The stick welding electrodes design offers the simplicity, portability, and versatility of the stick welding (SMAW) process. However, there are many different welding electrodes.
After reading this article, you will learn about the characteristics of stick welding rods, their categories, and their uses.
Table of Contents
- What are stick welding electrodes?
- Stick welding electrode categories by flux composition
- What kinds of stick welding electrodes are there?
- Stick welding electrode specifications by AWS
- Stick welding electrode categories by solidification rate
- Handling and storage of stick electrodes
- The amperage of stick electrodes
What are stick welding electrodes?
Stick welding electrodes are consumable composite short rods with a core of solid metal wire and a covering of flux material. The wire acts as both the electrode and the filler metal for the process. The flux material provides the shielding gases and the shielding slag.
Stick welding electrodes (or rods) come with lengths that range from 9″ (23cm) to 18″ (46cm). Their wire thickness range from 1/16″ (1.6mm) to 3/8″ (9.5mm). The wire’s diameter increments are 1/32″ (0.8mm).
One edge of the electrode is without covering to fit into the electrode holder and conduct the current. The other one has an uncovered tip to start the electric arc.
The core wire composition and the flux covering define the arc’s characteristics and the weld metal’s mechanical and metallurgical properties.
For example, a low-alloy electrode may have a low-carbon steel wire and the additional alloying elements in the flux. When the rod melts, they combine, and the metal in the joint has the desired composition.
For most welding jobs, the rod’s deposited metal is the same as the base metal (or workpiece). However, there are rods that weld workpieces of different compositions. For example, nickel rods that weld cast iron.
If the rod is not meant for welding but, for instance, hardfacing, then the deposited metal can be very different from the base metal.
What is the purpose of the wire in a stick rod?
The first purpose of the stick rod’s internal wire is to act as an electrode and transfer electrical current.
The wire is called an electrode because it makes contact with the nonmetallic conductor of the welding circuit. This nonmetallic conductor is the plasma gas that the arc (electrical current) passes through.
The other purpose of the rod’s wire is that of filler metal. It melts and provides most of the metal that fills the joint.
The wire also contains a small amount of deoxidizing elements such as silicon and manganese that clean the molten metal from impurities.
What is the purpose of the flux covering on a stick rod?
The electrode’s flux primary purpose is to provide the shielding gases and the cleaning slag material. The flux is complex and consists of minerals, organic materials, deoxidizers, arc stabilizers, metal and alloy powders, and binders.
It is the flux covering that makes stick welding so simple, portable, and versatile. So there is no need for external equipment such as gas cylinders, flux or alloy powders, etc.
The stick welding electrode’s flux covering helps the stick welding process in many ways.
1. Produces shielding gases
A big part of the flux breaks down from the heat and creates shielding gases, mostly carbon dioxide (CO2). Shielding gases isolate the plasma gas, the electrode tip, and the puddle from the atmosphere.
Shielding gases prevent elements such as oxygen and nitrogen from reacting with the molten metals. If they react, they will cause defects, such as porosity or slag inclusions, resulting in weak welds.
If welding defects appear, you should remove the weld metal and weld again.
2. Cleans the puddle from impurities
In the puddle, there are impurities from both the rod and the workpiece. Things get worse if the workpiece was not clean down to the bare metal. Even low amounts of mill scale or rust can degrade a weld.
High amounts of deoxidizers and other chemicals in the flux melt from the heat and travel as slag droplets through the arc into the puddle.
In the puddle, slag reacts with impurities and traps them. As the puddle cools, the pressure differences push the slag to the surface.
3. Provides elements to stabilize the arc
Other chemicals in the flux improve arc stability. For example, when welding with alternating current (AC), the arc tends to extinguish between the current cycles. Flux that contains potassium creates a plasma gas that lasts longer and sustains the arc.
4. Concentrates the plasma jet or arc force
At the end of the rod’s tip, the wire melts within the flux for a very short distance. This leaves the flux around intact in the form of a crater. Within this crater, the energy density is much higher than outside of it.
These pressure differences propel the plasma gas forward in a straight axial direction. A strong plasma jet or arc force helps to weld out of position and offers deeper penetration.
