JPS5853685B2 - Manufacturing method of inner liner for hot extrusion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an inner liner for hot extrusion.

Inner liners for hot extrusion of copper alloys such as Cu-Ni are generally extruded at high temperatures of 700 to 1050°C, so high-temperature strength of the mold material is strongly required, and 5KD61
, 5KD4, and other martensitic hot extrusion materials have the problem of early settling.

In order to improve this short life, A286, In
Super heat-resistant alloys such as CO, 718, etc. are increasingly being used as solid materials, but these alloys are expensive as raw materials, and the product price is extremely high because they use a large amount of alloy and have poor hot workability. It becomes expensive.

For this reason, there are cases where the alloy is overlaid only on the inner surface of the inner liner, but this takes a lot of man-hours and is difficult to achieve a large cost reduction.

Moreover, since the mechanical properties of the built-up portion are low, there is a problem in that heat cracks are likely to occur during use.

The present invention is a method for manufacturing a powder composite inner liner for hot extrusion in which a super heat-resistant alloy is bonded to the inner layer of the inner liner, and provides a method for manufacturing an inner liner made of an optimal composite combination alloy.

One object of the present invention is to significantly improve tool life compared to conventional methods by creating a composite product by combining the inner layer alloy material and the outer layer alloy material of the inner liner by powder metallurgy.

Another purpose is to shorten the process compared to conventional composite materials, to save resources in a short time, and to manufacture them economically. sex,
Rene (
Rene) 41°lN100. This makes it possible to use a high-strength super heat-resistant alloy equivalent to V700 in combination as an inner peripheral material, and can be expected to dramatically improve tool life.

To put it simply, the method of the present invention is achieved by simultaneously producing a composite inner liner for hot extrusion from a powder state in a shape that approximates the final product shape using a powder metallurgy method.

The present invention will be explained in detail by way of examples.

Example 1 Outer diameter 4577n71 Inner diameter 445 Length 1000 and Outer diameter 216mm Inner diameter 208mm Length 1oooo
Two types of mild steel pipes of 7n and 7n were arranged coaxially in the longitudinal direction as shown in the figure.

The bottom gap of the rear steel pipe was welded with a mild steel cover plate made of the same material.

A thin cylinder having a wall thickness of 0.3 mm and an outer diameter of 242 vvn was placed on the same axis within this metal capsule.

In the figure, 1 is an outer steel tube, 2 is an inner steel tube, 3 is a lower cover plate, and 4 is a thin-walled mild steel cylinder.

5 indicates a degassing pipe for exhaust. Next, a cylindrical space divided into two by a mild steel pipe was made with an average particle size of 25
Inc
A spherical alloy powder equivalent to O718 was filled into the inner circumference.

By filling the respective alloy powders across the thin cylinder 4, each powder can be filled uniformly and with high density without mixing the powders with each other.

Table 1 shows the chemical composition of each alloy powder.

The metal capsule filled with the powder was vibrated and filled on a vertical vibrator, and a thin mild steel cylinder (A4) was gently extracted.

The packing density of the powder in this state was examined and found to be 67%.

After that, the upper part of the capsule container was welded and sealed with a mild steel cover plate, and the inside of the capsule container was maintained in a vacuum state through the exhaust pipe 5.The volume dimension filled with the powder was measured, and the result was Inco 7.
18 alloy powder part has an approximate outer diameter of 242 mm, inner diameter of 216 mm,
Height: 920 cm, 5KD61 alloy, outer diameter: 445 cm, inner diameter: 2
It was 42 meters long and 920,711 pi high.

The weight of the 5KD61 equivalent is 527kg, Inco,
The portion equivalent to 718 weighed 46 kg.

The capsule filled with the powder in this state was compacted using a hot isostatic pressure device under conditions of a temperature of 1100° C., a pressure of 1200 atm, and a holding time of 2 hours.

After consolidation, the outer periphery, inner periphery, and end portions of the ingot were removed by turning a mild steel capsule.

The shape of the hollow inner liner material at this time is 405 mm in outer diameter, 220 mm in inner diameter, and 5KD61.
The average diameter connecting the boundary between Inco718 and Inco718 was 238 mm and the length was 750 mm.

Inco as the inner peripheral material, 718 is 5KD6 as the outer peripheral material
Compared to 1, it existed almost on the same axis.

The yield in this state is calculated from the weight of the raw material powder used: 5
KD61 was about 94%, and Inco, 718 was about 83%.

Previously Inco. When molten 718 is processed and finished as an inner liner of the same size, the yield is approximately 40%, which requires an ingot weight of 540 kg. Considering this, it is possible to improve the yield and reduce the amount of alloy used. was confirmed to be extremely large.

Therefore, this inner liner manufactured by the present invention is 5KD
JI No. 84 tensile test pieces were cut out from the 61 section and the Inco 718 section, air-cooled to austenitize by IHr at 1030'C, and tempered at 600°C for 2Hr.

These treatment conditions correspond to standard heat treatment conditions for 5KD61 as a peripheral material.

The tensile strength at that time was 170 kg/mi, elongation 15%, and reduction of area 40%.

Next, a similar tensile test was conducted at 700°C.
．． It was 4%.

This value is the same as the mechanical properties of 5KD61 when manufactured by the melting method.

On the other hand, Inco 71 was subjected to the same heat treatment as 5KD61.
8 has a tensile strength at room temperature of 85.0 kg/ma and an elongation of 31.6%.
, reduction of area 74.5%, tensile strength 137 at high temperature of 700℃
．． The weight was 6 kg/mm, the elongation was 26.7%, and the reduction of area was 56.8%.

