JPH10291029A - Straightening method for alpha+beta type titanium alloy straight bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To straighten an α+β type titanium alloy straight bar in relatively high productivity and to produce a straight bar having good straightness from a wire rod made of, particularly, an α+β type titanium alloy. SOLUTION: By inserting a bar having bends straightened from a wire rod coil of α+β type titanium alloy in any container among a round shape, a circular arc shape, an U shape, an V shape in cross section and holding at a prescribed hold temp. of below the βtransformation temp. for a prescribed time or more, bends of the bar is not increased at heat treatment and is efficiently reduced, further, stabilized straightness is obtained after subsequent cold straightening, cutting and grinding of a surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for straightening an α + β type titanium alloy straight bar, and more particularly to a method for manufacturing a straight bar from a wire coil made of an α + β type titanium alloy.

[0002]

2. Description of the Related Art In general, a two-roll straightener, a multi-roll straightener, and a spinner straightener for performing bending correction in a cold state are used for correcting a steel wire. However, general-purpose α + β-type titanium alloys have a higher proof stress at room temperature than steel and have a large springback, making it extremely difficult to correct them in the cold.
In particular, when straightening from the coil state, a sufficient straightness cannot be obtained because the amount of plastic deformation is insufficient with the above-mentioned general cold straightening machine for steel.

[0003] Further, when a straightening machine having a straightening ability is used for straightening, since the shape is maintained by the residual stress of the surface layer, the residual stress is reduced by heating, surface cutting and grinding in the next step. I lose my balance and bend. On the other hand, annealing may be performed to remove the residual stress given by the cold straightening.However, due to uneven heating, the residual stress that has maintained the shape of the rod is released unevenly, and is usually released. It is bent directly because it is placed directly on the hearth and the transport roller and there is no restraint. Therefore, it is necessary to repeat cold straightening and annealing several times,
Low productivity.

[0004] As a method of correcting a wire such as a titanium alloy which is difficult to correct in a cold state, there is a method of correcting the tension in a warm state or in a hot state. Japanese Patent Application Laid-Open No. 52-72356 discloses a method in which a wire having a predetermined size is energized and heated while applying tension from both ends. In this method, since the holding portions at both ends are not corrected, the yield is low, and the productivity is low because the holding portions are heated one by one.

On the other hand, in the continuous hot tension straightening device described in Japanese Patent Publication No. Hei 6-79743, a peripheral speed difference is given between two pinch rollers, and induction heating is performed between the pinch rollers to thereby reduce hot working. There is a method of continuously performing the tension correction in the above. However, if dedicated equipment is required, and if the temperature distribution between the pinch rollers subjected to the tensile force is not uniform, constriction occurs at a high temperature portion.

JP-A-8-1084 for titanium alloy plate
The vacuum creep shape correction method of a metal plate disclosed in Japanese Patent Publication No. 5 is a method of correcting creep by pressing a metal plate. However, it is difficult to hold a straight bar under pressure from the point of shape.

[0007]

The problem to be solved by the present invention is to relatively straighten an α + β type titanium alloy straight bar, and in particular, to straighten an α + β type titanium alloy wire rod from straightness. Producing a good straight rod.

[0008]

According to the present invention, a wire coil made of an α + β type titanium alloy is cold-coarse-corrected in a cold state, and then has a circular, arc-shaped, U-shaped or V-shaped cross section. One or more rods are inserted into a container having a length equal to or longer than the length of the titanium alloy rod so that the longitudinal direction is parallel to the container, and heated and maintained at a high temperature. By holding for a predetermined time or more according to the heating temperature, the crooked titanium alloy rod that has been bent after roughing is creeped and shaped along the bottom or side surface of the container to reduce bending and improve straightness. It is a way to make it.

In addition, since the rod whose straightness has been relatively improved by the heat treatment is finish-corrected in a cold state, the amount of plastic deformation can be small and the applied residual stress is small.
The bending generated by heating, surface layer cutting, and grinding in the next step is extremely small, and has little effect on straightness.

