JPS6250429A - Nickel-base casting alloy for hot forging die - Google Patents

Abstract

PURPOSE:To obtain a material for hot forging die excellent in both oxidation resistance and hot pressing strength and sufficiently practicable in the air by incorporating prescribed amounts of Al, Mo, W, Y and rare earth elements to Ni. CONSTITUTION:The Ni-base casting alloy for hot forging die has a composition consisting of, by weight, 4-8% Al, 7-13% Mo, 9-15% W, <=0.1% Y or >=1 kind among rare earth elements and the balance Ni. This alloy is excellent in both oxidation resistance and hot pressing strength and sufficiently practicable in the air even in case of heating up to about 1,000-1,150 deg.C and, in addition, it has superior machinability as compared with conventional alloys. Consequently, by use of this alloy as die material, the forging of super heat-resisting alloys at a high temp. of >=1,000 deg.C hitherto impossible except in vacuum or in an inert gas is made possible in the air. Accordingly, forging equipment is made simple and inexpensive and work efficiency is remarkably improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a mold material used for high-temperature forging of super heat-resistant alloys, which is performed by heating the mold to a high temperature of 1000 to 1150'C. It is.

[Conventional technology]

Conventional mold materials used in high-temperature forging of super heat-resistant alloys where the mold is heated to a high temperature of 1000"C or higher.

Mo-based alloys such as TZM are used.

On the other hand, when the mold temperature is 1000° C. or lower, such as in high-temperature forging of Ti alloys, conventional super heat-resistant alloys containing Cr, such as Mar-M 200, are used as the mold material.

[Problem that the invention seeks to solve]

Mo-based alloys have sufficiently high high-temperature strength but poor oxidation resistance, so high-temperature forging when used as a mold material must be performed in a vacuum or inert gas, making high-temperature forging equipment complicated. However, conventional super heat-resistant alloys containing Cr, such as Mar-M 200, have good oxidation resistance but low high-temperature compressive strength. Because it is insufficient, it cannot be used for high-temperature forging molds at temperatures of 1000°C or higher.

The present invention has excellent both oxidation resistance and high temperature compressive strength, and has a
The object of the present invention is to provide a high-temperature forging mold material that can be sufficiently used in the atmosphere even when heated to a temperature of 0 to 1150°C.

[Means for solving problems]

The present invention has A14-8% and Mo 7-13% by weight.
, W9 to 15%, 0.1% or less of one or more of Y or rare earth elements, and the remainder consists essentially of Ni excluding impurities, or an alloy having the above composition. The nickel for high-temperature forging molds according to claim 1, further comprising a body-centered cubic α-(Mo, W) phase consisting essentially of a solid solution of M6 and W at grain boundaries. It is a base casting alloy.

In the alloy of the present invention, AI combines with Ni, Mo, and W to precipitate a Ni, (Al, MO5W) type gamma prime phase, thereby increasing the high temperature strength of the alloy. It has two effects: imparting oxidation resistance. In order to make these effects sufficient, Al needs to be at least 4%, but if it exceeds 8%, the eutectic gamma prime will increase excessively and the high temperature strength will decrease, so in the alloy of the present invention, Al is limited to 4-8%.

Mo and W are Ni3 (Al, Mo) along with Ni and Al.

W)-type gamma prime phase is precipitated to increase the high-temperature strength of the alloy; solid solution in the austenite matrix increases the high-temperature strength of the alloy; It has three effects: crystallizes the α-(Mo, W) phase, increases the grain boundary strength of the alloy, and also improves the machinability of the alloy. On the other hand, if any of these elements is added excessively, the oxidation resistance will deteriorate. The effects of MO and W are very similar, but W has a greater effect of increasing high-temperature strength, while W has a greater effect of deteriorating oxidation resistance. From such a mutual relationship, in consideration of the balance between high temperature strength and oxidation resistance, Mo and W in one of the alloys of the present invention are limited to 7 to 13% and 9 to 15%, respectively.

When added in a very small amount, Y has the effect of improving the density and adhesion of the alumina film formed on the alloy surface and increasing oxidation resistance, but when added in excess, it lowers the initial melting temperature of the alloy.
Since it lowers grain boundary strength and high-temperature strength, it is limited to 0.1% or less in the alloy of the present invention.

