1 AWS Electrode classificationsJust like UNS and ISO numbering systems, the AWS

numbering system is used to classify electrodes and it can tell a welder quite a bit about the electrode stick like:

i. How the electrode should be handledii. What current should be used to operate the stick

iii. How to maximize its performance, etc.Now let’s see how the numbering system classify the electrodes and how it works.

1.1 Parameters for classification In AWS numbering the parameters used to classify the welding electrodes are as follow:

i. Type of consumableii. Tensile strength of the material used

iii. Position of useiv. Type of coating and current

1.1.1 Type of consumable 1st portion of AWS electrode number consists of one or two alphabet that tells the type of consumable and welding in which the consumable is used. The classification is as follow:

Consumable Prefix Type Of Welding Common Electrodes

Stick welding electrode E SMAW E6010,E7018

Solid wire ER MIG/GMAW ER5056,ER308

Flux cored wire E FCAW E70C-6,E71T-8

TIG electrode WX* TIG WL15,WC20

TIG filler rods ER TIG ER308,ER4043

Rod gas RG Oxy-fuel welding RG-65,RG-60Notes:*X=L for lanthanated, C for ceriated, T for thoriated, Z for zircoinated

Table. 1.1

The classification shown in table is rather a concise classification, for more detailed classification you can check the AWS standard reports available online. Here we are only going to study stick welding electrodes used in SMAW.

1.1.2 Tensile strength of material For stick welding electrode the first two digits of the classification represents tensile strength of the electrode. Tensile strength pf the weld metal, measured in kilo pounds per square inch (k PSI).

For example in E-7018, 70 represents 70 kilo Psi.

1.1.3 Position of use The third digit of the code tells position of use. The classification of position is shown in table. 1.2.

Digit Positions of use

1 All positions

2 Horizontal and flat

3 Flat only

4 Overhead, flat, horizontal, vertical down

Table. 1.2

1.1.4 Type of coating and current The fourth digit tells the coating and type of current and its polarity. (Shown in table 1.3)

Types of Current: Alternating current (AC)

Current changes its polarity depending upon the frequency of AC current. In America the polarity changes 120 times per second, current is 60Hz. In Pakistan polarity changes 100 times per second, current is 50Hz. Direct current electrode positive(DCEP or DC+)

DCEP or reversed polarity is used for deeper penetration. Direct current electrode negative(DCEN or DC-)

DCEN or straight polarity is used for faster melt-off and deposition rate.

Table 1.3

Some commonly used SMAW welding electrodes are as follow:

E6010 E6010 electrodes are characterized by a deeply penetrating, forceful, spray-type arc

and readily removable, thin, friable slag which may not seem to completely cover the weld bead. Fillet welds usually have a relatively flat weld face and have a rather coarse, unevenly spaced ripple. The coverings are high in cellulose, usually exceeding 30% by weight. The other materials generally used in the covering include titanium dioxide, metallic deoxidizers such as ferromanganese, various types of magnesium or aluminum silicates, and liquid sodium silicate as a binder. Because of their covering composition, these electrodes are generally described as the high-cellulose sodium type.These electrodes are recommended for all welding positions, particularly on multiple-pass applications in the vertical and overhead welding positions and where welds of good soundness are required. They frequently are selected for joining pipe and generally are capable of welding in the vertical position with either uphill or downhill progression.The majority of applications for these electrodes is in joining carbon steel. However, they have been used to advantage on galvanized steel and on some low-alloy steels. Typical applications include shipbuilding, buildings, bridges, storage tanks, piping, and pressure vessel fittings. Since the applications are so widespread, a discussion of each is impractical.Sizes larger than 3/16 in [5.0 mm] generally have limited use in other than flat or horizontal-fillet welding positions.These electrodes have been designed for use with dcep (direct current, electrode positive). The maximum amperage that can generally be used with the larger sizes of these electrodes is limited in comparison to that for other classifications due to the high spatter loss that occurs with high amperage.E7018M

Electrodes are similar to E7018-1H4R electrodes, except that the testing for mechanical properties and for classification is done on a groove weld that has a 60 degree included angle and, for electrodes up to 5/32 in [4 mm], welded in the vertical position with upward progression. The impact test results are evaluated using all five test values and higher values are required at –20°F [–30°C]. The maximum allowable moisturein-coating values in the “as-received” or reconditioned state are more restrictive than that required for E7018R.E7018M is intended to be used with dcep-type current in order to produce the optimum mechanical properties. However, if the manufacturer desires, the electrode may also be classified as E7018 provided all the requirements of E7018 are met.In addition to their use on carbon steel, the E7018M electrodes are used for joining carbon steel to high-strength low-alloy steels and higher carbon steels. Fillet welds made in the horizontal and flat welding positions have a slightly convex weld face, with a smooth and finely rippled surface. The electrodes are characterized by a smooth, quiet arc, very low spatter, and medium arc penetration.