FIG. 1 shows that a Ti-6Al-4V wire rod coil having a coil diameter of about 1.1 m and a diameter of 17 mm having a finishing temperature of hot rolling in an α + β two-phase region (hereinafter referred to as α + β process) having a diameter of 1.1 m is pulled. The graph shows the change in the amount of bending depending on the holding time when the rod which was roughly corrected by bending and cut into a length of 5 m was placed in a heating furnace in various ways and held at 800 ° C. Here, the amount of bending was measured by placing the rollers at intervals of 1 m, placing the dial gauge in the center between the rollers so that the surface of the rod was in contact with the roller, and rotating the rod once around the axis on the roller. The value is a half of the difference between the maximum value and the minimum value, and is an average value measured at five points in the entire length. The bending amount when a plurality of bars are processed simultaneously is the average value of the bending amount of each bar.
Further, a rod having a bending amount of about 5 mm after the rough correction was used. The heating furnace used was a roller transfer type.

As shown in FIG. 1, when the rod after rough correction made of Ti-6Al-4V is placed directly on the conveying roller of the heating furnace, the distortion imparted by the rough correction due to uneven heating during heating becomes uneven. Since it is released and has no restraint against the deformation of the rod, the bending remains generated.
mm. When five Ti-6Al-4V rods after rough correction are tied with steel wires at five locations in the length direction, since there is no tying at the side part between the tying parts, the lower part is caused by its own weight. And a local bend occurs in the binding part,
The amount of bending increases with an increase in the holding time, and reaches about 13 mm.

On the other hand, as shown in FIGS. 2 (a), 2 (b) and 2 (c), a rod after rough correction made of Ti-6Al-4V has an outer diameter of 1 mm.
01 mm, 8 mm thick, 6 m long
When ten or ten rods are inserted, as shown in FIG. 1, the bent titanium alloy rod undergoes creep deformation as the holding time increases, and the amount of bending decreases along the bottom or side surface of the steel pipe. When the holding time is longer than a predetermined holding time, the bending amount becomes 1 mm or less.

When a plurality of rods are inserted, the weight of the upper rod is added to the weight of the lower rod in addition to the weight of the lower rod.
Since only one rod is inserted along the bottom or side surface in a shorter time than when only one rod is inserted, the upper rod, to which the weight of other rods is unlikely to be added, also follows the lower rod whose bending has been reduced in a short time, so insert only one rod The bending amount becomes 1 mm or less in the same holding time as in the case where the bending is performed.

Here, the allowable bending amount of the steel rod is as follows.
In general, the target bending amount is set to 1 mm or less because it is generally 1.0 mm or less and 0.5 mm or less in severe cases.

Even when a steel container having a cross section as shown in FIGS. 2 (d), (e) and (f) having an arc shape or a U-shape or a V-shape is used, the steel pipe shown in FIG. The same effect as in the case of using is obtained.

As described above, the bent bar made of the α + β type titanium alloy after the rough correction has a cross section of any one of a circle, an arc, a U-shape, and a V-shape, and the length is equal to or longer than the length of the bar. One or more tubes were inserted into a certain container so that their longitudinal directions were parallel, and the container was heated and held at a high temperature.

As shown in FIG. 2 (g), five rods made of Ti-6Al-4V having a diameter of 17 mm after rough correction and a diameter of 17
Even if two steel straight rods of mm are inserted randomly,
From FIG. 1, the bending amount decreases with the increase of the holding time, and the holding time at which the bending amount becomes 1 mm or less is almost the same as when the steel straight bar is not inserted, but is smaller than that of the titanium alloy bar. By having a heavy and straight straight steel bar together, the steel straight bar acts as a weight, applies a heavy load to the titanium alloy bar, and facilitates creep deformation,
Since the titanium alloy rod acts as a core along the creep deformation, the bending amount is smaller than that when only the titanium alloy rod is inserted, and is about 0.3 mm or less.

If the diameter of the steel rod inserted together is extremely smaller or larger than the diameter of the titanium alloy rod, the inserted rods are not filled and a large gap is formed. When a thin titanium alloy rod is located in the gap, the rod does not touch the upper part and the weight of the rod does not add to the titanium alloy rod in the gap. When the rod is positioned, the steel alloy rod is not in contact with the titanium alloy rod at the upper part of the gap, so that bending due to its own weight is likely to occur, and the bending amount is not easily reduced. When the steel straight bar is too thin, the weight of the steel straight bar becomes less than or equal to that of the titanium alloy bar, and the steel straight bar does not function as a weight for applying a load. Therefore, the effect of reducing the amount of bending is reduced. Therefore, one or more steel straight rods having the same diameter as the titanium alloy rod were inserted together. Preferably,
The number of steel straight rods inserted together is 1/3 to 2/3 of the number of α + β titanium alloy rods.

