EP2406034A1

EP2406034A1 - Cored wire electrode

Info

Publication number: EP2406034A1
Application number: EP10710154A
Authority: EP
Inventors: Gerhard Posch; Günter MOITZI; Michael Fiedler; Franz Rotter; Walter Berger
Original assignee: Voestalpine Boehler Welding Austria GmbH
Current assignee: Voestalpine Boehler Welding Austria GmbH
Priority date: 2009-03-11
Filing date: 2010-03-08
Publication date: 2012-01-18
Also published as: WO2010102318A8; JP2012519598A; WO2010102318A1; US20120061354A1; AT507914B1; US8963047B2; AT507914A1; DE202009007217U1

Abstract

The invention relates to a cored wire electrode for producing a high-strength melt/weld bond and describes a method for manufacturing cored wire electrodes having a diameter of less than 2 mm. In order to prevent oxidation and water absorption of the powder and preserve the original thermal reaction potential of the mineral constituents of the same, according to the invention the cored wire electrode is characterized in that in the longitudinal direction the cold-formed metal tube has a leak-proof melt/weld bond or a weld seam which has lower fusion penetration than the tube wall is thick and in this way a distance of the metal bond of the tube wall to the powder core is formed.

Description

Flux cored wire

The invention relates to a cored wire electrode for producing a fusion-welded joint parts of high-strength steels with a minimum yield strength (RP ₀ .2) of the weld metal of 690N / mm ² , consisting of a metal tube with an outer diameter of less than 2mm, which is a Füllpulverkern wrapped and optionally wearing a coating.

Furthermore, the invention relates to a method for the substantially continuous production of cored wire electrodes with a diameter of less than 2mm, for producing a fusion-welded joint parts of high strength steels with a minimum yield strength (RP ₀ .2) of the weld metal of 690N / mm ² substantially with a production sequence: providing a metal strip, forming the metal strip in the longitudinal direction to a substantially U-shaped in cross-section, introducing filler into the U-shaped band, forming the strip into a tube with a collision of abutting lateral faces and a Füllwrahtpulverkern, joining the joint by welding, deformation of the cross section and optionally coating the surface of the tube or the electrode.

Flux cored electrodes are used for joining by melt welding of parts as welding consumables, wherein in a device of a supply, for example a wire coil, the electrode wire is removed and this discharged from a supply or conveying means, a so-called welding head, for arc fusion welding is in which welding head and the electrical energy supply to the electrode.

The welding head can be hand-guided or moved mechanically, whereby an automatic welding can optionally take place until the use of computer-controlled welding robots.

A cored wire electrode is a tubular electrode and contains internally predominantly mineral constituents and / or deoxidizers and / or metallic constituents, in particular for alloying the weld melt. The Composition of the Füllpulverkernes is carefully selected and the ingredients should be present in a welding process at least not adversely affecting form and ensure a high weld quality.

For supplying the welding power to the flux cored electrode, a bare metal surface thereof is required. In many cases, the electrode surface is coppered for better introduction of the current, which additionally results in a hindrance of the oxidation.

To avoid pore and / or crack formation in the weld metal, it is important to keep the moisture content, in particular in the filler powder of the electrode, as low as possible so that hydrogen absorption from the molten filler metal is largely avoided during arc welding.

In order to absorb moisture from the filling powder during storage of the

To avoid electrode, are available in the prior art essentially two production variants.

In the case of a production route of a flux-cored wire, filler powder is introduced as homogeneously as possible into a tight tube, the ends of the tube are closed, and the thus-prepared primary material is rolled into wire and / or subjected to a draw deformation. A high strain hardening of the pipe wall in the course of deformation can be overcome by annealing treatments of the intermediate product.

Another known method of manufacturing filler wire electrode material is to form a metal strip into a U-section shape, fill the U-shape with filler powder, and then convert it into a tube and inductively weld the axial abutment surfaces. Such a starting material having an outer diameter of, for example, 30 mm can, as mentioned above, if necessary, be further shaped with an intermediate annealing treatment for the first consolidation of the pipe material into a filler wire.

