EP2279056A1 - Protective gas mixture for arc welding of aluminum and alloys thereof - Google Patents

Protective gas mixture for arc welding of aluminum and alloys thereof

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Publication number
EP2279056A1
EP2279056A1 EP09733253A EP09733253A EP2279056A1 EP 2279056 A1 EP2279056 A1 EP 2279056A1 EP 09733253 A EP09733253 A EP 09733253A EP 09733253 A EP09733253 A EP 09733253A EP 2279056 A1 EP2279056 A1 EP 2279056A1
Authority
EP
European Patent Office
Prior art keywords
vpm
helium
nitrogen
welding
protective gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP09733253A
Other languages
German (de)
French (fr)
Inventor
Bernd Hildebrandt
Achim Wankum
Michael Wolters
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Messer Group GmbH
Original Assignee
Messer Group GmbH
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Filing date
Publication date
Application filed by Messer Group GmbH filed Critical Messer Group GmbH
Publication of EP2279056A1 publication Critical patent/EP2279056A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/38—Selection of media, e.g. special atmospheres for surrounding the working area
    • B23K35/383—Selection of media, e.g. special atmospheres for surrounding the working area mainly containing noble gases or nitrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/23—Arc welding or cutting taking account of the properties of the materials to be welded
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/08—Non-ferrous metals or alloys
    • B23K2103/10—Aluminium or alloys thereof

Definitions

  • the invention relates to a protective gas for arc welding of aluminum and aluminum alloys.
  • arc welding is understood as meaning all variations of arc welding with a consumable or non-consumable electrode using a protective gas, in particular metal inert gas (MIG), metal active gas (MAG) and tungsten inert gas welding processes (TIG).
  • MIG metal inert gas
  • MAG metal active gas
  • TIG tungsten inert gas welding processes
  • the special features of welding aluminum and aluminum alloys result from the property of aluminum to form an oxide layer on the surface immediately upon contact with atmospheric oxygen.
  • the formation of the firmly adhering oxide on the surface is the result of the base character of aluminum.
  • the purpose of the welding protection gas is to protect both the weld pool and the consumable filler from oxidation by atmospheric oxygen and at the same time to increase the electrical conductivity of the electrical arc path between the electrode and the workpiece.
  • Argon or an argon-helium gas mixture is usually used as protective gas. Although the latter are more expensive, the mixture component helium leads due to a hotter arc and a more favorable energy distribution in the arc to a better penetration behavior and allows higher welding speeds.
  • helium can contribute to the reduction or avoidance of pores and reduce the consumption of filler metal.
  • the problem with shielding gas mixtures containing a high proportion of helium is the high cost of helium, the tendency of helium to expand the arc, and the increasing instability of the arc with increasing helium content.
  • Admixtures in the two- to three-digit vpm range (0.001% to 0.1%) are often sufficient to achieve measurable effects.
  • a protective gas mixture of argon and one or more components from the group helium, hydrogen, oxygen and carbon dioxide with an admixture of 80 to at most 250 vpm of nitrogen, preferably 120 to 180 vpm of nitrogen, known in the TIG -, MIG, MAG and plasma welding of steel materials, copper, nickel and aluminum can be used.
  • the inert gas leads to a Einbrandintensivitation without deteriorating the Zwangslagen s.
  • a protective gas for arc welding of steel and non-ferrous materials such as aluminum which consists of argon or an argon-helium-nitrogen mixture with an admixture between 50 and 450 vpm nitrogen monoxide (NO).
  • a specified composition of this inert gas mixture comprises 150 vpm of nitrogen, 300 vpm of nitric oxide, 10 vol .-% helium and argon as the remainder.
  • the inert gas is in the TIG AC welding a stable quiet arc with higher energy input and lower acoustic emission, better wetting at the Seam edges, a good penetration profile and a weld with very finely scaly appearance effect.
  • the problem is, however, the proportion of corrosive and toxic nitric oxide.
  • DE 27 48 417 C2 discloses a process for reducing harmful ozone formed by welding by adding a small amount (25 to 50 vpm) of nitrogen oxides to the argon used in the TIG welding as protective gas.
  • nitrogen oxides are used as ozone-reducing nitrogen oxides.
