The 400 series group of stainless steels typically have an 11% chromium and 1% manganese increase, above the 300 series group. This stainless steel series tends to be susceptible to rust and corrosion under some conditions although heat-treating will harden them. The 400 series of stainless steels have a higher carbon content, giving it a martensitic crystalline structure that provides the end product with high-strength and high-wear resistance. The 400 series steels tend to be used in agricultural equipment, gas turbine exhaust silencers, hardware, motor shafts, and more.