SK65498A3 - 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 solid wire or tube wires with self-protection or under protection or under protection 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. Until now, 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 AJ = 0 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 a flux of pH = 1.3 to 3.2 at welding parameters in the voltage range U = 25 to 32 V, current 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.

Another disadvantage of this method is that due to the very difficult workability of the weld deposit of a given chemical composition, the worn weld deposit cannot be reprocessed with a further weld deposit, in most cases preheating to 350 to 400 ° C is required.

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 welding of the rails under the fluxing material other than those mentioned above was not carried out because there was a presumption that the welding of unalloyed filler material results from the metallurgical welding processes, mainly by diffusion of carbon from the base material of the rails into the overlay, either unsuitable martensitic structure. surfacing and its surroundings. Therefore, highly alloyed Cr-based, nickel-Ni-based filler materials have been used so far for welding under the fluxing machine, for example fillers under the trade designation OK-Tubrodur 15.65 and 14.71, which are generated by welding heat and generally combined with previous heating. 10 ° C and higher austenitic structure of the deposit and martensitic structure of the subfloor layer.

It is an object of the present invention to provide a method of automatic or semiautomatic welding of worn rail heads of rail superstructure which achieves a hardness of cladding in the cladding range of about 250 HV to 315 HV, substantially corresponding to the hardness of the base material. permissible rail defects when using filler material 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 unlimited repetition of further weld corrections.

A further 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 hitherto preheating the rail sections with considerably lower consumption of these expensive filler materials. . The advantage of this procedure is particularly evident in the repair of the tongues of the switches, where undesirable deformations have arisen during 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 preferred features are set out in the dependent proposals.

Method of automatic or semiautomatic welding of additive material according to the invention using flux of pH = 1.3 to 3.2 to worn upper or side surfaces of a rail track, for example rail heads, tongues of switches, frogs and rail crossings, made of steel with a chemical 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 process impurities. 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 displacement velocity v = 40 to 70 cm / min, where Q = η.όΟ.ϋ.Ι / v, where η is efficiency, U voltage, I current intensity, v displacement velocity and constant K = 1 for upper surface welding rails and K = 2.6 for welding the side 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. Since the chemical composition of the rails and the filler material is within certain tolerances, it is preferable to select the welding parameters of the upper surface of the rail head in the following range: voltage U = 24 to 27 V, current intensity I = 250 to 350 A, Welding parameters for 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, the chemical composition and impurities of the base material and additive material are always welded without leaks. 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 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 the feed rate 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: U = 34 to 38 V, current intensity I = 450 to 550 A.

If it is necessary to achieve a 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 onto the rail in the present manner.

In this way, on the one hand, a considerable saving of the superalloy additive 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 preferred that the animal axis of the nozzle, through which the additive material is fed in the form of a wire, is perpendicular.

Overview of the figures in the attached 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 Cross-sectional overhead 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 a groove-tramway head and Figure 2 shows a cross-sectional view of a rail-head, where the shaded portion shows the shape of a worn head and the shaded portions complement it to the original unused shape. The worn top of the rail head is indicated by 1 and the worn side of the head is indicated by 2. Worn surfaces are cleaned, sharpened to a metallic luster, and the head is restored to its original shape by welding the filler wire 9 with a welding machine. 7, with the following parameters. caterpillars

4, the deposition is 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 prior to the subsequent deposition of the next adjacent or upper caterpillar, the previous caterpillar 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 of α = 0 ° to 45 °, thereby achieving a minimum corrugation of the welded area formed by envelope 4, Ψ. suitable surfacing. Beads 4, d 'are welded to the base material of the rail 5, 6 and to the side and top surfaces of the previous bead, respectively. The surface area 5 of the upper caterpillar 4 is K times greater than the surface area P of the side caterpillar 4 ¹ . where K = 2.6. In this ratio, it also diffuses when welding the carbon from the base material of the rail into the weld at the same heat input Q, so that when welding the side seals 4, it is possible to increase the heat input Qb to Q _b = Qh. K, without significantly increasing the carbon content of the side surfacing, wherein Qb = the heat supplied Q when the side surface is welded, Qh = the heat supplied when the upper surface is welded.

K = constant 2.6

Q = η.όΟ.υ.Ι / v (kJ / cm) η = efficiency of the source (0.95 for automatic 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 unwanted 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 manufactured by Železárny Trínec AG - CZ, which are made of steels known under the trade designation 75 ČSD with hardness approx. 250 HV, 85 ČSD -Vk with hardness approx. 270 HV and 95 ČSD -Vk with hardness approx. 290 HV. The welding is carried out by means of a fluxing machine with a basicity of pH = 1.3 to 3.2, for example flux with the trade designation OK 10.71. It is welded with a non-alloyed additive 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 ČSD-Vk rails which achieve a weld overlay of not more than 10% the base material of the rail, i. in the range of 250 to 350 HV, it does not contain martensite, the permissible defects corresponding to the permissible defects 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 The (A) 1 (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 known under the trade designation A234 with a target chemical composition in weight percent: 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 operation of the rail superstructure.

Table no. 2

Por. number Type rails Welding parameters Heat delivered Q (kJ / cm) hardness HV The (A) I (A) in (cm / min) 1 75 ČSD 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 I 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 the 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 velocity v within the given heat input Q values. Welding of the upper rail surface ranges from Qh = 5.9 to 11.5 kJ / cm, Welding speed vh = 40 to 75 cm / min, voltage Uh = 24 to 34 V and current intensity Ih ⁼ 250 to 350 A, heat delivered Qb for rail side welding is in the range Qb = 15.3 to 29.9 kJ / cm, welding speed in _B = 40 to 75 cm / min, voltage Ub = 34 to 38 V, current intensity I _B = 450 to 550 A .

When welding with these parameters, the diffusion of carbon into the deposit is suppressed, so that the deposit contains carbon C in the range of 0.1 to 0.3%, so that the heat input Q ensures that the critical speed is not exceeded when cooled in air at 10 ° C cooling, which leads to the formation of martensitic structures and no cracks 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 rail sections, such as connecting rail ends (see Fig. 3), switch tongues (see Figs. 5 and 6), frogs and the crossing of the rails, as follows: the worn surfaces are cleaned and sanded to a metallic luster and one undercoat is applied in a thickness of at least 1 bead 4, 4J with the additive material and the process according to claims 1 and 4. On this undercoat welds other caterpillars 44, 44 'up to the material used up to now under the trade designation 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 AJ =

1.4%, the remainder being iron Fe and process impurities. It is also possible to use additive material OK Tubrodur 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 welding beads 4.4a the upper layer may consist of one or more layers welded caterpillars 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 from 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 welding speed v = 40 to 75 cm / min, where Q = η.60.υ.Ι / ν, where η is efficiency, U is voltage, I is current intensity, v is 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 1 = 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 of nickel Ni, vanadium V, molybdenum Mo, niobium Nb, chromium Cr, aluminum Al and titanium Ti does 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.υ.Ι / ν, 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 V 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 is at an angle α = 0 to 45 ° with the vertical.