Walking down the welding aisle at any supply store, you’ll see boxes labeled with mysterious codes like E6010, E7018, and E6013. These welding rod numbers aren’t random – they’re a standardized classification system that tells you everything about the electrode inside. Understanding this system is essential for choosing the right rod for your project.
Welding rod numbers (AWS classification) identify electrode properties for shielded metal arc welding (SMAW), commonly called stick welding. The first two digits indicate minimum tensile strength in thousands of PSI, the third digit shows welding position capability, and the last digits specify flux coating type and current characteristics. For example, an E7018 rod has 70,000 PSI tensile strength, works in all positions, and uses a low-hydrogen flux coating.
This guide breaks down the entire AWS numbering system digit by digit, so you can read any welding rod code like a pro.
What Is the AWS Classification System?
The American Welding Society (AWS) created the classification system we use today under the AWS A5.1 standard for carbon steel electrodes. This system provides a universal language that welders, engineers, and manufacturers all understand. When you pick up an E7018 from Lincoln Electric, Hobart, or Forney, you know exactly what you’re getting regardless of brand.
The prefix “E” simply stands for electrode – the technical term for what most welders call a rod or stick. Every welding rod follows this same basic format, making it easy to compare different electrodes at a glance.
SMAW (Shielded Metal Arc Welding) is the formal name for stick welding. The flux coating on these rods creates a protective gas cloud when you strike an arc, shielding your weld from atmospheric contamination that would weaken the metal. This self-shielding capability is what makes stick welding so versatile for field work, farm repairs, and construction sites.
How to Read Welding Rod Numbers? Step by Step
Reading a welding rod number is like decoding a secret message. Once you understand the pattern, you can instantly identify the rod’s capabilities. Let’s break down each position using the common E7018 electrode as our example.
Position 1-2: Tensile Strength (in thousands of PSI)
The first two digits (or sometimes three) represent the electrode’s minimum tensile strength – how much pulling force the welded metal can withstand before breaking. This number is expressed in thousands of pounds per square inch (PSI).
- 60 = 60,000 PSI tensile strength (mild steel applications)
- 70 = 70,000 PSI tensile strength (structural steel)
- 80 = 80,000 PSI tensile strength (higher strength applications)
Definition: Tensile strength measures the maximum stress a material can withstand while being stretched or pulled before breaking. Higher tensile strength means stronger welds capable of handling heavier loads.
For most general welding projects, 60-series rods (60,000 PSI) provide plenty of strength. Structural applications, building codes, and critical welds typically require 70-series rods (70,000 PSI). The difference in cost is minimal, but the 70-series offers significantly stronger welds.
Position 3: Welding Position Capability
The third digit tells you which welding positions you can use the electrode in. This is crucial because not all rods work in every position – some formulations simply won’t hold up against gravity when welding vertical or overhead.
- 1 = All positions (flat, horizontal, vertical, overhead)
- 2 = Flat and horizontal positions only (F, H)
- 4 = Flat, horizontal, overhead (F, H, OH) – rare
Position “1” electrodes are the most versatile and commonly used. They contain flux formulations that solidify quickly, preventing the molten metal from dripping out of the joint when welding overhead or vertical-up. This fast-freeze characteristic is what makes a rod work against gravity.
Position “2” rods have heavier flux coatings and higher deposition rates but can only be used in flat or horizontal positions. Attempting to weld vertical or overhead with a position “2” rod will result in the weld metal falling out of the joint.
Position 4-5: Flux Coating Type and Current
The last two digits (sometimes treated as a single digit in older systems) specify the flux coating composition and the type of welding current the rod requires. This is where things get technical, as these digits indicate the specific chemical formulation of the flux.
The flux coating does more than just shield the weld – it influences arc characteristics, penetration depth, slag removal ease, and weld appearance. Different flux formulations are optimized for different applications and power sources.
| Last Digit | Flux Type | Current Type | Penetration |
|---|---|---|---|
| 0 | Cellulosic (high cellulose) | DCEP (DC+) | Deep |
| 1 | Cellulosic (with potassium) | AC or DCEP | Deep |
| 3 | High titania (rutile) | AC, DCEN, or DCEP | Light |
| 4 | Iron powder, titania | AC, DCEN, or DCEP | Medium |
| 8 | Low-hydrogen | AC, DCEN, or DCEP | Medium |
Common Welding Rod Types Explained
Now that you understand the numbering system, let’s look at the most common welding rods you’ll encounter. Each has specific characteristics that make it ideal for certain applications.