  • EP 0 475 030 B1 describes a protective gas mixture for the TIG, MIG and MAG welding of aluminum, which consists of argon or an argon-helium Mixture with an admixture of 80 to 250 vpm of nitrogen.
  • TIG AC welding this creates a quiet, stable burning and concentrated arc and increased energy input.
  • MIG welding sagging of the fillet welds
  • N 2 O nitrogen oxide
  • TIG welding seam discoloration
  • MIG welding severe sagging of the fillet welds
  • N 2 O in the shielding gas reacts with oxygen to form nitric oxide (NO) and nitrogen dioxide (NO 2 ), which have a corrosive and toxic effect, thus endangering both the user and the welding result.
  • NO nitric oxide
  • NO 2 nitrogen dioxide
  • a protective gas mixture described in EP 0 761 380 A1 for TIG AC welding of aluminum materials comprises a ternary system of at least 50% by volume of helium, 300 to 1000 vpm of nitrogen, and the remainder of argon. Based on the approach that helium in the shielding gas on the one hand makes it difficult to switch the polarity of the tungsten electrode from emission to reception due to its low promotion of gas ionization compared to argon, but on the other hand increases the penetration depth and compactness of the weld bead in TIG welding of aluminum, should said protective gas mixture, the positive effect of helium are utilized without significantly affecting the arc stability or the welding rate.
  • EP 0 949 038 A1 discloses a protective gas mixture which, in addition to argon and helium, contains at least a proportion of from 300 vpm to 1000 vpm of nitrogen and whose helium content is less than 50% by volume.
  • the nitrogen content should be at stable and smooth arc and high welding rate lead to a deep and round penetration of good quality with seam geometry without annoying seam discoloration.
  • the present invention has for its object to show for the arc welding of aluminum and its alloys an alternative to the known shielding gases, which leads to good welding results and reduces the health burden on the user and the burden on the environment.
  • a protective gas mixture containing up to 70 vpm nitrous oxide (N 2 O), 250 to 1000 vpm of nitrogen, balance argon and / or helium.
  • N 2 and N 2 O counteracts the property of helium to expand the arc, thereby increasing the spatial concentration of the arc. Furthermore, the stability of the arc is ensured even at higher levels of helium.
  • the ozone-reducing effect of the N 2 O content leads to an improvement in terms of occupational safety and environmental protection.
  • the content of nitrogen which is much higher than that of the N 2 O content, counteracts the formation of corrosive and toxic NO and NO 2 when using He-Ar mixtures doped only with N 2 O, which in turn further reduces the health burden on the user and the environment is reduced.
  • the proportion of N 2 O is preferably between 50 and 70 vpm.
  • An amount of less than 70 vpm N 2 O still has a positive effect in terms of ozone reduction and on the stability of the arc; in the case of N 2 O contents of more than 50 ppm, but in particular between 10 and 50 ppm, these advantageous effects are still present but less pronounced.
  • the nitrogen content in the quaternary mixture Ar-He-N 2 -N 2 O is adapted to the helium content.
  • the preferred nitrogen content increases with increasing helium content, but remains in the range of below 1000 vpm.
  • the content of N 2 O in the protective gas mixture does not changed.
  • preferred mixtures contain the following nitrogen contents (in a
  • protective gas according to the invention for TIG and MIG welding of aluminum contain admixtures of oxygen, carbon dioxide and / or nitrogen monoxide.
  • active components By incorporating active components, improved penetration is achieved, thus further increasing overall weld quality.
  • the admixtures are preferably above 10 vpm to below 100 vpm, all admixtures taken together preferably above 10 vpm to below 300 vpm.
  • the protective gas according to the invention is suitable for arc welding of aluminum or aluminum alloys both with a consumable and non-consumable electrode.
  • a stable and quiet arc with high energy input easy switching of the polarity of the tungsten electrode, an excellent penetration profile, a high energy input, a good quality of the weld, in particular without disturbing seam discoloration and pores, as well as a high welding speed and a good forced attitude behavior is achieved.
  • NO and NO 2 By reducing the formation of NO and NO 2 , the burden on humans and the environment compared to the use of mixtures according to the prior art is substantially reduced.

