Alloy spring steel wire is manufactured using silicon-manganese, chromium-vanadium, and other alloy spring steels. Softening of the wire rod involves incomplete annealing. Decarburization must be prevented during heat treatment, and for silicon-containing spring steel wire rods, the precipitation of graphite carbon must also be prevented. Recrystallization annealing is used for the heat treatment of semi-finished products. Pickling and coating processes are similar to those for producing carbon spring steel wire. Depending on requirements, silicon-manganese spring steel wire is available in different delivery conditions, including cold drawing, annealing, normalizing, high-temperature tempering, bright finish, and oil quenching-tempering; chromium-vanadium spring steel wire is available in cold drawing, annealing, and bright finish. Generally, alloy spring steel wire, after being wound into springs, must undergo quenching and medium-temperature tempering before use.
Tempered spring steel wire mainly includes oil-quenched-tempered carbon spring steel wire and silicon-manganese alloy spring steel wire, as well as oil-quenched-tempered carbon spring steel wire and chromium-silicon alloy spring steel wire for valves. The purpose of oil quenching and tempering after drawing spring steel wire is to give the wire a high elastic limit and yield strength ratio, as well as good toughness and fatigue resistance. Springs made from quenched and tempered steel wire have stable geometry and mechanical properties, small load fluctuations, and can be heated below the tempering temperature to eliminate residual stress generated during winding.
