SK284023B6 - Method of welding material onto rails - Google Patents

Abstract

Described is an automatic or semi-automatic method of welding additional material onto the worn top and/or side surfaces of steel rails using a flux at pH 1.3 to 3.2, the rails having the following chemical composition by weight: carbon 0.45 to 0.82 %, manganese 0.7 to 1.5 % and silicon 0.07 to 0.55 %, the remainder being iron and manufacturing impurities. The additional material has the following chemical composition by weight: carbon 0.06 to 0.10 %, manganese 0.5 to 1.5 % and silicon 0.05 to 0.5 %, the remainder being iron and manufacturing impurities. It is applied to the head of the rail with an arc giving a heat input Q of (5.9 to 8.0 kJ/cm) x K at a speed of advance v of 40 to 75 cm/min, where Q = 'eta' x 60 x U x I/v, 'eta' being the efficiency, U the voltage, I the current and v the speed of advance and K being 1 for welding material on to the top of the rail and K being 2.6 for welding material on to the sides. If the material is alloyed with up to 5 % by wt. in total of the following alloys: nickel 1.8 to 4.5 %, vanadium 0.0 to 0.2 %, molybdenum 0.0 to 0.3 %, niobium 0.0 to 0.1 %, chromium 0.0 to 0.4 %, aluminium 0.0 to 1.6 % and titanium 0.0 to 0.1 %, the upper heat-input limit is increased to 11.5 kJ/cm.

Description

Technical field

The invention relates to a method of automatic or semi-automatic welding of worn sections of rail heads and other exposed rail track points, such as the tongues of switches, frogs and rail crossings. It is advantageous to carry out the drilling without dismantling them directly on the rail track.

BACKGROUND OF THE INVENTION

According to known methods, welding of worn sections of rail heads, tongues of switches, frogs and rail crossings is carried out by means of filler materials, electric arc, by hand-coated electrode or welding machine using full-wire or self-protecting tube wires, or or under the flux. Automatic welding is more advantageous than manual welding in terms of labor productivity, constant quality of weld over the entire length of the welded section due to minimized human factor impacts. So far, filler materials of medium or high-alloy steels have been used in the submerged-arc welding process, with a percentage by weight in the range of: carbon C = 0.04 to 0.15%, silicon Si = 0.05 to 1.0% , manganese Mn = 1.1 to 15.0%, chromium Cr = 0.05 to 20.0%, nickel Ni = 0.05 to 13.0%, molybdenum Mo = 0.05 to 1.0% , aluminum Al = 0.02 to 1.5%, vanadium V = 0.05 to 0.6%, the remainder being iron Fe and process impurities. These materials are welded to the rail according to the manufacturer's recommendations preheated to 350 to 400 ° C under flux with pH = 1.3 to 3.2 at welding parameters in the range of voltage U = 25 to 32 V, current intensity I = 270 to 500 A and welding speeds v = 55 to 85 cm / min.

The main disadvantages of this method of welding are the use of expensive, high-alloy material and in some cases excess or even harmful hardness of the surfacing, which is more than 30% higher than the hardness of the base material of the rail. track wheels. Higher hardness than the rail hardness is unsuitable and harmful in the present case, for example in curves where it causes rapid wear on the wheel flanges of the tramway or rail bogie, which in turn entails replacement and refurbishment costs.

Further disadvantages of this method are that due to the very difficult workability of the weld of the chemical composition, the worn-out weld can not be remanufactured by a further weld overlay that preheating to 350 to 400 ° C is required in most cases.

The disadvantages of the expensive filler material and the high hardness of the weld layer do not occur in manual arc welding, in which coated electrodes are used as the filler material, the percent by weight of which ranges from: carbon C = 0.06 to 0.75%, silicon Si = 0.1 to 0.5%, manganese Mn = 0.7 to 1.5%, molybdenum Mo = 0.1 to 0.35%, the remainder being iron Fe and process impurities.

The disadvantage of manual arc welding, however, is the aforementioned low labor productivity and the unguaranteed consistent quality of the weld deposit.

