EP0957181B1 - Alloy steel for sliding surfaces - Google Patents

Abstract

A chromium steel alloy with 0.2 to 0.65% of carbon, 12.0 to 20.0% of chromium, 0.3 to 5.0% of molybdenum, 0.02 to 0.4% of nitrogen, up to 2% of manganese, up to 1.4% of silicon, up to 2% of nickel, up to 0.5% of copper, up to 0.2% of vanadium and/or niobium and up to 0.1% of aluminum, the remainder being iron including impurities resulting from smelting, is suitable as a material for gliding elements of sports equipment, in particular winter sports equipment.

Description

The invention relates to a material for sliding elements of sports equipment, especially for sliding edges of winter sports equipment such as Skis, ski bobs and sledges.

Such materials are subject to an extremely varied load; they require a high surface quality, especially one high lubricity as well as high wear resistance, overall stability and Corrosion resistance and a low tendency to vibrate or good Damping properties.

High wear resistance and corrosion resistance reduce the Need to regrind the edges, while the straightness or Distortion resistance is crucial when applying the edges for example on the ski. Finally, sliding elements require -Edge materials good processability, especially good Forming behavior to produce them economically by rolling or drawing to be able to.

For producing ski edges with an L-shaped cross section through rollers or drag the German laid-open specification 22 04 270 the Use of a hardenable steel before, its performance characteristics after tempering through a special heat treatment can be set. This heat treatment consists of pearlitizing the one embedded in situ in the body of the ski below the tread Flank while maintaining the martensitic head. To achieve that, is heating the flank to a temperature above the Tempering temperature and simultaneous cooling of the head required. On this results in a ski edge head with high hardness and a relative soft flank, which means a correspondingly low tool wear guaranteed in the subsequent punching of recesses.

However, this heat treatment has the disadvantage that it is considered Consequence of unilateral heating to curvature, i.e. to so-called Saber deviations comes to a volume contraction at the Conversion of the originally martensitic structure of the profile flank into the pearlitic state is due.

To avoid the occurrence of saber deviations, the German laid-open specification 42 18 099 the deviation in the Rockwell hardness about the cross section and the length of the ski edge profile in hardened and tempered condition to below 2 HRC and writes for that Pearlitize an even introduction of heat and after that Pearlitize pre-bend the heat-treated edge profile. The flank should be stretched evenly by bending in this way those resulting from the partial heat treatment Eliminate curvatures.

The aforementioned method is extremely complex and often leads not to the desired success because it is extremely difficult to achieve the required Uniformity of hardness across the width and length of the profile as well as a uniform degree of cornering over the length of the flank to reach. In addition, the tempering steels used are used are not corrosion resistant and therefore a common one Require regrinding.

In a known from the German patent application 40 00 744 Process for heat treatment in situ is the ski edge with the help of a Austenitized laser beam at temperatures above 700 ° C and the austenite converted to martensite when cooling. In-situ heating requires however, careful cooling of the mostly plastic material glued, for example laminated body of the ski. To serve at Austenitizing rotating copper wheels to dissipate the heat in the Edge / body area. This too is difficult because of it despite the heat dissipation due to the remaining residual heat not suitable for every synthetic or adhesive for making skis. in addition there is a relatively low structural stability and internal tensions, which is the cause of edge chipping in the event of lateral impact stress and may be delayed.

Furthermore, the Swiss patent specification 682 492 suggests the use of a wire with a nitriding layer, which by way of a subsequent Deformation adjusted to an austenitic structure and finally is heat treated. When forming the wire to the edge profile decreases the thickness of the nitriding layer and there is a risk that the remaining Thickness is too small and the layer tears open locally.

The known methods are very complex overall and often lead nor reproducible properties. The invention is therefore the Problem underlying finding a material that is suitable for the production of Sliding elements, especially ski and snowboard edges, are suitable and one possesses advantageous combination of properties.

0,2 bis 0,65% Kohlenstoff

12,0 bis 20,0% Chrom

0,3 bis 5,0% Molybdän

0,02 bis 0,4% Stickstoff

bis 2% Mangan

bis 1,4% Silizium

bis 2% Nickel

bis 0,5% Kupfer

bis 0,2% Vanadium und/oder Niob

bis 0,1% Aluminium

Rest Eisen einschließlich erschmelzungsbedingter Verunreinigungen.

The solution to this problem is a chrome steel alloy with

0.2 to 0.65% carbon

12.0 to 20.0% chromium

0.3 to 5.0% molybdenum

0.02 to 0.4% nitrogen

up to 2% manganese

up to 1.4% silicon

up to 2% nickel

up to 0.5% copper

up to 0.2% vanadium and / or niobium

up to 0.1% aluminum

Remainder iron including impurities due to melting.