E6010: The Deep Penetrator
E6010 is often called the “digging rod” because its aggressive arc digs into the workpiece. This deep penetration makes it ideal for root passes on pipe welds and welding through rust, paint, or mill scale.
- Strength: 60,000 PSI
- Position: All positions
- Flux: Cellulosic (high cellulose content)
- Current: DCEP (DC+) only – will not work on AC welders
- Penetration: Deep
- Best For: Pipe root passes, farm equipment repair, rusty/dirty metal, open root butt welds
The cellulosic flux coating creates a digging arc that burns through surface contaminants. This makes 6010 the go-to choice for field work where metal preparation isn’t perfect. However, the weld bead is somewhat rough and the slag is thick – this rod is about function, not cosmetics.
Important: E6010 requires DC electrode positive (reverse polarity). It will not run on AC-only welders. Many newer inverter welders also struggle with 6010 due to its unique arc characteristics.
E6011: The AC-Friendly Alternative
E6011 is essentially the AC-compatible version of E6010. It offers similar deep penetration and digging characteristics but runs on both AC and DC machines.
- Strength: 60,000 PSI
- Position: All positions
- Flux: Cellulosic with potassium (stabilizes AC arc)
- Current: AC or DCEP
- Penetration: Deep
- Best For: Same as 6010 but for AC welder owners, general repair work
The addition of potassium to the flux coating stabilizes the arc on alternating current. This makes 6011 the preferred deep-penetration rod for hobbyists with “buzz box” AC welders. If you have an AC-only machine, 6011 is your substitute for 6010.
E6013: The Beginner’s Rod
E6013 is widely considered the easiest welding rod to use. Its smooth, stable arc and forgiving nature make it perfect for beginners and thin sheet metal work.
- Strength: 60,000 PSI
- Position: All positions
- Flux: High titania (rutile)
- Current: AC, DCEN, or DCEP
- Penetration: Light to medium
- Best For: Beginners, sheet metal, cosmetic welds, general fabrication
Experienced welders often say 6013 “can’t make a bad-looking weld” – the arc is so smooth and stable that it produces pretty beads even with poor technique. The light penetration prevents burn-through on thin materials. This is the rod most welding schools start students on.
However, 6013’s light penetration can be a disadvantage on thicker materials or dirty surfaces. It’s not ideal for structural applications or heavy fabrication where deep penetration is needed.
E7018: The Structural Standard
E7018 is the industry standard for structural welding and code work. Its low-hydrogen flux coating produces high-quality, crack-resistant welds with excellent mechanical properties.
- Strength: 70,000 PSI
- Position: All positions
- Flux: Low-hydrogen with iron powder
- Current: AC, DCEN, or DCEP
- Penetration: Medium
- Best For: Structural steel, pressure vessels, heavy equipment, code-required welds
The “low-hydrogen” designation means the flux coating contains minimal moisture-absorbing compounds. This is critical because hydrogen in the weld can cause cracking – especially in high-strength steels or restrained joints. For this reason, 7018 is required for most structural and pressure vessel applications.
Storage warning: E7018 absorbs moisture from the air and must be kept in a rod oven at 250-300degF once the original package is opened. Wet 7018 will produce porosity and hydrogen cracking. If you’re buying 7018 for occasional use, consider hermetically sealed “low-hydrogen in a vacuum” containers.
E7024: The Production Rod
E7024 is designed for high deposition rates in flat and horizontal positions. Its heavy iron powder coating acts as a metal filler, allowing you to deposit more weld metal faster.
- Strength: 70,000 PSI
- Position: Flat and horizontal only
- Flux: High iron powder, titania
- Current: AC, DCEN, or DCEP
- Penetration: Medium
- Best For: Production welding, heavy plate, long flat welds
The massive iron powder content (up to 50% of the coating weight) makes 7024 deposit weld metal very quickly. This is ideal for long flat welds where you need to fill a joint efficiently. The weld bead is smooth and convex, with easy slag removal.
However, 7024’s heavy flux makes it impossible to use in vertical or overhead positions – the slag would simply drip out. Don’t attempt vertical-up welding with this rod.
Flux Coating Types Explained
The flux coating is what distinguishes one welding rod from another. Understanding flux types helps you predict how a rod will behave before you even strike an arc.
Cellulosic Flux (E6010, E6011)
Cellulosic flux contains high amounts of organic cellulose material. When the arc strikes, this cellulose combusts violently, creating a forceful digging arc and a gas shield that pushes contaminants away from the weld pool.
