EP2971204B1 - Nickel-based alloy with silicon, aluminum, and chromium - Google Patents

Description

The invention relates to a nickel-based alloy with silicon, aluminum, chromium and reactive elements as alloying constituents.

Nickel-base alloys are used inter alia to produce electrodes of ignition elements for internal combustion engines. These electrodes are exposed to temperatures between 400 ° C and 950 ° C. In addition, the atmosphere changes between reducing and oxidizing conditions. This produces a material destruction or loss due to high-temperature corrosion in the surface region of the electrodes. The generation of the spark leads to a further load (spark erosion). Temperatures of several 1000 ° C occur at the base of the spark, and currents of up to 100 A flow in the first nanosecond during a breakthrough. With each flashover, a limited volume of material in the electrodes is melted and partially vaporized, producing a loss of material.

In addition, vibrations from the engine increase the mechanical loads.

• Eine gute Beständigkeit gegen Hochtemperaturkorrosion, insbesondere Oxidation, aber auch Sulfidierung, Aufkohlung und Nitrierung. Sodann ist eine Beständigkeit gegen die durch den Zündfunken entstehende Erosion erforderlich. Zusätzlich sollte der Werkstoff nicht empfindlich gegen Thermoschocks und warmfest sein. Des Weiteren sollte der Werkstoff eine gute Wärmeleitfähigkeit, eine gute elektrische Leitfähigkeit und einen ausreichend hohen Schmelzpunkt haben. Er sollte sich gut verarbeiten lassen und preisgünstig sein.

An electrode material should have the following properties:

• Good resistance to high-temperature corrosion, in particular oxidation, but also sulfidation, carburizing and nitriding. Then a resistance to the erosion caused by the spark is required. In addition, the material should not be sensitive to thermal shocks and heat-resistant. Furthermore, the material should have a good thermal conductivity, a good electrical conductivity and a sufficiently high melting point. He should be easy to work with and cheap.

In particular, nickel alloys have a good potential to fulfill this property spectrum. They are inexpensive compared to precious metals, show no phase transformations to the melting point, such as Cobalt or iron, are comparatively insensitive to carburizing and nitriding, have good heat resistance, good corrosion resistance, and are readily formable and weldable.

For both damage mechanisms, namely high-temperature corrosion and spark erosion, the type of oxide layer formation is of particular importance.

In order to achieve an optimum oxide layer formation for the specific application, various alloying elements are known in nickel-based alloys.

In the following, all concentrations are in mass%, unless expressly stated otherwise.

By the DE 29 36 312 A1 For example, a nickel alloy has been disclosed consisting of about 0.2 to 3% Si, about 0.5% or less Mn, at least two metals selected from the group consisting of about 0.2 to 3% Cr, about 0.2 to 3% Al and about 0.01 to 1% Y, balance nickel.

In the DE-A 102 24 891 For example, a nickel-based alloy is proposed which comprises 1.8 to 2.2% silicon, 0.05 to 0.1% yttrium and / or hafnium and / or zirconium, 2 to 2.4% aluminum, balance nickel.

In EP 1 867 739 A1 For example, there is proposed a nickel base alloy containing 1.5 to 2.5% silicon, 1.5 to 3% aluminum, 0 to 0.5% manganese, 0.05 to 0.2% titanium in combination with 0.1 to 0.3% zirconium, wherein Zr can be replaced wholly or partially by the double mass hafnium.

In DE 10 2006 035 111 A1 For example, there is proposed a nickel-base alloy comprising 1.2 to 2.0% aluminum, 1.2 to 1.8% silicon, 0.001 to 0.1% carbon, 0.001 to 0.1% sulfur, and 0.1% or less chromium , maximum 0.01% manganese, maximum 0.1% Cu, maximum 0.2% iron, 0.005 to 0.06% magnesium, maximum 0.005% lead 0.05 to 0.15% Y and 0.05 to 0.10% hafnium or lanthanum or in each case 0.05 to 0.10% hafnium and lanthanum, balance nickel and manufacturing-related impurities.

In the brochure "Wires of ThyssenKrupp VDM Automobilindustrie", issue 01/2006, on page 18 an alloy according to the state of the art - NiCr2MnSi with 1.4 to 1.8% Cr, max. 0.3% Fe, max. 0.5% C, 1.3 to 1.8% Mn, 0.4 to 0.65% Si, max. 0.15% Cu and max. 0.15% Ti described.