The automatic boiling of the rails under the fluxing material other than those mentioned was not carried out because there was a presumption that the welding of unalloyed filler material would result from either the unsuitable martensitic structure or the unwanted market due to the diffusion of carbon from the base material into the weld. in the deposit and its surroundings. Therefore, highly alloyed chromium-based, nickel-Ni-based fillers have been used so far for welding under automatic fluxing, for example fillers under the trade designation OK-Tubrodur 15.65 and 14.71, which are generated by the heat supplied during welding and generally combined with previous heating. 10 ° C and higher the austenitic structure of the weld deposit and the martensitic structure of the subfloor layer.

It is an object of the present invention to provide a method of automatic or semi-automatic welding of worn rail heads of rail superstructure which achieves a hardness of weld over a cladding range of about 250 HV to 315 HV, substantially corresponding to the hardness of the base material. correspondingly permissible rail errors when using filler material which is several times cheaper than previously used in fusion welding. It is also an object of the invention to save on the cost of preheating the rails and the possibility of unrestricted repetition of further weld repairs.

Another object of the present invention is to achieve a hardness of the overlay or top layer of overlay from 285 HV to 350 HV and, using known medium and high alloy materials from about 400 HV to 500 HV, without the previously necessary preheating of the rail sections. materials. The advantage of this procedure is particularly evident in the repair of the tongues of switches, where undesirable deformations have occurred with the hitherto necessary preheating.

SUMMARY OF THE INVENTION

These objects are solved by the features set forth in claims 1, 4 and 7, while other advantageous features are set out in the dependent proposals.

Method of automatic or semi-automatic welding of filler material according to the invention using flux with a basicity of pH = 1.3 to 3.2 on worn upper or side surfaces of a rail track, for example rail heads, tongues of switches, frogs and rail crossings made of steel by weight chemical composition in the range: carbon C = 0.45 to 0.82%, manganese Mn = 0.7 to 1.5%, silicon Si = 0.07 to 0.55%, the remainder being iron Fe and production dirt. The substance of the invention consists in that the additive material with the chemical composition by weight: carbon C = 0.06 to 0.10%, manganese Mn = 0.5 to 1.5%, silicon Si = 0.05 to 0.5%, the remainder being iron Fe and process impurities, are welded to the rail by an electric arc at an amount of heat delivered Q = (5.9 to 8.0 kJ / cm). K and the feed rate v = 40 to 70 cm / min, where Q = η. 60.U. I / v, where η is the efficiency, U voltage, I current intensity, v displacement speed and constant K = 1 for welding the upper surface of the rail and K = 2.6 for welding the lateral surface of the rail.

The method of the present invention, using inexpensive filler material and without the need to preheat the rail, results in a weld deposit whose hardness does not differ from that of the base material by more than 10% and is therefore in the range of 250 HV to 315 HV. there is no adverse martensitic structure or cracks. Given that the chemical composition of the rails and additive material is within certain tolerances,

286 worthy if the parameters of the welding of the upper surface of the railhead in the following range are selected: voltage U -24 to 27 V, current intensity I = 250 to 350 A, parameters for welding of the rail side surfaces: voltage U = 34 to 38 V, current intensity I = 450 to 550 A. When welding with these parameters, even in the case of an inappropriate collision of the mass chemical composition and impurities of the base material of the rail and the additive material, the weld is always welded without impervious martensitic structure and without harmful cracks. If it is necessary to achieve a higher hardness of cladding up to about 350 HV, it is advantageous to use an additive material with a chemical chemical composition: nickel Ni = 1.8 to 4.5%, vanadium V = 0.0 to 0.2%, molybdenum Mo = 0, 0 to 0.3%, niobium Nb = = 0.0 to 0.1%, chromium Cr = 0.0 to 0.4%, aluminum Al = 0.0 to 0.6%, titanium Ti = 0.0 up to 0,1%, the total content of alloying elements not to exceed 5%. This additive material is welded at a feed rate of heat Q = (5.9 to 11.5 kJ / cm). K at a displacement speed of v = 40 to 75 cm / min, it is advisable to select the welding parameters of the upper rail surfaces in the range: voltage U = 24 to 34 V, current intensity I = 250 to 350 A, when welding on the side walls of the rail: voltage U = 34 to 38 V, current intensity 1 = 450 to 550 A.

