JPH02200303A - Cold rolling method for extremely thin titanium alloy sheet - Google Patents

Abstract

PURPOSE:To produce the extremely thin cold rolled sheet of a high-strength titanium alloy which has excellent dimensional accuracy and is thin in thickness by applying tension to a titanium alloy sheet via leader coils, passing and rolling the sheet and subjecting the sheet to cold rolling at a specific total cold draft. CONSTITUTION:The pure titanium sheets TR35C for the leader are butted against the front and rear parts of the titanium alloy sheet A and are TIG- welded W to coil the sheet. The leader coils are respectively wound on tension reels provided on the front and rear surfaces of a cold rolling mill and the tension is applied via the leader coils to the titanium A, then the sheet is passed and rolled. The titanium alloy has poor plastic workability and is liable to generate edge cracks at the time of the cold rolling and, therefore, the total cold draft is limited to <=40% in the cold rolling. The treatment to restore the cold rollability is executed after the cold rolling. As a result, the thin cold rolled sheet of the high-strength titanium alloy which has beautiful surfaces and the excellent dimensional accuracy and is thin in thickness is efficiently produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a cold-rolled ultra-thin titanium alloy plate. Titanium alloys are lightweight and have excellent corrosion resistance and strength, so they are used in the aerospace and marine industries. The present invention relates to a method for manufacturing ultrathin cold-rolled plates of titanium alloys.

[Conventional technique vIi] In this specification, titanium alloy is, for example, Ti-6AQ-2S.
Refers to α-β titanium alloys such as n-4No-2Zr alloy and Ti-6A Q-4V alloy.

Titanium alloy has excellent corrosion resistance and strength, but is a difficult-to-work material with poor plastic workability. Therefore, it is difficult to produce a plate with a thickness of 6 mm or less using normal hot rolling. For thinner titanium alloy plates, several hot-rolled plates are stacked together to form a special slab, which is then further hot-rolled. It is manufactured by so-called pack rolling, but even with this method the thickness is 0.4
It is difficult to roll a thin plate having a thickness of less than am, and titanium thin plates rolled by this method have large variations in plate thickness and poor surface smoothness.

Ultra-thin plates of titanium alloy are usually produced by grinding or applying solvent to the surface of hot-rolled plates, but it is technically unstable to grind or apply solvent to the surface to a uniform thickness. It's also not efficient.

JP-A-63-177905 relates to a method for cold rolling α+β titanium alloy plates. This publication describes a method in which a cut plate of a titanium alloy having a thickness of, for example, 5 s+m to 10 m+m is cold rolled by a normal cold rolling method at a total reduction of 30% or less, and then annealed.

However, in the cold rolling of cut plates, there is no single winder, so it is difficult to produce very thin plates with good shape, and there is a limit to the thickness that can be obtained. In addition, when cold rolling materials with a thickness of 5 to 10 m with a total reduction rate limited to 30% or less, the number of intermediate annealing increases, making the production of ultra-thin titanium alloy plates extremely complicated. .

[Problems to be Solved by the Invention] The present invention provides a method for manufacturing an ultra-thin plate of titanium alloy by cold rolling with high efficiency and making the ultra-thin plate with an excellent shape.

[Means and effects for solving the problem] Claim (1)
First, the invention will be explained. If a titanium alloy plate can be rolled with small-diameter rolls while applying tension to the plate using, for example, a Sendzimir cold rolling mill, it is possible to increase the rolling reduction per bath and efficiently cold-roll the plate. One possible way to apply tension to the plate is to wrap the titanium alloy plate around tension reels at the front and rear sides of the cold rolling mill. However, the titanium alloy plate subjected to this cold rolling is, for example, Ti-6A Q-2Sn
-4No-2Zr alloy has a tensile strength of approximately 110 kgf/
In+” and has high strength, making it difficult to wind onto a tension reel.

It is conceivable to join a carbon steel or stainless steel leader coil to the front and rear parts of a titanium alloy plate and wind it around a tension reel via the leader coil, but it is possible to connect a titanium alloy plate and carbon steel or a titanium alloy When a plate and stainless steel are welded together, a fragile intermetallic compound is generated in the weld, making the weld extremely brittle.Welding is impossible in a general sense, so it is not possible to roll the titanium alloy plate under tension. Can not. In addition, mechanical joining such as rivets is satisfactory in terms of joining properties, but since holes are drilled into thin plates and joined with rivets, when the joint comes into contact with the take-up roll, the rivet's drilled hole This is not a satisfactory joining method because the rivet becomes large, the rivet comes off, and the rivet is cut from the drilled hole.