Abstract

The protective gas according to the invention for MIG/WIG welding of aluminum comprises a quaternary mixture of argon, helium, nitrogen and dinitrogen oxide, wherein the fraction of dinitrogen oxide is up to 70 vpm, preferably 50 to 70 vpm and wherein the nitrogen fraction is between 250 and 1000 vpm, but increases within these limits as the helium fraction increases. A good welding result is accomplished through the gas mixture according to the invention and the situation with regard to environmental and work safety is substantially improved.

Description

Schutzgasgemisch zum Lichtbogen-Schweißen von Aluminium und seinen Inert gas mixture for arc welding of aluminum and its
Legierungenalloys
Die Erfindung betrifft ein Schutzgas zum Lichtbogen-Schweißen von Aluminium und Aluminiumlegierungen.The invention relates to a protective gas for arc welding of aluminum and aluminum alloys.
Als „Lichtbogenschweißen" werden im Folgenden alle Variationen des Lichtbogenschweißens mit abschmelzender oder nicht- abschmelzender Elektrode unter Einsatz eines Schutzgases verstanden, insbesondere Metall-Inertgas (MIG)-, Metall-Aktivgas (MAG)- und Wolfram-Inert-Gas-Schweißverfahren (WIG). Die Erfindung bezieht sich auf das Schweißen von Aluminium und Aluminiumlegierungen, die im Folgenden auch unter dem Begriff des „Aluminiumwerkstoffs" subsumiert werden; auch das Verschweißen unterschiedlicher Aluminiumwerkstoffe miteinander soll von der Erfindung umfasst werden.In the following, "arc welding" is understood as meaning all variations of arc welding with a consumable or non-consumable electrode using a protective gas, in particular metal inert gas (MIG), metal active gas (MAG) and tungsten inert gas welding processes (TIG The invention relates to the welding of aluminum and aluminum alloys, which are also subsumed below by the term "aluminum material"; also the welding of different aluminum materials together should be covered by the invention.
Die Besonderheiten beim Schweißen von Aluminium und Aluminiumlegierungen resultieren aus der Eigenschaft des Aluminiums, an der Oberfläche bei Kontakt mit Luftsauerstoff sofort eine Oxidschicht zu bilden. Die Bildung des fest haftenden Oxids an der Oberfläche ist Folge des unedlen Charakters von Aluminium. Das Schweißschutzgas hat die Aufgabe, sowohl das Schweißbad wie auch den abschmelzenden Schweißzusatz vor Oxidation durch Luftsauerstoff zu schützen und gleichzeitig die elektrische Leitfähigkeit der Strecke des elektrischen Lichtbogens zwischen Elektrode und Werkstück zu erhöhen. Als Schutzgas kommt dabei üblicherweise Argon oder ein Argon-Helium-Gasgemisch zum Einsatz. Letztere sind zwar teurer, der Gemischbestandteil Helium führt jedoch aufgrund eines heißeren Lichtbogens und einer günstigeren Energieverteilung im Lichtbogen zu einem besseren Einbrandverhalten und ermöglicht höhere Schweißgeschwindigkeiten. Außerdem kann Helium zur Verminderung oder zur Vermeidung von Poren beitragen und den Verbrauch an Schweißzusatzwerkstoff reduzieren. Problematisch bei Schutzgasgemischen mit einem hohem Anteil an Helium sind dagegen die hohen Kosten des Heliums, die Tendenz des Heliums, den Lichtbogen aufzuweiten sowie die mit steigendem Heliumanteil zunehmende Instabilität des Lichtbogens. In jüngerer Zeit wurde daher versucht, die schweißtechnischen Eigenschaften von Schutzgasgemischen, die auf Argon-Helium-Gemischen aufbauen, durch Zumischungen weiterer Gase zu verbessern. Dabei genügen oft Beimischungen im zwei- bis dreistelligen vpm-Bereich (0,001 % bis 0,1 %), um messbare Effekte zu erzielen.The special features of welding aluminum and aluminum alloys result from the property of aluminum to form an oxide layer on the surface immediately upon contact with atmospheric oxygen. The formation of the firmly adhering oxide on the surface is the result of the base character of aluminum. The purpose of the welding protection gas is to protect both the weld pool and the consumable filler from oxidation by atmospheric oxygen and at the same time to increase the electrical conductivity of the electrical arc path between the electrode and the workpiece. Argon or an argon-helium gas mixture is usually used as protective gas. Although the latter are more expensive, the mixture component helium leads due to a hotter arc and a more favorable energy distribution in the arc to a better penetration behavior and allows higher welding speeds. In addition, helium can contribute to the reduction or avoidance of pores and reduce the consumption of filler metal. On the other hand, the problem with shielding gas mixtures containing a high proportion of helium is the high cost of helium, the tendency of helium to expand the arc, and the increasing instability of the arc with increasing helium content. Recently, therefore, attempts have been made to improve the welding properties of inert gas mixtures which are based on argon-helium mixtures by adding further gases. Admixtures in the two- to three-digit vpm range (0.001% to 0.1%) are often sufficient to achieve measurable effects.