The methods of the prior art have the common disadvantage that at least partially the filling powder to high temperatures, wherein Decomposition and / or oxidation reactions of the powder components can occur is heated.

A further disadvantage can be given by the fact that during the welding process prior to the melting of the electrode, its metallic surface is oxidized and thus oxygen is introduced into the liquid metal of the weld seam.

The invention has for its object to provide a Fülldrahtelektrode of the type mentioned above, which is formed to prevent oxidation and water absorption of the Füllpulverkernes from an airtight welded tube, wherein at least the mineral constituents in the filling powder have their original thermal reaction potentials. In this case, the outer surface of the electrode should ensure a substantially unimpeded supply of the welding current.

It is another object of the invention to provide a generic method by means of which a Fülldrahtelektrode can be done with an airtight welding of the shock of a bent sheet metal strip to a tube, while the filling powder is kept substantially warming.

The object of the invention is achieved in that the cold-formed metal tube in the longitudinal direction has a dense fusion weld or a weld having a lower penetration than the pipe wall thickness corresponds and thus a distance of the metallic bond of the pipe wall is formed to the powder core.

The advantages achieved with the filler wire electrode according to the invention are essentially given by the cold deformation of the metal tube and the tightness of the additional material-free weld with low penetration. In this way, it is ensured that an oxidation of metallic constituents of the filling powder as well as a moisture entry into this is prevented and the thermal reaction potentials of the respective mineral components are obtained individually and in combination, so that only in the arc advantageously a release of reagents and / or gases , eg. Fluorides, for setting the Hydrogen and a compound formation, for example, to establish flux for the Schweißnahtausformung.

According to one with regard to a secure and crack-free butt joint of the starting material and the following cold deformation is advantageous if the metallic bond of the pipe wall is less than 0.3 to 0.9, preferably less than 0.5 to 0.8 times the pipe wall thickness.

Conveniently, based on the total cross-section of the electrode, the area fraction of the Füllpulverkerns less than 60%, but more than 10%, preferably less than 45%, but more than 12%. As a result, both the welding properties of the electrode and the alloy formation with regard to melting of the welding filler can be optimized.

When of the cored wire electrode, the powder core of slag-forming agents, in particular fluorides, carbonates, oxides and / or the like., From metal powder, especially alloy powder, from deoxidizers, especially aluminum, silicon, magnesium, manganese, zirconium and the like. And compounds of these elements, including Microalloying, formed when melting the same in the arc, a liquid, homogeneous, deoxidized and purified by the slag reactions melt with low hydrogen content and flux slag, which ultimately serves for at least partial coverage of the liquid phase. When melting the substantially anhydrous constituents, in particular the mineral constituents of the powder core, gaseous reaction products are also released which have an inert gas effect and a further degassing action of the liquid metal.

Both for a protective gas development immediately before melting the Fülldrahtelektrode during welding and for ensuring the current transition, it may be advantageous if the metal tube carries a coating. This coating can also serve as protection against oxidation of the electrode surface.

A particular advantage is given according to the invention when the coating fluorine Polymers, optionally of PTFE (poly-tetra-fluoro-ethylene) and carbon, preferably in a ratio of 1: 2 to 1: 4, is formed. PTFE causes a protective gas formation and hydrogen bonding, whereby the carbon ensures the passage of electricity into the tubular body. Ratio values smaller than 0.5 deteriorate the introduction of the welding current, which can lead to premature heating of the tubular body and overloading of the current injection means. At lower than 0.25, the carbon can cause alloying problems.

The filler wire electrode is advantageously composed in such a way that the weld metal formed from it has a concentration of the main alloying elements of in% by weight carbon traces to 0.2, silicon traces to 1.0, manganese 0.1 to 2.0, chromium 0.01 to 0.5, nickel 0.01 to 3.0, molybdenum 0.001 to 1.0 and, if appropriate, special alloying additives in total up to 0.5, the remainder iron and impurity elements.

Such a weld metal alloy is a high-strength, fine-grained iron-based material with a yield strength RPo _{, 2} of substantially more than 690 N / mm ² .