5. Protects the bead’s surface
The slag that concentrates on top of the bead keeps protecting it from the air until the temperature drops low enough to avoid oxidation.
6. Improves the appearance of the bead
The slag allows the bead to cool at lower rates. Slower cooling results in a better-looking and smoother bead. The thicker the slag is, the higher the insulation and the better the appearance.
7. Stabilizes the weld metal in out of position welding
The slag also helps when welding out of position. It holds the molten metal in place until it solidifies.
8. Increases the productivity
Some coatings contain 10-50% iron powder that acts as additional filler metal. This addition increases the metal deposition rate and the traveling speed of the rod. As a result, the low productivity rates of the stick welding process improve.
9. Provides alloying elements to the weld metal
The coating may also contain various alloying elements to maintain or alter the weldmeatl composition. For example, molybdenum, chromium, nickel, and vanadium.
What happens to the slag on the bead?
After finishing each bead, the slag has served its purpose and is not needed anymore. You usually remove it right away to inspect the bead.
If you have a multipass weld, you must remove the slag after each bead. Otherwise, it will get trapped in the joint as slag inclusions. If that happens, you must remove them and weld again.
Why must the flux be symmetrical around the wire?
When welding, the wire is melting for a short distance inside the flux. The flux around the melted wire concentrates and directs the arc. For this, the flux must be concentric, perfectly even, and in excellent condition without cracks.
If the flux is not symmetrical, either from factory error or incorrect handling, the arc will not be stable. It can lose focus, become uneven, and bend to the weaker side.
The results will be reduced gas shielding, an inconsistent bead with swallow penetration, slag inclusions, porosity, etc.
Stick welding electrode categories by flux composition
Depending on the dominant chemical material in their flux, electrodes show different welding behavior and divide into three categories:
1. Rutile rods
The largest part of these rods’ flux consists of a mineral called rutile (or titania). Popular rutile rods are the E6013, E7014, and E7024.
- Rutile rods are the easiest to weld with. Their arc starts and restarts easier and is very stable.
- The stability of the arc also produces fewer spatter.
- Rutile rods create a bead that is good-looking with a slag covering that is easy to clean.
- The arc of rutile rods has light penetration. This is useful when welding thin metals.
- Rutile produces fewer fumes compared to the other flux types.
- Every stick welding machine can burn rutile rods if their amperage range allows it.
- The main disadvantage of rutile rods is that they offer poor puddle visibility. In the puddle, the slag and the molten metal don’t distinguish very well from each other. So you can’t control the puddle as well as with a basic rod.
- Rutile rods require a somewhat clean joint and cannot tolerate high amounts of dirt.
- They also contain a small amount of organic matter. This releases hydrogen which makes these rods not suitable for projects with cold cracking risk.
- Slag inclusions are more often when using rutile rods, especially when welding vertical down.
2. Cellulosic rods
These rods have a flux covering that contains a high amount of cellulose, around 30%. Cellulose is an organic matter that comes from plant fibers. Popular cellulosic rods are the E6010 and the E6011.
- Cellulose has a high amount of moisture. When it burns, it releases a lot of hydrogen. This gas helps to create a powerful arc that gives intense penetration.
- The gasses from cellulose rods are “explosive.” This offers excellent coverage and protection for the molten metal.
- This flux type creates low amounts of slag. As a result, the weld metal freezes. Fast freezing makes these rods excellent for all position welding.
- The previous advantages make cellulose rods ideal for welding open root pipe joints.
- Their deep penetration makes them the best rods to weld on dirty workpieces.
- The high amount of moisture in the cellulosic flux gives a significant disadvantage. It increases the risk of cold cracking. However, welders cope with this by controlling the heat until the hydrogen can escape from the weld.
- Their aggressive arc makes cellulose rods hard to weld with.
- The forceful gasses from cellulose result in a more concave bead and create more sparks, spatter, and fumes.
- The slag on the bead is thin, but it needs a good brushing to clean it.
- They require a high Open Circuit Voltage (OCV) to start the arc. Furthermore, most inverter welding machines cannot run E6010 rods.