As shown in FIG. 2 (h), Ti-6Al-
When four steel straight rods with a diameter of 17 mm are placed on top of five 4V-made rough-corrected rods, the bending amount decreases as the holding time increases, and the bending amount decreases from FIG. Is shorter than 1 mm. This is because the steel straight bar, which is heavier and straighter than the titanium alloy bar, is at the top, so that the steel straight bar acts as a weight and applies a heavier load to all the titanium alloy bars. In addition to the creep deformation, the titanium alloy rod serves as a core along with the creep deformation, so that the bending amount is reduced in a slightly shorter time than when only the titanium alloy rod is inserted.

Here, when the diameter of the steel straight rod inserted together is extremely larger than the diameter of the titanium alloy rod, a gap formed by contact between the thick steel straight rods is formed. When a large titanium alloy rod is located in the gap, the titanium alloy rod creep-deforms because the steel straight rod is not in contact with the upper part, and the role of the core along the titanium alloy rod is reduced. When the diameter of the steel straight bar is extremely thin, the weight of the steel straight bar becomes less than or equal to the titanium alloy bar, and the role of the weight for applying the load is reduced, so that the effect of reducing the amount of bending is reduced. . Therefore, one or more steel straight rods having the same diameter as the titanium alloy rod were inserted together. Preferably, the number of steel straight rods to be inserted together is 1/3 to 2/3 of the number of α + β type titanium alloy rods.

Next, when the finishing temperature of the hot rolling is in the β phase region (hereinafter referred to as β process), the winding diameter of the coil is about 1.1 m,
After a Ti-6Al-4V coil having a diameter of 17 mm is roughly corrected by tension and bending, it is placed in the same manner as in the case of the α + β process (the method of placing the coil directly on the conveying roller of the heating furnace, bundling, as shown in FIG. 2). (Placed in a container) and kept at 800 ° C. in a heating furnace. Further, a rod having a bending amount of about 5 mm after the rough correction was used. The change in the amount of bending due to the holding time differs depending on the placement. As in the case of the α + β process material shown in FIG. 1, the bending increases when placed directly on the transport roller or when tying the steel tube. When inserted into a container having a U-shaped or V-shaped cross section, and when a straight steel bar is inserted together, the amount of bending decreases with an increase in the holding time and becomes 1 mm or less. The holding time at which the amount of bending falls to 1 mm or less is shorter than that of the α + β process.
The β process material is longer because it has better creep resistance.

2 (a), 2 (b), 2 (c), 2 (g),
(H) A steel pipe into which a titanium alloy rod or a steel straight rod having a diameter similar to that of the titanium alloy rod is inserted together is rotated about a cylindrical axis by a rotary conveyance type walking beam heating furnace. In the case of heat treatment, the temperature difference due to the position in the steel pipe and the difference between the load applied from above and the difference in the straightness of the object along creep deformation (the degree of contact with the steel pipe or steel straight rod) Since the titanium alloy rods are averaged by rotating, all the titanium alloy rods undergo creep deformation on average, and the amount of bending is reduced more on average than when the rod is not rotated. Therefore, in order to reduce the variation in straightness, insert a roughly straightened titanium alloy rod or steel straight rod together into a cylindrical container, and rotate the cylindrical container around the cylindrical axis. And

Therefore, in the present invention, the bending amount of the α + β type titanium alloy rod having the bending after the rough correction is set to 1 mm.
In order to make the following, place the titanium alloy rod at the time of heat treatment in a container whose cross section is circular, arc-shaped, U-shaped or V-shaped, and whose length is longer than the length of the titanium alloy rod. A method of inserting one or more steel bars having a diameter similar to that of a titanium alloy rod together with a method of inserting one or more steel rods so that their longitudinal directions are parallel to each other. A method of placing it on the top of an alloy rod, or a method of inserting it into a cylindrical container and rotating the container around a cylindrical axis, and joining together one or more steel straight rods having the same diameter as the titanium alloy rod The cylindrical container inserted into the container was rotated around a cylindrical axis.