Aus der EP 0 502 318 B1 ist ein Schutzgasgemisch aus Argon und einer oder mehreren Komponenten aus der Gruppe Helium, Wasserstoff, Sauerstoff und Kohlendioxid mit einer Beimischung von 80 bis höchstens 250 vpm Stickstoff, vorzugsweise 120 bis 180 vpm Stickstoff, bekannt, das beim WIG-, MIG-, MAG- und Plasmaschweißen von Stahlwerkstoffen, Kupfer, Nickel und Aluminium eingesetzt werden kann. Das Schutzgas führt zu einer Einbrandintensivierung ohne Verschlechterung des Zwangslagenverhaltens.From EP 0 502 318 B1 a protective gas mixture of argon and one or more components from the group helium, hydrogen, oxygen and carbon dioxide with an admixture of 80 to at most 250 vpm of nitrogen, preferably 120 to 180 vpm of nitrogen, known in the TIG -, MIG, MAG and plasma welding of steel materials, copper, nickel and aluminum can be used. The inert gas leads to a Einbrandintensivierung without deteriorating the Zwangslagenverhaltens.
In der DE 296 23 194 U1 wird ein Schutzgas zum Lichtbogenschweißen von Stahl und Nichteisenwerkstoffen wie Aluminium vorgeschlagen, welches aus Argon oder einem Argon-Helium-Stickstoff Gemisch mit einer Beimischung zwischen 50 und 450 vpm Stickstoffmonoxid (NO) besteht. Eine konkret angegebene Zusammensetzung dieses Schutzgasgemisches umfasst 150 vpm Stickstoff, 300 vpm Stickstoffmonoxid, 10 Vol.-% Helium und Argon als Rest. Das Schutzgas soll beim WIG - Wechselstromschweißen einen stabilen ruhigen Lichtbogen mit höherer Energieeinbringung und mit geringerer Schallemission, eine bessere Benetzung an den Nahtflanken, ein gutes Einbrandprofil und eine Schweißnaht mit sehr feinschuppigem Aussehen bewirken. Problematisch ist allerdings der Anteil des korrosiv und giftig wirkenden Stickstoffmonoxids.In DE 296 23 194 U1 a protective gas for arc welding of steel and non-ferrous materials such as aluminum is proposed, which consists of argon or an argon-helium-nitrogen mixture with an admixture between 50 and 450 vpm nitrogen monoxide (NO). A specified composition of this inert gas mixture comprises 150 vpm of nitrogen, 300 vpm of nitric oxide, 10 vol .-% helium and argon as the remainder. The inert gas is in the TIG AC welding a stable quiet arc with higher energy input and lower acoustic emission, better wetting at the Seam edges, a good penetration profile and a weld with very finely scaly appearance effect. The problem is, however, the proportion of corrosive and toxic nitric oxide.
Aus der DE 27 48 417 C2 ist ein Verfahren zur Verringerung von beim Schweißen gebildeten, gesundheitsschädlichem Ozon durch Zugabe einer geringen Menge (25 bis 50 vpm) Stickoxide zu dem als Schutzgas verwendeten Argon beim WIG- Schweißen bekannt. Als ozonmindernde Stickoxide kommen dabei insbesondere NO und N2O (Lachgas) zum Einsatz.DE 27 48 417 C2 discloses a process for reducing harmful ozone formed by welding by adding a small amount (25 to 50 vpm) of nitrogen oxides to the argon used in the TIG welding as protective gas. In particular, NO and N 2 O (nitrous oxide) are used as ozone-reducing nitrogen oxides.