3. Basic or Low-Hydrogen rods
Basic rods have a flux that contains 30% limestone mineral and 20% of fluorite mineral. Popular basic electrodes are the E7018, E7016, and E7028. This flux type has two differences from the previous types.
Why are they called “basic”?
They are called basic rods because they contain materials with an alkaline (basic) behavior. They don’t contain any cellulose or rutile materials that are acidic. As a result, basic rods create stronger joints.
With the collaboration of other deoxidizers in the flux, such as titanium and silicon, the alkaline materials trap and remove most of the weld metal’s oxygen.
If oxygen stays in the weld metal, it will form oxides trapped in the weld. These inclusions will make the weld weaker.
Why are they called “low-hydrogen”?
They are called low-hydrogen rods because they don’t contain materials with high levels of hydrogen. Furthermore, they are baked at high temperatures without going bad and lose any residual hydrogen they have.
Basic rods weld hydrogen-sensitive hardened steel or steel that might harden as it cools down. This is a special advantage of basic rods.
If hydrogen stays in welds of hardened metals and they take stress, they will crack. That can happen even after a long time.
The previous flux types, both rutile and even more cellulose, have moisture in their flux and release high amounts of hydrogen in the weld.
- Rods with basic flux and low hydrogen content offer crack-resistant welds. They are heavy-duty professional rods made for critical welds, for example, welding bridges or buildings.
- The final weld metal of a basic rod is very clean with low amounts of impurities. It is tougher, ductile (elastic), and has higher corrosion resistance.
- With basic rods, you have excellent puddle visibility. The molten metal and the molten slag stay separate.
- Finally, these rods offer a good-looking bead and an easy to remove slag.
- The gasses of basic flux cannot cover a big area. For example, the backside of open root joins.
- Basic rods work best with long continuous beads. Frequent stops and restarts have a high risk of porosity.
- To retain their low-hydrogen characteristics, basic rods need complete air-tight packaging, strict time periods to weld, and special storage.
- These rods require a high Open Circuit Voltage (OCV) of 70V to start the arc. Affordable welding machines don’t offer that.
- Even with high OCV, basic rods are harder to strike the arc than other rods.
- Basic rods cannot give great results with a dirty joint. They need a clean one.
- Because of the fluorite content, the fumes of basic rods are more harmful than the other types.
There is another welding electrode category called acidic, but it is abandoned. Acidic electrodes contain large amounts of iron oxides in their flux, which resulted in weaker weld metal. Acidic electrodes are the EXX20, EXX22, and EXX27.
A table comparing welding rod flux types
What kinds of stick welding electrodes are there?
There is a crazy number of stick welding electrodes, perhaps more than 300. There the rods for most metals but not all of them.
- The most common rods weld ferrous workpieces, for example, mild steel, low alloy steels, cast iron, and stainless steel.
- There are rods for non-ferrous workpieces, for example, aluminum, nickel, and copper alloys.
- Rod variations made for welding heavy-duty fabrications that will endure extremely low or high temperatures, pressures, corrosion, and so on.
- Special rods for underwater welding and demanding military applications.
- Rods to weld dissimilar metals, for example, stainless steel to tool steel.
- Furthermore, there are rods not for welding but for other special uses, for example, hardfacing, cladding, cutting, and gauging.
- There are no rods for metals with low melting points, such as lead, because the arc’s heat is too much for them.
- Also, there are no rods for reactive metals such as titanium, zirconium, tantalum, and niobium. That’s because the shielding gases of SMAW are not true inert gases that these metals require.
Stick welding electrode specifications by AWS
The American Welding Society (AWS) classifies stick welding electrodes according to their chemical composition and or mechanical properties.
For the most common ferrous metals, the classification includes the welding positions and the current type they support. Each electrode has a designation printed on them.
These rods are the most common ones and are used for low-carbon steel.
Their designation starts with the prefix letter E, indicating a covered electrode and not a simple filler metal.
The first two or three digits refer to the minimum tensile strength of the filler metal. Tensile strength is the force a material can withstand when pulled apart before it breaks. The unit of measurement is kilo pounds per square inch (ksi).
Low-carbon steel stick rods have a tensile strength of at least 60ksi (60,000psi) or at least 70ksi. In reality, they have at least 10% higher tensile strength.