FIG. 3 shows that Ti-
6Al-4V wire rod coil is corrected by tension and bending,
Changes in the holding time and the amount of bending of the rod when five rods cut into a length of 5 m are inserted into a steel pipe having an outer diameter of 101 mm, a thickness of 8 mm, and a length of 6 m and held at various temperatures are shown. here,
The amount of bending is an average value of five bars measured in the same manner as described above. Further, a rod having a bending amount of about 5 mm after the rough correction was used. The heating furnace used was a roller transfer type.

FIG. 3 shows that when the holding temperature is 650 ° C. or more,
The amount of bending of the rod decreased with increasing the holding temperature,
In about 30 minutes at 650 ° C., the bending amount of the rod becomes 1 mm or less in about 240 minutes. When the holding temperature is 600 ° C., the amount of bending hardly decreases even if the holding temperature increases. Therefore, from the viewpoint of efficiency, the holding temperature was set to 650 ° C. or higher in the case of the α + β process in order to reduce the bending amount of the rod to 1 mm or less when the holding time was 240 minutes or less. In addition, when heated above the β transformation point, the grains grow rapidly, and the material produced by hot rolling changes significantly. Therefore, the upper limit of the holding temperature is set to less than the β transformation point.

FIG. 4 shows Ti-6A manufactured by the β process.
A rod obtained by correcting a 1-4V wire rod coil by tension and bending and cutting it to a length of 5 m is an outer diameter of 101 mm, a thickness of 8 mm, and a length of 6 mm.
5 shows changes in the holding time and the amount of bending of a rod when five steel pipes are inserted into a steel pipe of m and held at various temperatures. Here, the amount of bending is an average value of five bars measured by the same method as described above. Further, a rod having a bending amount of about 5 mm after the rough correction was used. The heating furnace used was a roller transfer type.

FIG. 4 shows that when the holding temperature is 750 ° C. or more,
The amount of bending of the rod decreased with the increase of the holding temperature, 900 ° C
In about 40 minutes at 750 ° C., the bending amount of the rod becomes 1 mm or less in about 210 minutes. When the holding temperature is 700 ° C., the amount of bending hardly decreases even if the holding temperature increases. Therefore, from the viewpoint of efficiency, the holding temperature was set to 750 ° C. or higher in the case of the β process in order to reduce the bending amount of the rod to 1 mm or less when the holding time was 240 minutes or less. Further, when heated above the β transformation point, the grains grow rapidly, and the material formed by hot rolling changes significantly.
It was below the transformation point.

Also, another α + β type titanium alloy, Ti
-3Al-2.5V shows the same behavior as in FIGS. 3 and 4, and the holding time at which the bending amount of the rod at each holding temperature is 1 mm or less is slightly shorter than that of Ti-6Al-4V. But about the same.

FIG. 5 shows the bending amount of the rod before the heat treatment in the rod after the rough correction made of Ti-6Al-4V manufactured by the α + β process and the β process, and the holding time at which the bending amount of the rod is reduced to 1 mm or less by the heat treatment. Shows the relationship. Here, the holding time at which the bending amount of the bar is 1 mm or less was determined from the change in the bending amount with respect to the holding time of the rod having various bending amounts before the heat treatment as shown in FIGS. From FIG. 5, in the α + β process and the β process, the holding time at which the bending amount of the rod decreases to 1 mm or less at both the holding temperature of 800 and 950 ° C. increases almost in proportion to the bending amount of the rod before the heat treatment. 3 and 4, the decrease in the amount of bending of the rod until the bending of the rod becomes 1 mm or less is almost proportional to the holding time. Therefore, the reduction in the amount of bending per unit time is due to the α + β process and the β process. In each case, it is almost constant at each holding temperature.