The present inventors welded pure titanium leader coils to the front and rear parts of a titanium alloy plate, and wound the leader coils around tension reels provided at the front and rear sides of a cold rolling mill. Tension was applied to the titanium alloy plate through the plate and the plate was rolled, but since pure titanium has a tensile strength of about 45 kgf/2 and is soft, it was easy to wind it around a tension reel. In addition, sufficient ductility was ensured at the welded joint between the titanium alloy and pure titanium leader coils, making it possible to cold-roll the titanium alloy plate while applying the desired tension.

Welding of titanium alloy plate and pure titanium leader coil is
For example, a stable joint can be obtained by TIG welding, resistance welding, or MIG welding.

The present inventors cold-rolled titanium alloy plates with a thickness of 0.4 to 3 mm using this method, but the reduction rate per pass was large, and the total cold rolling rate was 40% or less. Cold rolling was achieved.

Figure 1 shows a Ti-6 order 1m-4V alloy plate (thickness: 0.
4 mm) is a diagram showing the relationship between the rolling tension and the total cold rolling rate on the occurrence of edge cracks when cold rolling is performed with the addition of a tension of 4 mm).

The titanium alloy material cold rolled at a total rolling reduction of 40% or less was heat treated and refined to form a cold rolled coil.

Conventionally, cold-rolled titanium alloy coils with a thickness of less than 0.4 mm have not been manufactured, but they can be manufactured efficiently using the method of the present invention. When manufacturing thinner cold-rolled sheets or foils, the treatment described in the first aspect and described in claim (2) is performed.

As already mentioned, titanium alloy has poor plastic workability and tends to cause edge cracks during cold rolling. After cold rolling, a treatment is performed to restore cold rolling properties.

As a treatment for restoring the cold rollability of the titanium alloy, the cold rolled material is intermediately annealed (heat treated) at 600°C to 950°C. It is said that this heat treatment recrystallizes the metal structure, removes the working strain caused by cold rolling, and restores the cold rollability of the cold rolled coil.

However, according to the findings of the present inventors, although the rolling structure and mechanical properties of cold-rolled coils are improved by this heat treatment, the cold workability of the edge portions is not sufficiently restored by this heat treatment alone. The inventors of the present invention, who tend to cause edge cracks during the first cold rolling, performed side trimming during this heat treatment.

This side trimming removes the edge portions of the cold-rolled coil where edge cracks are likely to occur, making it possible to prevent edge cracks from occurring during the next cold rolling.

FIG. 2 is a diagram illustrating an example of this effect, showing the influence of trimming on the occurrence of edge cracks. In addition, in Fig. 2, the rolling tension is 10 to 15 kgf/--2 and the plate thickness is 0.4.
7+ue→0.08+u+t. The inventors are T
i-6A Q-2Sn-4No-2Zr alloy plate (plate width:
380m5+) was cold-rolled by the method of claim (1) so that the total cold-rolling ratio was 40%, and before heat treatment, both sides of the cold-rolled coil were subjected to side trimming of 31cm. We created a cold-rolled coil that was not available before. All of these cold-rolled coils are heat treated and then subjected to the claims (
In the same manner as described in 1), a titanium alloy coil was over-rolled and cold-rolled while applying tension. As shown in Figure 2, coils without side trimming tend to develop side cracks when the total cold rolling rate exceeds approximately 20%, but coils with side trimming tend to develop side cracks when the total cold rolling rate exceeds approximately 20%. Even when it reached 40%, no side cracks occurred. Side trimming may be performed after heat treatment, but the shape of the plate after heat treatment is poor and it is difficult to perform side trimming to accurate dimensions, and the stress from side trimming remains on the edges, so side trimming is not recommended. It is desirable to perform this before heat treatment. In the cold rolling according to claim (2), as in claim (1), tension is applied to the cold-rolled titanium alloy material and the material is passed through the sheet.