The second from last digit refers to the welding positions you can weld with the rod.
- EXX1X is for all welding positions flat, horizontal, vertical, and overhead. However, many rods have difficulty welding in the vertical down position.
- EXX2X is for the flat position and horizontal fillet welds only.
- EXX3X is for the flat position only but is obsolete.
- EXX4X indicates excellent welding results in the vertical down position.
The last digit ranges from 0 to 8 and, in combination with the previous one, indicates a lot about the flux composition, the rod’s penetration, and the current types it supports.
|EXX11||Cellulose-Potassium||AC & DCEP||DEEP|
|EXX12||Rutile-Sodium||AC & DCEN||MEDIUM|
|EXX13||Rutile-Potassium||AC & DC||LIGHT|
|EXX14||Rutile-Iron powder||AC & DC||LIGHT|
|EXX16||Low Hydrogen-Potassium||AC & DCEP||MEDIUM|
|EXX18||Low Hydrogen-Iron powder||AC & DCEP||MEDIUM|
|EXX20||Iron Oxide-Sodium||AC & DC||MEDIUM|
|EXX24||Rutile-High iron powder||AC & DC||LIGHT|
|EXX27||High iron Oxide-Iron powder||AC & DC||MEDIUM|
|EXX28||Low Hydrogen-High iron powder||AC & DCEP||MEDIUM|
|EXX48||Low Hydrogen-Iron powder||AC & DCEP||MEDIUM|
For example, E7024.
- E – it is a stick welding electrode.
- 70 – it has at least 70ksi tensile strength.
- 2 – it welds in the flat position and the horizontal position, but only fillet welds.
- 4 – it welds with all current types.
- 24 – the flux covering has high amounts of rutile mineral and high amounts of iron powder.
Low hydrogen rods such as the EXXX5, EXXX6, and EXXX8 may have suffixes that indicate their diffusible hydrogen content. Furthermore, the suffix may indicate any moisture resistance of the rod’s coating.
- Hz. The letter z indicates the maximum diffusible hydrogen limit in milliliters per 100 grams of weld metal.
- 16mL/100g of weld metal
- 8mL/100g of weld metal
- 4mL/100g of weld metal
- R meets the absorbed moisture test requirements, offering higher resistance to moisture absorption when exposed to the environment (at 80°F (27°C) and 80% relative humidity).
For example, E7018-H4R.
- H4 means it gives a maximum of 4ml of diffusible hydrogen per 100gr of weld metal.
- R means that the flux is resistant to moisture absorption for 9 hours instead of 4 hours typical basic rods have.
These rods are low-hydrogen rods but with added alloying elements in their flux. These alloying elements offer welds with higher strength, heat, cold or corrosion resistance, and so on. Low-alloy rods have a tensile strength range of 70ksi up to 120ksi.
Their designations are the same but with suffixes that refer to the added alloying elements, for example, E10018-A1.
A list of low-alloyed suffixes and their alloying elements
- A1 has 0.5% Molybdenum (Mo) that offers high strength at high temperatures.
- B1 has 0.5% Mo and 0.5% Chromium (Cr) that adds corrosion resistance.
- B2 has 1.25% Cr and 0.5% Mo.
- B3 has 2.25% Cr and 1% Mo.
- B5 has 0.5% Cr and 1% Mo.
- C1 has 2.5% Nickel (Ni) that offers high toughness at cold temperatures.
- C2 has 3.5% Ni .
- C3 has 1% Ni, 0.15% Cr, and 0.35% Mo.
- D1 has 0.25% Mo and 1.75% Manganese (Mn) which adds higher strength and cracking resistance.
- D2 has 0.45% Mo and 1.75% Mn.
Other low-alloy suffixes
- G can have 0.5% Ni, 0.3% Cr, 0.2% Mo,1% Mn, and 0.1% Vanadium (V). Only one of these has to meet the requirement. Manufacturers make rods with a G suffix for specific jobs that other electrodes cannot cover. Rods with this suffix are always different.
- L attaches to previous suffixes and indicates lower carbon, for instance, -B2L.
- M indicates special military requirements. In most cases, it is similar to E7018-1H4R but better.
