AWS A5.1/A5.1M is the Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding: E7018 is one of the most common used stick electrodes rods so it will be used as an example. E7018 E = Electrode, The first two digits = tensile strength. WELDING ELECTRODE CLASSIFICATIONS MILD STEEL COATED ELECTRODES. Tensile Strength Min. Yield Strength E60xx 62,000 psi 50,000 psi.
- (2) Almost any E60XX or E70XX electrodes can be used. First, select electrode based on the joint requirements. If code, specifications, or contract documents require notch toughness, electrode selection should be limited to those that meet the specific application requirements. (3) Almost any E70XX electrode can be used.
- The strength of the electrode should match the strength of the base metal. If yield stress (σy) of the base metal is ≤ 60 - 65 ksi, use E70XX electrode. If yield stress (σy) of the base metal is ≥ 60 - 65 ksi, use E80XX electrode. E70XX is the most popular electrode used for fillet welds made by the SMAW method.
The electrode is 1/8″ in diameter
The “E” stands for arc welding electrode.
Next will be either a 4 or 5 digit number stamped on the electrode. The first two numbers of a 4 digit number and the first 3 digits of a 5 digit number indicate the minimum tensile strength (in thousands of pounds per square inch) of the weld that the rod will produce, stress relieved. Examples would be as follows:
E60xx would have a tensile strength of 60,000 psi E110XX would be 110,000 psi
The next to last digit indicates the position the electrode can be used in.
- EXX1X is for use in all positions
- EXX2X is for use in flat and horizontal positions
- EXX3X is for flat welding
The last two digits together, indicate the type of coating on the electrode and the welding current the electrode can be used with. Such as DC straight, (DC -) DC reverse (DC+) or A.C.
I won’t describe the type of coatings of the various electrodes, but will give examples of the type current each will work with.
ELECTRODES AND CURRENTS USED
- EXX10 DC+ (DC reverse or DCRP) electrode positive.
- EXX11 AC or DC- (DC straight or DCSP) electrode negative.
- EXX12 AC or DC-
- EXX13 AC, DC- or DC+
- EXX14 AC, DC- or DC+
- EXX15 DC+
- EXX16 AC or DC+
- EXX18 AC, DC- or DC+
- EXX20 AC ,DC- or DC+
- EXX24 AC, DC- or DC+
- EXX27 AC, DC- or DC+
- EXX28 AC or DC+
E60xx Electrode Yield Strength FormulaSMAW is performed using either AC or DCcurrent. Since DC current flows in one direction, DC current can be DC straight, (electrode negative) or DC reversed (electrode positive). With DC reversed,(DC+ OR DCRP) the weld penetration will be deep. DC straight (DC- OR DCSP) the weld will have a faster melt off and deposit rate. The weld will have medium penetration.
Ac current changes it’s polarity 120 times a second by itself and can not be changed as can DC current.
ELECTRODE SIZE AND AMPS USED
ELECTRODE DIAMETER (THICKNESS)
20 – 40
UP TO 3/16″
40 – 125
UP TO 1/4″
75 – 185
105 – 250
140 – 305
210 – 430
275 – 450
Note! The thicker the material to be welded, the higher the current needed and the larger the electrode needed.
SOME ELECTRODE TYPES
E6010 This electrode is used for all position welding using DCRP. It produces a deep penetrating weld and works well on dirty, rusted, or painted metals
E6011 This electrode has the same characteristics of the E6010, but can be used with AC and DC currents.
E60xx Electrode Yield Strength Chart
E6013 This electrode can be used with AC and DC currents. It produces a medium penetrating weld with a superior weld bead appearance.
E7018 This electrode is known as a low hydrogen electrode and can be used with AC or DC. The coating on the electrode has a low moisture content that reduces the introduction of hydrogen into the weld. The electrode can produce welds of x-ray quality with medium penetration. (Note, this electrode must be kept dry. If it gets wet, it must be dried in a rod oven before use.)
It is hoped that this basic information will help the new or home shop welder identify the various types of electrodes and select the correct one for their welding projects.
Author: Bruce Bauerlein
Yield Strength Of Steel
** Arc Welding Electrode Classification System. **
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.
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.
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.
E60xx Electrode Yield Strength Chart
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.
E60xx Electrode Yield Strength Calculation
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.
Yield Strength Formula
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.