DESC:FIELD OF THE INVENTION
The present invention relates to the field of welding. More specifically the present invention relates to gas metal arc welding process.
BACKGROUND OF THE INVENTION
Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG)welding or metal active gas (MAG) welding, is a welding process in which an electric arc forms between a consumable MIG wire electrode and the work piece metal(s), which heats the work piece metal(s), causing them to melt and join. Along with the wire electrode, a shielding gas feeds through the welding gun, which shields the process from contaminants in the air.
Originally developed in the 1940s for welding aluminum and other non-ferrous materials, gas metal arc welding was soon applied to steels because it provided faster welding time compared to other welding processes. The cost of inert gas limited its use in steels until several years later, when the use of semi-inert gases such as carbon dioxide became common. Further developments during the 1950s and 1960s gave the process more versatility and as a result, it became a highly used industrial process. Today, GMAW is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation. Unlike welding processes that do not employ a shielding gas, such as shielded metal arc welding, it is rarely used outdoors or in other areas of moving air. A related process, flux cored arc welding, often does not use a shielding gas, but instead employs an electrode wire that is hollow and filled with flux.
Shielding gases are inert or semi-inert gases that are commonly used in gas metal arc welding. Their purpose is to protect the weld area from oxygen, and water vapor. Depending on the materials being welded, these atmospheric gases can reduce the quality of the weld or make the welding more difficult. Other arc welding processes use alternative methods of protecting the weld from the atmosphere as well – shielded metal arc welding, for example, uses an electrode covered in a flux that produces carbon dioxide when consumed, a semi-inert gas that is an acceptable shielding gas for welding steel. Improper choice of a welding gas can lead to a porous and weak weld, or to excessive spatter; the latter, while not affecting the weld itself, causes loss of productivity due to the labor needed to remove the scattered drops.
Carbon dioxide is often used for welding of abrasion resistant extra high strength steel plates because its readily available and produces good weld at low cost. However, the low cost per unit volume of gas doesn’t always translate to the lowest cost per meter of deposited weld. Other factors such as low deposition efficiency due to spatter loss, high level of fume generation, higher wire consumption, poor weld bead profile, reduced tensile strength and lesser welding speed can influence the final weld cost and should be carefully considered.
The weld surface resulting from the use of 100% carbon dioxide shielding is usually heavily oxidized when compared with argon and carbon dioxide based shielding. These metallic oxides which get formed on the surface of the weld metal results in the depletion of the alloying elements in the weld. However, the major disadvantage of 100% carbon dioxide shielding is the harsh globular metal transfer. This results in improper bead finish and also a shabby welding work.
In addition to using inert shielding gases, de-oxidizers usually are present in the electrode metal itself in order to prevent oxidation. An electrode / filler with higher de-oxidizing elements are needed to compensate for the loss of alloying elements across the arc. Any deficiency of these elements in filler wire results in poor mechanical & metallurgical properties.
Hence, there is a need in the art for a gas metal arc welding process which is cost effective, has low spatter loss, lower wire consumption, and low levels of fume generation resulting in a weld joint with good mechanical properties.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts in a simplified format that is further described in the detailed description of the present disclosure. This summary is not intended to identify key or essential inventive concepts of the claimed subject matter, nor is it intended for determining the scope of the claimed subject matter. In accordance with the purposes of the disclosure, the present disclosure as embodied and broadly described herein describes a gas metal arc welding process and a system thereof.
In accordance with embodiments of the invention, a gas metal arc welding process is disclosed. The process includes obtaining a shielding gas mixture comprising of about 80% argon and about 20% carbon dioxide. The process includes forming an electric arc between a consumable weld electrode and a work piece to form a weld deposit on the work piece from the consumable weld electrode. The process includes completely shielding the electric arc and the weld deposit with the shielding gas mixture.
In accordance with embodiments of the invention, a gas metal arc welding system is disclosed. The system includes an argon tank comprising argon and a carbon dioxide tank comprising carbon dioxide. The system further includes a gas mixture coupled to the argon tank and the carbon dioxide tank to generate a shielding gas mixture comprising of about 80% argon and about 20% carbon dioxide. The system further includes a wire feeder which includes a consumable electrode. The system further includes a gas metal arc welding torch coupled to the gas mixture and the wire feeder. The gas metal arc welding torch is to form an electric arc between a consumable weld electrode and a work piece to form a weld deposit on the work piece from the consumable weld electrode. The gas metal arc welding torch is to completely shield the electric arc and the weld deposit with the shielding gas mixture.
The advantages provided by the invention include, but not limited to, provide an efficient and cost effective gas metal arc welding process that has low spatter loss, lower wire consumption, and low levels of fume generation resulting in a weld joint with good mechanical properties, due to the use of about 80% argon–about 20% carbon dioxide mixture as shielding gas.
These aspects and advantages will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
These and other features, aspects, and/or advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
FIG. 1illustrates gas metal arc welding process implemented by a system in accordance with an embodiment of the present invention; and
FIG. 2 and FIG. 3 illustrate example test results in accordance with the embodiment of the present invention.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of some operations involved to help to improve understanding of aspects of the present disclosure. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show some specific details that are pertinent to understanding some example embodiments of the inventive concepts so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION:
