Published on December 17, December 1, SMAW or stick electrodes are consumable, meaning they become part of the weld, while TIG electrodes are non-consumable as they do not melt and become part of the weld, requiring the use of a welding rod. Electrode selection is critical to ease of cleanup, weld strength, bead quality and for minimizing any spatter. Electrodes need to be stored in a moisture-free environment and carefully removed from any package follow the directions to avoid damage. When molten metal is exposed to air, it absorbs oxygen and nitrogen, and becomes brittle or is otherwise adversely affected.
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- Grounding Electrodes
- Corrosion Resistance
- Clarification over tungsten electrodes for TIG/GTAW welding
- ENCYCLOPEDIA OF TERMS
- Arc welding
- Gas tungsten arc welding
- Which countries export Woven products of iron/steel, except stainless steel? (1995-2017)
- Clarke Welder 95e
- Miller Thunderbolt Xl Tig
- Acdc Tig Nz
Grounding ElectrodesVIDEO ON THE TOPIC: Turning Stainless Steel Welding Electrodes Into Chefs Knife From Stick welding
Published on December 17, December 1, SMAW or stick electrodes are consumable, meaning they become part of the weld, while TIG electrodes are non-consumable as they do not melt and become part of the weld, requiring the use of a welding rod. Electrode selection is critical to ease of cleanup, weld strength, bead quality and for minimizing any spatter.
Electrodes need to be stored in a moisture-free environment and carefully removed from any package follow the directions to avoid damage.
When molten metal is exposed to air, it absorbs oxygen and nitrogen, and becomes brittle or is otherwise adversely affected. A slag cover is needed to protect molten or solidifying weld metal from the atmosphere. This cover can be obtained from the electrode coating. The composition of the welding electrode coating determines its usability, as well as the composition of the deposited weld metal and the electrode specification.
The formulation of welding electrode coatings is based on well-established principles of metallurgy, chemistry, and physics. The coating protects the metal from damage, stabilizes the arc, and improves the weld in other ways, which include:. The metal-arc electrodes may be grouped and classified as bare or thinly coated electrodes, and shielded arc or heavy coated electrodes.
The composition of the electrode covering determines the usability of the electrode, the composition of the deposited weld metal, and the specification of the electrode. These include corrosion resistance, ductility, high tensile strength, the type of base metal to be welded, the position of the weld flat, horizontal, vertical, or overhead ; and the type of current and polarity required. When the fourth or last digit is 0, the type of coating and current to be used are determined by the third digit.
Table The welding electrode identification system for stainless steel arc welding is set up as follows:. The most important aspect of solid welding electrode wires and rods in their composition, which is given by the specification. The specifications provide the limits of composition for the different wires and mechanical property requirements.
Occasionally, on copper-plated solid wires, the copper may flake off in the feed roll mechanism and create problems. It may plug liners, or contact tips. A light copper coating is desirable. The electrode wire surface should be reasonably free of dirt and drawing compounds.
This can be checked by using a white cleaning tissue and pulling a length of wire through it. Too much dirt will clog the liners, reduce current pickup in the tip, and may create erratic welding operation. Temper or strength of the wire can be checked in a testing machine. Wire of a higher strength will feed through guns and cables better. The minimum tensile strength recommended by the specification is , psi , kPa.
The continuous electrode wire is available in many different packages. They range from extremely small spools that are used on spool guns, through medium-size spools for fine-wire gas metal arc welding. Coils of electrode wire are available which can be placed on reels that are a part of the welding equipment. There are also extremely large reels weighing many hundreds of pounds. The electrode wire is also available in drums or payoff packs where the wire is laid in the round container and pulled from the container by an automatic wire feeder.
The coatings of welding electrodes for welding mild and low alloy steels may have from 6 to 12 ingredients, which includes:. There are many types of coatings other than those mentioned here, most of which are usually combinations of these types but for special applications such as hard surfacing, cast iron welding, and for nonferrous metals.
Electrodes must be kept dry. Moisture destroys the desirable characteristics of the coating and may cause excessive spattering and lead to porosity and cracks in the formation of the welded area. After they have dried, they should be stored in a moisture-proof container. Bending the electrode can cause the coating to break loose from the core wire. Electrodes should not be used if the core wire is exposed. These electrodes have no coatings other than those required in wire drawing.
