Various conditions have to be considered during welding rod selection; the welding rod has to match the mechanical properties and chemical composition of the base metal, joint geometry, welding position, cost, and operational condition are also taken into consideration during the selection process. Although thousands of shielded metal arc welding (SMAW) electrodes exist, E6010, E6011, E6012, E6013, E7018, and E7024 are the most common electrodes in use.
Welding Rod Classifications Explained
AWS Standards classify carbon steel electrodes and low-alloy steel electrodes for shielded metal arc welding as follow:
The classification is based on an “E” prefix and four or five digits; each digit of the electrode designation is used to designate a specific property of the electrode. The following is the breakdown explanation of the digits and what each digit indicates for our common electrodes (E6010, E6011, E6012, E6013, E7018, and E7024):
E – Electrode
The First Two or Three Digits Indicate Tensile Strength X 1000 Psi
- E60xx – Tensile Strength of 60,000 psi
- E70xx – Tensile Strength of 70,000 psi
The Next Digit Refers To Welding Positions
- Exx1x Flat, Horizontal, Vertical (up), Overhead.
- Exx2x Flat, Horizontal.
- Exx3x Flat.
- Exx4x Flat, Horizontal, Overhead, Vertical (down).
The Last Digit Refers To the Usability of the Electrode (Electrode Coating, Current and Penetration)
- Exxx0 – Cellulose, Sodium – DC+ (Deep Penetration)
- Exxx1 – Cellulose, Potassium – AC/DC+ (Deep Penetration)
- Exxx2 – Rutile, Sodium – AC/DC- (Medium Penetration)
- Exxx3 – Rutile, Potassium – AC/DC+/DC- (Light Penetration)
- Exxx4 – Rutile, Iron Powder – AC/DC+/DC- (Medium Penetration)
- Exxx5 – Low Hydrogen, Sodium – DC+ (Medium Penetration)
- Exxx6 – Low Hydrogen, Potassium – AC/DC+ (Medium Penetration)
- Exxx7 – Iron Powder, Iron Oxide – AC/DC- (Medium Penetration)
- Exxx8 – Low Hydrogen, Iron Powder – AC/DC+ (Medium Penetration)
- Exxx9 – Iron Oxide, Rutile, Potassium– AC/DC+/DC- (Medium Penetration)
E 6010 Welding Electrode
E 6010 welding rod deposits molten metal which solidifies rapidly; therefore, the electrode is categorized as a fast freezing electrode. As the welds made tend to solidify fast, the electrode requires a skilled welder to produce a sound weld.
E 6010 electrode is a general-purpose electrode performs welding in all positions and efficiently in vertical-up and over-head positions; however, the electrode deposition rate is not high. The electrode arc is easy to control and produce flat weld bead with light slag formation.
E 6010 is used with DC current, the advantages of the E 6010 electrode that it produces deep penetration welding and can be used on painted, galvanized, and unclean surfaces.
E 6011 Welding Electrode
E 6011 electrode is also categorized as a fast freezing electrode. E 6011 electrode is a general-purpose electrode performs welding in all positions and efficiently in vertical-up and over-head positions; it is used mainly for sheet metal welding and low silicon deposit application. The electrode arc is easy to control and produces a flat weld bead with light slag formation.
E 6011 can be used with either AC or DC current. The electrode produces deep penetration welding and can be used on painted, galvanized, and unclean surfaces.
E 6012 Welding Electrode
E 6012 welding rod provides a fast freeze and fast fill characteristic; therefore, the electrode is categorized as a fill-freezing electrode.
E 6012 electrode is a general-purpose electrode that performs welding in all positions with medium deposition rate and medium penetration. The electrode provides a more forceful arc than E 6013 electrode.
E6012 electrode is used for sheet metal welding and other low current applications.
E 6013 Welding Electrode
E 6013 electrode is as E 6012 categorized as a fill-freezing electrode. The electrode is exactly like E 6012; however, it is easier to use and produce better appearance welds with minimal spatter.
E 7018 Welding Electrode
E 7018 is a low hydrogen electrode; the electrode is used with metal that tends to crack and thick sections. The electrode produces weld with excellent toughness and high ductility and reduces the risk of hydrogen embrittlement cracking when welding thick sections.
E 7018 produces excellent quality welds with steel requiring strength of 70,000 PSI and above; the electrode can be used with medium carbon, high carbon, and low-alloy steel.
One of the important points to consider for E 7018 is the storage and drying procedure; the electrode must remain in a low humidity environment to minimize the moisture in the electrode coating to reduce hydrogen level and avoid hydrogen cracking.
E 7024 Welding Electrode
E 7024 welding rod deposits metal rapidly; therefore, the electrode is categorized as a fast-fill electrode. The electrode is used for high-speed welding on a flat or horizontal surface. E 7024 electrode arc penetration is shallow; the weld bead is slightly convex and smooth with heavy slag formation. The electrode contains an iron powder, which increases the welding deposition rate.
E 6010 vs. 6011 Electrodes
Both E 6010 and E 6011 electrodes are general-purpose electrodes used on vertical-up and over-head welding; both electrodes produce deep penetration welding and can be used on painted, galvanized, and unclean surfaces.
The only difference that E 6010 rod is used with DC current, while E 6011 rod can be used with either AC or DC current.
E 6011 vs. 6013 Electrodes
E 6010 electrode can be used on painted, galvanized, and unclean surfaces, while E 6013 is used on clean or new sheet metal. Therefore, E 6010 is mostly found in maintenance and repair works, while E 6013 in new construction and fabrication.
E 6013 is the common electrode used for sheet metal welding; E 6010 and E 6011 replace E 6013 whenever the electrode is not available or whenever the welder prefers faster solidification.
E 6010 vs. 7018 Electrodes
Both electrodes have different tensile strength; E 6010 has a tensile strength value of 60,000 PSI, while E 7018 of 70,000 PSI.
E 6010 electrode can be used on painted, galvanized, and unclean surfaces, while E 7018 is used on clean or new sheet metal.
E6010 is used for deep penetration welding, while E 7018 is used for welding metal that tends to crack, producing quality welds with excellent toughness and high ductility.
Usually, both electrodes are used together in various industrial applications (pipelines welding, storage tanks, etc.). E 6010 is used for welding the joint root-pass for proper penetration, and E 7018 is used for the hot-pass, fill-up, and cap beads.
How to Choose a Welding Electrode?
Strength comes first; while selecting the proper electrode, the electrode’s mechanical properties and chemical composition have to match the base metal.
Join design and joint position is essential in the selection of the electrode. Power source availability is another factor to consider; some electrodes can be used with AC or DC current, while others can be used with either AC or DC.
When deep penetration is required for the root pass, E 6010 or E 6011 will be the selection for providing welding with sufficient penetration. However, when the joint is wide root openings or thin material, the option will be E 6013.
For welding thick sections, or for application where toughness and high ductility joint is demanded or where the development of embrittlement cracking is an issue, E 7018 is usually the proper selection.
When considering productivity for flat or horizontal joints, E7024 is the option that offers higher deposition rates.