If it is necessary to achieve a weld hardness of the upper surface of the rail in the range of about 350 HV to 500 HV without preheating the repaired section of the rail, it is preferred that the backing layer is welded to the rail in the present manner.

In this way, on the one hand, a considerable saving of the high-alloy filler material is achieved, which no longer fills the entire contents of the worn rail, but only the upper surface part thereof. In addition, due to the backing layer, the diffusion of carbon C from the base material of the rail into the upper surface weld overlay is greatly reduced, so that the hitherto necessary preheating of the repaired section is eliminated. In doing so, at least the same quality of the overlay is achieved as in the previous preheating.

If a hardness of approx. 400 HV is to be achieved, which does not significantly increase during the subsequent mechanical hardening during operation, it is advantageous to weld a more alloyed material with a guide mass composition to the base layer: carbon C = 0.15%, silicon Si = max 0, 5%, manganese Mn = 1.1%, chromium Cr = 1%, nickel Ni - 2.3%, molybdenum Mo = 0.5%, aluminum Al = 1.4%, the remainder being iron Fe and process impurities.

In order to achieve a weld that has a hardness of up to 500 HV with subsequent mechanical strengthening, it is advantageous to weld a highly alloyed filler material with a guide chemical composition to the undercoat: carbon C = 0.3%, silicon Si = 0.55%, manganese Mn = 13.5%, chromium Cr = 16%, nickel Ni = 1.7%, molybdenum Mo = 0.8%, vanadium V = 0.6%, the remainder being iron Fe and process impurities.

In order to create as little as possible a corrugated contour of the surfacing and thus to facilitate subsequent sanding as well as suitable boiling, it is advantageous if the animal has an axis of the nozzle through which the additive material in the form of a wire is fed with a perpendicular angle α = 0 to 45 °.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages according to the invention are shown schematically on selected embodiments of the deposition. The accompanying drawings show an example of a rail profile on which worn heads are welded with filler material according to the invention, wherein the individual figures represent:

Fig. 1 - Cross section of grooved or tramway rail.

Fig. 2 is a cross-sectional view of a head or rail, FIG. 3 - Connecting the ends of two overhead rails.

Fig. 4 - Cross section of the overhead rail (see Fig. 3) during welding.

Fig. 5 - Switch language.

Fig. 6 - Cross section tongue of the switch (see Fig. 5) during welding.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows the groove-tramway head and Figure 2 shows the rail-head in cross-section where the shaded section shows the shape of the worn head and the shaded parts complement it to the original unworn shape. The worn upper part of the rail head is indicated by 1 and the worn side part of the head is indicated by 2. Worn surfaces are cleaned, grinded to a metallic luster and the head is restored to its original shape by welding the filler wire 9 7, with the following parameters. The bead beads 4, 4 'are applied to the non-preheated rails of the track superstructure in the longitudinal direction at an ambient temperature of greater than or equal to 10 ° C and before the next bead or top bead is applied, the previous bead is always cleaned. As can be seen from Figure 2, the animal of the axis of the nozzle axis 8, through which the welding wire 9 is fed, has a perpendicular 3 in the range α = 0 ° to 45 °, thereby achieving a minimum corrugation of the welded area formed by the envelope 4, 4 '. on the other hand a suitable weld deposit. The caterpillars 4, 4 'are welded to the base material of the rail on the building surface 5, 5' and to the lateral and upper surfaces of the previous caterpillar, respectively. The surface area 5 of the upper caterpillar 4 is K times larger than the surface area 5 'of the side caterpillar 4', with K = 2.6. In this ratio, the carbon from the base material of the rail into the weld deposit also diffuses when welding, at the same heat input Q, so that the heat input Q _b can be increased to Q _b = Q _b when welding the side seals 4 '. K without significantly increasing the carbon content of the side surfacing, where Q _b = the heat supplied Q when the side surface is welded, Q _h = the heat supplied when the upper surface is welded.