These wire drawing coatings have some slight stabilizing effect on the arc but are otherwise of no consequence. Bare electrodes are used for welding manganese steel and other purposes where a coated electrode is not required or is undesirable. A light coating has been applied on the surface by washing, dipping, brushing, spraying, tumbling, or wiping. The coatings improve the characteristics of the arc stream.
They are listed under the E45 series in the electrode identification system. Shielded arc or heavy coated welding electrodes have a definite composition on which a coating has been applied by dipping or extrusion.
The cellulose coatings are composed of soluble cotton or other forms of cellulose with small amounts of potassium, sodium, or titanium, and in some cases added minerals. The mineral coatings consist of sodium silicate, metallic oxides clay, and other inorganic substances or combinations thereof.
Cellulose coated electrodes protect the molten metal with a gaseous zone around the arc as well as the weld zone. The shielded arc or heavy coated electrodes are used for welding steels, cast iron, and hard surfacing. See figure below. The oxygen readily combines with the molten metal, removing alloying elements and causing porosity. Nitrogen causes brittleness, low ductility, and in Some cases low strength and poor resistance to corrosion.
They reduce impurities such as oxides, sulfur, and phosphorus so that these impurities will not impair the weld deposit. They provide substances to the arc which increases its stability. This eliminates wide fluctuations in the voltage so that the arc can be maintained without excessive spattering. By reducing the attractive force between the molten metal and the end of the electrodes, or by reducing the surface tension of the molten metal, the vaporized and melted coating causes the molten metal at the end of the electrode to break up into fine, small particles.
The coatings contain silicates which will form a slag over the molten weld and base metal. Since the slag solidifies at a relatively slow rate, it holds the heat and allows the underlying metal to cool and solidify slowly. This slow solidification of the metal eliminates the entrapment of gases within the weld and permits solid impurities to float to the surface.
Slow cooling also has an annealing effect on the weld deposit. The physical characteristics of the weld deposit are modified by incorporating alloying materials in the electrode coating. The fluxing action of the slag will also produce weld metal of better quality and permit welding at higher speeds. Pure tungsten This type of electrode has a relatively low current-carrying capacity and a low resistance to contamination.
Thoriated tungsten electrodes 1 or 2 percent thorium are superior to pure tungsten electrodes because of their higher electron output, better arc-starting and arc stability, high current-carrying capacity, longer life, and greater resistance to contamination.
Tungsten welding electrodes containing 0. There is, however, some indication of better performance in certain types of welding using ac power. Finer arc control can be obtained if the tungsten alloyed electrode is ground to a point see figure When electrodes are not grounded, they must be operated at maximum current density to obtain reasonable arc stability.
Tungsten electrode points are difficult to maintain if standard direct current equipment is used as a power source and touch-starting of the arc is standard practice.
Maintenance of electrode shape and the reduction of tungsten inclusions in the weld can best be accomplished by superimposing a high-frequency current on the regular welding current. Tungsten electrodes alloyed with thorium and zirconium retain their shape longer when touch-starting is used.
The welding electrode extension beyond the gas cup is determined by the type of joint being welded. The tungsten electrode of torch should be inclined slightly and the filler metal added carefully to avoid contact with the tungsten. This will prevent contamination of the electrode. If contamination does occur, the electrode must be removed, reground, and replaced in the torch.
In general, direct current shielded arc electrodes are designed either for reverse polarity electrode positive or for straight polarity electrode negative , or both. Many, but not all, of the direct current electrodes can be used with alternating current.
Direct current is preferred for many types of covered, nonferrous, bare and alloy steel electrodes. Recommendations from the manufacturer also include the type of base metal for which given electrodes are suited, corrections for poor fit-ups, and other specific conditions. In most cases, straight polarity electrodes will provide less penetration than reverse polarity electrodes, and for this reason will permit greater welding speed.
Good penetration can be obtained from either type with proper welding conditions and arc manipulation. Coated electrodes which can be used with either direct or alternating current are available. Alternating current is more desirable while welding in restricted areas or when using the high currents required for thick sections because it reduces arc blow.