The aim of the subject invention is to provide a nickel-based alloy by which it comes to an increase in the life of components made therefrom, which by raising the spark erosion and corrosion resistance at the same time sufficient formability and weldability (workability) can be brought. The alloy should in particular have a high corrosion resistance and even with very corrosive acting fuels such. B. with a proportion of ethanol, have a sufficiently high corrosion resistance.

The goal is achieved by a nickel base alloy consisting of (in mass%) Si 1.5 - 3.0% al 1.5 - 3.0% Cr > 0.1 - 3.0%, where 4.0 ≤ <Al + Si + Cr ≤ <8.0 is satisfied with the contents of Si, Al and Cr in%, Fe 0.005 to 0.20%, Y 0.012-0.20%, <0.001-0.20% of one or more of Hf, Zr, La, Ce, Ti, where 0.02 ≤ <Y + 0.5 * Hf + Zr + 1.8 * Ti + 0 , 6 * (La + Ce) ≤ <0.30 is satisfied with the contents of Y, Hf, Zr, La, Ce, Ti in%. C 0.001 - 0.10% N 0,0005 - 0,10% Mn 0.001 - 0.20% mg 0.0001 - 0.08% O 0.0001 to 0.010% S Max. 0.0150% Cu Max. 0.80% optionally Ca 0.001 to 0.06% Co Max. 0.50% W Max. 0.20% Not a word Max. 0.20% Nb Max. 0.20% V Max. 0.20% Ta Max. 0.20% pb Max. 0.005% Zn Max. 0.005% sn Max. 0.005% Bi Max. 0.005% P Max. 0.50% B Max. 0.020% Ni Remainder and the usual production-related impurities.

Preferred embodiments of the subject invention are set forth in the dependent claims.

• 1,8 bis 3,0 %
• 1,9 bis 2,5 %

The silicon content is between 1.5 and 3.0%, whereby preferably defined contents can be set within the spreading ranges:

• 1.8 to 3.0%
• 1.9 to 2.5%

• 1,5 bis 2,5 %
• 1,6 bis 2,5 %
• 1,6 bis 2,2 %
• 1,6 bis 2,0 %

This applies equally to the element aluminum, which is set at levels between 1.5 to 3.0%. Preferred contents can be given as follows:

• 1.5 to 2.5%
• 1.6 to 2.5%
• 1.6 to 2.2%
• 1.6 to 2.0%

• 0,8 bis 3,0 %
• 1,2 bis 3,0 %
• 1,9 bis 3,0 %
• 1,9 bis 2,5 %

This applies equally to the element chromium, which is set at levels between> 0.1 to 3.0%. Preferred contents can be given as follows:

• 0.8 to 3.0%
• 1.2 to 3.0%
• 1.9 to 3.0%
• 1.9 to 2.5%

For the elements Al, Si and Cr, the formula 4.0 <Al + Si + Cr <8.0 must be satisfied with the contents of Si, Al and Cr in%. Preferred ranges result for 4.5 ≦ <Al + Si + Cr <<7.5%
5.5 ≦ Al + Si + Cr ≦ 6.8%

• 0,005 bis 0,10 %
• 0,005 bis 0,05 %

This also applies to the element iron, which is set in amounts between 0.005% and 0.20%. Preferred contents can be given as follows:

• 0.005 to 0.10%
• 0.005 to 0.05%

Furthermore, it is favorable to add to the alloy yttrium with a content of 0.01% to 0.20% and 0.001 to 0.20% of one or more of the elements Hf, Zr, La, Ce, Ti,
where 0.02 ≦ Y + 0.5 * Hf + Zr + 1.8 * Ti + 0.6 * (La + Ce) ≦ 0.30 with the contents of Y, Hf, Zr, La, Ce, Ti in% is satisfied. Preferred ranges are given as follows: Y 0.01 to 0.15% Y 0.02 to 0.10% Hf, Zr, La, Ce, Ti 0.001 to 0.15%, respectively
with 0.02 ≦ Y + 0.5 * Hf + Zr + 1.8 * Ti + 0.6 * (La + Ce) ≤ 0.25
Hf, Zr, La, Ce, Ti 0.001 to 0.10% each
with 0.02 ≦ Y + 0.5 * Hf + Zr + 1.8 * Ti + 0.6 * (La + Ce) ≦ 0.20
Hf, Zr, Ti in each case 0.01 to 0.05% or La, Ce in each case 0.001 to 0.10%
with 0.02 ≦ Y + 0.5 * Hf + Zr + 1.8 * Ti + 0.6 * (La + Ce) ≦ 0.20

