Japanese Patent Application Laid-Open No. 61-147864 discloses a continuous hot-rolled annealed sheet of a titanium alloy comprising a specific component. Cold-rolled in the same direction as the hot-rolling direction at a cold rolling reduction of 67% or more, and then at 650 to 900 ° C.
A method for producing a titanium alloy sheet, which comprises annealing at a temperature within the range described above.

Japanese Patent Application Laid-Open No. 62-109956 discloses a hot-rolled sheet of a titanium alloy comprising a specific component as it is or after annealing, having a cold work of 85% or less. A method for producing a titanium alloy sheet, comprising cold working at a low rate and then subjecting to strain aging. Hereinafter, these methods are referred to as Prior Art 1.

On the other hand, as a method for improving the anisotropy of the mechanical properties at room temperature, not limited to the proof stress, Japanese Patent Application Laid-Open No. 62-54508 discloses a method of cutting a continuous hot-rolled coil of a titanium alloy in the width direction. A method for producing a titanium alloy sheet, comprising rolling the cut titanium alloy piece at a temperature in the range of 800 to 970 ° C. in a direction orthogonal to the hot rolling direction at a pressing rate of 70% or more is disclosed. ing. Hereinafter, this method is referred to as Prior Art 2.

Japanese Patent Application Laid-Open No. 60-230968 discloses α +
In the β region, cross-rolling is performed under a cross ratio of 0.6 to 1.4, then recrystallization annealing is performed, and then again in the α + β region, cross-rolling is performed under a cross ratio of 0.6 to 1.4, A method for producing a titanium alloy plate, which comprises annealing and performing solution aging treatment, is disclosed. Hereinafter, this method is referred to as Prior Art 3.

[0007]

However, the above-mentioned prior arts 1 to 3 have the following problems.

Prior art 1 It is possible to improve only the anisotropy of proof stress with a titanium alloy plate having a specific component. Moreover, it is not efficient because the cold rolling reduction needs to be increased.

Prior art 2 Rolling for improving anisotropy is performed hot and it is necessary to apply a large reduction, so that it is not efficient.

Prior art 3 Because of the rolling of a thick plate, it is not suitable for mass production as compared with the case of a hot continuous rolled plate, and the rolling itself needs to be performed in a high temperature range.

Accordingly, an object of the present invention is to provide a method of manufacturing an α + β type titanium alloy sheet which can easily and surely improve the anisotropy of mechanical properties.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for controlling heat in one direction.
Hot-rolled α-β titanium alloy sheet
Cold rolling or warm rolling is performed at a rolling reduction in the range of 20 to 45% in the direction perpendicular to the direction, and thus the anisotropy of the mechanical properties of the titanium alloy sheet is improved. is there.

In the present invention, hot-rolled in one direction
The direction perpendicular to the hot rolling direction on the α + β type titanium alloy plate
The reason why cold rolling or warm rolling is performed at a predetermined reduction rate will be described.

In the case of an α + β type titanium alloy sheet, the cold rolling limit in the direction orthogonal to the hot rolling direction is generally low,
May be below. In such a case, the rolling material
It is necessary to perform so-called warm rolling, which is performed after rolling in a temperature range of 250 to 500 ° C. and rolling. This makes it possible to obtain a rolling reduction of 20% or more. Even if the α + β type titanium alloy plate is heated to a temperature of 500 ° C., the amount of oxidized scale generated on the surface of the titanium alloy plate is small, so that the pickling finishing step is reduced and the crystal grains are coarsened. Hardly progresses. Therefore, in the present invention, in the case of an α + β type titanium alloy sheet having a low cold rolling limit, warm rolling is performed on the titanium alloy sheet. In the case of an α + β type titanium alloy sheet having a high cold rolling limit, it goes without saying that cold rolling may be used.

In the present invention, the reason why the rolling reduction is limited as described above is that not only the mechanical properties at room temperature, that is, hardness, proof stress, tensile strength and anisotropy in total elongation are improved, but also Is greatly improved as compared with the material before rolling. The reason for limiting the rolling reduction will be described later.

[0016]

Next, an embodiment of the present invention will be described.
Al: 4.65%, V: 3.02%, Mo: 1.95%, Fe: 1.98%, O: 0.072%,
H: α + β with a diameter of 750mm consisting of 0.003% (or more by weight)
Type titanium alloy ingot is hot forged, 143mm thick,
A slab having a width of 1000 mm was prepared. The heating temperature of the ingot during hot forging was 1100 ° C, and the finishing temperature was 830 ° C. Next, the slab thus prepared was rolled by a continuous hot rolling mill to prepare a coil having a thickness of 2.8 mm and a width of 1080 mm. The heating temperature of the slab during hot rolling is 860
° C and the finishing temperature were 770 ° C.

Next, a plurality of test pieces having a thickness of 2.5 mm and a width of 80 mm were cut out from the coil thus prepared, and the test pieces were subjected to reductions of 10, 20, 30, 40, 45 and 50%. Rolling was performed in a direction perpendicular to the hot rolling direction. Of these, 3
The specimens rolled at 0, 40, 45 and 50% reduction were warm-rolled at a temperature of 300 ° C. and the remaining specimens were:
Cold rolling was performed.

