Understanding Welding Rod Types and Their Numbering System

Comprehensive Guide to Welding Rod Types and Their Numbering Convention

Welding rods come in a variety of types, each engineered with specific properties to suit different welding applications. The alphanumeric numbers stamped on these rods serve as a standardized coding system that conveys critical information about their characteristics. These codes help welders select the appropriate rod based on tensile strength, welding position, flux composition, and additional design features.

Deciphering the Welding Rod Numbering System

The industry has developed a uniform four- or five-digit numbering scheme, primarily governed by the American Welding Society (AWS), to identify key properties of welding electrodes. This system ensures consistency and clarity across manufacturers and users, facilitating precise selection for various projects.

Understanding Each Digit in the Code

Let’s explore what each part of the number signifies, illustrated with practical examples for clarity.

First Two Digits: Tensile Strength

The initial two digits denote the maximum tensile strength of the weld metal, expressed in pounds per square inch (psi). To determine the rated strength, multiply these digits by 10,000. For instance, a rod marked 7018 indicates a tensile strength of 70,000 psi, suitable for high-stress applications.

• 60 = 60,000 psi
• 70 = 70,000 psi
• 80 = 80,000 psi
• 90 = 90,000 psi

Third Digit: Welding Position

This digit specifies the optimal welding positions for the rod, indicating whether it is suitable for flat, horizontal, vertical, overhead, or all-position welding. For example, a 7018 electrode with a third digit of 1 is versatile for all positions, while one with a 3 is restricted to flat welding only.

• 1 – Suitable for all positions
• 2 – Flat and horizontal only
• 3 – Flat position only
• 4 – Flat, horizontal, vertical down, and overhead

Fourth Digit: Flux Composition

The fourth digit describes the flux coating material, which influences arc stability, penetration depth, and suitability for specific metals. Different flux types like rutile, basic, and iron powder are used depending on the application. For example, a 6014 rod with a flux code of 4 employs rutile iron powder, offering medium penetration and compatible with DC and AC power sources.

Flux Composition and Penetration Chart

Additional Optional Designators

Some electrodes feature extra identifiers following the main four or five digits, indicating specific standards or properties. Common designators include:

• -1: Enhanced toughness and ductility, especially for E7018 and E7024 rods.
• H: Meets diffusible hydrogen testing standards, e.g., H4, H8, H16, specifying maximum hydrogen levels.
• R: Conforms to absorbed moisture standards, indicating low moisture content.
• M: Meets specific military or specialized requirements for high-performance applications.

Example of a Complete Electrode Code

Consider the electrode code E7018-1 H8. Here, ‘E’ denotes an electrode, ’70’ indicates 70,000 psi tensile strength, ‘1’ signifies suitability for all positions, ‘8’ refers to the flux type (rutile with low hydrogen properties), ‘-1’ indicates enhanced toughness, and ‘H8’ specifies a diffusible hydrogen limit of 8 mL/100g of weld metal.

Understanding Low Alloy Steel Suffixes for Chemical Composition

Electrodes sometimes include additional alphanumeric suffixes that specify the chemical makeup of the weld metal, especially for low-alloy steels. For example, codes like E7018-B2L give detailed insights into the alloying elements present.

In this system:

• A: Carbon-Molybdenum Steel
• B: Chromium-Molybdenum Steel
• C: Nickel Steel
• D: Manganese-Molybdenum Steel

For example, E7018-B2L indicates a chromium-molybdenum steel with specific low-carbon content, enhancing weld ductility and crack resistance. The suffixes, like -A1 or -B2, define the precise chemical range, aiding in selecting the right electrode for specific steel grades.

Special Considerations for Stainless Steel Electrodes

The marking system for stainless steel electrodes slightly differs. Instead of tensile strength, it references the American Iron and Steel (AIS) type designation. The code structure includes:

• E: Electrode for arc welding
• First three digits: AIS stainless steel type
• Last two digits: Indicates the welding position and current, similar to standard codes

For example, E308-16 signifies an electrode suitable for all positions, with type 308 stainless steel, and compatible with AC and DCEP power sources.

Final Thoughts

Mastering these coding conventions ensures high-quality welds and proper electrode selection. For most hobbyists and professional welders, understanding the first four digits often suffices to choose the right welding rod. Familiarity with these codes enhances precision and efficiency in welding projects.

Additional Resources:

• 14 Effective Stick Welding Tips & Tricks for Beginners
• Best All-Purpose Welding Rods for Versatile Use