• 0,001 bis 0,05 %

Carbon is similarly adjusted in the alloy at levels between 0.001-0.10%. Preferably, contents can be adjusted in the alloy as follows:

• 0.001 to 0.05%

• 0,001 bis 0,05 %

Similarly, nitrogen is set in the alloy at levels between 0.0005-0.10%. Preferably, contents can be adjusted in the alloy as follows:

• 0.001 to 0.05%

The element Mn may be given in the alloy as follows: Mn 0.001 to 0.20% preferably the following ranges are given: Mn 0.001 to 0.10% Mn 0.001 to 0.08%

• 0,001 bis 0,08 %

Magnesium is set at levels of 0.0001 to 0.08%. It is preferably possible to adjust this element in the alloy as follows:

• 0.001 to 0.08%

The alloy may further include calcium in amounts between 0.0001 and 0.06%, as needed.

The sulfur content is limited to max. 0.015% limited. Preferred contents can be given as follows: S Max. 0.010%

• 0,0001 bis 0,008 %

The oxygen content is set in the alloy at a content of 0.0001 to 0.010%. Preferably, the following content can be adjusted:

• 0.0001 to 0.008%

The copper content is limited to max. 0.80% limited. Preferably, a restriction occurs
Max. 0.50%
Max. 0.20%

Finally, impurities may still have the following elements: Co max.0,50% W Max. 0.02% (maximum 0.10%) Not a word Max. 0.02% (maximum 0.10%) Nb Max. 0.02% (maximum 0.10%) V Max. 0.02% (maximum 0.10%) Ta Max. 0.02% (maximum 0.10%) pb Max. 0.005% Zn Max. 0.005% sn Max. 0.005% Bi Max. 0.005% P Max. 0.050% (max 0.020%) B Max. 0.020% (max 0.010%)

The alloy of the invention is preferably melted open, followed by treatment in a VOD or VLF plant. But also a melting and pouring in a vacuum is possible. Thereafter, the alloy is poured in blocks or as a continuous casting. If necessary, the block / continuous casting is then annealed at temperatures between 800 ° C and 1270 ° C for 0.1 h to 70 h. Furthermore, it is possible to remelt the alloy additionally with ESU and / or VAR. Thereafter, the alloy is brought into the desired semifinished product. For this, if necessary, annealed at temperatures between 700 ° C and 1270 ° C for 0.1 h to 70 h, then hot formed, possibly with intermediate anneals between 700 ° C and 1270 ° C for 0.05 h to 70 h. The surface of the material can optionally (also several times) be removed chemically and / or mechanically in between and / or after the hot forming for cleaning. Thereafter, if necessary, one or more cold forming with degrees of deformation up to 99% in the desired semi-finished mold, optionally with intermediate anneals between 700 ° C and 1250 ° C for 0.1 to 70 h, if necessary under inert gas such. As argon or hydrogen, followed by a cooling in air, in the moving annealing atmosphere or in a water bath be performed. Then finds a solution annealing in the temperature range of 700 ° C to 1250 ° C for 0.1 to 70 h, optionally under inert gas, such as. As argon or hydrogen, followed by cooling in air, in the moving annealing atmosphere or in a water bath instead. Possibly. In between and / or after the last annealing chemical and / or mechanical cleaning of the material surface can take place.

The alloy according to the invention can be well in the product forms band, in particular in thicknesses of 100 microns to 4 mm, sheet, in particular in thicknesses of 1 mm to 70 mm, rod, in particular in thicknesses of 10 mm to 500 mm, and wire in particular in thicknesses from 0.1 mm to 15 mm, manufacture and use pipes, in particular in wall thicknesses of 0.10 mm to 70 mm and diameters of 0.2 mm to 3000 mm.

These product forms are produced with a mean particle size of 4 μm to 600 μm. The preferred range is between 10 μm and 200 μm.

The nickel-based alloy according to the invention is preferably usable as a material for electrodes of spark plugs for gasoline engines.