Nj is a base element of the alloy of the present invention, and acts as a basic element constituting both the austenite matrix and the gamma prime phase.

By optimizing the contents of A1, Mo, and W and the casting conditions in the alloy of the present invention, a body-centered cubic α-(Mo, W) phase, which is essentially a solid solution of Mo and W, is created at the grain boundaries. Although it can be crystallized, this phase has the effect of strengthening grain boundaries and increasing high-temperature strength as well as increasing the machinability of the alloy, so it is desirable that it be present in a small amount.

〔Example〕

Example 1 In order to evaluate the characteristics of the present invention alloy as a high-temperature forging mold, the present invention alloys No. 001 and No. 2 in Table 1 and the conventional alloy Mar-M 200 No. 11 were cast, and the as-cast 10+nmφ×12m or 10 fieldsφX
Cut out a 20m test piece and conduct a compression test for 1017 seconds at 1050 to 1100°C (10mφ x 12mm)
, compression creep test at 1050-1100°C (1
Oxidation resistance test (10 mmφ x 20
mm), and the compressive deformation resistance, compressive creep strain, and oxidation loss were measured. The results are shown in Table 1.
It can be seen that the alloy of the present invention has a higher compressive deformation resistance at high temperatures exceeding 1000° C. and a much higher compressive creep resistance than conventional alloys. In addition, the oxidation resistance is as good as that of the conventional alloy.8 Example 2 Inventive alloy N004 and conventional alloy Mar-M20 in Table 1
The alloy samples of the present invention, which were cast with 0 NO and H and subjected to machinability tests in the as-cast state, had body-centered cubic crystals essentially consisting of a solid solution of 1 and 2 MO and W at the grain boundaries. (Mo.

The major difference in structure is that conventional alloys contain MC-type carbides at grain boundaries, whereas conventional alloys contain MC-type carbides at grain boundaries.

Machinability was determined using cemented carbide and TjCN-based coating tips, cutting speed 10m/win, feed rate 093u.
The flank wear width of the insert was measured and evaluated after turning for 5 minutes under conditions of ++/rev, depth of cut of 0.5 nn.6 The flank wear width is shown in Table 1.1 Compared to the conventional alloy, the alloy of the present invention was It can be seen that the machinability is approximately twice as good.

Example 3 A mold was made using the casting material of the present invention alloy No. 3 shown in Table 1, and I N-100 powder extrusion material was used as the casting material.
Isothermal forging was carried out in the atmosphere at 070°C and 10-3/'C using BN as a lubricating mold release agent to obtain a cast product with a complex shape of 2G and 2n* from a cylindrical material of 14mm x 17nn. There was no damage to the mold.

Example 4 A mold was manufactured using a cast material of the invention alloy N005 shown in Table 1,
Was under the conditions of 1020-1080℃, 1O-3/'C
From paloy's φ75 x 152mm material to φ16
Several 0 x 35mm disks in the atmosphere! Although it was manufactured by forging, there was no damage to the mold.

【Effect of the invention〕

By using the alloy of the present invention as a mold material, high-temperature forging of super heat-resistant alloys of 1000°C or higher, which could previously only be done in vacuum or inert gas, becomes possible in the atmosphere, and the forging equipment becomes simple and inexpensive. Also, work efficiency is greatly improved. Furthermore, since the alloy of the present invention has better rigidity than conventional super heat-resistant alloys, it can be
The following high-temperature forging also has the effect of reducing mold costs.

Agent: Patent attorney Tachibana Takaishi;

ゝ、− ゛ゞ－

Claims (1)

[Claims] 1 Al: 4-8%, Mo: 7-13%, W: 9-8% by weight
15%, Y or one or more rare earth elements 0
．． A nickel-based casting alloy for high-temperature forging molds, containing 1% or less of Ni, with the remainder essentially consisting of Ni excluding impurities. 2. The nickel base for high-temperature forging molds according to claim 1, characterized in that the grain boundaries contain a body-centered cubic α-(Mo, W) phase consisting essentially of a solid solution of Mo and W. Casting alloy.