JPH0481217A - Method for hot extruding hard-to-work material - 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 (Industrial Application Field) The present invention relates to a method for hot extrusion of difficult-to-process materials, and more specifically, the present invention relates to a method for hot extrusion of difficult-to-process materials, and more specifically, to The present invention relates to a method in which the composite billet is coated with a skin material having excellent properties, processed into a composite billet, and then heated and hot extruded.

(Prior art) Conventionally, when hot-extruding difficult-to-process materials, as shown in FIG. It is generally known to heat the composite billet to a predetermined temperature and hot extrude it. Note that 7 indicates a joint portion formed by electron beam welding.

The reason why such a hot extrusion method is adopted for difficult-to-process materials is that if the difficult-to-process material billet itself is directly hot extruded, it will come into contact with the atmosphere, lubricant, extrusion container, etc. from heating to the start of extrusion. The billet surface is cooled and ductility cannot be maintained during extrusion, resulting in billet cracking. On the other hand, when processed into a composite billet, there is a skin material on the surface where cooling is intense, which prevents the difficult-to-process material itself from cooling, and also retains heat during extrusion, allowing smooth extrusion. ing.

(Problems to be Solved by the Invention) According to the conventional technique of heating and hot extruding the composite billet shown in FIG. In the case of extrusion, the billet is exposed to a cold atmosphere to some extent from the time it is taken out of the furnace to the start of processing, so the outer shell must have a certain thickness.

Therefore, the shape of the core material (hard-to-process material) is inevitably limited,
Processing yield was getting worse.

Also, depending on the combination of the core material and the outer skin material, hot extrusion using a normal extrusion press may not be possible below the eutectic point between the two, but in this case, an economical normal extrusion press may be Hot extrusion becomes difficult.

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, the present invention aims to provide a method for hot extrusion of difficult-to-process materials that can enhance the heat retention effect of a heated composite billet and suppress eutectic reactions. It is a purpose.

(Means for Solving the Problems) The present invention covers the outside of a difficult-to-process material 1 that is difficult to process at room temperature with a skin material 2 that has better workability than that material, processes it into a composite billet, and then heats it to form a composite billet. In the inter-extrusion method, the following technical measures are taken to achieve the above objectives.

That is, the present invention is characterized in that a heat insulating paint 3 is applied to the interface between the difficult-to-process material 1 and the outer skin material 2.

(Function) According to the present invention, by applying the heat insulating paint 3 to the interface between the difficult-to-process material (core material) ■ and the outer skin material 2, the core material 1 and the outer skin material 2 are no longer in direct contact with each other. The paint 3 suppresses the transfer of heat between the core material 1 and the outer skin material 2, and as a result, the temperature of the core material 1 is maintained, making it possible to perform extrusion processing even with the outer skin material 2 having a thinner thickness than before. . Moreover, due to the non-contact, the eutectic reaction between the core material 1 and the outer skin material 2 can be avoided, and hot extrusion at a temperature higher than the eutectic point becomes possible.

(Example) As an example of the present invention, in FIG. 1, 1 is a core material, 2 is an outer skin material, 3 is a heat insulating paint, and 4 is a welded part. In FIG. 1, the core material 1 is Ti 50 ato
mic%N1 SUS 316 was used for the outer skin material 2. Ti
-50 atomic% Al is considered to be a difficult-to-process material, and cannot be plastically deformed at room temperature. At a strain rate of 1 x 10° S-1, which simulates normal extrusion processing,
Cracks occur at temperatures below 00°C. Therefore, the heating temperature was set to 1300°C. Furthermore, the eutectic temperature of Ti and Fe is 10
It is 85°C.

As for the experimental conditions, the outer skin material 2 has a constant outer diameter of 67φ,
Two conditions were used: the outer diameter of the core material 2 tobacco was 50φ and 60φ.

The heat insulating paint 3 applied to the interface between the two was a glass lubricant dissolved in a solvent. Note that if the heat insulating paint 3 is not used, a reaction between the core material 1 and the outer skin material 2 is expected, so two conditions were used: one in which Cr plating was applied to the interface as an intermediate material.

The evaluation method is to heat the billet mentioned above and perform hot extrusion, and check whether any defects such as breakage occur at that time, and after extrusion, cut out the cross section and conduct a fluorescent penetrant test to see if there are any cracks (x). It was determined whether or not (○). The results are shown in Table 1.

Table 1 Note that although glass was used as the heat insulating paint this time, other materials such as ceramics such as alumina, graphite, etc. may be used, and the material is not limited to this. Furthermore, even materials that can be processed below the eutectic point are expected to be effective.

(Effects of the Invention) As is clear from Table 1, in the present invention, by applying a heat insulating paint to the interface between the core material and the outer skin material, the outer skin material can be made thinner due to the heat insulation effect, and the yield can be improved. At the same time, eutectic reactions can also be prevented.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a composite billet used in the present invention, and FIG. 2 is an explanatory diagram of a conventional billet. 1-Difficult-to-process materials, 2-Outer skin materials, 3-Insulating paint.

Claims (2)

[Claims] (1) In a method in which the outside of a difficult-to-process material (1) that is difficult to process at room temperature is coated with a skin material (2) that has better workability, and the material is processed into a composite billet and then heated and hot extruded, A method for hot extrusion of a difficult-to-process material, comprising applying a heat-insulating paint (3) to the interface between the difficult-to-process material (1) and the outer skin material (2). (2) The method for hot extrusion of a difficult-to-process material according to claim (1), characterized in that the heating temperature of the composite billet is set to a temperature equal to or higher than the eutectic point of the difficult-to-process material (1) and the outer skin material (2). .