• Die Oxidationsbeständigkeit steigt mit zunehmendem Si-Gehalt. Es ist ein Mindestgehalt von 1,5 % Si notwendig, um eine ausreichend große Oxidationsbeständigkeit zu erhalten. Bei größeren Si-Gehalten verschlechtert sich die Verarbeitbarkeit. Die Obergrenze wird deshalb auf 3,0 Gew.-% Si gelegt.

The claimed limits for the alloy can therefore be explained in detail as follows:

• The oxidation resistance increases with increasing Si content. A minimum content of 1.5% Si is necessary to obtain a sufficiently high oxidation resistance. At higher Si contents, the processability deteriorates. The upper limit is therefore set to 3.0 wt% Si.

With a sufficiently high Si content, an aluminum content of at least 1.5% further increases the oxidation resistance. At higher Al contents, the processability deteriorates. The upper limit is therefore set to 3.0 wt% Si.

With a sufficiently high Si content and Al content, a chromium content of at least 0.1% further increases the oxidation resistance. At higher Cr contents, processability deteriorates. The upper limit is therefore set to 3.0 wt% Cr.

For a good oxidation resistance, it is necessary that the sum of Al + Si + Cr is larger than 4.0% to ensure sufficiently good oxidation resistance. If the sum of Al + Si + Cr is larger than 8.0%, processability deteriorates.

Iron is limited to 0.20% because this element reduces the oxidation resistance. Too low an Fe content increases the cost of producing the alloy. The Fe content is therefore greater than or equal to 0.005%.

A minimum content of 0.01% Y is necessary to obtain the oxidation resistance-enhancing effect of Y. The upper limit is set at 0.20% for cost reasons.

Oxidation resistance further increases with the addition of at least 0.001% of one or more of the elements Hf, Zr, La, Ce, Ti, where Y + 0.5 * Hf + Zr + 1.8 * Ti + 0.6 * (La + Ce) must be greater than or equal to 0.02 in order to obtain the desired oxidation resistance. The addition of at least one or more of the elements Hf, Zr, La, Ce, Ti, greater than 0.20% increases the cost, where Y + 0.5 * Hf + Zr + 1.8 * Ti + 0.6 * ( La + Ce) is additionally restricted to less than or equal to 0.30 (with the contents of Y, Hf, Zr, La, Ce, Ti in%).

The carbon content should be less than 0.10% to ensure processability. Too small C contents cause increased costs in the production of the alloy. The carbon content should therefore be greater than 0.001%.

Nitrogen is limited to 0.10% because this element reduces oxidation resistance. Too small N contents cause increased costs in the production of the alloy. The nitrogen content should therefore be greater than 0.0005%.

Manganese is limited to 0.20% because this element reduces oxidation resistance. Too small Mn contents cause increased costs in the production of the alloy. The manganese content should therefore be greater than 0.001%

Already very low Mg contents improve the processing by the setting of sulfur, whereby the occurrence of low-melting NiS Eutektika is avoided. For Mg, therefore, a minimum content of 0.0001% is required. Excessively high levels can lead to intermetallic Ni-Mg phases, which significantly impair processability. The Mg content is therefore limited to 0.08% by weight.

The oxygen content must be less than 0.010% to ensure the manufacturability of the alloy. Too small oxygen levels cause increased costs. The oxygen content should therefore be greater than 0.0001%.

The levels of sulfur should be kept as low as possible, since this surfactant affects the oxidation resistance. It will therefore max. 0.015% S set.

Copper is limited to 0.80% as this element reduces the oxidation resistance.

Just like Mg, even very low Ca contents improve the processing by the setting of sulfur, thereby avoiding the occurrence of low-melting NiS eutectics. For Ca, therefore, a minimum content of 0.0001% is required. If the contents are too high, intermetallic Ni-Ca phases can occur, which again significantly impair processability. The Ca content is therefore limited to 0.06 wt .-%.

Cobalt is reduced to max. 0.50% because this element reduces the oxidation resistance.

Molybdenum is reduced to max. 0.20% limited because this element reduces the oxidation resistance. The same applies to tungsten, niobium and vanadium.

The content of phosphorus should be less than 0.050%, since this surfactant affects the oxidation resistance.