- Pros: Deep penetration, burns through rust/paint, excellent for root passes
- Cons: Heavy slag, rough weld appearance, produces significant smoke
- Best For: Pipe welding, field repairs, dirty metal
Rutile/Titania Flux (E6013, E7024)
Rutile flux is based on titanium dioxide (titania). It produces a smooth, stable arc with minimal spatter and creates a visually appealing weld bead. This is the most user-friendly flux type.
- Pros: Easy to use, smooth arc, pretty welds, low spatter
- Cons: Light penetration, not ideal for dirty metal
- Best For: Beginners, sheet metal, cosmetic applications
Low-Hydrogen Flux (E7018)
Low-hydrogen flux uses calcium carbonate and other compounds that minimize hydrogen content in the weld. This produces ductile, crack-resistant welds with excellent mechanical properties.
- Pros: Crack-resistant, high-quality welds, code-approved
- Cons: Requires dry storage, more difficult to restart hot rod
- Best For: Structural welding, high-strength steel, critical applications
Amperage Settings by Rod Size
Setting the correct amperage for your welding rod is crucial for good weld quality. Too low and the rod will stub, too high and you’ll burn through. Here are typical amperage ranges for common rod diameters:
| Rod Diameter | E6010/E6011 | E6013 | E7018 |
|---|---|---|---|
| 1/16 inch (1.6mm) | 20-40 amps | 25-45 amps | N/A |
| 5/64 inch (2.0mm) | 40-70 amps | 45-70 amps | 50-80 amps |
| 3/32 inch (2.4mm) | 60-90 amps | 65-100 amps | 75-110 amps |
| 1/8 inch (3.2mm) | 80-115 amps | 85-140 amps | 100-130 amps |
| 5/32 inch (4.0mm) | 110-160 amps | 130-170 amps | 140-180 amps |
Start in the middle of the recommended range and adjust based on your arc characteristics. The sound of a properly set arc is often described as “bacon frying” – a steady crackling sound. If the rod stubs into the workpiece, increase amperage. If the arc sounds harsh and the metal melts too fast, decrease amperage.
Rod Diameter vs Material Thickness
Choosing the right rod diameter for your material thickness prevents burn-through on thin metal and ensures proper penetration on thick plate.
| Material Thickness | Recommended Rod Diameter |
|---|---|
| 1/16 inch (1.6mm) | 1/16 inch rod |
| 1/8 inch (3.2mm) | 3/32 inch rod |
| 3/16 inch (4.8mm) | 1/8 inch rod |
| 1/4 inch (6.4mm) | 1/8 inch or 5/32 inch rod |
| 3/8 inch (9.5mm) and thicker | 5/32 inch or 3/16 inch rod |
Choosing the Right Welding Rod for Your Project
Based on common applications from welding forums and practical experience, here’s a quick reference guide:
- Sheet metal and thin gauge: E6013 in 3/32″ diameter – light penetration prevents burn-through
- Farm equipment repair (rusty/dirty): E6010 (DC) or E6011 (AC) – digs through contaminants
- Structural welding: E7018 – code-required, crack-resistant welds
- General DIY and hobby: E6013 – forgiving and easy to use
- Pipe welding root pass: E6010 – deep penetration for open root
- Long flat production welds: E7024 – high deposition rate
- Vertical and overhead: E6011, E6013, or E7018 – all position rods with fast-freeze slag
Frequently Asked Questions
Is 6013 or 7018 stronger?
E7018 is stronger than 6013. E7018 has a tensile strength of 70,000 PSI compared to E6013’s 60,000 PSI. The 7018 also produces more ductile, crack-resistant welds due to its low-hydrogen flux coating, making it the better choice for structural applications.
What do the numbers on welding rods mean?
Welding rod numbers indicate tensile strength, welding position, and flux coating type. The first two digits show minimum tensile strength in thousands of PSI (60 = 60,000 PSI). The third digit indicates position capability (1 = all positions, 2 = flat/horizontal only). The last digits specify flux coating composition and current type.
What does 6013 welding rod mean?
E6013 is an all-position electrode with 60,000 PSI tensile strength and a high-titania flux coating. The ’60’ indicates 60,000 PSI strength, ‘1’ means all positions, and ’13’ specifies a rutile flux that runs smoothly on AC or DC. It’s known as the beginner’s rod due to its forgiving arc and light penetration.
What is 1G, 2G, 3G, 4G, 5G, 6G welding?
These are welding position certification codes. 1G = flat groove weld, 2G = horizontal groove weld, 3G = vertical groove weld, 4G = overhead groove weld, 5G = horizontal fixed pipe weld, and 6G = 45-degree inclined pipe weld (the most difficult). The ‘G’ stands for groove weld, while ‘F’ would indicate fillet weld positions.
