JPS5825465A - Manufacture of rolled titanium alloy material having excellent structure - Google Patents

Abstract

PURPOSE:To manufacture a rolled Ti alloy material having an excellent structure by eliminating heat of working to keep a material to be rolled at a specified tem. during finish rolling causing a rise in the temp. of the material due to heat of working and by regulating the cooling temp. to a specified temp. CONSTITUTION:In the continuous rolling of a Ti alloy material including finish rolling at above a rolling speed causing a rise in the temp. of the material to be rolled due to heat of working, by eliminating heat of working, the temp. of the material during the rolling is kept at <=950 deg.C. Heat of working is controlled by a cooling means such as water cooling between rolls and/or water cooling immediately after rolling. The coiling temp. is also regulated to 950-650 deg.C. Thus, a fine and uniform crystal structure is provided to th alpha+beta type Ti alloy, and a rolled Ti alloy material having superior mechanical properties can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing a rolled titanium alloy material with a good structure;
In particular, the present invention relates to a method for manufacturing a rolled titanium alloy material with a good texture by continuous rolling on a multi-stage stand.

Titanium alloys have a high specific strength (ratio of strength to weight), so they are used in fields such as aircraft and space development equipment that require light weight and high strength, as well as applications that require high reliability. Or for applications that require durability under harsh conditions such as high temperatures, high loads, and corrosion! It's hanging. However, for these applications, just being strong and highly corrosion resistant is not enough, and when supplied in the form of 41KIl''t or zelkova, % gelt or * as a structural component. Since a molding process is always carried out in the production stage of a product, it is essential to have suitable g properties.In order to improve the ductility of the grain, it is essential to have a uniform and fine structure.

By the way, there are few reports on the manufacturing method for titanium alloy material #'ig processed material. For example, forged material is disclosed in JP-A No. 1@5l-47JI85, but rolled material has not been practically used. There have been no cases where this has occurred, nor have there been any reports of it.

By the way, the production of the above forged material is as follows: / After forging, processing is performed continuously in the α + β region for 10 times or more, then heated to the β region, and then cooled at a cooling rate of 20 ° C / min or more to the α + β region t times. α
This is done by cooling to a temperature of Kx, which aims to refine the structure.

Therefore, the purpose of the present invention is to provide a method for producing a rolled titanium alloy material, to produce a rolled titanium alloy material with excellent mechanical properties of α+β type titanium alloy with a uniform and fine crystal structure. The purpose is to provide a method.

Thus, we have shown a uniform and fine texture,
This is the result of extensive research into the production of titanium alloy materials with excellent mechanical properties through high-speed rolling.

The inventors have discovered that controlling cooling issues in the rolling process is extremely effective in achieving uniform and fine microstructures, and have completed the present invention.

Herein, one aspect of the present invention is that at least the rolling speed is higher than the rolling speed at which the temperature of the rolled material increases due to processing heat, and the finishing EEm℃ or lower,
In addition, the present invention is a method for producing a rolled titanium alloy material with a good structure, which is characterized in that the Nlυ temperature is adjusted to 950 to 660°C.

The present invention will be explained in detail below.

Titanium alloy has high deformation resistance and low specific heat, so
In the case of low speed and low machining where the heat generated by machining is significant,
When the temperature Wl#'i of the material to be rolled due to heat generation is ignored at a rate of about 6/sec or more, the temperature of the material to be rolled due to industrial heat increases significantly. For this reason, for example, in hot rolling at around 960°C, the transformation point of about 970°C is exceeded. Therefore, it is necessary to remove the processing heat that causes the temperature increase of the material by appropriate means. In this regard, according to the present invention, by regulating the temperature of the rolled material during hot rolling to 960° C. or lower, excessive temperature rise of the rolled material can be prevented and a good structure can be ensured. If the temperature of the material to be rolled rises to 950° C. or higher during rolling, the transformation point of approximately 970° C. will be exceeded, and the structure will become an acicular beta (b) structure, making it impossible to obtain a good structure after rolling.

Furthermore, the present inventors have discovered that the temperature control of continuous rolling of titanium alloy material ii! We conducted various experiments regarding lK and found that when the winding temperature exceeds 950°C, the structure becomes coarse and an undesirable acicular structure occurs;
If it is below this level, there will be no particular deterioration of the structure, but winding will be difficult.
Therefore, by controlling the grain size, the winding temperature can be controlled to 960°C or less, and by working on this, the excellent effects described above can be obtained.

