In the use of high-strength springs, early piano wire was more common, but the corrosion resistance was very poor. In order to prevent rust, chromate treatment is required. In the past, the zinc coating of crude steel was given to make it have a self-corrosion protection effect, but in order to prevent it from being placed in the atmosphere to cause discoloration, chromate treatment was necessary after plating. Chromate treatment is a chemical treatment of the coating, and the coating contains hexavalent chromium. From the perspective of environmental protection, it is problematic. High-strength stainless steel wire can solve this problem well.
High tensile strength spring wire can maintain good toughness by controlling the dense strain martensite structure during cold working, and become a high-strength stainless steel wire for spring that can rival piano wire. Because it belongs to the austenitic system, it has good corrosion resistance and is a very environmentally friendly material. Its main features are: (1) Excellent corrosion resistance Regarding corrosion resistance, as austenitic stainless steel, it is the same general-purpose stainless steel as SUS304. (2) It has a tensile strength comparable to that of piano wire. In the field of fine wire diameter, it has the characteristics of strength and elasticity comparable to that of piano wire B. (3) High spring fatigue strength Compared with conventional stainless steel wire for springs, spring design under high stress is possible, and the fatigue strength is excellent. (4) Excellent resistance to residual strain The residual shear strain (residual stress) is very small, and the dynamic elasticity is extremely excellent. (5) Excellent heat resistance Compared with piano wire, it has excellent heat resistance. (6) The cost of low-cost material itself is slightly higher than that of piano wire, but the total cost of anti-rust treatment is cheaper. Particularly below φ0.2mm, the material cost is lower than that of piano wire, so a significant cost reduction can be achieved.