What are the differences between 7015 and 7018 welding rods?

The 7015 and 7018 welding rods are both types of electrodes used in shielded metal arc welding (SMAW), commonly known as stick welding. While they share some similarities, there are significant differences between these two types of welding rods. Here are the main differences:

The 7015 and 7018 welding rods belong to different American Welding Society (AWS) classifications. The 7015 welding rod is classified as an E7015 electrode, while the 7018 welding rod is classified as an E7018 electrode. The “E” in the classification indicates that these electrodes are intended for use in SMAW processes.

Tensile Strength:
One of the significant differences between the two welding rods is their tensile strength. The 7015 welding rod typically has a lower tensile strength compared to the 7018 welding rod. This means that welds made with the 7018 electrode are generally stronger and able to withstand higher loads and stresses.

Coating and Flux Composition:
The composition of the flux coating on the welding rods differs between the 7015 and 7018 electrodes. The 7015 welding rod has a high-cellulose potassium coating, which promotes deep penetration and is often used for welding thick metals in all positions. On the other hand, the 7018 welding rod has a low-hydrogen potassium coating, which helps reduce the risk of hydrogen-induced cracking and produces smooth, clean welds with good mechanical properties.

Welding Position:
While both welding rods are suitable for various welding positions, the 7015 electrode is particularly well-suited for all-position welding, including vertical and overhead positions. The deep penetration provided by the high-cellulose coating makes it useful for welding in challenging positions. The 7018 electrode is also versatile and can be used in all positions, but its low-hydrogen coating makes it especially suitable for critical applications and situations where hydrogen-induced cracking must be avoided.

Welding Applications:
Due to their different characteristics, the 7015 and 7018 welding rods are often used for different applications. The 7015 welding rod is commonly used for general fabrication, construction, and maintenance work, especially when welding thicker materials in various positions. The 7018 welding rod, with its superior strength and clean welds, is preferred for critical applications in industries such as construction, structural welding, pressure vessel fabrication, and heavy machinery manufacturing.

In summary, the key differences between the 7015 and 7018 welding rods lie in their tensile strength, flux coating composition, and suitability for specific welding applications. Welders should select the appropriate welding rod based on the requirements of their welding projects, considering factors such as material thickness, welding position, and the need for high-strength and high-quality welds.