The content of boron should be kept as low as possible because this surfactant affects the oxidation resistance. It will therefore max. 0.020% B is set.

Pb is set to max. 0.005% limited because this element reduces the oxidation resistance. The same applies to Zn, Sn and Bi.

Claims (18)

1. A nickel base alloy, consisting of (in % by mass) Si 1.5 - 3.0 % Al 1.5 - 3.0 % Cr > 0.1 - 3.0 %, wherein 4.0 ≤< Al + Si + Cr ≤< 8.0 is satisfied by the contents of Si, Al and Cr in %, Fe 0.005 to 0.20 %, Y 0.012 - 0.20 %, < 0.001 to 0.20 % of one or more of the elements Hf, Zr, La, Ce, Ti, wherein 0.02 ≤< Y+ 0.5*Hf + Zr +1.8*Ti+ 0.6*(La + Ce) < 0.30 is satisfied by the contents of Y, Hf, Zr, La, Ce, Ti in %. C 0.001 - 0.10 % N 0.0005 - 0.10 % Mn 0.001 - 0.20 % Mg 0.0001 - 0.08 % O 0.0001 - 0.010 % S max. 0.0150 % Cu max. 0.80 % optionally Ca 0.001 to 0.06 % Co max. 0.50 % W max. 0.20 % Mo max. 0.20 % Nb max. 0.20 % V max. 0.20 % Ta max. 0.20 % Pb max. 0.005 % Zn max. 0.005 % Sn max. 0.005 % Bi max. 0.005 % P max. 0.50 % B max. 0.020 % Ni rest and the usual production-related impurities.
2. An alloy according to claim 1, comprising a Si content (in % by mass) comprised between 1.8 and 3.0 %.
3. An alloy according to claim 1 or 2, comprising a Si content (in % by mass) comprised between 1.9 and 2.5 %.
4. An alloy according to one of the claims 1 through 3, comprising an Al content (in % by mass) comprised between 1.5 and 2.5 %.
5. An alloy according to one or more of the claims 1 through 4, comprising an Al content (in % by mass) comprised between 1.6 and 2.5 %.
6. An alloy according to one or more of the claims 1 through 5, comprising an Al content (in % by mass) comprised between 1.6 and 2.2 %, in particular between 1.6 and 2.0 %.
7. An alloy according to one or more of the claims 1 through 6, comprising a Cr content (in % by mass) comprised between 0.8 and 3.0 %.
8. An alloy according to one or more of the claims 1 through 7, comprising a Cr content (in % by mass) comprised between 1.2 and 3.0 %.
9. An alloy according to one or more of the claims 1 through 8, comprising a Cr content (in % by mass) comprised between 1.9 and 3.0 %, preferably between 1.9 and 2.5 %.
10. An alloy according to one or more of the claims 1 through 9, in which the formula 4.5 ≤< Al + Si + Cr ≤< 7.5 is satisfied by the contents of Si, Al and Cr in %.
11. An alloy according to one or more of the claims 1 through 10, comprising a Fe content (in % by mass) comprised between 0.005 and 0.10 %.
12. An alloy according to one or more of the claims 1 through 11, comprising a Y content (in % by mass) comprised between 0.015 and 0.15 %.
13. An alloy according to one or more of the claims 1 through 12, comprising a Y content (in % by mass) comprised between 0.015 and 0.15 % and 0.001 to 0,15 % of one or more of the elements Hf, Zr, La, Ce, Ti, wherein 0.02 ≤< Y+ 0.5*Hf + Zr + 1.8*Ti+ 0.6*(La + Ce) ≤< 0.25 is satisfied by the contents of Y, Hf, Zr, La, Ce, Ti in %.
14. An alloy according to one or more of the claims 1 through 13, comprising a C content (in % by mass) comprised between 0.001 and 0.05 % and comprising an N content (in % by mass) comprised between 0.001 and 0.05 %.
15. An alloy according to one or more of the claims 1 through 14, comprising a Mn content (in % by mass) comprised between 0 001 and 0.10 %.
16. An alloy according to one or more of the claims 1 through 15, comprising a Mg content (in % by mass) comprised between 0.0015 and 0.08 %.
17. A use of the nickel-base alloy according to one or more of the claims 1 through 16 as an electrode material for ignition elements of combustion engines.
18. A use according to claim 17, as an electrode material for ignition elements of gasoline engines.