In der EP 0 475 030 B1 wird ein Schutzgasgemisch für das WIG-, MIG- und MAG - Schweißen von Aluminium beschrieben, das aus Argon oder einem Argon-Helium- Gemisch mit einer Beimischung von 80 bis 250 vpm Stickstoff besteht. Beim WIG - Wechselstromschweißen dient dies der Ausbildung eines ruhigen, stabil brennenden und konzentrierten Lichtbogens und einer erhöhten Energieeinbringung. Oberhalb von 250 vpm Stickstoff treten jedoch störende Nebeneffekte wie Nahtverfärbungen (WIG-Schweißen) und ein Absacken der Kehlnähte (MIG-Schweißen) auf.EP 0 475 030 B1 describes a protective gas mixture for the TIG, MIG and MAG welding of aluminum, which consists of argon or an argon-helium Mixture with an admixture of 80 to 250 vpm of nitrogen. In TIG AC welding, this creates a quiet, stable burning and concentrated arc and increased energy input. Above 250 vpm of nitrogen, however, annoying side effects such as seam staining (TIG welding) and sagging of the fillet welds (MIG welding) occur.
Aus der EP 0 673 295 B1 ist bekannt, ein Schutzgas aus Argon oder aus einem Argon-Helium-Gemisch mit einer Beimischung von 80 bis 250 vpm N2O (Lachgas), vorzugsweise 120 bis 180 vpm N2O beim WIG- und MIG-Schweißen von Aluminium einzusetzen. N2O hat eine ozonreduzierende Wirkung und bewirkt beim WIG - Wechselstromschweißen die Ausbildung eines ruhigen, stabil brennenden und konzentrierten Lichtbogens und damit eine erhöhte Energieeinbringung. Oberhalb eines Anteils von 250 vpm N2O dagegen treten jedoch auch hier störende Nebeneffekte wie Nahtverfärbungen (WIG-Schweißen) und ein starkes Durchsacken der Kehlnähte (MIG-Schweißen) auf. Zudem reagiert N2O im Schutzgas mit Sauerstoff zu Stickstoffmonoxid (NO) und Stickstoffdioxid (NO2), die korrosiv und giftig wirken und somit sowohl den Benutzer gefährden als auch das Schweißergebnis beeinträchtigen. Unterhalb von 80 vpm N2O sollen die genannten vorteilhaften Effekte verschwinden.It is known from EP 0 673 295 B1, a protective gas of argon or of an argon-helium mixture with an admixture of 80 to 250 vpm N 2 O (nitrous oxide), preferably 120 to 180 vpm N 2 O in the TIG and MIG -Welding of aluminum use. N 2 O has an ozone-reducing effect and causes the formation of a quiet, stable burning and concentrated arc in TIG - AC welding and thus an increased energy input. Above a level of 250 vpm N 2 O, however, disturbing side effects such as seam discoloration (TIG welding) and severe sagging of the fillet welds (MIG welding) also occur here. In addition, N 2 O in the shielding gas reacts with oxygen to form nitric oxide (NO) and nitrogen dioxide (NO 2 ), which have a corrosive and toxic effect, thus endangering both the user and the welding result. Below 80 vpm N 2 O, the aforementioned beneficial effects are expected to disappear.
Ein in der EP 0 761 380 A1 beschriebenes Schutzgasgemisch zum WIG - Wechselstromschweißen von Aluminiumwerkstoffen umfasst ein ternäres System aus wenigstens 50 Vol.-% Helium, 300 bis 1000 vpm Stickstoff, Rest Argon. Ausgehend von dem Ansatz, dass Helium im Schutzgas einerseits die Umschaltung der Polung der Wolframelektrode von Emission auf Empfang aufgrund seiner gegenüber Argon geringen Förderung der Gasionisation erschwert, aber andererseits beim WIG - Schweißen von Aluminium die Eindringtiefe und die Kompaktheit der Schweißraupe vergrößert, soll durch die genannte Schutzgasmischung die positive Wirkung des Helium ausgenutzt werden, ohne die Lichtbogenstabilität oder die Schweißrate wesentlich zu beeinträchtigen.A protective gas mixture described in EP 0 761 380 A1 for TIG AC welding of aluminum materials comprises a ternary system of at least 50% by volume of helium, 300 to 1000 vpm of nitrogen, and the remainder of argon. Based on the approach that helium in the shielding gas on the one hand makes it difficult to switch the polarity of the tungsten electrode from emission to reception due to its low promotion of gas ionization compared to argon, but on the other hand increases the penetration depth and compactness of the weld bead in TIG welding of aluminum, should said protective gas mixture, the positive effect of helium are utilized without significantly affecting the arc stability or the welding rate.