The further object of the invention to provide a method of the type mentioned is achieved by mixing a filler powder from substantially anhydrous raw materials and introduced this mixture in the transversely bent to the U-shape band and subsequently the side regions of the tape into a tube be further developed, according to which the impact of the longitudinally abutting, lateral end faces of the tube is connected by welding additional free beam welding, such as laser or electron beam welding, with the proviso that the penetration or created by melting the pipe wall metallic bond in the direction of the powder core out is less than the thickness of the tube wall, and that from the thus prepared tube by cold forming a Fülldrahtelektrode is produced.

The procedural advantages are mainly in a use of substantially anhydrous raw materials while maintaining a full thermal reaction potential, especially mineral components, and in the choice of Welding agent and the welding technology, aimed at a desired intended tight metallic bond at the impact of the electrode starting material, which is further processed by cold deformation in the sequence. An additive-free beam welding provides a high quality Teilverschmelzung the shock even at high welding performance, measured in weld length per unit time, which shows fusion even at high degrees of cold deformation cracking and fracture tendency of the solidified material. Because according to the invention, the welding is carried out only on the outer part of the lateral end faces of the tube, no temperature load of the filling powder is given in the inner region, whereby on the one hand, the thermal reaction potential of at least some powder components is maintained and on the other hand, the metal powder part is not oxidized.

Particularly advantageous and essential to the invention for a seam production of the desired type on the pipe is when the connection ungsschweißung the abutting faces of the joint with a penetration depth of 0.3 and less to 0.9, preferably from 0.5 and less to 0.8 times the pipe wall thickness is made.

Highest accuracy and safety of the welding of the outer part of the joint with high welding power or welding speed can be procedurally achieved when the welding beam, formed as a laser or electron beam, at an angle between 5 ° and 45 °, preferably from 10 ° to 30 ° Pipe axis is directed to the collision of the lateral end faces of the tube.

Process-related but also economic advantages can be achieved if the joint of the pipe is welded tight at a speed of more than 40 m / min, preferably of more than 65 m / min.

Both manufacturability and welding properties can be optimized when the weld-bonded tube is coated and reformed into a flux-cored electrode by cold working. On the basis of representations that convey only execution paths, the invention will be explained in more detail.

1 shows a welded tube wall - schematically

Fig. 2 to Fig. 7 each have a cross section of a filling electrode - increased

Fig. 1 shows the connection region of a semi-finished material F before a cold deformation for producing a Fülldrahtelektrode in cross section. A shock 3 of lateral, adjacent end faces of a molded tube 1 is externally connected by fusion welding 11 metal. The inner part E of the tube wall with a thickness W does not have any connection to the powder core 2 due to liquefaction of the tube substance.

Figures 2 to 7 show Fülldrahtelektroden with a diameter of 1.2mm.

A starting material with a diameter of 4.0 mm was made of a unalloyed steel strip, for example with a width of 12 mm and a thickness of 0.8 mm, wherein after shaping in cross-section to form a U-band introduction of filling powder in this followed by forming a tube were made. A formed in the course of pipe forming shock of abutting, lateral faces was welded at a welding speed of 60m / min throughput with laser technology such that about 50% of the shock had a metallic fusion compound. In investigations, good results were obtained at a welding speed of over 40 m / min to 100 m / min and above with regard to the quality of the desired fusion weld and economical production, wherein an angle of the welding beam of a laser device to the tube axis in the range of 5 ° to 45 °, with an optimum of about 20 °, provided good welds.

A cold deformation of the starting material was carried out in the usual form by means of drag rollers and / or driven rollers and / or drawing dies to a Cored wire.

FIGS. 2 to 4 show cross sections of filler wire with a proportion of filler powder of 47% residual pipe proportion based on the cross-sectional area.

FIGS. 5 to 7 show the cross sections of the cored wire electrodes, which have a powder part of 18% remaining surface area of tube wall part.

For the investigations, the liquid metal formed during the welding was doped for a better distinction.

