WO2002046485A1 - Nickel-based alloy composition for high thermal resistance elements, in particular for hot deformation process tools and for high temperature working - Google Patents

Abstract

Nickel-based composition particularly suitable for high thermal resistance elements, in particular for hot deformation process tools and for high temperature working, like, e.g. dies for isothermal forming, comprising: a Nickel (Ni) content ranging from 57.0 % to 62.0 %; a maximum Tungsten (W) content of 10.0 % and a maximum Iron (Fe) content of 1.5 %. in Fig. a die for high temperature applications made of said composition is shown.

Description

NICKEL-BASED ALLOY COMPOSITION FOR HIGH THERMAL RESISTANCE ELEMENTS, IN PARTICULAR FOR HOT DEFORMATION PROCESS TOOLS AND FOR HIGH TEMPERATURE WORKING

DESCRIPTION 5 The present invention relates to a Nickel-based composition for high thermal resistance elements, in particular for hot deformation tools and for high- temperature working. Specifically, this composition is suitable to the forming of tools apt to work under 10 extremely onerous thermal conditions, liable to be subjected to thermal cycles of wide thermal ranges.

Analogous tools are, e.g., dies, cutting tools and the like.

A field requiring high-performance compositions, 15 combined with a satisfactory machinability, is represented by forging, in which the die and the forged piece have the same temperature .

This technique enables to hot-roll products characterised by low thicknesses and volumes, yet 20 exhibiting stable and uniform mechanic properties.

In several technological fields, tools and dies made of high-performance materials enable quicker and more accurate working. In the case of the dies, a low-wear holder block complex suffering from minimum 25 thermomechanical distortions can substantially speed up the related manufacturing processes, dispensing with burdensome finishing interventions like grinding, shaping, etc.

Moreover, reproduction accuracy is enhanced, even 30 after a high number of uses . These advantages become particularly important in the case of large-scale productions .

An example of a composition for tools and dies as abovementioned is taught in US Pat. No.5, 505, 798 35 (Nelson) .

Notable known compositions are the high Nickel ones (refer to "Development of a Die Material for Isothermal Forging of Superalloys in air" , Ohno, Watanabe, Nonomura, 110^th ISIJ Meeting, October 1985) yet the performances attained are still unsatisfactory.

A further example of Nickel-based composition is that of US Pat. No.5, 538, 683 (Pinnow et al . ) .

The technical problem underlying the present invention is to provide a Nickel-based composition for high thermal resistance elements allowing to attain improved performances, with respect to the known art. This problem is solved by a composition for high thermal resistance elements, in particular for hot deformation tools and for high temperature working, characterised in that it comprises: a Nickel (Ni) content ranging from 57.0% to 62.0%; a maximum Tungsten (W) content of 10.0%; and a maximum Iron (Fe) content of 1.5%.

The present invention further relates to a tool formed with the composition as hereto set forth, and in particular to such a forging die. Hereinafter, reference will be made to some preferred embodiments of the composition, by way of example and not for limitative purposes, and to the attached drawings, wherein:

* Fig. 1 is a schematic sectional view of a die-die block complex made with the composition according to the invention; and

* Fig. 2 is a schematic elevational view of a press employing the die of Fig. 1.

In Fig. 1, a forging-type die is indicated with 1. Such a die, when it is employed in the forming of metal workpieces, should be capable of being subjected to extremely elevated heating of up to 1100°C and above, to be subsequently cooled down with an optimum distortion control . In the case of plastics workpieces the temperatures are lower, yet the working conditions are equally severe, also in light of the fact that for this type of workpieces an elevated manufacturing speed and the utmost accuracy, sometimes such as to dispense with further finishing steps, are expected.

In the present embodiment, as it is shown in Fig. 1, a die 1 comprises a (male) top counter plunger 2, housed in a suitable die block 3, and a bottom die block 4, housing a (female) matrix die 5. Through the matrix die 5 two guide grooves 6 for inserting ejection tools, and at least one injection runner 7 having a profile divergent towards the inside of the former, are formed.

The counter plunger 2 and the matrix die 5 are connected by screw-type fastening means (not shown in Fig.) and dowel pins 8.

The entire complex hereto disclosed is employed in a press 10 of the type depicted in Fig. 2, provided with suitable pressing and lifting means 11 apt to implement an adequate pressure inside of the die 1 during injection.

The press adjusting, cooling and injecting means 11 are of traditional type, and therefore a further description thereof will be omitted.

The matrix die 5, i.e. that section of the die 1 which contains the hot-injected material to be pressed, is made of a composition which, in its most general form, comprises: a Nickel (Ni) content ranging from 57.0% to 62.0%; A maximum Tungsten (W) content of 10.0%; and a maximum Iron (Fe) content of 1.5%.

According to a preferred embodiment of the composition, it has a Chromium (Cr) content of above 6%, moreover comprising Manganese (Mn) , Silica (Si) , Carbon (C) and Molybdenum (Mo) .

Two embodiments of the abovedisclosed composition, of course by way of example and not for limitative purposes example, will hereinafter be disclosed. Example 1

The composition disclosed in the present example is used in order to obtain a material of elevated purity, of highly refined structure, and remarkable isotropic properties, the latter being particularly useful in dies subjected to remarkable mechanical stresses and in particular to thermal fatigue (e.g., dies for pressure die-casting, dies for hot-pressing and matrix dies for aluminium and copper alloy extrusions) .

Example 2

The composition disclosed in the present example is used in order to obtain a material enabling a decreased friction coefficient, also avoiding deformation and stress during ejection, in particular decreasing the sliding friction, important for an easy filling up of the cavities even at low temperatures and with a low pressure, and for an anticipated and easier post- solidification ejection.

This entails a shortening of the pressing cycle, and the attainment of an enhanced quality and of an increase of the maintenance interval .

* * *

To the abovedescribed composition a person skilled in the art, in order to satisfy further and contingent needs, may effect several further modifications and variants, all however encompassed by the protective scope of the present invention, as set forth in the appended claims.

Claims

1. A Nickel-based composition for high thermal resistance elements, in particular for hot deformation tools and for high temperature working, characterised in that it comprises: a Nickel (Ni) content ranging from 57.0% to 62.0%; a maximum Tungsten (W) content of 10.0%; and a maximum Iron (Fe) content of 1.5%.

2. The composition according to claim 1, comprising a Chromium (Cr) content of above 6%. '■

3. The composition according to claim 1, comprising Iron (Fe) , Manganese (Mn) , Chrome (Cr) , Silica (Si) , Carbon (C) , Nickel (Ni) , Molybdenum (Mo) , Tungsten (W) .

4. The composition according to claim 2, having percents as resumed in the following table:

5. A tool (1), comprising a composition as set forth in any one of the claims 1 to 4

6. A die (1), in particular for forging, comprising a composition as set forth in any one of the claims 1 to 4.