K = constant 2.6

Q = η. 60 .U. I / v (kJ / cm) η = source efficiency (0.95 for submerged arc welding)

U = welding voltage (V)

I = Welding current intensity (A) v = Welding nozzle feed rate (cm / min)

The carbon content of the deposition greatly affects the structure of the deposition and must not exceed 0.3% by weight so that the deposition does not contain a martensitic structure and undesirable cracks.

The weight percent chemical composition of the steel rails on which the overlay is carried out: carbon C = 0.4 to 0.85%, manganese Mn = 0.7 to 1.45%, silicon Si = 0.08 to 0.55%, the remainder being iron Fe and process impurities. These are, for example, rails according to the company standard TŽ 4201150 of the company „Železámy Tŕinec AG“ - CZ, which are made of steel known under the trade designation 75 ČSD with hardness approx. 250 HV, 85 ČSD -Vk with hardness approx. hardness approx. 290 HV. Navaro

The process is carried out by means of a fluxing machine with a basicity of pH = 1.3 to 3.2, for example it is in the trade designation OK 10.71. It is welded with non-alloyed filler material in the form of a wire with a chemical chemical composition by weight: carbon C = 0.06 to 0.10%, manganese Mn = 0.5 to 1.5%, silicon Si = 0.05 to 0.50% ; the remainder being iron Fe and process impurities.

The following table I shows the parameters of the additive material - welding wire under the trade designation A106 with the indicative weight percent chemical composition: carbon C = 0.07%, silicon Si = 0.06%, manganese Mn = 1.11%, phosphorus P = 0,009%, sulfur S = 0,011% for the upper surfaces (sequence number 1 to 12) and the lateral surfaces (sequence number 13 to 17) of the 75 CSD and 95 CSDVk rails, which achieve a maximum 10% higher weld hardness than the base material rails, t. j. in the range of 250 to 350 HV, it does not contain martensite, the permissible errors corresponding to the permissible errors of the rail base material. This weld hardness is suitable for repairing sections of the track superstructure with a lower required hardness, e.g. curves or straight track segments.

Table no. 1

Por. number Type of rail Welding parameters Heat delivered Q (kJ / cm) Hardness HV U (V) I (A) in (cm / min) 1 95 ČSD-Vk 24 350 75 6.38 287 2 24 350 61 7.85 295 3 24 360 75 6.57 315 4 27 300 75 6.15 310 5 75 ČSD 24 250 43 7.95 255 6 24 250 57 6.00 260 7 24 300 60 6.84 267 8 24 350 61 7.85 265 9 24 360 75 6.57 270 10 24 280 65 5.90 265 11 24 330 57 7.92 263 12 27 350 75 7.18 271 13 34 450 60 14.50 252 14 34 450 45 19,30 264 15 34 550 55 19.38 272 16 36 450 60 15.39 258 17 38 550 60 19.90 261

If a hardness of 285 to 350 HV is required, it is preferable to use an additive material with the following chemical composition in weight percent: carbon C = 0.06 to 0.10%, manganese Mn = 0.5 to 1.5%, silicon Si = 0.05 to 0.5%, nickel Ni = 1.8 to 4.5%, vanadium V = 0.0 to 0.2%, molybdenum Mo = 0.0 to 0.3%, niobium Nb = 0.0 to 0.1%, chromium Cr = 0.0 to 0.4%, aluminum Al = 0.0 to 1.6%, titanium Ti = 0.0 to 0.1%, the remainder being iron Fe and production impurities, the lower limit of said alloying elements may be 0,0% and the sum of all elements shall not exceed 5%. It is an additive material known under the trade designation A234 with a target chemical composition in percent by weight: carbon C = 0.07%, silicon Si = = 0.3%, manganese Mn = 1.2%, nickel Ni = 2.3%, phosphorus P = 0.01 I%, sulfur S = 0.14%, which is welded at the parameters given in Table 2, which also shows the hardness of the weld, this hardness does not increase at the next mechanical stress in the running of the superstructure.