0,30 bis 0,50% Kohlenstoff

15,0 bis 18,5% Chrom

0,5 bis 2,5% Molybdän

0,03 bis 0,15% Stickstoff

0,15 bis 1,60% Mangan

0,10 bis 0,90% Silizium

0,40 bis 1,30% Nickel

bis 0,3% Kupfer

bis 0,1% Vanadium und/oder Niob

bis 0,05% Aluminium

Rest einschließlich erschmelzungsbedingter Verunreinigungen Eisen.

After heat treatment, the steel alloy according to the invention has a high hardness and wear resistance as well as an excellent vibration behavior with an effective damping factor of η ₃₀₀ <0.5 with high corrosion resistance, in particular against chlorides and nitrates. This is due in particular to the simultaneous presence of carbon, nitrogen and molybdenum. This applies in particular to a chrome steel alloy

0.30 to 0.50% carbon

15.0 to 18.5% chromium

0.5 to 2.5% molybdenum

0.03 to 0.15% nitrogen

0.15 to 1.60% manganese

0.10 to 0.90% silicon

0.40 to 1.30% nickel

up to 0.3% copper

up to 0.1% vanadium and / or niobium

up to 0.05% aluminum

Remainder including melting impurities iron.

The composition of the chromium steel alloy according to the invention preferably satisfies the following condition: (0.05 to 0.25) • ([% C] + 6 [% N]) = (% Mo) / (% Cr)

The heat treatment consists of heating at 1000 - 1100 ° C in a preferably continuous furnace system with a subsequent one Cooling down while suppressing pre-carbide deposits. The desired working hardness is achieved through subsequent heat treatment set in the temperature range 200 - 600 ° C and serves to Suppress pre-carbide excretion.

The invention is based on the knowledge that with certain chromium steel alloys with the help of molybdenum and nitrogen not only a better hardenability and structural homogeneity can be achieved, but also a much better effective damping factor η ₃₀₀ Measuring time of 300 ms according to the formula η 300 = γ 300 / γ 0 in γ _{0 is} the initial amplitude at the start of vibration.

While the effective damping factors of conventional ski edge materials are 0.6 to 0.7, they decrease in the chrome steel alloy according to the invention to less than 0.5. The reason for this is the fine grain and the homogeneous distribution of carbides and carbonitrides as well as that of relatively high levels of molybdenum and nitrogen determined Composition of the basic structure.

The invention is described below using exemplary embodiments of the explained in more detail.

Steel alloys A 2 to A 5 according to the invention became ski edge profiles rolled out and then on by the aforementioned heat treatment set a hardness of 40 to 50 HRC. Conventional materials A 1 and B 1 to B 3 were rolled and heat treated in the same way; your Hardness ranged from 45 to 49 HRC.

The wear resistance δ given in the table was determined using the grinding wheel method. The measured material removal after a grinding path of 2000 m is given in the table.

The data in the table show that the steel alloys A 2 to A 5 have the Hardness, wear resistance and vibration damping as a result the contents of carbon, nitrogen, molybdenum and Chromium significantly better than steel alloys B 1 to B 3 are.

Claims (4)

1. Chromium steel alloy with 0.2 to 0.65 % carbon, 12.0 to 20.0 % chromium, 0.3 to 5.0 % molybdenum, 0.02 to 0.4 % nitrogen, up to 2 % manganese, up to 1.4 % silicon, up to 2 % nickel, up to 0.5 % copper, up to 0.2 % vanadium and / or niobium, up to 0.1 % aluminium and the remainder iron including melt impurities.
2. Steel alloy according to claim 1 with 0.30 to 0.50 % carbon, 15.0 % to 18.5 % chromium, 0.5 to 2.5 % molybdenum, 0.03 to 0.15 % nitrogen, 0.15 to 1.60 % manganese, 0.10 to 0,90 % silicon, 0.40 to 1.30 % nickel, up to 0.3 % copper, up to 0.1 % vanadium and / or niobium, up to 0.05 % aluminium and the remainer iron including melt impurities.
3. Steel alloy according to claims 1 or 2 the carbon, nitorgen, molybdenum and chromium content of which complies with the following condition: (0.05 to 0.25) x ([% C] + 6 [% N]) = (% Mo) / (% Cr)
4. Use of a steel alloy according to one of claims 1 to 3 as a material for sliding surfaces of sports equipment.