JPS6199546A - Manufacturing method of thin strip - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention is a method suitable for producing a ribbon directly from molten metal, and a ribbon whose structure does not have columnar crystals.

[Background of the invention]

Methods for directly producing ribbons from molten metal can be roughly divided into the single roll method and the twin roll method. In either case, the crystal grains in the ribbon produced by these methods become columnar crystals, because the molten metal rapidly cools and solidifies from the surface in contact with the roll in the thickness direction of the ribbon, resulting in crystal growth. It's for a reason. Therefore, the mechanical properties (tensile strength, elongation) of the ribbon are poor and have become a problem.

In the published patent publication (Sho 58-96844), Ni-Ti
Shape memory alloys are produced in single rolls and are reported to have better mechanical properties than conventional processed products. but,
This is because the structure becomes fine due to the quenching effect, and the crystal grains are columnar crystals.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a method for manufacturing a ribbon having no columnar crystals.

[Summary of the invention]

There are two main advantages to manufacturing ribbons using the molten metal quenching method.

1) Since the ribbon is manufactured directly from molten metal, the manufacturing cost of the ribbon becomes low. 2) It is possible to make thin strips of difficult-to-process materials that cannot be forged or rolled. On the other hand, the drawback is that the crystal grains in the longitudinal and width directions of the ribbon are columnar crystals, resulting in poor mechanical properties, especially toughness. The long axis of the typical columnar crystals in ribbons produced by the melt quenching method is more than 10 times the short axis. The generated columnar crystals are made of materials that are difficult to process (for example, Cu-Aρ).
-Ni type and Ni-Ti type shape memory alloys, intermetallic compounds, etc.) cannot be processed and cannot be destroyed, which is a problem.

As a result of various studies, we found that the molten metal 2 is once jetted onto the surface of one roll 4, rapidly solidified, and then rolled with the other roll 5 in a hot state to produce a ribbon 6, as shown in Figure 3. Six features of the present invention are the rolling temperature of the ribbon when rolling with the other roll 5. According to the present invention, the temperature range is preferably 50% or more of the melting point of the ribbon 6. If the temperature is lower than this, the ribbon will not be rolled and columnar crystals will remain. It consists in strong processing. As a result, the columnar crystals before being subjected to strong working are recrystallized by the strong working, so no columnar crystals are observed.
The rolling temperature of the present invention is preferably equal to or higher than the recrystallization temperature. Fig. 1 is a reproduction of the crystal grains in the cross section in the width direction of the Ml strip produced by the method of the present invention, based on a II microphotograph. FIG. 2 shows crystal grains produced by the conventional method (single roll method) for comparison.

In the conventional method, most of the crystals are columnar crystals. However, in the ribbon produced by the method of the present invention, no columnar crystals are observed, and the length #(L) of the crystal grains is 3 times or less than the short axis (11). Moreover, this relationship is 80% or more of the ribbon. Therefore, improvement in mechanical properties is expected compared to conventional methods.

Example 1 Using the molten metal quenching device shown in Fig. 3, Cu-1 was added to the master alloy.
A thin strip was produced using a 4%AQ-4%Ni (wt%) shape memory alloy.The mother alloy was charged into a quartz nozzle 1, melted by a work coil 3, and rotated at high speed (1000 rpm).
The molten metal 2 is placed on the outer periphery of the rolling roll 4 (φ300).
was once poured, and after cooling and solidifying, the ribbon was rolled at a temperature of about 900° C. with rolls 5 (φ120) rotating in synchronization with rolls 4. The temperature of this thin film was measured in advance by the single roll method (diameter 300+am). That is, the molten metal ejected from the nozzle flies in the roll rotation direction while contacting the roll, cools and solidifies, and becomes a ribbon. Therefore, the surface temperature of the ribbon at each predetermined distance from the nozzle tip to the roll's outer periphery was measured using an infrared radiation thermometer. It was installed at a position 200H from the roll surface so that the light receiving area was 5 cm in diameter. Furthermore, the signals detected by the infrared radiation thermometer were recorded using an electromagnetic oscilloscope. Using the method described above, various manufacturing conditions (roll circumferential speed,
The surface temperature of the ribbon at each predetermined distance (ejection temperature and ejection pressure of the molten metal) is measured, and based on this, using the apparatus shown in Fig. 3, the positional relationship between the nozzle 1 and the roll 5 is adjusted to the set rolling temperature. It was installed in a certain position. Note that the pressing force was 1 t. As a result, thickness 0.2 arm, 1111Loa
ds, a thin 1E6 with a length of 10III+ was manufactured. FIG. 1 shows an observation of crystal grains in a cross section in the width direction of this ribbon. In the ribbon produced by the method of the present invention, columnar crystals as shown in Figure 2 (conventional method) are not detected.Table 0 shows the method of the present invention and the conventional method (
The results of a comparison of the mechanical properties of the ribbon produced by the single roll method and the single roll method are shown in Figure 1. The method of the present invention has the effect of immediately providing improved mechanical properties.

This is because in the case of the conventional method, grain boundary fracture occurs within the ductility limit due to the remarkable growth of columnar crystals, whereas in the method of the present invention, since there is no columnar crystal, plastic deformation occurs and ductile fracture occurs. The roll rotation speed and molten metal temperature are measured while detecting the surface temperature of the ribbon poured onto the roll surface.

It is possible to perform plastic working at a predetermined temperature while controlling the amount of molten metal poured.

Example 2 Using 5US304 steel as the master alloy, only the rolling temperature was set to 120
A thin ribbon was produced in the same manner as in Example 1 except that the temperature was 0°C.

As a result, thickness 0.15+eta, Ml 2rthr
A thin film of s was obtained. The cross-sectional structure of the ribbon does not have columnar crystals, and the major axis is less than 1.2 times the minor axis, and this relationship holds true for the 9
It was 0% or more.

〔Effect of the invention〕

According to the present invention, a ribbon having no columnar crystals can be produced, and a ribbon with excellent mechanical properties can be produced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of crystal grains in a ribbon produced by the method of one embodiment of the present invention, FIG. 2 is a schematic diagram of a ribbon produced by a conventional method,
FIG. 3 is a configuration diagram of a molten metal quenching device used in the present invention. 1... Quartz nozzle, 2... Molten metal, 3... Workco 1st port (0L) (#,) ¥30

Claims (1)

[Claims] 1. A method for manufacturing a thin strip in which the material is directly rapidly solidified from a molten state and formed into a thin strip, which is characterized by rolling the thin strip in the cooling and solidifying process at a temperature range of 50% or more of the melting point of the thin strip. How to make obi.