Aus der EP 0 949 038 A1 ist ein Schutzgasgemisch bekannt, das neben Argon und Helium zumindest einen Anteil von 300 vpm bis 1000 vpm Stickstoff enthält und dessen Heliumanteil weniger als 50 Vol.-% beträgt. Der Stickstoffanteil soll bei stabilem und ruhigem Lichtbogen und hoher Schweißrate zu einem tiefen und runden Einbrand von guter Qualität mit Nahtgeometrie ohne störende Nahtverfärbungen führen.EP 0 949 038 A1 discloses a protective gas mixture which, in addition to argon and helium, contains at least a proportion of from 300 vpm to 1000 vpm of nitrogen and whose helium content is less than 50% by volume. The nitrogen content should be at stable and smooth arc and high welding rate lead to a deep and round penetration of good quality with seam geometry without annoying seam discoloration.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, für das Lichtbogenschweißen von Aluminium und seinen Legierungen eine Alternative zu den bekannten Schutzgasen aufzuzeigen, das zu guten Schweißergebnissen führt und die gesundheitlichen Belastungen für den Anwender sowie die Belastungen für die Umwelt reduziert.The present invention has for its object to show for the arc welding of aluminum and its alloys an alternative to the known shielding gases, which leads to good welding results and reduces the health burden on the user and the burden on the environment.
Gelöst ist diese Aufgabe durch ein Schutzgasgemisch, das bis zu 70 vpm Distickstoffoxid (N2O), 250 bis 1000 vpm Stickstoff, Rest Argon und/oder Helium enthält.This object is achieved by a protective gas mixture containing up to 70 vpm nitrous oxide (N 2 O), 250 to 1000 vpm of nitrogen, balance argon and / or helium.
Die Zugabe von N2 und N2O wirkt der Eigenschaft des Heliums entgegen, den Lichtbogen aufzuweiten, und erhöht damit die räumliche Konzentration des Lichtbogens. Weiterhin wird die Stabilität des Lichtbogens auch bei höheren Gehalten an Helium gewährleistet. Die ozonreduzierende Wirkung des N2O-Gehalts führt zu einer Verbesserung im Hinblick auf Arbeits- und Umweltschutz. Zugleich wirkt der gegenüber dem N2O - Anteil sehr viel höhere Gehalt an Stickstoff der bei Verwendung von lediglich mit N2O dotierten He-Ar-Gemischen beobachteten Entstehung von korrosiven und giftigen NO und NO2 entgegen, wodurch abermals die gesundheitlichen Belastungen des Anwenders sowie der Umwelt gemindert wird.The addition of N 2 and N 2 O counteracts the property of helium to expand the arc, thereby increasing the spatial concentration of the arc. Furthermore, the stability of the arc is ensured even at higher levels of helium. The ozone-reducing effect of the N 2 O content leads to an improvement in terms of occupational safety and environmental protection. At the same time, the content of nitrogen, which is much higher than that of the N 2 O content, counteracts the formation of corrosive and toxic NO and NO 2 when using He-Ar mixtures doped only with N 2 O, which in turn further reduces the health burden on the user and the environment is reduced.
Bevorzugt beträgt der Anteil an N2O zwischen 50 und 70 vpm. Ein Anteil von weniger als 70 vpm N2O führt noch zu einem positiven Effekt im Hinblick auf die Ozonreduktion sowie auf die Stabilität des Lichtbogens; bei N2O - Anteilen von über O, jedoch weniger als 50 vpm, insbesondere zwischen 10 und 50 vpm, sind diese vorteilhaften Effekte zwar noch vorhanden, jedoch weniger stark ausgeprägt.The proportion of N 2 O is preferably between 50 and 70 vpm. An amount of less than 70 vpm N 2 O still has a positive effect in terms of ozone reduction and on the stability of the arc; in the case of N 2 O contents of more than 50 ppm, but in particular between 10 and 50 ppm, these advantageous effects are still present but less pronounced.