This value is slightly inferior to that obtained by heat-treating ingot lumber.

Example 2 In general, Ni-based or Co-based super heat-resistant alloys have a higher coefficient of thermal expansion and lower thermal conductivity than martensitic hot die steel.

In addition, martensitic hot die steel undergoes arutenside transformation during the cooling process.

When these two types of materials are combined, transformation stress is generated in addition to thermal stress at the bonding interface.

If this generated stress is large, problems of deformation or cracking occur.

In particular, martensitic transformation has a small plastic deformability of the material3.
Since it grows in the low temperature range of around 00℃, the stress generated is large and it is easy to cause cracks during heat treatment.

In the case of the present invention, the stress generated during the cooling process after hot isostatic pressure, the heating process during austenitization, the subsequent cooling process, and the heating/cooling process during tempering pose problems.

Since numerical analysis of these thermal stresses is actually difficult, composites of numerically representative combinations of materials were actually prepared using the same method as in Example 1, and the sensitivity to stress generation during heat treatment was measured and investigated.

Table 2 shows the chemical composition of the alloy powder used, and Table 3 shows the physical properties.

Among the steel types in Tables 2 and 3, 5KDX is a tentative name, and is a martensitic hot work tool steel that is an improved material of JIS 5KD61 and has high high temperature strength.

In addition, HD has a high M that exhibits an austenitic structure even at room temperature.
It is an n-type hot die steel.

Further, the thermal expansion coefficient and thermal conductivity are measured values at room temperature and 700°C.

As a result of combining the steel types shown in Table 2 to form a powder composite, Table 4 shows the investigation results of the occurrence of heat treatment cracking and the degree of deformation.

The degree of deformation is determined by the combination of steel types.
0mm, inner diameter 220mm, length ☆☆ After finishing to 770mm and air cooling to austenitize at 1050℃, measure the difference between the maximum outer diameter and minimum outer diameter and the difference between the maximum inner diameter and minimum inner diameter. When a difference occurs, the machining allowance becomes large and the yield decreases, so it is indicated by a △ mark in Table 4.

In addition, the occurrence of cracks is indicated by an x mark.

Similar evaluations were made after air cooling after tempering at 600°C.

In Table 4, the ○ mark indicates that the degree of cracking and deformation was small.

From the above results, cracks occur in iron-based super heat-resistant alloy A286 and martensitic hot work tool steel 5KDX during air cooling from 1050°C, and in martensitic hot work tool steel 5KDX and Ni.
It has been found that the degree of deformation becomes large in the superheat-resistant alloys based on Co and Co-base.

However, it was concluded that these would not pose a major problem as long as there was some allowance for processing costs.

When austenitic hot work tool steel was used for the outer circumferential material, no cracking or deformation was observed, indicating that the combination of these had the most favorable effect.

Te5t of the combination inner liner shown in Table 4
Among A, &3, &4, A6, and Ken8 are actually Cu-
A practical extrusion test of Ni alloy was conducted.

Table 5 shows the results.

As described above, the inner liner for hot extrusion manufactured by the method of the present invention greatly exceeds the current conventional method in terms of yield, manufacturing man-hours, and tool life, and its industrial value is extremely large.

In addition, in the case of an inner liner for hot extrusion, what is required is excellent deformation resistance during hot operation, and the inner peripheral material is made of iron-based, Ni-based, or Co-based super heat-resistant alloy steel. Among them, materials with high high temperature strength are desirable.

The present invention does not limit the composition of these super heat resistant alloys, and any conventional super heat resistant alloys may be used.

On the other hand, the composition of the hot work tool steel for the outer peripheral material is not particularly limited, but like the inner peripheral material, it is desirable to use a material with as high high temperature strength as possible, and it is also necessary to have sufficient toughness to withstand high stress. Selected from a hot work tool steel system called die steel.

However, as mentioned above, it is more preferable to use hot die steel having an austenite base because of the problem of deformation caused by heat treatment after composite formation.

[Brief explanation of drawings]

The figure is a schematic sectional view of a capsule illustrating the compounding process of the present invention.

Claims (1)

[Claims] 1. A method for manufacturing a hollow composite hot extrusion inner liner in which the inner peripheral material is an iron-based, Ni-based, or Co-based super heat-resistant alloy, and the outer peripheral material is an iron-based hot work tool steel, Two metal tubes, an inner tube and an outer tube, each having an outer diameter and an inner diameter corresponding to the inner and outer diameters of the final product, and a thin-walled metal tube with a diameter corresponding to the diameter of the joint between the inner and outer circumferential materials of the final product. The tubes are arranged concentrically, and the spherical alloy powder of Doma super heat-resistant alloy is placed in the space between the thin-walled tube and the inner tube, and the iron-based hot-work tool steel is placed in the space between the thin-walled tube and the outer tube. a step of arranging the two types of alloy powders in a layer by removing the thin-walled tubes after filling each with spherical alloy powder; and a step of sealing both end surfaces between the two metal tubes with a metal cover plate and removing A step of sealing the sealed alloy powder in a vacuum using air, followed by a step of compacting the sealing alloy powder using a hot isostatic pressure method, and at the same time joining the interface between the two types of alloy powder on the inner and outer circumferential sides by diffusion bonding. A method for manufacturing an inner liner for hot extrusion, which is characterized by being manufactured by incorporating a process of removing , thereby saving resources and having a long service life.