For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to some example embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this disclosure belongs. The system and examples provided herein are illustrative only and not intended to be limiting. Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.
FIG. 1 illustrates gas metal arc welding process implemented by a system 100 in accordance with an embodiment of the present invention. The system 100 includes argon tank 102 comprising argon and a carbon dioxide tank 104 comprising carbon dioxide. In an example, the system 100 includes 13 kilo liters (KL) of the argon tank and a 20KL of the carbon dioxide tank.
The system 100 further includes a gas mixture 106 coupled to the argon tank 102 and the carbon dioxide tank 104. The gas mixture 106 is to generate a shielding gas mixture comprising of about 80% argon and about 20% carbon dioxide. In an example, the gas mixture 106 is a 2000 Standard Cubic Feet per Hour (SCFH) capacity argon-carbon dioxide gas mixture.
The system 100 further includes a wire feeder 108 which includes a consumable electrode. In an example, the consumable electrode is stored in the wire feeder 108 in form of a tubular wire. The consumable electrode is a copper coated solid wire having a diameter of 1.2 millimetres and is having a finer grain structure. The consumable electrode comprises approximately 0.06% to0.15% of carbon by weight, approximately 1.40% to1.85% of manganese by weight, approximately 0.80% to 1.15% of silicon by weight, approximately 0.025% of phosphorous by weight, approximately 0.035 % of sulphur by weight, and approximately 0.50% of copper by weight. The consumable electrode may include approximately 0.50% of other materials as required by weight. The wire feeder 108 may be a high speed welding wire feeder 108 operating at a high welding wire feed, i.e., at approximately 7 meters/minute to11 meters/minute.
The system 100 further includes a gas metal arc welding torch 110. The welding torch 110 is coupled to the gas mixture 106 and the wire feeder 108. The gas mixture 106 is directly coupled to the welding torch 110 via a gas conduit 112.
During operation, the gas metal arc welding torch 110 receives the weld electrode from the wire feeder 108, power from a welding power source 114, and the shielding gas mixture flow from the gas mixture 106 in order to perform gas metal arc welding of a work piece 116. In an embodiment, the work piece 116 is an abrasion resistant extra high strength steel plate.
As such, the as metal arc welding torch 110 is brought near the work piece 116 to form an electric arc between the consumable weld electrode and the work piece116. In an example, the welding torch 110 and the wire feeder 108 may be configured to provide a nearly constant contact tip-to-work piece distance. This results in formation of a weld deposit on the work piece116 from the consumable weld electrode. As the consumable electrode is of a finer grain structure, a narrower heat affected zone is created on the work piece 116. This improves the mechanical & metallurgical properties of the weld like yield strength, tensile strength & impact strength.
The gas metal arc welding torch 110also completely shields the electric arc and the weld deposit with the shielding gas mixture. This leads to a welding process with reduced fumes generation. In an example, the amount of fumes generated by about 80% argon-about 20% carbon dioxide based shielding mixture is one-fourth (¼) of the 100 % carbon dioxide shielding for gas metal arc welding. As such, this result in lower weld spatters and achieve weld joint with good mechanical properties. Additionally, the consumption of the electrode is lowered due to the lower weld spatters. Also, a good weld bead appearance is obtained due to the lower weld spatters.
Further, productivity of the process is increased and consumption of the shielding gas is lowered due to higher welding speed. In addition, welding distortion is minimized and distortion correction of heavy welding structures is reduced due to the completely shielding of the electric arc and the weld deposit with the shielding gas mixture.
Also, the system 100 includes regulator 118 coupled to the argon tank 102 and the carbon dioxide tank 104 to control a flow of the argon from the argon tank 102 and a flow of the carbon dioxide from the carbon dioxide tank 104 to maintain a composition of the shielding gas mixture at about 80% argon and about 20% carbon dioxide. This results in improved welding process.
Test Results:
Considering the quality of weld, a detailed test was conducted for gas arc welding using only carbon dioxide (CO2) and 80% argon-20% carbon mixture (ACM) as shielding gases for comparing the tensile strength, impact strength, bend test. FIG. 2 photographically illustrates a weld 202 obtained using CO2as shielding gas. FIG. 3 photographically illustrates a weld 302 obtained using ACM as shielding gas.
From the test report, the following are the advantages of ACM over CO2,
? The tensile strength (595.04 N/mm2) and Yield strength (417.34 N/mm2) for ACM is slightly more than tensile strength (581.12 N/mm2) and Yield strength (378.90 N/mm2) for CO2.
? The average impact strength (59.6 J) for ACM is better than average impact strength (46.8 J) for CO2.
? For the bend test there is no openings observed and it is accepted.
? A high percentage of argon gas in the mixture tends to promote higher deposition efficiency due to the creation of lesser spatters.
? The ACM gas mixture produces a fine globular metal transfer that approaches a spray.
? It also reduces the amount of oxidation that occurs, compared to CO2.
? As can be gathered from the FIG. 2 and FIG. 3, ACM welding provides uniform welding and less spatters than CO2 welding.
Further the radiography test were conducted on the welds obtained, as indicated in FIG. 2 and FIG. 3, for checking the weld defects like crack, lack of penetration, porosity etc. The tests indicate that there are no significant discontinuities.
Thus, the gas metal arc welding process can be used where heavy fabrication and high load carrying structure welding can be carried out with good welding bead, aesthetics and improved mechanical properties minimizing the chipping and grinding manual work.
While specific language has been used to describe the present disclosure, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concepts as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. Clearly, the present disclosure may be otherwise variously embodied, and practiced within the scope of the following claims.
,CLAIMS:1. A gas metal arc welding process comprising:
obtaining a shielding gas mixture comprising of about 80% argon and about 20% carbon dioxide;
forming an electric arc between a consumable weld electrode and a work piece to form a weld deposit on the work piece from the consumable weld electrode; and
completely shielding the electric arc and the weld deposit with the shielding gas mixture.

