Covered Electrodes: Uses Based on Their Classification

Everything about those numbers and colors that are so hard to remember. Which is the best electrode for each material and situation.

Covered electrodes for arc welding are classified based on the properties of the filler metal and the type of coating. The combinations of both create a wide range of options, so wide that it can be overwhelming. But don’t worry, as you’ll likely only use 2 or 3 types of electrodes.

The AWS A5.1-69 Alphanumeric Coding Standard for Electrodes

This is the internationally used standard for designating welding electrodes and replaces the color coding on electrodes. The standard code for a covered electrode used in SMAW welding is of the type EXXXX-XX or EXXXXX-XX, and it consists of four parts:

The E prefix indicates that the electrode is suitable for arc welding, or SMAW.

Tensile Strength

The first two digits in codes E-XXXX-XX, and the first three in codes of the form E-XXXXX-XX, indicate the tensile strength:

E-60XX-XX indicates an approximate tensile strength of 60,000 psi (4218.5 kg/cm²).
E-70XX-XX indicates an approximate tensile strength of 70,000 psi (4921.5 kg/cm²).
E-110XX-XX indicates an approximate tensile strength of 110,000 psi (7733.75 kg/cm²).

This value broadly indicates the hardness or strength of the material.

Electrode Position

The next digit (E-XXXX-XX) indicates the position in which the electrode can be used for welding:

E-XX1X: Any position, including vertical.
E-XX2X: Horizontal position.
E-XX3X: Flat position only.
E-XX4X: Recommended for vertical down, flat, and overhead positions.

Current Type and Polarity

This characteristic is linked to the type of coating. The last number (E-XXXX-XX) provides this information:

E-XXX0 - CC+ Organic slag, strong arc, and deep penetration.
E-XXX1 - AC CC+ Organic slag, strong arc, and deep penetration.
E-XXX2 - AC CC- Rutile slag, medium arc, and moderate penetration.
E-XXX3 - AC CC- Rutile slag, soft arc, and shallow penetration.
E-XXX4 - AC CC- Rutile slag, soft arc, and shallow penetration.
E-XXX5 - CC+ Basic slag, medium arc, and moderate penetration.
E-XXX6 - AC CC+ Basic slag, medium arc, and moderate penetration.
E-XXX7 - AC CC Mineral slag, soft arc, and moderate penetration.
E-XXX8 - AC CC+ Basic slag, medium arc, and moderate penetration.

Weld Metal Alloy

The suffix (E-XXXX-XX) indicates the approximate alloy of the filler material, always referring to steel electrodes:

A1: 0.5% molybdenum.
B1: 0.5% chromium, 0.5% molybdenum.
B2: 1.25% chromium, 0.5% molybdenum.
B3: 2.25% chromium, 1% molybdenum.
B4: 2% chromium, 0.5% molybdenum.
B5: 0.5% chromium, 1% molybdenum.
C1: 2.5% nickel.
C2: 3.25% nickel.
C3: 1% nickel, 0.35% molybdenum, and 0.15% chromium.
D1 and D2: 0.25% to 0.45% molybdenum, 1.75% manganese.
G: Minimum 0.5% nickel, 0.3% chromium, 0.2% molybdenum, 0.1% vanadium, 1% manganese (only one of these elements is required).

You won’t always find this nomenclature format on electrodes. The important part is the 4 or 5 central digits. For example:

The 6013 is medium strength, the "1" indicates it can be welded in any position, and the "3" indicates it has a soft arc and shallow penetration.

The 7018 has higher strength, the "1" indicates it can be welded in any position, and the "8" indicates it has a medium arc and moderate penetration.