Smaw Electrode Classification



  1. Welding Electrode Identification
  2. Smaw Electrode Classification
  3. Smaw Electrode Classification

Subjects: t4e, kckcc, taaccct, round 2, welding, aws, american welding society, smaw, shielded, metal, arc, electrode classification, electrode, rod, tensile, ksi. A video about the American Welding Society (AWS) system's electrode classification for Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW).This.

** Arc Welding Electrode Classification System. **

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The SMAW electrode classification code contains an E and three numbers, followed by a dash and either “15” or “16” (EXXX15). The E designates that the material is an electrode and the three digits indicate composition. Sometimes there are letters following the three digits; these letters indicate a modification of the standard composition. The “15” or “16” specifies the type of current with which these electrodes may be used. Both designations indicate that the electrode is usable in all positions: flat, horizontal, vertical and overhead.

Welding Electrode Identification

The “15” indicates that the covering of this electrode is a lime type, which contains a large proportion of calcium or alkaline earth materials. These electrodes are usable with dc reverse-polarity only.

The designation “16” indicates electrodes that have a lime-or titania-type covering with a large proportion of titanium-bearing minerals. The coverings of these electrodes also contain readily ionizing elements, such as potassium, to stabilize the arc for ac welding.

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Electrode Chemical Requirements.

The AWS (American Welding Society) divides SMAW (Shielded Metal Arc Welding) electrodes into two groups: mild steel and low-alloy steel. The E60XX and E70XX electrodes are in the mild steel specification. The chemical requirements for E70XX electrodes are listed in AWS A5.1 and allow for wide variations of composition of the deposited weld metal. There are no specified chemical requirements for the E60XX electrodes. The low-alloy specification contains electrode classifications E70XX through E120XX. These codes have a suffix indicating the chemical requirements of the class of electrodes (e. g., E7010-A1 or E8018-C1). The composition of low-alloy E70XX electrodes is controlled much more closely than that of mild steel E70XX electrodes. Low-alloy electrodes of the low-hydrogen classification (EXX15, EXX16, EXX18) require special handling to keep the coatings from picking up water. Manufacturers’ recommendations about storage and rebaking must be followed for these electrodes. AWS A5.5 provides a specific listing of chemical requirements.

Weld Metal Mechanical Properties. The AWS requires the deposited weld metal to have a minimum tensile strength of 60,000 to 100,000 psi (413,700 to 689,500 kPa), with minimum elongations of 20 to 35 percent.

Arc Shielding.

Classification

The arc shielding action, illustrated in figure 10-31, is essentially the same for the different types of electrodes, but the specific method of shielding and the volume of slag produced vary from type to type. The bulk of the covering materials in some electrodes is converted to gas by the heat of the arc, and only a small amount of slag is produced. This type of electrode depends largely upon a gaseous shield to prevent atmospheric contamination. Weld metal from such electrodes can be identified by the incomplete or light layer of slag which covers the bead.

Smaw Electrode Classification

For electrodes at the other extreme, the bulk of the covering is converted to slag by the arc heat, and only a small volume of shielding gas is produced. The tiny globules of metal transferred across the arc are entirely coated with a thin film of molten slag. This slag floats to the weld puddle surface because it is lighter than the metal. It solidifies after the weld metal has solidified. Welds made with these electrodes are identified by the heavy slag deposits that completely cover the weld beads. Between these extremes is a wide variety of electrode types, each with a different combination of gas and slag shielding.

The variations in the amount of slag and gas shielding also influence the welding characteristics of the different types of covered electrodes. Electrodes that have a heavy slag carry high amperage and have high deposition rates. These electrodes are ideal for making large beads in the flat position. Electrodes that develop a gaseous arc shield and have a light layer of slag carry lower amperage and have lower deposition rates. These electrodes produce a smaller weld pool and are better suited for making welds in the vertical and overhead positions. Because of the differences in their welding characteristics, one type of covered electrode will usually be best suited for a given application.

Smaw Electrode Classification

Stick WeldingCovered Electrodes for SMAW of Carbon Steel per AWS A5.1
Arc-Welding Processes – SMAW
ClassificationCoveringWeld
Position
CurrentCharacteristics, applications
E6010 High-cellulose
sodium
F, V,
O, H
dcep A general purpose electrode for joining of carbon steel. Deep-penetrating forceful arc. Thin slag. Us in all positions, single and multiple pass, plate and pipe, galvanized and alloy steels. Ships, bridges, buildings, piping, tanks, pressure-vessel fittings.
E6011 High-cellulose
potassium
F, V,
O, H
ac, dcep Similar to E6010, but for use with ac. Dcep gives reduced penetration.
E6012 High-titania
sodium
F, V,
O, H
ac, dcen Dense slag that covers the bead, low-penetrating arc. Use to bridge joints with poor fitup. Fillets have smooth convex face. Runs well at amps higher than E6010/E6011.
E6013 High-titania
potassium
F, V,
O, H
ac, dcen,
dcep
Similar to E6012; quieter arc, smoother bead, cleaner weld metal, fewer inclusions Characteristics vary with supplier. Run at lower current than for E6012.
E6022 High iron oxide F ac, dcep,
dcen
Use for single-pass, high-current, high-speed welding of groove welds in flat position horizontal lap joints and fillet welds in sheet metal.
E6027 High iron oxide,
iron powder
H-fillets,
F
ac, dcep For fillet of groove welds, flat position, heavy slag, good sidewall fusion. Use at high amperages on thick plate.
E7014 Iron powder,
titania
F, V,
O, H
ac, dcep Iron powder boosts deposition rate and efficiency. Use at high amperages on carbon and low-alloy steels. Low-penetrating arc, use to bridge poor fitups. Smooth, fine-rippled bead, convex fillets.
E7018,
7018-1
7018R
7018-1R
7018H16, H8, H4
Low-hydrogen
potassium,
iron powder
F, V,
O, H
ac, dcep Iron-powder addition increases deposition rate. Use on carbon, high-carbon, and low-alloy steels. Smooth arc, low spatter. Flat and horizontal welds are finely rippled. Convex. Other types: E7018-1H16R, E7018-1H8R, E7018-1H4R.
E7018M Low-hydrogen
iron powder
F, V,
O, H
dcep Yield strength, 53,000-72,000 lb/in. Ductility high, extra impact strength and compositional limits and limits on moisture and hydrogen. Similar to E7018-1H4R, MIL-7018-M. Characteristics similar to E7018.
E7024
E7024-1
Iron powder, titania H-fillets,
F
ac, dcep,
dcen
Iron powder for high deposition rate, high travel speed, flat, smooth fillets, finely rippled. Smooth, quiet arc, low penetration. E7024-1 deposits more-ductile weld metal of improved Charpy values.




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