Thus, according to the present invention, in a continuous rolling mill in which finish rolling is performed at a rolling speed higher than that at which the temperature of the rolled material increases due to processing heat, for example, at a speed of 5 m/s or higher, an appropriate cooling means, such as water cooling between the rolls, is used. , water cooling immediately after rolling or a combination of both to remove processing heat. Therefore, the temperature of the bedclothes equipment is regulated to 960°C or less, and the 4I temperature is set to 960 to 650°C for 14 times. . By controlling the temperature in this manner, it becomes possible to obtain a rolled titanium alloy material with a good structure as described below.

As a means for removing processing heat, water cooling between the rolls as described above, water cooling immediately after rolling, or a combination of both may be considered, but the method is not necessarily limited to these. When water cooling is employed, the temperature f may be adjusted by adjusting the flow rate.

The present invention is preferably used for α+β type titanium alloy HTi-6, which is a typical α+β type titanium alloy.
There are ht-4V and Ti-4At-4Mn, and other examples include FiTi-? At-4Mo, T
i-1Mo-26V, Ti-4At-4Mo-I
V, TITl-1Fe-2Or-2. However, it will be understood that the present invention is not limited to these 0-)K.

Next, the present invention will be specifically explained using examples.

Example Ti-6At-4V alloy was vacuum arc melted to produce a 1 ton IV ingot, which was bloomed and peeled to remove surface flaws. As shown in Table 1, round bars tst+ with diameters of 180 cm and 22 cm were made and rolled into round bars with a diameter of 9- by a continuous hole R1111E rolling mill at the finishing rolling speed shown in Table 1.

Since rolling was carried out at high speed, a temperature rise due to rolling was observed. between rolls and/or
Immediately after rolling, the specimens were cooled by water spray K, and the resulting rolled materials were subjected to microstructure** as described in 1wk.

Wang Yandong case and results together with those of comparative case [111 Table K
Shown all together.

In Table 1, symbols A-E indicate examples of the present invention, and symbols F-H indicate comparative examples, respectively.

As is clear from the results of the first fitting, by cooling the titanium alloy material heated to the α+β region during or immediately after continuous rolling, the finishing temperature is regulated to 960°C or less, and the K winding temperature is If the temperature is adjusted to 950°C or lower, a good structure can be obtained.

As mentioned above, titanium alloy has a small specific heat and has a strength of 41"
Due to the high shape resistance, high-speed rolling generates a large amount of heat, and the center temperature of the rolled material tends to rise.

As in the comparative example shown with the symbol J, the heating temperature is 8.
Even if the temperature is as low as 50℃, the finishing temperature is not desirable.
[Kt increases, causing tissue dispensing.

To determine the structure, as shown in the attached diagram djBK schematic diagram, the α+β structure consisting of uniaxed crystals is grade 1 (Fig.
One set with needle-like surfaces is classified as grade 4 (see figure (d)).
, those in which acicular β fibers were concentrated in the center were classified as grade 2 (see Figure (G)).

As explained above, the present invention is an effective method for α÷/corrugated tough alloy plate stand continuous rolling, particularly for EE rolling at high speed and reduction. That is, as mentioned above,
Since titanium alloys have a high specific strength, processing heat causes a temperature rise in the rolled material, and the higher the rolling speed and reduction ratio, the greater the temperature rise. Therefore, when performing high-speed hard reduction rolling, it is necessary to perform processing in the β region of 980°C or higher), but since the structure becomes unstable, only low-speed light processing is possible. Since rolling becomes possible, its practical value is very great.

[Brief explanation of the drawing]

The attached drawing is a schematic diagram of the crystal structure showing the criteria for determining equiaxed crystal structure. (α) (b) (C) (d) Procedural amendment (voluntary) October 22, 1930 Director General of the Japan Patent Office Shima 1) Haruki Tono 1, indication of the case Showa SA patent Application No. 1λ/g'13 2. Name of the invention ゛ Method for producing rolled titanium alloy material with good structure 3, relationship to the case of the person making the amendment Patent applicant address 75 Kitahama S-chome, Higashi-ku, Osaka Name (
211) Sumitomo Metal Industries Co., Ltd. 4, Agent 5, Subject of amendment Drawing 6, Contents of amendment As attached Correct mistakes 3) (

Claims (1)

[Claims] In continuous rolling of titanium alloy materials, which are finish rolled at least at a rolling speed higher than that at which the temperature of the rolled material rises due to processing heat, the temperature of the rolled material during rolling is reduced to 950°C by removing the processing heat. or less, and the rolling temperature is 960~
A method for producing a rolled titanium alloy material with a good structure, the method comprising adjusting the temperature to 650°C.