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
system.

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)

E**1*    suitable for use in flat, horizontal, vertical (up) and overhead
E**2*    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-)    

E***0    Cellulose,Sodium            Deep        DC+        (It does not matter
E***1    Cellulose,Potassium            Deep        AC or DC+    which way around
E***2    Rutile,Sodium            Medium        AC or DC-        the electrode is with
E***3    Rutile,Potassium            Light        AC or DC+ or DC-    AC. With DC you can
E***4    Rutile,Iron Powder            Medium        AC or DC+ or DC-    choose between DC+
E***5    Low Hydrogen,Sodium        Medium        DC+        and DC- by plugging
E***6    Low Hydrogen,Potassium         Medium        AC or DC+    in your leads on the
E***7    Iron Powder,Iron Oxide        Medium        AC or DC-        welding set the opp
E***8    Low Hydrogen,Iron Powder        Medium        AC or DC+    way to how they are
E***9    Iron Oxide,Rutile,Potassium        Medium        AC or DC+ or DC-    marked)


ADDITIONAL REQUIREMENTS

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)

As with all my articles, I encourage you to do your own research into these subjects. These articles are my own point of view and are not intended to be advice in any way.





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