2. The gas metal arc welding process as claimed in claim 1, wherein the work piece is an abrasion resistant extra high strength steel plate.

3. The gas metal arc welding process as claimed in claim 1, wherein the consumable electrode is a copper coated solid wire having a diameter of 1.2 millimeter and is having a finer grain structure

4. The gas metal arc welding process as claimed in claim 3, wherein the consumable electrode comprises approximately 0.06% to0.15% of carbon by weight, approximately 1.40% to1.85% of manganese by weight, approximately 0.80% to 1.15% of silicon by weight, approximately 0.025% of phosphorous by weight, approximately 0.035 % of sulphur by weight, and approximately 0.50% of copper by weight.

5. The gas metal arc welding process as claimed in claim 1, wherein a welding wire feed is approximately 7 meters/minute to11 meters/minute.

6. The gas metal arc welding process as claimed in claim 1, comprising:
controlling a flow of the argon from an argon tank and a flow of the carbon dioxide from a carbon dioxide tank to maintain a composition of the shielding gas mixture at about 80% argon and about 20% carbon dioxide.

7. A gas metal arc welding system comprising:
an argon tank comprising argon;
a carbon dioxide tank comprising carbon dioxide;
a gas mixture coupled to the argon tank and the carbon dioxide tank to generate a shielding gas mixture comprising of about 80% argon and about 20% carbon dioxide;
a wire feeder including a consumable electrode; and
agas metal arc welding torch coupled to the gas mixture and the wire feeder to:
form an electric arc between a consumable weld electrode and a work piece to form a weld deposit on the work piece from the consumable weld electrode; and
completely shield the electric arc and the weld deposit with the shielding gas mixture.