Final answer:
For welding low-alloy steel, the most appropriate electrode from the list provided is E8018-B2, as it is specifically designed for welding 1.25% Chromium, 0.5% Molybdenum steel, which is a type of low-alloy steel.
Step-by-step explanation:
Electrodes are an essential component of welding, and different types of electrodes are used for welding various materials. For welding low-alloy steels, a common practice is to use a low hydrogen electrode that matches the tensile strength of the base metal being welded. Among the options provided:
- E6010 is a high cellulose sodium electrode used for welding mild steels.
- E7018 is a low-hydrogen iron powder type electrode that produces tough welds and is often used for structural steel welding.
- E8018-B2 is designed for welding 1.25% Chromium, 0.5% Molybdenum steel, which is a common grade in low-alloy steel.
- E9018-G is used for welding high strength, low-alloy steels.
Therefore, the correct electrode for welding low-alloy steel from the given options would be E8018-B2, based on the requirement that it is an appropriate match for the type of steel being welded.