In besonders vorteilhaften Weiterbildungen der Erfindung wird der Stickstoffgehalt im quaternären Gemisch Ar-He-N2-N2O dem Heliumgehalt angepasst. Der bevorzugte Stickstoffgehalt erhöht sich dabei mit steigendem Heliumgehalt, verbleibt jedoch im Bereich von unter 1000 vpm. Der Gehalt an N2O im Schutzgasgemisch wird nicht verändert. Durch die Anpassung des Stickstoffgehalts an den Heliumanteil werden die Schweißeigenschaften optimiert, da Helium, wie erwähnt, einerseits für die Intensivierung des Einbrandes von Vorteil ist, andererseits jedoch auch zu einer mit steigendem Heliumgehalt zunehmenden Instabilität und Verbreiterung des Lichtbogens führt. Die angepassten Stickstoffanteile erhalten die Vorteile des Heliumanteils, erhöhen jedoch gleichzeitig die Stabilität und Konzentration des Lichtbogens.In particularly advantageous developments of the invention, the nitrogen content in the quaternary mixture Ar-He-N 2 -N 2 O is adapted to the helium content. The preferred nitrogen content increases with increasing helium content, but remains in the range of below 1000 vpm. The content of N 2 O in the protective gas mixture does not changed. By adapting the nitrogen content to the helium content, the welding properties are optimized, since helium, as mentioned, on the one hand for the intensification of the penetration of advantage, on the other hand but also leads to an increasing helium content increasing instability and broadening of the arc. The adjusted nitrogen content provides the benefits of helium but increases the stability and concentration of the arc.
Insbesondere enthalten bevorzugte Gemische folgende Stickstoffanteile (bei einemIn particular, preferred mixtures contain the following nitrogen contents (in a
Gehalt von bis zu 70 vpm N2O, Rest Ar): bei einem Anteil von weniger als 10% Helium: 250 bis 350 vpm Stickstoff, bei einem Anteil von 10 bis 50% Helium: 400 bis 500 vpm Stickstoff, bei einem Anteil von 50 bis 100% Helium: 700 bis 800 vpm Stickstoff.Content of up to 70 vpm N 2 O, remainder Ar): at a fraction of less than 10% helium: 250 to 350 vpm nitrogen, at a fraction of 10 to 50% helium: 400 to 500 vpm nitrogen, in a proportion of 50 to 100% helium: 700 to 800 vpm of nitrogen.
Die mittleren Werte der angegebenen Bereiche des Stickstoffanteils sind dabei jeweils besonders bevorzugt.The mean values of the specified ranges of the nitrogen content are in each case particularly preferred.
Weiter vorteilhafte Ausführungsformen des erfindungsgemäßen Schutzgases zum WIG- und M IG-Schweißen von Aluminium enthalten Beimengungen von Sauerstoff, Kohlendioxid und/oder Stickstoffmonoxid. Durch die Einbringung aktiver Komponenten wird ein verbesserter Einbrand erzielt und so die Schweißqualität insgesamt weiter erhöht. Die Beimengungen betragen bevorzugt jeweils über 10 vpm bis unter 100 vpm, alle Beimengungen zusammengenommen bevorzugt über 10 vpm bis unter 300 vpm.Further advantageous embodiments of the protective gas according to the invention for TIG and MIG welding of aluminum contain admixtures of oxygen, carbon dioxide and / or nitrogen monoxide. By incorporating active components, improved penetration is achieved, thus further increasing overall weld quality. The admixtures are preferably above 10 vpm to below 100 vpm, all admixtures taken together preferably above 10 vpm to below 300 vpm.
