In ER 70/49 S-X, what does the '49' indicate?

The '49' in the designation ER 70/49 S-X indicates the minimum tensile strength of the filler metal, expressed in megapascals (MPa) divided by 10. This means that for ER 70/49, the filler metal has a minimum tensile strength of 490 MPa. Understanding this designation helps welders ensure they are selecting the appropriate filler metal for their specific applications, particularly when it comes to the strength requirements of the weld they are working on.

This specification is crucial for welders as it informs them of the strength capabilities of the filler material, allowing them to make informed decisions about whether a particular filler wire will meet the mechanical demands of the welded structure. In practice, knowing the tensile strength ensures that a welder can trust that the filler metal will perform adequately under the expected stresses.