1. Classification and Importance of Spring Steel Wire
　　▣ Performance Characteristics of Spring Steel Wire
　　Spring steel wire, as a critical material, plays an important role in many fields. Its strength, toughness, and spring coiling performance are all key factors affecting its performance. Depending on the variety, standard, and specification, the tensile strength grade of spring steel wire can vary widely from 1000-3000 MPa. Its diameter range is also quite wide, ranging from 0.08 mm to 20 mm.
　　▣ Production Technology and Process
　　Common spring steel wire production processes include the as-drawn method, lead quenching method, galvanizing method, and oil quenching method. Among them, the as-drawn method is suitable for the production of various spring steel wires; the lead quenching method introduces lead bath quenching at a specific stage to improve performance; the galvanizing method is used to improve the corrosion resistance of the product; and the oil quenching method is often used for high-strength applications such as automobile suspension springs and valve springs.
　　▣ Surface Treatment and Wire Drawing Process
　　In terms of surface treatment, methods such as pickling and phosphating are usually used to remove iron oxide scale and form a phosphating film to improve the effect of the cold drawing process and obtain a smoother surface. For spring steel wires with extremely high requirements, such as valve spring steel wires, skinning treatment is also required to reduce surface defects. The wire drawing process is a key part of spring steel wire production. In order to ensure the toughness of the product and prevent torsional cracks caused by strain aging, an appropriate total reduction rate and pass reduction rate need to be adopted, and the outlet temperature during drawing must be strictly controlled. At the same time, good lubrication and sufficient cooling are also essential.
　　2. Usage Characteristics and Applications of Spring Steel Wire
　　▣ Usage Characteristics and Environmental Adaptation
　　The spring works within the elastic range and should be able to fully return to its original shape after unloading, so the steel wire is required to have excellent elastic limit, yield strength, and tensile strength. A high yield ratio means that the elastic limit is closer to the tensile strength, thereby improving the strength utilization rate and making the spring force stronger. In addition, the spring works under alternating stress for a long time, so it needs to have excellent fatigue limit, creep resistance, and relaxation resistance.
　　▣ Forming Process and Heat Treatment
　　In addition, the forming process and heat treatment process of spring steel wire are also factors that cannot be ignored. In the supply state, cold-drawn spring steel wire and oil-quenched and tempered spring steel wire can be directly wound into springs, and the spring must be stress-relieved before it can be used.
　　3. Classification and Material Selection of Spring Steel Wire
　　▣ Classification of Springs and Material Selection Principles
　　According to the operating state, springs can be divided into static springs and dynamic springs. A static spring refers to a spring with a limited number of vibrations during its service life, such as safety valve springs, spring washers, and weighing pan springs. A dynamic spring refers to a spring with more than 1×106 vibrations during its service life, such as engine valve springs and vehicle suspension springs. When selecting materials, the first thing to ensure is that the material can meet the functional requirements of the spring, then the strength requirements, and finally the economic factors are comprehensively considered.
　　▣ Common Steel Grades and Standards
　　Carbon spring steel occupies a pivotal position in spring steel, and its application is wide and its usage is huge. This type of steel contains 0.60%～0.90% carbon and 0.3%～1.20% manganese, and no other alloy elements are added, so the cost is relatively low. At present, there are two main types of national and industry-recommended carbon spring steel wire standards, and the specific standard needs to be selected according to actual needs. Alloy spring steel is added with alloy elements such as Si, Mn, Cr, V, W, and B, and its content is controlled within the range of 0.45%～0.70% carbon.