From the inclination of the straight line as shown in FIG. 5, the holding time required to reduce the amount of bending at each holding temperature by 1 mm is obtained. In the α + β process, t1 in equation (3) is obtained.
In the (1) and β processes, t2 (1) in equation (4) is obtained.
Therefore, since the reduction in the amount of bending of the rod is substantially proportional to the holding time, the holding time required to achieve the desired amount of bending after heat treatment at each holding temperature is roughly the same as the desired amount of bending per meter of the rod. It is the product of the difference between the amount of bending after correction (before heat treatment) (the target correction amount: Δd) and t1 (1) or t2 (1). In each of the α + β process and the β process, t1 of the formula (5) is obtained. , (6) becomes t2. t1 (1) = 4.5 × 10 ⁻⁵ × exp (1.3 × 10 ⁴ / (T + 273)) (3) t2 (1) = 1.6 × 10 ⁻⁴ × exp (1.3 × 10 ⁴ / (T + 273)) (4) Here, t1 (1), t2 (1): holding time (min) required to reduce the bending amount of the bar by 1 mm T: holding temperature (° C.) t1 = 4 0.5 × 10 ⁻⁵ × Δd × exp (1.3 × 10 ⁴ / (T + 273)) (5) t2 = 1.6 × 10 ⁻⁴ × Δd × exp (1.3 × 10 ⁴ / (T + 273)) ) (6) where, t1, t2: time (minutes) T: holding temperature (° C.) Δd: target correction amount (mm) (the difference between the target correction amount per 1 m of the rod and the post-coarse correction correction amount) difference)

FIG. 6 shows a range of the holding temperature and the holding time suitable for reducing the bending amount of the rod to 1 mm or less when Δd is 4 mm. Holding temperature is less than 650 ° C for α + β process (α + β two-phase region finish), β process (β-phase region finish)
When the temperature is lower than 750 ° C., the rod is hardly deformed due to the low holding temperature, or the rod needs to be held for a long time of more than 240 minutes to reduce the bending amount of the rod to 1 mm or less, resulting in low efficiency. Further, when heated above the β transformation point, the grains grow rapidly, so that the material formed by hot rolling changes significantly. In the α + β process (α + β two-phase region finishing), when the holding temperature is 650 ° C. or more and less than the β transformation point, the holding time t1 (minute)
As described above, in the β process (β phase region finishing), the holding time t2 (minutes) or more but less than 750 ° C. or more and less than the β transformation point is the range where the amount of bending of the rod is 1 mm or less (shaded portion in FIG. 6).
On the other hand, if the holding time is shorter than t1 or t2, the holding time is short, so that the deformation amount is small, and the bending amount of the rod does not become 1 mm or less.

[0032]

The present invention will be described in more detail with reference to the following examples. When the finishing temperature of the hot rolling is 920 ° C. in the α + β temperature range and 1020 ° C. in the β phase temperature range, the winding diameter of the coil is about 1.1 m, and the diameter of the Ti—
The wire coil made of 6Al-4V was roughly corrected by tension and bending, and then cut to a length of 5 m. The rod can be placed in various ways,
After performing the heat treatment at the holding temperature and the holding time, two-roll straightening was performed in a cold state, and a part of the surface layer was ground or cut. Also, the amount of bending after each step was measured.

As the heating furnace, a roller hearth type furnace and a rotary conveying type walking beam furnace were used. The grinding amount is about 0.3 mm to the diameter, and the cutting amount is about 1.
0 mm. The amount of bending is the maximum value of the dial gauge when the rollers are placed at 1m intervals, the dial gauge is set at the center between the rollers so that the surface of the rod contacts, and the rod is rotated once around the axis on the roller. And half of the difference between
And the average value measured at 5 points in the total length. The bending amount when a plurality of bars are simultaneously processed is an average value of the bending amounts of the respective bars. The pipe with the rod inserted has an outer diameter of 101m.
Other U-shaped and V-shaped holders are formed by cutting and processing a steel pipe having a length of 8 m, a thickness of 8 mm, and a length of 6 m. The steel rod inserted with the titanium rod is 17 mm in diameter.

A 17 mm diameter wire coil obtained by hot rolling Ti-3Al-2.5V at 850 ° C. in the α + β temperature range and 970 ° C. in the β phase temperature range was also used.
A rod was manufactured in the same process as in the case of -4V.

Table 1 shows the amount of bending after each step, heat treatment conditions (placement, holding temperature, holding time), the value of t1 in equation (1) and the value of t2 in equation (2), and the amount of bending of the rod to 1 mm. This shows the value of the correction amount Δd required to perform the correction.