Arc blow causes blowholes, slag inclusions, and lack of fusion in the weld. Alternating current is used in atomic hydrogen welding and in those carbon arc processes that require the use of two carbon electrodes. It permits a uniform rate of welding and electrode consumption. In carbon-arc processes where one carbon electrode is used, direct current straight polarity is recommended, because the electrode will be consumed at a lower rate.
If certain elements or oxides are present in electrode coatings, the arc stability will be affected. In bare electrodes, the composition and uniformity of the wire is an important factor in the control of arc stability. Thin or heavy coatings on the electrodes will riot completely remove the effects of defective wire. Aluminum or aluminum oxide even when present in 0.
Iron oxide, manganese oxide, calcium oxide, and stabilize the arc. When phosphorus or sulfur are present in the electrode in excess of 0. These defects increase in magnitude as the carbon content of the steel increases.
Sulfur is particularly harmful to bare, low-carbon steel electrodes with a low manganese content. Manganese promotes the formation of sound welds. If the heat treatment, given the wire core of an electrode, is not uniform, the electrode will produce welds inferior to those produced with an electrode of the same composition that has been properly heat treated.
The results, determined from atypical heat, are as shown. Density at 75 F 24 C 7. This characteristic makes the alloy useful for applications requiring a combination of excellent corrosion resistance and low magnetic permeability. The magnetic permeability of HP. The magnetic susceptibility data in Table 25 were obtained on mill-annealed sheet samples using the Curie Force Method. For many applications the F C annealed condition provides adequate corrosion resistance and a higher strength level.
Morgantown, WV Elemental manganese, nickel, chromium, iron emissions per unit length of weld and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc SMAW processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes.
Clarification over tungsten electrodes for TIG/GTAW welding
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ENCYCLOPEDIA OF TERMS
ASTM's steel standards are instrumental in classifying, evaluating, and specifying the material, chemical, mechanical, and metallurgical properties of the different types of steels, which are primarily used in the production of mechanical components, industrial parts, and construction elements, as well as other accessories related to them. The steels can be of the carbon, structural, stainless, ferritic, austenitic, and alloy types. These steel standards are helpful in guiding metallurgical laboratories and refineries, product manufacturers, and other end-users of steel and its variants in their proper processing and application procedures to ensure quality towards safe use. Additive Manufacturing Standards.
Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals when cool result in a binding of the metals. It is a type of welding that uses a welding power supply to create an electric arc between a metal stick " electrode " and the base material to melt the metals at the point of contact. Arc welders can use either direct DC or alternating AC current, and consumable or non-consumable electrodes. The welding area is usually protected by some type of shielding gas , vapor, or slag. Arc welding processes may be manual, semi-automatic, or fully automated. First developed in the late part of the 19th century, arc welding became commercially important in shipbuilding during the Second World War. Today it remains an important process for the fabrication of steel structures and vehicles. To supply the electrical energy necessary for arc welding processes, a number of different power supplies can be used.
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Gas tungsten arc welding
Account Options Sign in. Export Control; Quarterly Report. United States. Department of Commerce. Selected pages Page. Page Contents General Statement.
Which countries export Woven products of iron/steel, except stainless steel? (1995-2017)
Scientific Research An Academic Publisher. Affiliation s. Welding is a process involving the joining of two crystalline work pieces usually of metal by bringing their fitted surfaces into such intimate contact that crystal-to-crystal bonding occurs. Depending on the welding techniques, heat required for welding can be obtained from a burning gas or an electric arc, or generated by electric resistance .
Clarke Welder 95e
Table 1. AWS Electrode classification by colour and work function eV. Stainless Steel World magazine is a leading international magazine on stainless steels and corrosion resistant alloys CRAs with a worldwide distribution.
Miller Thunderbolt Xl Tig
For many applications, grounding electrodes provide the essential function of connecting the electrical system to the earth. The earth is considered to be at zero potential. In some cases, the grounding electrode serves to ground the electrical system. In other instances, the electrode is used to connect noncurrent carrying metallic portions of electrical equipment to the earth.
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Gas tungsten arc welding GTAW , also known as tungsten inert gas TIG welding , is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode is protected from oxidation or other atmospheric contamination by an inert shielding gas argon or helium , and a filler metal is normally used, though some welds, known as autogenous welds, do not require it.