By repeating the process of claim (2), an ultra-thin plate of high-strength titanium alloy with a desired thickness can be obtained. However, in this method, the ultra-thin plate after rolling is wound into a coil shape, so there are only 5 cut plates. Unlike cold rolling, it is possible to manufacture long products with thin thickness, and the shape is also excellent.

[Example: Ti-6A Q-4V and Ti-6A shown in Table 1]
Q-2No-4Zr-2Sn alloy thin plate 38011
The material was cut into m widths, the leader material was a JIS class 2 (TP35C) cold-rolled plate with a thickness of 0.4 ++++++ cut into the same width, and the ends were butt welded with a TIG welder to form a coil. A schematic diagram of the manufactured coil is shown in FIG. 3.

Figure 3 (a) shows a pure titanium plate for a leader on the front and back of a thin metal plate to be tested, which is made into a coil by TIG welding.
The cold rolling range is about 25 mm from the welded part of the pure titanium plate and the test metal plate toward the test metal plate, so it is the range that is removed by 50 mm from the length of the test metal plate.

In addition, in (b), test metal plates A and B are first joined by butt TIG welding, and then butted against a pure titanium plate for a leader before and after that, and made into a coil by TIG welding.The cold rolling range is (a ), it is about 25 mm from the joint between the pure titanium and the test gold plate to the test gold side,
The intermediate match metal plate and the welded part of the test metal plate were cold rolled. The test metal plates A and B used for making this coil were of the same type.

The coil produced in this manner had very good setability on the reel of a Sendzimir rolling mill.

Cold rolling was carried out using a Sendzimir rolling mill with alloy rolls with a work roll diameter of 5511mm, and the initial tension was set at 10 kg/mis.
”, the shape was corrected with a total load of 20 Ton, and the load was reduced to 5 Ton.
The rolling load was increased in n increments up to a total cold rolling rate of 35%.

The reason why the load was increased in 5 ton increments is to prevent shape deterioration due to tension-load imbalance, and to prevent consequent squeezing. 7. To prevent edge cracking in cold-rolled coils. Therefore, both ears were slit on each side by 3 mm and 7 mm wide, and after washing the rolling oil etc. with a solvent, the coil was loosely wound and vacuum annealed at 830° C.XIHr.

Then, the total cold rolling rate was set to 35 to 40%, and the cycle of → slitting → vacuum annealing was repeated for two cycles.

0,1ast X 375td X C (1) An ultrathin titanium alloy plate was manufactured. Table 2 shows the properties of the manufactured ultra-thin titanium alloy plate, which fully satisfies AM34911K, has a flatness of 0.5m*1500mm, and has a very high plate thickness variation of approximately ±5μm. Manufactured precision titanium alloy foil plate.

The produced ultra-thin plates have been applied to honeycomb materials for aircraft, and the results have been good, and the excellent properties of titanium alloys such as high corrosion resistance, high specific strength, and non-magnetic properties are expected to be used in space and ocean exploration, which are expected to be actively developed in the future. We believe that this technology can make a significant contribution to fields that also utilize .

[Effects of the Invention] By carrying out the present invention, it is possible to efficiently produce a cold-rolled sheet of high-strength titanium alloy that has a beautiful surface, excellent dimensional accuracy, and is thin in thickness.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the occurrence of edge cracks, rolling tension, and total cold rolling reduction during cold rolling of titanium alloy sheets. A diagram showing an example of the effect of side trimming of a plate. FIG. 3 is an explanatory diagram of the configuration of a coil in an example. It is. Patent applicant Nippon Steel Corporation

Claims (2)

[Claims] (1) Pure titanium leader coils are welded to the front and rear parts of the titanium alloy plate, and the leader coils are wound around tension reels provided at the front and rear sides of the cold rolling mill, and the leader coils are A method for cold rolling an ultra-thin titanium alloy plate, characterized by applying tension to a titanium alloy plate, rolling it through the plate, and cold rolling it at a total cold rolling rate of 40% or less. (2) A cold-rolled titanium alloy material with pure titanium leader coils on the front and rear parts is subjected to side trimming and annealing, and the leader coils are attached to tension reels provided on the front and rear surfaces of the cold-rolled material. The process of winding each titanium alloy plate, applying tension to the titanium alloy plate through a leader coil, rolling it through the plate, and cold rolling it at a total cold rolling rate of 40% or less is repeated once or twice or more. A method for cold rolling ultra-thin titanium alloy plates, characterized by