Norton ensures that the spring can work reliably by selecting materials that not only meet high strength and yield limits, but also have high elastic limits, fatigue limits, impact toughness, plasticity, and good heat treatment processability. Norton spring material selection fully considers the purpose, importance, and load characteristics, size, cycling characteristics, working temperature, and surrounding medium of the spring, as well as processing, heat treatment, and economic factors, in order to match the actual requirements. Norton torsion springs have anti-corrosion, long service life, and anti-magnetic properties.