JPS6112857A - Titanium and titanium alloy for propagating ultrasonic wave - Google Patents

Abstract

PURPOSE:To obtain Ti or a Ti alloy for propagating ultrasonic waves having little ununiformity in the rate of propagation of ultrasonic waves and favorable mechanical characteristics by forming all of the alpha-phase in the metallic structure of Ti or a Ti alloy by the transformation of a beta-phase. CONSTITUTION:Ti or a Ti alloy is heated to >= about 1000 deg.C, preferably about 1050-1100 deg.C, and heat treatment is carried out so that the alpha- or alpha-beta-phase in the metallic structure of the material is transformed into a single beta-phase. The material is then cooled to form a single alpha-phase by the transformation of the beta- phase. Thus, Ti or a Ti alloy for propagating ultrasonic waves having little ununiformity in the ultrasonic characteristics is obtd. without deteriorating the mechanical properties.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to titanium and titanium alloys used as i-bodies for transmitting ultrasonic waves in ultrasonic application equipment such as ultrasonic welding. Titanium and titanium alloys have conventionally been used as materials for ultrasonic application equipment because they have extremely high ultrasonic transmission efficiency, high fatigue strength, and are easy to handle due to their low specific gravity. Conventionally, titanium and titanium alloys having a stable α+β structure have a high specific strength and are advantageous as structural materials, so those with an α+β structure have been used.

For this reason, the heat treatment method for titanium and titanium alloys is α+β.
The processing conditions were selected to produce a stable structure. For example, a method of annealing titanium and titanium alloy materials by heating them at 700 to 750°C below the β-transformation temperature and then air cooling or slow cooling, or annealing the material to 950°C.
Methods such as solution aging treatment, which involves heating and quenching before and after, and then heating and air-cooling at 550° C., are used.

When titanium and titanium alloys obtained by these treatments are used as ultrasonic transmission media, there will be considerable variation in the transmission of ultrasonic waves even if they are made from the same material. For this reason, when processed into the same dimensions and incorporated into ultrasonic application equipment, variations in the transmission of this sound wave cause differences in the transmission of ultrasonic energy, resulting in a problem in which the ultrasonic usage performance is unstable.

In this case, the variation in transmitted sound waves that affects the transmission ability of ultrasonic energy in titanium and titanium alloys used as a medium for ultrasound transmission in ultrasound application equipment is as small as possible, and is 2% or less in terms of sound wave velocity. This is desirable.

As a result of intensive research into reducing the variation in the transmission speed of ultrasonic waves in titanium and titanium alloys, the present inventor found that the transmission speed of ultrasonic waves is that all the α phase in titanium and titanium alloys is α phase transformed from the β phase. The present invention was developed based on the knowledge that the variation is extremely small.

That is, the present invention provides titanium and titanium alloys for ultrasonic transmission, characterized in that all the α phases in the titanium and titanium alloys are α phases transformed from β phases.

The present invention will be further explained in detail below.

Heat treatment of titanium and titanium alloys is performed at 950°C as mentioned above because it is desired that they have high strength when used as structural materials.
A material exhibiting the best strength was obtained by heat treatment at a moderate temperature. Titanium and titanium alloys are heat-treated at 1000°C or higher, preferably 1050-1100°C to change the metallographic structure of the material from α or α+β to β single-phase, and then cooled to transform from the β phase. Obtain the phase with only α.

In this case, the heat treatment temperature may be selected so that the metal property of the material to be treated can reach the β single phase region, and the treatment time may be selected as long as it is commensurate with the temperature. I am going to perform heat treatment in a high temperature range for a long time.

This is because the mechanical properties of the material deteriorate. Therefore 110
It is not preferable to perform heat treatment at a high temperature of 0° C. or higher.

As a result of these treatments, all of the α phase in the metal structure of titanium and titanium alloys has been transformed from β phase to α phase, and there is almost no variation in ultrasonic properties. It has good characteristics to match.

As a result, problems caused by differences in the sorting and work performance of titanium materials for ultrasonic equipment have been completely eliminated.

Example Diameter 2 of Ti-6A1-47 having the composition shown in Table 1
A round bar with a length of 6M and a length of 1000 mm was heated in an electric furnace at 1050°C for 5 minutes, and then a small amount was taken out of the electric furnace and cooled in the air. Using this material, five test pieces with a diameter of 26 mm and a length of 100 mm were made. Table 2 shows the results of measuring the propagation speed of sound waves and observing the metal structure of each test piece. As shown in Table 2, those subjected to the above-described special heat treatment have a rod-shaped structure of α phase transformed from β phase.

Table 1 Note that the propagation speed of sound waves was measured using an ultrasonic thickness gauge.

As seen in Table 2, the speed of transmission of sound waves is.

The maximum value is 6168m7' and the minimum value is 6133mA.

The variation is extremely small, about 15%. Moreover, the metal compositions were all α phase transformed from β phase. Furthermore, the results of the evaluation of the metal properties of the material of the present invention are shown in the third section.
Shown in the table.

Revision of specification (no change in content) Table 2 Table 3 As seen in Table 3, the titanium and titanium alloys of the present invention have properties comparable to those of conventional titanium and titanium alloys.

Comparative Example 1 Same Ti-6Al-4V as used in Example 1, diameter 26
A round bar with a length of 100M was heated in an electric furnace at 720°C for 2 hours, then taken out and cooled in the air. From this, four test pieces each having a length of 100H were used to measure the propagation speed of sound waves. Table 4 shows the results and photographs of the metal structure. As shown in Table 4, there are scattered α phases that are not transformed from the β phase,
The tissue has small spherical and needle-like structures.

It is different from the structure of only the α phase transformed from the rod-shaped β phase shown in Photo Table 2 of this method example.

The transmission speed is 6008 to 6258 between maximum and minimum.
There is a large variation in m/see, and the difference is about 4 cm, which makes problems during use unavoidable.

The characteristics evaluation results of this metal material are shown in Table 3.

(Margin below) Details of the specification 1)’ (no change in content) Table 4 February 25, 1985

Claims (1)

[Claims] Titanium and titanium alloys for ultrasonic transmission in which the α phase in the metal structure is all α phase transformed from the β phase