What designation is used for welding electrodes that must be baked before use on certain steels?

The correct designation for welding electrodes that must be baked before use on certain steels is E7018. This type of electrode is specifically designed to be used in welding low-alloy steels where its low hydrogen content is crucial to preventing weld fissures and ensuring integrity in the weld metal.

The reason E7018 electrodes require pre-baking is that they are sensitive to moisture. If they absorb moisture, hydrogen can be introduced into the weld, leading to cracking and other defects, especially in high-strength steels. Pre-baking effectively removes this moisture, thereby reducing the risk of hydrogen-induced cracking during the welding process.

While other options like E100XX, E8018, and E308L denote different classifications of electrodes, they do not carry the same requirements regarding pre-baking. E100XX refers to a series of electrodes designed for specific applications, E8018 is also a low-hydrogen electrode but may have different guidelines depending on the type of steel and situation, and E308L is a stainless steel electrode that typically does not have the same moisture sensitivity issues as E7018.