Das erfindungsgemäße Schutzgas ist zum Lichtbogen-Schweißen von Aluminium oder Aluminiumlegierungen sowohl mit abschmelzender als auch nicht- abschmelzender Elektrode geeignet. Insbesondere wird ein stabiler und ruhiger Lichtbogen mit hohem Energieeintrag, ein problemloses Umschalten der Polung der Wolframelektrode, ein hervorragendes Einbrandprofil, eine hohe Energieeinbringung, eine gute Qualität der Schweißnaht, insbesondere ohne störende Nahtverfärbungen und Poren, sowie eine hohe Schweißgeschwindigkeit und ein gutes Zwangslagenverhalten erreicht. Durch die Reduktion der Bildung von NO und NO2 werden die Belastungen für Mensch und Umwelt gegenüber dem Einsatz von Gemischen nach dem Stand der Technik wesentlich reduziert. The protective gas according to the invention is suitable for arc welding of aluminum or aluminum alloys both with a consumable and non-consumable electrode. In particular, a stable and quiet arc with high energy input, easy switching of the polarity of the tungsten electrode, an excellent penetration profile, a high energy input, a good quality of the weld, in particular without disturbing seam discoloration and pores, as well as a high welding speed and a good forced attitude behavior is achieved. By reducing the formation of NO and NO 2 , the burden on humans and the environment compared to the use of mixtures according to the prior art is substantially reduced.

Claims

Patentansprüche claims
1. Schutzgasgemisch zum Lichtbogenschweißen von Aluminium und seinen Legierungen, enthaltend bis zu 70 vpm Distickstoffoxid, 250 bis 1000 vpm Stickstoff, Rest Argon und/oder Helium.1. inert gas mixture for arc welding of aluminum and its alloys, containing up to 70 vpm of nitrous oxide, 250 to 1000 vpm of nitrogen, balance argon and / or helium.
2. Schutzgasgemisch nach Anspruch 1 , dadurch gekennzeichnet, dass der Anteil von Distockstoffoxid zwischen 50 und 70 vpm beträgt.2. protective gas mixture according to claim 1, characterized in that the proportion of Distockstoffoxid is between 50 and 70 vpm.
3. Schutzgasgemisch nach Anspruch 1 oder 2, gekennzeichnet durch einen Anteil von 0 bis 10% Helium und 250 bis 350 vpm Stickstoff.3. protective gas mixture according to claim 1 or 2, characterized by a proportion of 0 to 10% helium and 250 to 350 vpm of nitrogen.
4. Schutzgasgemisch nach Anspruch 1 oder 2, gekennzeichnet durch einen Anteil von 10 bis 50% Helium und 400 bis 500 vpm Stickstoff.4. protective gas mixture according to claim 1 or 2, characterized by a proportion of 10 to 50% helium and 400 to 500 vpm of nitrogen.
5. Schutzgasgemisch nach Anspruch 1 oder 2, gekennzeichnet durch einen Anteil von 50 bis 100% Helium und 700 bis 800 vpm Stickstoff.5. protective gas mixture according to claim 1 or 2, characterized by a proportion of 50 to 100% helium and 700 to 800 vpm of nitrogen.
6. Schutzgasgemisch nach einem der vorhergehenden Ansprüche, gekennzeichnet durch Beimengungen von Sauerstoff, Kohlendioxid und/oder Stickstoffmonoxid. 6. protective gas mixture according to one of the preceding claims, characterized by admixtures of oxygen, carbon dioxide and / or nitrogen monoxide.
EP09733253A 2008-04-19 2009-04-06 Protective gas mixture for arc welding of aluminum and alloys thereof Withdrawn EP2279056A1 (en)

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DE102008019859A DE102008019859A1 (en) 2008-04-19 2008-04-19 Inert gas mixture for arc welding of aluminum and its alloys
PCT/EP2009/054059 WO2009127545A1 (en) 2008-04-19 2009-04-06 Protective gas mixture for arc welding of aluminum and alloys thereof

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IT1403947B1 (en) * 2011-02-17 2013-11-08 Rivoira S P A PROTECTIVE GAS FOR WELDING ALUMINUM AND ITS ALLOYS
CN103962754A (en) * 2013-01-29 2014-08-06 南车青岛四方机车车辆股份有限公司 Three-element mixed protective gas for aluminum alloy MIG (Metal-Inert Gas Welding) welding and welding method
US11040417B2 (en) * 2013-12-16 2021-06-22 Praxair Technology, Inc. Welding gas compositions and method for use

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