To your Question , RICH
"the American Welding Society (AWS) classification A5.1. These include the
6010, 6011, 6012, 6013, 7014, 7024, and 7018 electrodes"
Are these really mild steel? The first numbers indicating high tensile strength seems to say they are more? "
YES they are Mild Steel Yet they do Have High Tensile strength properties . they can be worked as a mild Steel until you either Weld with them or add them to a forged product when the rod/rods harden the base steel binds /is welded by the forge heat and the Chemical reaction of the Welding process that melts the rod adds to the metal being worked .
When this happens the Melted rod cools off and the properties of the steel change at the weld, the rods become the 2 part of the Numbers on the rod " The High Tensile part of the rod .
So in a short answer Yes they are a Mild Steel , However they have a varying tensile rating as to how much the rod after being welded or forged become a Harden piece of Steel. there is quite a bit of difference By What rod is used .
Sam