JPS62286639A - Forging method for large-sized article of titanium alloy - Google Patents

Abstract

PURPOSE:To forge an ingot without bringing it to machine cutting, and to obtain its excellent inner quality and mechanical quality, by specifying a forging ratio in a specific temperature, and specifying the number of times of heating in all precesses. CONSTITUTION:An ingot 1 is heated to above a beta transas temperature, the ingot 1 is brought to cogging in the longitudinal direction, and a surface structure is crushed. Subsequently, by a repetition of upsetting and cogging, heat forging whose forging ratio is >= 5 is executed, in a heating temperature exceeding the beta transus temperature. Thereafter, in a heating temperature whose betatransus temperature is -50-100 deg.C, heat forging whose forge ratio is >= 3 is executed. Also, by setting the number of times of heating in all processes to at least three times, desired equi-axed fine particles are obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a forging method for manufacturing large titanium alloy products.

(Prior art) Generally, the method for manufacturing large titanium alloy products is as follows:
First, a titanium alloy melted in a vacuum melting furnace is made into an ingot with a round cross section, and either the ingot is directly machined into a product, or the center of the ingot is pierced, and the ingot is forged into a ring. Methods of producing large products by rolling are known.

(Problems to be Solved by the Invention) However, such a manufacturing method is difficult in terms of hot processing, and is often subject to restrictions on the dimensions and shape of the product.
Difficulties often arise in obtaining the desired product.

An object of the present invention is to provide a method for forging a forged ingot without mechanical cutting as in conventional methods.

(Means for Solving the Problems) The present invention, in forging a titanium alloy material whose final forging dimension is 1/2 or more of the diameter of the ingot, heats the ingot to a temperature equal to or higher than the β transus temperature. The surface structure is crushed by forging in the longitudinal direction, and then upsetting and forging are repeated to perform heating forging at a forging forming ratio of 5 or higher at a heating temperature higher than the shift transus temperature, and then at a β transus temperature of -50 to 100. ℃
This is a method for forging a large titanium alloy product, which is characterized by carrying out heat forging at a heating temperature with a forging forming ratio of 3 or more, and carrying out heat forging at least three times in the entire process.

The forging forming ratio is the sum of the ratios before and after deformation of the cross-sectional area perpendicular to the main forging method in each forging and upsetting, and as shown in Figure 1, the cross-sectional area of the ingot 1 in each step is So ,
81, S2,..., the forging forming ratio is (where i is an odd number).

(Function) In the present invention, the reason why the forging ratio at the β transus temperature or higher is set to 5 or more is to obtain a fine grain material with a β grain size of 200 to 300 μm or less, and the β transus −50=
The reason why the forging forming ratio at 100° C. is set to 3 or more is that if it is less than 3, α+β equiaxed fine grains with an α grain size of 20 μm or less cannot be obtained.

In addition, the reason why the number of times of heating in the entire process is set at least three times is that grain size cannot be obtained in one time during processing recrystallization, and the desired equiaxed fine grains can be obtained by repeating heating three or more times. It is from. Note that FIG. 2 shows the steps of the present invention.

(Example) Next, examples of the present invention will be shown.

[Example 1] A Ti-6At--IV alloy ingot (diameter: 600 mm, length: 450 m) was repeatedly forged and upturned by the forging process shown in Fig. 1, resulting in a diameter of 600 mm, length 4
It was forged to a forming size of 50 m. At that time, the heating temperature and forging forming ratio were conducted under the conditions shown in Table 1, and the macrostructure, microstructure, and as-forged paulownia material were evaluated under each condition.The results are shown in Table 1. .

As is clear from this result, the present invention (A3 and A4
) is found to have excellent internal quality and mechanical properties.

[Example 2] A Tf 6At, 2Sn alloy ingot (diameter 600 mm, length 450 wam) was forged and upturned in the same manner as in Example 1, and forged to a diameter of 6001111 and a length of 450 m. . At that time, the heating temperature and forging forming ratio were conducted under the conditions shown in Table 2, and the macrostructure, microstructure, and as-cast material were evaluated.

The results are shown in Table 2.

As is clear from these results, it can be seen that the materials of the present invention (3 and 4) have excellent internal quality and mechanical properties.

[-122--2I (Effects of the Invention) As explained above, according to the present invention, an ingot can be forged without mechanical cutting, and excellent internal quality and mechanical properties can be obtained. , it brings great industrial and economic benefits, and its effects are enormous.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the forging process according to the present invention, and FIG. 2 is an explanatory diagram showing the relationship between temperature and forging in the method of the present invention. 1... Ingot, s, , s, , s2... Cross-sectional area. Agent Patent Attorney Masamitsu Aki Sawa and 1 other person Oki 1 Figure 22 Voluntary continuation amendment 1. Indication of the case Patent Application No. 128685/1983 2 Name of the invention Method for forging large titanium alloy products 3, III Relationship with the case involving a person who commits a crime Client Address 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (665) Nippon Steel Corporation (1 idiot) 4 Agent residence Chuo-ku, Tokyo Nihonbashi Kabutocho 12-1-6,
Item of amendment Specification # (Detailed description of the invention) Contents of amendment 1, r9 in the third column from the left of table fjS1 on page 6 of the specification
"Heating to 50'C or less" is corrected to "Heating to 930C or less." 2. "920" in the third column from the left of Table 2 on page 8 of the specification
``Heating below 895'C'' is corrected to ``Heating above 895'C''.

Claims (1)

[Claims] (1) Forging When forging a titanium alloy material whose final forming size is 1/2 or more of the ingot diameter, the ingot is heated to a temperature higher than the β transus temperature, and the ingot is forged in the longitudinal direction to remove the surface structure. Crushing, then repeating upsetting and forging to perform hot forging with a forging forming ratio of 5 or more at a heating temperature above the β transus temperature, and then at a β transus temperature of -50 to 100°C.
A method for forging a large titanium alloy product, characterized by carrying out heat forging at a heating temperature with a forging forming ratio of 3 or more, and carrying out heat forging at least three times in the entire process.