Each of the test pieces rolled as described above was annealed at a temperature of 800 ° C. for 1 hour, and the relationship between the rolling reduction, the total elongation and the tensile strength (YS, TS) was examined. FIG. 1 also shows these results. In FIG.
The L direction is a rolling direction, and the C direction is a direction orthogonal to the rolling direction L.

As is apparent from FIG. 1, the unidirectional continuous rolled material (rolling ratio in the figure is 0%) has a difference in proof stress between the rolling direction and the direction perpendicular to the rolling direction of 25 kgf / mm ² and a difference in tensile strength. Is 20kgf /
mm ² also, but from 20 in a direction perpendicular to the hot rolling direction 45
It has been found that when cold or warm rolling is performed within the range of%, the mechanical properties are almost eliminated, and the elongation is improved as compared with the hot rolled material as a rolled material. On the other hand, it was found that when the rolling reduction exceeded 45%, anisotropy appeared again in tensile strength and elongation.

Next, another embodiment of the present invention will be described. Al: 6.12%, V: 3.87%, Fe: 0.01%, O: 0.104%, H: 0.
Hot forging of α + β type titanium alloy ingot of diameter 750mm consisting of 012% (more than weight%), 147mm in thickness and 75 in width
A 0 mm slab was prepared. The heating temperature of the ingot during hot forging was 1200 ° C, and the finishing temperature was 1100 ° C.
Next, the slab thus prepared was rolled by a continuous hot rolling mill under conditions of a cross ratio of 16.2, and the thickness was 30 m.
A thick plate having a width of 1150 mm was prepared. The heating temperature of the slab during hot rolling was 950 ° C, and the finishing temperature was 800 ° C.

Next, a plurality of test pieces having a thickness of 28 mm and a width of 80 mm were cut out from the thick plate thus prepared, and these test pieces were cut at a rolling reduction of 10, 20, and 30% and orthogonal to the hot rolling direction. The rolling was performed in the direction in which the rolling was performed. Of these, the test pieces rolled at rolling rates of 20 and 30% were warm-rolled at a temperature of 450 ° C., and the remaining test pieces were cold-rolled.

Each of the test pieces rolled as described above was annealed at a temperature of 800 ° C. for 1 hour, and the relationship between the rolling reduction, the total elongation, and the tensile strength (YS, TS) was examined. These results are shown in FIG. In FIG.
The L direction is a rolling direction, and the C direction is a direction orthogonal to the rolling direction L.

As is clear from FIG. 2, the unidirectional continuous rolled material (rolling ratio in the figure is 0%) has a difference in proof stress of 25 kgf / mm ² between the rolling direction and the direction perpendicular to the rolling direction, and a difference in tensile strength. Is 15kgf /
mm ² also, but 20 to 39% in a direction perpendicular to the hot rolling direction
When subjected to warm rolling, the mechanical properties almost disappear,
As for elongation, it is 5 to 7 compared to hot rolled material which is a rolled material.
%.

[0024] The Ti-6Al-4V titanium alloy used in this example was subjected to warm rolling as described above because of its low cold workability. The rolling limit is reached. Therefore, when such a material is used, if the rolling reduction of 20% or more is ensured, the anisotropy of the mechanical properties at room temperature can be sufficiently reduced, so that warm rolling is performed. Limit was found to be effective.

[0025]

As described above, according to the present invention, the anisotropy of the mechanical properties of an α + β type titanium alloy sheet having a large anisotropy of mechanical properties manufactured by a tandem mill or the like can be easily and easily obtained. A useful effect such that the improvement can be surely achieved and the total elongation can be improved is provided.

[Brief description of the drawings]

Fig. 1 Reduction rate, total elongation and tensile strength (YS, T) of Ti-4.5Al-3V-2Mo-2Fe titanium alloy in cold and warm conditions
6 is a graph showing the relationship with S).

FIG. 2 is a graph showing the relationship between the rolling reduction of a Ti-6Al-4V titanium alloy in cold and warm conditions, and the total elongation and tensile strength (YS, TS).

────────────────────────────────────────────────── ⁶ Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C22F 1/00 683 C22F 1/00 683 685 685A 685Z 686 686A 694 694A (56) ) Tokiko 2-19182 (JP, B2) Iron and Steel, Vol. 72, No. 5, PP. S735-S736 (1986) (58) Fields investigated (Int. Cl. ⁶ , DB name) C22F 1/18 B21B 1/24 B21B 3/00

Claims (2)

(57) [Claims] 1. An α + β type titanium which is hot-rolled in one direction.
20 to 4 in the direction perpendicular to the hot rolling direction
Cold rolling or warm rolling at a rolling reduction within a range of 5%, thereby improving the anisotropy of the mechanical properties of the titanium alloy sheet, characterized by the fact that the titanium alloy sheet has anisotropy in mechanical properties. . To wherein said titanium alloy plate was rolled between the cold rolling or warm, characterized in that the recrystallization annealing is subjected method of alpha + beta type titanium alloy plate according to claim 1, wherein.