All images of flux-cored electrodes show a deformed weld area, with the metallic bond 11 being distant from the powder core.

Claims

claims

1. flux cored wire for fabricating a fusion welded joint of parts made of high-strength steel with a minimum yield strength (Rp _0. ₂₎ of the weld metal of 690 N / mm ^2, consisting of a metal tube having an outer diameter of less than 2mm, which envelops a Füllpulverkern and optionally carries a coating, characterized in that the cold-formed metal tube in the longitudinal direction has a dense melt-welded joint or a weld, which has a lower penetration than the pipe wall thickness corresponds and such a distance of the metallic bond of the

Pipe wall is formed towards the powder core.

2. flux cored wire electrode according to claim 1, characterized in that the metallic bond of the tube wall is less than 0.3 to 0.9, preferably less than 0.5 to 0.8 times the tube wall thickness.

3. flux cored wire electrode according to claim 1 or 2, characterized in that based on the total cross-section of the electrode, the area fraction of the Füllpulverkerns less than 60%, but more than 10%, preferably less than 45%, but more than 12%.

4. cored wire electrode according to one of claims 1 to 3, characterized in that the dust core of slag-forming agents, in particular fluorides, carbonates, oxides and / or the like. From metal powder, in particular alloy powder, from deoxidizers, in particular aluminum, silicon,

Magnesium, manganese, zirconium and the like. And compounds of these elements, including microalloying agents is formed.

5. flux-cored wire electrode according to one of claims 1 to 4, characterized in that the metal tube carries a coating.

6. flux cored wire electrode according to claim 5, characterized in that the coating of fluorine polymers, optionally PTFE (poly-tetra-fluoro-ethylene) and carbon preferably in a ratio of 1: 2 to 1: 4 is formed.

7. cored wire electrode according to one of claims 1 to 6, characterized in that the weld metal formed from this, a concentration of the main alloy elements of in wt .-% carbon traces to 0.2, silicon

Lanes up to 1.0, manganese 0.1 to 2.0, chromium 0.01 to 0.5, nickel 0.01 to 3.0, molybdenum 0.001 to 1.0, and optionally special alloying additives in total up to 0.5, the remainder iron and impurity elements.

8. A process for the substantially continuous production of

Flux cored electrodes with a diameter of less than 2 mm, for producing a fusion-welded joint of parts of high-strength steels with a minimum yield strength (RP ₀ ₂ ) of the weld metal of 690 N / mm ² essentially with one production sequence: provision of a metal strip, shaping of the metal strip in the longitudinal direction to a substantially U-shaped in cross-section,

Introducing filling powder into the U-shaped band, forming the band into a tube with a collision of adjoining lateral end faces and a cored wire powder core, joining the joint by welding, deformation of the cross section and optionally coating the surface of the tube or the electrode, characterized in that from im

Substantially anhydrous raw materials, a filler powder mixed and introduced this mixture in the transversely bent to the U-shape band and subsequently the side regions of the band are formed into a tube, after which the collision of longitudinally abutting, lateral end faces of the tube by welding additional free beam welding, such as Laser or electron beam welding is connected with the proviso that the penetration or created by melting the tube wall metallic bond in the direction of the dust core is less than the thickness of the tube wall and that from the tube thus created by cold forming a Fülldrahtelektrode is produced.

9. The method according to claim 8, characterized in that the

Joint welding of abutting faces of the joint with a penetration depth of 0.3 and less to 0.9, preferably from 0.5 and less to 0.8 times the pipe wall thickness is made.

10. The method according to any one of claims 8 or 9, characterized in that the welding beam formed as a laser or electron beam at an angle between 5 ° and 45 °, preferably from 10 ° to 30 °, to the tube axis on the impact of the lateral end faces of Tube is directed.

11. The method according to any one of claims 8 to 10, characterized in that the impact of the tube at a speed of more than 40m / min, preferably of over 65m / min is tightly welded.

12. The method according to any one of claims 8 to 11, characterized in that the pipe connected by welding is coated and further developed by cold deformation to form a Fülldrahtelektrode.