In the filler metal designation ER 70/49 S-X, what does the 'S' signify?

In the filler metal designation ER 70/49 S-X, the 'S' signifies that the filler metal is solid. This is important because it differentiates the type of filler metal based on form. In welding terminology, 'S' specifically indicates that the filler material is not designed to be used in a cored form or as a flux-cored wire, which would be denoted differently.

Understanding this designation enables welders and engineers to select the appropriate filler metal based on the welding process and the specifications for strength and chemical composition. Solid filler metals are commonly used in various applications, providing reliable weld integrity in different types of steel welding, including structural applications and general fabrication.

The other choices relate to other characteristics of filler metals but do not pertain specifically to the meaning of 'S' in the designation. This highlights the importance of being familiar with filler metal classifications and designations in understanding their applications in welding processes.