Hardness is the ability of a material to withstand abrasion. Increasing hardness can be achieved by raising the carbon content, and by quenching which leads to the formation of martensite.
Metal strength is the amount of force necessary to deform a material. Normalizing a piece of steel will improve its strength by creating a consistent microstructure throughout the material.
Ductility is the ability of a metal to deform under tensile stress. Cold-formed steel has a low ductility due to the dislocations in the microstructure. Process annealing will improve this by enabling crystals to reform and therefore eliminate some of the dislocations.
Toughness is the ability to withstand stress without breaking. Quenched steel can be made tougher by tempering which adds spheroids to the microstructure.
Machinability is the ease with which steel can be shaped by cutting, grinding, or drilling. Machinability is influenced primarily by hardness. The harder the material, the more difficult to machine.
Weldability is the ability of steel to be welded without defects. It is primarily dependent on chemical composition and heat treatment. Melting point, as well as electrical and heat conductivity, all have an influence on the weldability of a material.