[0036]

[Table 1]

[0037]

[Table 2]

As shown in Table 1, the diameter of the α + β two-phase region finish was 17
mm heat-treated at a holding temperature of 800 ° C. and a holding time of 40 minutes by variously placing rods obtained by roughly correcting a Ti-6Al-4V wire coil of No. No. 1 or No. In No. 2, the amount of bending of the rod was larger than before the heat treatment. On the other hand, No. 1 in which the rod was inserted into the pipe, which is the method of placing the rod of the present invention. Nos. 3, 4, 17 and No. 3 in which steel straight rods were inserted together. No. 5, 6, or No. 5 inserted in a U-shaped or V-shaped container. Nos. 7, 8 and No. 7 where the pipe was further rotated
In Nos. 9 and 10, the bending amount of the rod after the heat treatment was reduced to less than 1 mm.

Α + β Two phase finish Ti- 17 mm diameter
No. 6 rods obtained by inserting five rods obtained by roughly correcting a 6Al-4V wire coil into a pipe and heating and holding. In 13 to 23, a rod having a holding temperature of 650 ° C. or more and a holding time of t1 or more is
Although the bending amount after the heat treatment is reduced to less than 1 mm, when the holding temperature is less than 650 ° C. or the holding time is less than t1, the bending amount of the rod does not become 1 mm or less.

Ti-6Al having a diameter of 17 mm and a β phase finish
No. 4 in which a single rod obtained by roughly correcting a -4V wire rod coil was inserted into one pipe. Nos. 11 and 5 inserted. Nos. 24 to 34, in which a steel straight bar was inserted together. In the case of 12, the holding temperature is 7
The rod having a holding temperature of 75 ° C. or more and having a holding time of t 2 or more has a bending amount of less than 1 mm after the heat treatment, but has a holding temperature of 75 ° C.
When the temperature is less than 0 ° C. or the holding time is less than t2, the bending amount of the rod does not become 1 mm or less.

No. 9mm diameter Ti-6A 35-38
No. 1-4V or No. Ti with a diameter of 17 mm from 39 to 46
-3Al-2.5V, Ti-6A with a diameter of 17mm
Similarly to the case of 1-4V, the rod having the holding temperature and the holding time within the range of the present invention has a bending amount of the rod after the heat treatment of 1 mm or less.

In addition, the steel rods No.
5, 6, 10, and 12 have a smaller amount of bending after heat treatment by about 0.2 mm than others.

When the bending amount of the rod after the heat treatment is 1 mm or less, the bending amount after the cold roll correction or the surface cutting or grinding is also 1 mm or less. However, if the bending amount of the rod after heat treatment is more than 1 mm, the bending amount may be 1 mm or less after the cold two-roll straightening. The amount increases and exceeds 1 mm.

[0044]

According to the present invention, the bending amount of a rod made of an α + β type titanium alloy having a bending after rough correction is inserted into a container having a circular, arc-shaped U-shaped or V-shaped cross section, and a predetermined holding temperature. By holding for a predetermined time or more, there is no increase in bending of the rod during heat treatment, and the bending of the rod is efficiently reduced,
Stable straightness can be obtained even after the subsequent cold straightening, surface cutting, and grinding.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in the amount of bending of a bar depending on how to place the bar after rough correction of Ti-6Al-4V having α + β two-phase region finish after heat treatment.

2 (a) to 2 (h) are views showing how to place (hold) a rod according to the present invention, and FIG. 2 (a) shows Ti-6 in a steel pipe (pipe).
One rod after Al-4V rough correction, (b) five rods,
(C), when ten are inserted, (d), the cross section is an arc,
(E) uses a U-shaped container, (f) uses a V-shaped container,
(G) When five rods after Ti-6Al-4V rough correction and two steel straight rods were randomly inserted into a steel pipe (pipe), (h) Rough correction of Ti-6Al-4V The case where four steel straight rods are inserted into the upper part of the latter five rods is shown.

FIG. 3 is a diagram showing a change in the amount of bending of a rod at each holding temperature when a rod after coarse correction of Ti-6Al-4V having an α + β two-phase region finish is inserted into a pipe and subjected to heat treatment.

FIG. 4 is a diagram showing a change in the amount of bending of a rod at each holding temperature when a rod after rough correction of Ti-6Al-4V having β-phase region finish is inserted into a pipe and subjected to heat treatment.

