FI88518B - FOERFARANDE FOER TILLVERKNING AV VAEXELKORSNINGSSTYCKEN - Google Patents

Abstract

To manufacture frogs or rail sections in the wheel-running region of points with a highly wear-resistant wheel-running surface of a hardenable steel of composition C 0.01 to 0.05 % Si 0.01 to 0.2 % Mn 0.01 to 0.2 % Co 0 to 15 % Mo 1.5 to 6 % Ni 7 to 20 % Ti 0.1 to 1 % Cr O to 13 % Al 0 to 0.2 % B 0 to 0.1 % Zr 0 to 0.1 % the wheel-running surface is applied by explosive plating or electron beam welding or compound-rolling to a base body of readily weldable steel, especially a steel having not more than 0.24 % of C, not more than 0.04 % of P and S, not more than 0.65 % of Si and not more than 1.7 % of Mn.

Description

1 8 B S1 8

Method of making gear junctions

The present invention relates to a method of manufacturing gear crossings or rails for a wheel crossing area: a well-wear-resistant wheel tread made of hardenable steel having the following composition is assembled on a base of high-weld steel: C 0.01 to 0.05% A %

Si 0.01 - 0.2% B 0 - 0.1%

Mn 0.01-0.2% Zr 0-0.1%

Co 0-15% Fe residue MO 1.5-6%

Ni 7-20%

Ti 0.1-1%

Cr 0-13%

EP-A-105 864 already discloses junction pieces, in particular junction tips made of steel for rail junction pieces or switches, the tip or running surface of which consists of the above-mentioned hardenable steel. The stress on the tips of the intersections is particularly high in the crossing area of the wheel from the knee rail to the tip of the gear, and the stress increases disproportionately with high axle weight and especially with increasing driving speeds, so that greater distortions can occur at the tip. . life span. According to the patent, the material proposed in the above-mentioned patent EP-A was formed by a welding method around a base body made of normal rail steel. The manufacture of an entire junction made of such wear-resistant steel is relatively expensive, and the use of joints in combination with such a wear-resistant layer 2 8 8 518 in the wheel crossing area or at the tip of the junction allows basic materials or normal cast steel to be welded together at joints without difficulty. The welding of the basic materials together by means of an electric flash welding machine can of course be carried out without major measures. Since, according to previously known methods of making junction pieces, the wear layer material was made by welding it over a base body of normal rail steel, there was always the difficulty of not being able to obtain a homogeneous thermal joint without deteriorating quality. In the over-welding of consumables, a constant mixing of the base material results, which results in the formation of more or less obvious areas of inhomogeneity, depending on the method. Thus, the advantages of the material used in the wear layer cannot be fully exploited in the known overlay welding methods.

It is an object of the present invention to provide a method as mentioned at the beginning, in which the tread component can be homogeneously combined with the base body by means of heat in order to improve the quality of the junction body. In particular, the formation of inhomogeneous boundary layers between the various components of the crossing or rail sections of the switch must be avoided. The solution to this problem according to the present invention is essentially that a residue made of highly weldable steel, in particular with a composition of s 0.24% C, s 0.04% P or S, s 0.65% Si and s 1.7% Mn On the base containing Fe, the tread of the wheel is assembled by blast coating, electron beam welding or butt rolling. Blasting in principle uses a well-known technique for metallically joining the surfaces of similar or different components. In blasting, the joint is achieved by means of a high pressure acting for a short time, whereby the metal surfaces are brought into contact with each other by means of a plastic change in the ato distances.

3,88518

The melting temperature is not usually reached in the plant area, and therefore the compression welding method is also discussed. Blasting allows the joining of metals that would form brittle points during fusion welding. By selecting the component proposed in the present invention as a wear layer, the formation of a mixing zone by means of an explosion coating is avoided, and in this way all the advantages in terms of the wear resistance of the wheel tread can be achieved. The same is true for butt rolling.

Alternatively, in the case of said electron beam welding, the material selected as the wear layer determines the required conditions. Electron beam welding can only combine components with a relatively low carbon content; the use of the substance mentioned at the beginning as a wear layer fulfills the required conditions. Electron beam welding provides a very thin joint layer, thus largely avoiding inhomogeneities. In both cases, the base body consists of highly weldable steel, so that the welding of the junction pieces with the connecting rails can be carried out without difficulty. Unlike the known materials with particularly good wear properties used as crossings, such as manganese steel, and rejuvenated, low-alloy steel, such crossings are easily welded together with connecting rails and can therefore be used in a continuous manner. On the other hand, the welding of the tip of manganese steel and also of the low-alloy rejuvenated junction with the rail material requires special measures due to the reduced weldability of such steels, which can be relatively consumable.

The homogeneity of the thermal connection between the material of the wheel tread and the base body is further improved by hardening 350 to 450, in particular 400 degrees, when coating the wheel tread 4,88518, in particular by means of electron beam welding. In addition, at a temperature of 400 degrees, the advantage is achieved that the stress relief annealing of the filler weld is carried out at the same time, whereby the base material is one of the well-welded materials.

By means of the present method, treads with a thickness of 12 to 25 mm, in particular 15 to 20 mm, can be assembled in the recommended manner.

There is thus provided an intersection piece or gear knee rail in which a highly weldable preferred base material is combined with a low volume and thus also light weight layer of abrasion resistant material to produce a joint material; this can be set for a very high load bearing crossing area. This enables the low-cost production of good quality junction pieces; the pieces are also suitable for continuous welding without special measures. In particular, when spray coating is used to coat the wear layer or wheel tread, a relatively thin layer thickness of 15 mm can be achieved, while when electron beam welding is preferably selected, a thickness of about 20 mm is chosen to allow a certain exhaust incineration rate. In the case of electron beam welding, the upper limit of the carbon content of 0.03% must be taken into account. In spray coating, the upper limit is irrelevant.

Claims (3)

5,88518 A method for manufacturing gear junctions or rails in a wheel crossing area, in which a wheel tread made of highly wear-resistant hardenable steel having the following composition is assembled on a base of high-weld steel: C 0.01 - 0.05% Al 0 - 0.2% Si 0.01 - 0.2% B 0 - 0.1% Mn 0.01-0.2% Zr 0-0.1% Co 0-15% Fe residue Mo 1.5-6% Ni 7-20% Ti 0.1-1% Cr 0-13% characterized in that the wheel tread is assembled by means of blast coating or electron beam welding or butt rolling on a base of highly weldable steel, which contains in particular s 0.24% C, s 0.04% P or S, s 0.65 Si and s 1.7% Mn and residual Fe. Method according to Claim 1, characterized in that the coating is carried out at a temperature of 350 to 450 ° C, preferably: * 400 ° C, after coating the wheel tread, in particular by electron beam welding. Method according to Claim 1 or 2, characterized in that the tread is made thick to a thickness of 12 to 25 mm, in particular 15 to 20 mm. - · »· 6 88518