Table no. 2

Por. number Type of rail Welding parameters Heat delivered Q (kJ / cm) Hardness HV U (V) I (A) in (cm / min) 1 75CSD 25 250 60 5.94 328 2 25 300 60 7.13 328 3 34 350 60 11.31 339 4 34 480 60 15.50 286 5 38 550 60 19.86 289 6 95 ČSD-Vk 34 450 60 14,54 292 7 25 250 60 6.18 332 8 30 330 60 9.41 346 9 34 480 60 15.50 297 10 38 550 60 19.86 296

Sequence numbers 1 to 3 as well as 7 and 8 describe welding examples on the upper surface of the rail, while sequence numbers 4 to 6 as well as 9 and 10 describe welding examples on the side of the rail.

The present method of automatic and semiautomatic welding of worn sections of rail heads requires a suitable combination of the chemical composition of the material, the welded filler material and the welding parameters, i.e. voltage U, current intensity I, and displacement speed v within the given heat input Q values. Welding of the upper rail surface ranges from Q _H = 5.9 to 11.5 kJ / cm, Welding speed in _H = 40 to 75 cm / min, voltage Uh = 24 to 34 V and current intensity Ih = 250 to 350 A , the delivered heat Q _B for the welding of the side surfaces of the rail is in the range Q _b = 15.3 to 29.9 kJ / cm, the welding speed in _B = 40 to 75 cm / min, the voltage U _B = 34 to 38 V , current intensity I _B = 450 to 550 A.

When welding with the above parameters, the diffusion of carbon into the weld deposit is suppressed so that the weld deposit has a carbon C in the range of 0.1 to 0.3%, so the heat input Q ensures that the critical cooling does not exceed critical temperatures. the cooling rate, which leads to the formation of martensitic structures and no cracks will occur in or around the surfacing.

If hardness of approx. 350 HV to approx. 500 HV is required, which is necessary when repairing extremely stressed sections of rails, such as connecting rail ends (see Fig. 3), switch tongues (see Figures 5 and 6), frogs and the crossing of the rails, as follows: the worn surfaces are cleaned and abraded in a metallic luster and one undercoat is applied at a thickness of at least 1 bead 4, 4 ', with the additional material and the process according to claims 1 and 4. the layer is welded on to other bead 44, 44 'up to the material used up to now under the trade mark OK - Tubrodur 15.43 with a guide chemical composition in weight percent: carbon C = 0.15%, silicon Si = max 0.5%, manganese Mn = 1, 1%, chromium Cr = 1%, nickel Ni = 2.3%, molybdenum Mo = 0.5%, aluminum Al = 1.4%, the remainder being iron Fe and process impurities. It is also possible to use the additive material OK-Tububur 15.65 with a guide chemical composition: carbon C = 0.3%, silicon Si = 0.55%, manganese Mn = 13.5%, chromium Cr = 16.5%, nickel Ni = 1.7%, molybdenum Mo = 0.8%, vanadium V = 0.6%, the remainder being iron Fe and process impurities, the backing layer may consist of one or more layers of 4.4 'welding beads and the top layer may be one or by multiple layers of welded beads 44,44 '.

Welding parameters of the upper surface layer by medium or high-alloy material are recommended by the manufacturer and are generally known. By providing a low carbon backing layer, a reduction in the carbon content of the surfacing of the intermediate or high-alloy material is achieved. This achieves the stability of the weld deposit against brittle failure and the hardness of the weld deposit according to the requirements for the given exposed sections (for example using OK -

- Tubrodur 15.43 from 350 to 400 HV and using OK -

- Tubrodur 15.65 (400 to 500 HV). The method of welding the worn rail sections of the rail track can be used in the repair of highly worn rails of railway, tramway, crane, cableway and other analogous tracks, as well as the tongues of switches and frogs and rail crossing. The present procedure in no way alters the shape and cross-section of the rail or rail superstructure.