- A numerical suffix –1 may follow the earlier prefixes and indicate improved toughness and ductility (elasticity) at very low temperatures.
An example of a low-alloy rod is E10018-A1 used for carbon-molybdenum low-alloy steels. The A1 suffix means the flux covering has an added 0.5% of molybdenum for higher strength at high temperatures.
Stainless steel stick rods start with the prefix E indicating a covered electrode. After that comes a three-digit indication of the weld metal’s chemical composition.
Next, there might be a letter that indicates changes to the chemical composition. For example, L indicates a lower carbon amount, H indicates higher carbon.
As a suffix, there are two digits that indicate the flux composition, the welding positions, and the current type.
|EXXX-16||Rutile||AC & DCEP||Flat and |
|AC & DCEP||Flat and|
For example, E308L-15:
- 308 – the weld metal is the AISI 308 stainless steel low-carbon grade with 20% chrome, and 10% nickel.
- L – the weld metal contains lower carbon (0.03%) than the typical 308 (0.08%) grade.
- 15 – it has a basic flux covering. The rod can weld at all positions with DCEP (DC+) current type.
E-XX(XX)-CI-X. E indicates a covered electrode. After that, letters indicate the primary elements of the rod.
The first suffix indicates that these are Cast Iron (CI) rods and not typical nickel rods. The two exceptions that don’t follow this are ENiCu-A and ENiCu-B.
The second suffix indicates the subclassification of the rod. This happens when there are different compositional limits of alloy elements. Two letters are used for this A and B.
For example, ENiFe-CI-A:
- Ni – it has a high percentage of nickel (55%).
- Fe – it has a high percentage of iron (45%).
- CI – the rod is a cast iron rod and not a nickel one.
- A – the rod has a higher percentage of aluminum than normal.
E-XXXX. E indicates a covered electrode. The next four numbers indicate the composition of the core wire, according to the Aluminum Association classification of aluminum alloys.
For example, E4043. 4043 indicates an AL4043 aluminum alloy and has high silicon amounts as the primary alloying element.
ECuXX-XX. E indicates a covered electrode. Cu that it has a copper alloy core wire. After that, the next two letters indicate the primary alloying element.
The suffix indicates the subclassification of the rod. This happens when there are different compositional limits of alloy elements. Three letters are used for this A, B, and C. Finally, a number may indicate further subdivisions.
For example, ECuAl-A2:
- Cu – it is a rod for copper alloys.
- Al – aluminum is the primary alloying element.
- A2 – it has an additional 1.50% of iron.
ENiXXXX-X. E indicates a covered electrode. Ni that it is a nickel rod. Next, there may be one or two atomic symbols of the primary alloying elements. The suffix indicates subdivisions of the rod according to changes in alloying element amounts.
For example, ENiCrFe-2:
- Ni – it is a nickel rod.
- Cr – chromium is the primary alloying element.
- Fe – iron is the second alloying element.
- 2 – it has added molybdenum.
Stick welding electrode categories by solidification rate
Depending on the amount of slag material and the iron content each rod has, it solidifies at different rates. According to the solidification rate, rods divide into three categories.
1. Fast freeze
Fast freeze rods have a thin coating with cellulose material. The largest part of the coating breaks down to form shielding gasses. Only a small part turns to slag. For this reason, the weld metal solidifies very fast.
These characteristics make them true all welding position electrodes, including vertical down. Their bead has characteristic ripples from their fast solidification.
The most common fast freeze rods are the E6010 and the E6011.
2. Fast fill
Fast fill rods may have rutile or basic flux covering. The big difference with this type is that they contain high amounts of iron powder in their flux, at least 50%. The flux of these rods is by far the thickest.
Fast-fill rods are the most productive ones. They melt very fast and deposit a lot of metal in the joint at high traveling speeds.
Because they take a long time to solidify and wet very well, they give a prettier bead. These rods are also easy to weld with since they only need a straight stringer pass.
The negative is that they are suitable only for the flat position and for horizontal fillet welds. Also, they require a much higher amperage for the same diameter that some welding machines may not cover. Fast-fill rods don’t come with thin diameters and short lengths.
Common fast-fill rods are the E7024 and the E7028.