FIG. 5: Ti + with α + β dual phase finish and β phase finish
The figure which shows the relationship between the amount of bending of the rod before heat treatment at the time of inserting the rod after rough correction | amendment of 6Al-4V into a pipe, and heat-treating, and the holding temperature at which the amount of bending after heat treatment falls to 1 mm or less.

FIG. 6: Ti-6Al-4V having a bending amount of 5 mm after rough correction (before heat treatment) of α + β dual-phase finish and β-phase finish
Range of the holding temperature and holding time in the heat treatment in which the bending amount is 1 mm or less (the target correction amount Δd in the heat treatment is 4 mm).
mm).

[Explanation of symbols]

 1: Titanium alloy rod after rough correction 2: Steel pipe or container into which titanium alloy rod is inserted 3: Straight steel rod

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 685 C22F 1/00 685Z 686 686A 691 691C 691B 694 694A

Claims (7)

[Claims] 1. A wire coil made of an α + β type titanium alloy,
After rough correction in the cold, the rod should be circular, arc-shaped, U-shaped or V-shaped in cross-section, and the length direction should be parallel to the container longer than the length of the rod. A method for straightening an α + β type titanium alloy straight bar, wherein one or more wires are inserted and heated at a high temperature. 2. A wire coil made of an α + β type titanium alloy in which the finishing temperature of hot rolling is in the α + β two-phase region is roughly straightened in the cold, and then the cross section of the rod is circular, arcuate or U-shaped. Or V
One or more of them are inserted into a container having a length equal to or greater than the length of the rod so that the longitudinal direction is parallel to the container.
A straightening rod made of an α + β titanium alloy, wherein a heat treatment is performed at a temperature equal to or higher than 50 (° C.) and lower than the β transformation point, and the holding time is equal to or longer than t1 (minute) in equation (1) with respect to the target correction amount Δd Method. t1 = 4.5 × 10 ⁻⁵ × Δd × exp (1.3 × 10 ⁴ / (T + 273)) (1) where, t1: time (minute) T: holding temperature (° C.) Δd: correction of aim Amount (mm) (Difference between the amount of desired bending per 1 m of rod and the amount of bending after rough correction) 3. The finishing temperature of hot rolling is α phase in the β phase region.
After a wire coil made of + β type titanium alloy is roughly corrected in a cold state, the bar has a cross section of any one of a circular shape, an arc shape, a U-shape, and a V-shape, and has a length equal to or greater than the length of the bar. One or more tubes are inserted in the container so that their longitudinal directions are parallel, and the holding temperature T is 750.
(° C) or more and less than the β transformation point, the holding time is the desired correction amount Δ
a straightening rod made of an α + β type titanium alloy alloy, wherein d is subjected to a heat treatment of t2 (minutes) or more in equation (2). t2 = 1.6 × 10 ⁻⁴ × Δd × exp (1.3 × 10 ⁴ / (T + 273)) (2) where, t2: time (minute) T: holding temperature (° C.) Δd: correction of aim Amount (mm) (Difference between the amount of desired bending per 1 m of rod and the amount of bending after rough correction) 4. The heat treatment according to claim 1, wherein one or more steel straight rods having a diameter similar to that of the titanium alloy rod are inserted together with the titanium alloy rod in addition to the coarsely corrected titanium alloy rod. A straightening method of a straight rod made of an α + β type titanium alloy, characterized in that: 5. The heat treatment according to claim 1, wherein a straight steel bar having a diameter similar to that of the titanium alloy rod is disposed on the titanium alloy rod which has been roughly corrected. A straightening method for straight rods made of α + β type titanium alloy. 6. A process according to claim 1, wherein a cylindrical container into which one or more coarsely corrected titanium alloy rods are inserted is rotated about a cylindrical axis.
Straightening method for straight rod made of β-type titanium alloy. 7. The heat treatment according to claim 1, wherein one or more steel straight rods having the same diameter as the titanium alloy rod are inserted together with the titanium alloy rod in addition to the coarsely corrected titanium alloy rod. A method of manufacturing an α + β-type titanium alloy straight rod, comprising rotating a cylindrical container obtained above around a cylindrical axis.