The Classification of Welding Electrodes
“What do all the numbers refer to that are printed on electrodes?”
The Layman might be puzzled by the array of letters and numbers that are printed on the end of welding electrodes.
They are there to classify the type of electrode. Most of the welding rods will use the AWS system which stands for
“American Welding Society”.
There are around 4 different types of classification in use today but most manufacturers tend to stick to the AWS
It makes sense that if you are about to weld 2 pieces of metal together then you will need to know that you are
using the correct welding rod for the job. The wrong one could end in the joint falling apart.
The classification system works like this:
A typical number printed on each rod might be “E7018”
The breakdown of these figures goes like this:
E indicates that it’s an electrode
70 indicates the strength of the welded joint and this is measured in thousands of pounds per square inch
1 indicates the welding position that the rod can be used in (see “Welding Position” below for details)
8 indicates the type of flux coating,the amount of penetration and the type of current that can be used
(see “Classification Table” below for details)
WELDING STRENGTH TABLE (The E70** bit)
Class Minimum Tensile Strength Minimum Yield Strength
E 60 62,000 psi 50,000 psi E 70 70,000 psi 57,000 psi
E 80 80,000 psi 67,000 psi E 90 90,000 psi 77,000 psi
E100 100,000 psi 87,000 psi E110 110,000 psi 95,000 psi
E120** 120,000 psi 107,000 psi
It might not be obvious but it is vitally important to match the correct strength of electrode to the type of metal
being welded together. If the rod is too weak the the joint could fail under load. Similary, too strong and there is
a chance that the joint will fail. There are numerous welding table books available from each of the manufacturers
giving all the data for each type of rod that they produce.
WELDING POSITION TABLE (The E*1 bit)
E1 suitable for use in flat, horizontal, vertical (up) and overhead E2 suitable only for use in the flat and horizontal
E*4 suitable for use in flat, horizontal,overhead and vertical (down)
The different welding positions are important as the weld pool behaves very differently in a vertical (up) position
compared to a vertical (down) position. Similarly, the same applies to overhead welding.The manufacturer will
have designed a very different rod to do the specific job so make sure you have the correct one.
CLASSIFICATION TABLE This is usually the last digit in the string. ( The E***8 bit)
Class Electrode coating(FLUX) Penetration Current type (eg, AC, DC+, DC-)
E0 Cellulose,Sodium Deep DC+ (It does not matter E1 Cellulose,Potassium Deep AC or DC+ which way around
E2 Rutile,Sodium Medium AC or DC- the electrode is with E3 Rutile,Potassium Light AC or DC+ or DC- AC. With DC you can
E4 Rutile,Iron Powder Medium AC or DC+ or DC- choose between DC+ E5 Low Hydrogen,Sodium Medium DC+ and DC- by plugging
E6 Low Hydrogen,Potassium Medium AC or DC+ in your leads on the E7 Iron Powder,Iron Oxide Medium AC or DC- welding set the opp
E8 Low Hydrogen,Iron Powder Medium AC or DC+ way to how they are E9 Iron Oxide,Rutile,Potassium Medium AC or DC+ or DC- marked)
Sometimes there is an extra bit on the end. Eg: E7018 (-1). These are laid out below.
Suffix Additional Requirement
-1 Increased toughness (impact strength) for E7018 rods. Also increased ductility in E7024 rods
-M Meets most Military requirements
-X Indicates that electrode is a low alloy type (There is a whole table of these alloys which I won’t
go into now)