What do the first two numbers of a welding electrode refer to?

The first two numbers of a welding electrode indeed refer to the tensile strength of the electrode material, measured in thousands of pounds per square inch (PSI). In the American Welding Society (AWS) classification system, this is reflected in the format of the electrode designation. For example, if an electrode's designation begins with "70," it indicates a tensile strength of 70,000 PSI. This is crucial for welders to select the appropriate electrode for the material being welded, ensuring that the resulting weld joint can withstand the necessary loads and stresses.

Understanding this aspect of the electrode designation helps welders make informed decisions about which electrodes to use, based on the required strength for the specific application and material type. Knowing the tensile strength assists in achieving successful, durable welds that meet structural safety and performance standards.