Claims (10)

PATENT CLAIMS A method of automatic or semi-automatic welding of filler material using a flux having a basicity of pH = 1.3 to 3.2 to worn upper or side surfaces of a rail track, such as rail heads, switch tongues and frogs, rail crossing, in particular tram and rail superstructure. with a chemical composition by weight of steel rails in the following ranges: carbon C = 0,45 to 0,82%, manganese Mn = 0,7 to 1,5%, silicon Si = 0,7 to 0,55%, the remainder being iron Fe and process impurities, characterized in that the additive material with a chemical chemical composition in the range: carbon C = 0.06 to 0.10%, manganese Mn = 0.5 to 1.5%, silicon Si = 0.05 up to 0.5%, the remainder being iron Fe and process impurities, is applied to the rail head by an electric arc at a heat input Q = (5.9 to 8.0 kJ / cm). K and the welding speed v = 40 to 75 cm / min, where Q = η. 60. U. I / v, where η is the efficiency, U is the voltage, I is the current intensity, v is the welding speed, where K = 1 for welding the upper surface of the rail and K = 2,6 for welding the lateral surface of the rail. Welding method according to claim 1, characterized in that the welding parameters of the upper surface of the rail are selected in the voltage range U = 24 to 27 V and the current intensity I = 250 to 350 A. Welding method according to claim 1, characterized in that the welding parameters of the side surface of the rail are in the range of voltage U = 34 to 38 V and current intensity I = 450 to 550 A. 4. Method of automatic or semi-automatic welding of filler material using a flux having a basicity of pH = 1.3 to 3.2 to worn upper or side surfaces of a rail track, such as rail heads, switch tongues and frogs, rail crossing, in particular tram and rail superstructure with a chemical composition by weight of steel rails in the following ranges: carbon C = 0,45 to 0,82%, manganese Mn = 0,7 to 1,5%, silicon Si = 0,7 to 0,55%, the remainder being iron Fe and process impurities, characterized in that the additive material with a chemical composition in weight percent is in the range: carbon C = 0.06 to 0.10%, manganese Mn = 0.5 to 1.5%, silicon Si = 0.05 to 0.5%, nickel Ni = 1.8 to 4.5%, vanadium V = 0.0 to 0.2%, molybdenum Mo = 0.0 to 0.3%, niobium Nb = 0, 0 to 0.1%, chromium Cr = 0.0 to 0.4%, aluminum Al = 0.0 to 1.6%, titanium Ti = 0.0 to 0.1%, where the total sum of contents nickel Ni, vanadium V, molybdenum Mo, niobium Nb, chromium Cr, aluminum Al and titanium Ti do not exceed 5%, the remainder being iron Fe and process impurities, the welding to the rail being carried out by electric arc at the amount of heat delivered Q = (5, 9 to 11.5 kJ / cm). K and the welding speed v = 40 to 75 cm / min, where Q = η. 60. U. I / v, where η = efficiency, U = voltage, I = current intensity, v = welding speed, where K = 1 for welding the upper surface of the rail and K = = 2,6 for welding the lateral surface of the rail. Welding method according to claim 4, characterized in that the welding parameters of the upper surface of the rail are selected in the range: voltage U = 24 to 34 V and current intensity I = 250 to 350 A. Welding method according to claim 4, characterized in that the welding parameters on the side surface of the rail are selected in the range: voltage U = 34 to 38 Va and current intensity I = 450 to 550 A. Welding method according to claims 1 and 4, characterized in that a layer of more alloyed material is welded onto the layer thus welded. Welding method according to claim 7, characterized in that a more alloyed additive material with a chemical chemical composition is used: carbon C = 0.15%, silicon Si = max 0.5%, manganese Mn = 1.1%, chromium Cr = 1.0%, nickel Ni = 2.3%, molybdenum Mo = 0.5%, aluminum Al = 1.4%, the remainder being iron Fe and process impurities. Welding process according to claim 7, characterized in that a more alloyed additive material with a chemical composition is used: carbon C = 0.3%, silicon Si = 0.55%, manganese Mn = 13.5%, chromium Cr = 16.0%, nickel Ni = 1.7%, molybdenum Mo = 0.8%, vanadium V = 0.6%, the remainder being iron Fe and process impurities. Welding method according to claims 1 and 4, characterized in that the filler material is fed through the nozzle so that the axis of the nozzle has an angle α = 0 to 45 ° with the vertical.