Fill-freeze rods have a freezing rate between the two previous types. Their flux can be rutile or basic. They are the most common rods and can handle a wide range of welding jobs.
They contain a small amount of iron powder 10-40% to increase their productivity.
These rods can weld in all positions, but many cannot give acceptable results in the vertical down position.
Popular fill-freeze rods are the E6012, E6013, E7014, E7016, and E7018.
Handling and storage of stick electrodes
The wire of the stick welding rod can rust from exposure to moisture. Rust will act as resistance to the current resulting in a defective arc.
The flux material of rods is brittle. With poor handling, it can crack or even chip off. Damaged flux will cause low shielding gas coverage problems and make the rod stick to the base metal.
The flux material of stick rods is hygroscopic. This meant that the flux absorbs and holds moisture from the environment. Moisture will cause defects, for example, porosity or even cold cracking on hardened steels.
If the rods are exposed to bad conditions, their flux may show signs of discolorization or brittleness. If this happens, then you cannot recondition them. You must discard them and get new ones.
For these reasons, you must store and handle each type of rod with care to avoid making faulty welds. And separate from each other to prevent moisture transfer between them.
With basic covering
Basic or low-hydrogen rods, as mentioned earlier, contain a low amount of hydrogen and are highly sensitive to moisture.
After taking them out of their air-tight packaging, you must use them within a limited time to keep their low-hydrogen characteristics.
Depending on the rod’s moisture resistance and the environment’s moisture levels, this limited period might be from 30 minutes to 9 hours. If the rod has moisture resistance, it is mentioned in the rod’s designation with the suffix R.
To store basic rods for a longer time, you must put them in welding ovens. If hydrogen from the air contaminates basic rods, you must recondition them with these ovens.
If you don’t need basic rods with low hydrogen characteristics, then moisture protection is not that strict.
With rutile covering
Rutile rods are somewhat sensitive to moisture. You must keep them in air-tight packages and store them in a dry environment at room temperature.
If they absorbed a high amount of moisture, you could use a welding oven to recondition them.
With cellulosic covering
Cellulosic rods contain a high amount of moisture in their flux, around 6%, and they need it to work well.
It would be best if you kept them at room temperature and away from places that are too hot and dry, for instance, close to ovens or under direct sunlight.
While they have no problem with the atmosphere’s moisture, they will go bad if they contact water.
There is a more detailed Weldpundit article about how to store stick electrodes with home tips.
The amperage of stick electrodes
All electrodes come with a specific amperage range. This range depends on the wire diameter, the flux type, and if there is additional iron powder in the covering. You must always stay within this range to have the best welding results and avoid defects or even injuries.
What happens if the amperage is too high?
The electrical resistance of the wire’s diameter sets the upper limit of amperage the rod can handle.
If you set the amperage higher than the rod’s limit, the wire’s resistance will overheat it. The wire will melt too fast, and you will observe changes in the arc behavior as you weld, especially when you reach the end of the rod. After a point, the rod will turn red.
Furthermore, too much heat will prematurely overheat the remaining flux material. As a result, it will lose its beneficial properties. And after a point, it will break apart.
What happens if the amperage is too low?
If you set the amperage lower than the rod’s limit, you will find it hard even to start the arc. It will only spark and give nothing else than stuck rods and a scarred workpiece.
Here is a table with the most common electrodes and their amperage range. Every manufacturer gives a different amperage range for their rods. Always read the packaging to know precisely the amperage range.
Most tables and charts show the amperage for DC+. AC needs a few amperes more.
Stick welding gains its versatility from the flux around the electrode, which combines many functionalities. Most importantly, the shielding gases, cleaning slag, arc stability, and weld metal composition.
The most common stick welding electrodes are those for mild steel. After that, for low-alloys, cast iron, and stainless steel.
According to the dominant chemical elements, the flux covering divides into three types: cellulose, rutile, and basic.
Electrodes are also divided into three categories fast-fill, fill-freeze, and fast-fill, depending on the time they need to solidify.
Basic rods need special storage to maintain their low hydrogen content. In contrast, cellulosic rods need protection from dryness.
Furthermore, you must make sure you are using each rod within its amperage range.
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