Carbon spring steel wire, according to GB/T4357-1989, is a low-carbon steel, cold-drawn wire with a round cross section. It is divided into seven varieties designated as A, B, E, F, G, H and I depending on the number of active carbon. The carbon content is generally 0.65~1.35%, and the wire diameter is 0.04~20mm. As the tensile strength, yield strength and modulus of elasticity increase with the increase of active carbon content, the active carbon content of the same variety of wire is generally divided into 3 categories, namely, low carbon (LC), medium carbon (MC) and high carbon (HC).
Spring steel wire is made of high-quality low-carbon steel wire rod by drawing or cold rolling, cold drawing and tempering processes. Commonly used spring steel wires: 65mn (0.6~0.9% C), 60si2mn (0.6~0.9% C), 55crsi (0.7% C), 51crv4 (0.8~1.05% C) and 50crva (0.45~0.75% C).
The mechanical properties of the different levels of active carbon are shown in Table 1. Active carbon content above 1.40% is not available.
Table 1 mechanical properties of carbon spring steel wires with different active carbon
Carbon content (active C)
Low Carbon (LC) 0.65%-0.75%
Medium Carbon (MC) 0.76%-1.00%
High Carbon (HC) 1.00%-1.40%
Tensile strength δb (MPa)
above 1800
1800-1300
above 1300
Yield strength δ0.2 (MPa)
above 1300
1250-950
above 950
Elongation A (%)
above 15
14-12
above 12
Under the standard of GB/T4357-1989, the Ultimate tensile strength (MPa) of spring steel wires with different carbon contents is shown in Table 2.
Table 2 Ultimate tensile strength (MPa) of spring steel wires with different carbon contents
Carbon content (active C)
Low Carbon (LC) 0.65%-0.75%
Medium Carbon (MC) 0.76%-1.00%
High Carbon (HC) 1.00%-1.40%
Ultimate tensile strength
above 1750
1700-1350
above 1350
The heat treatment of spring steel wires is mainly composed of stress relief annealing, low temperature annealing, high temperature annealing and tempering. Different spring wires are processed with different heat treatments to meet the requirements of structure and performance, and further improve the elasticity, ductility and fatigue strength of the spring wires.
Carbon spring steel wire is mainly used for the production of compression, torsion and wave springs, as well as a variety of springs, such as disc springs, sheet springs and wire springs.
Carbon spring steel wire is a steel wire made of low-carbon steel and obtains its shape by cold drawing, tempering and forming processes. According to GB/T4357-1989, the quality of carbon spring steel influence the mechanical performance, specifically, the tensile strength, yield strength and modulus of elasticity. It is produced in seven varieties depending on the number of active carbon; the lower the active carbon number, the lower the tensile strength, yield strength and modulus of elasticity. The active carbon content is generally 0.65~1.35 %, and the wire diameter is 0.04~20mm.
Spring steel wire is produced from high quality low-carbon steel wire rods by a mechanical drawing or cold rolling process, then tempered to obtain a significantly improved performance.
Common spring steel wires used for production include 65mn (0.6~0.9% C), 60si2mn (0.6~0.9% C), 55crsi (0.7% C), 51crv4 (0.8~1.05% C) and 50crva (0.45~0.75% C).
The mechanical properties of the different levels of active carbon are shown in Table 1. The Ultimate tensile strength (MPa) of spring steel wires with different carbon contents is shown in Table 2. The heat treatment of spring steel wires is mainly composed of stress relief annealing, low temperature annealing, high temperature annealing and tempering. Different kinds of springs require specific treatments in order to meet the structure and performance requirements while further improving the spring’s elasticity, ductility and fatigue strength.
Carbon spring steel are mainly used for the production of compression, torsion and wave springs, as well as a variety of springs, like disc springs, sheet springs and wire springs. It has the characteristics of good heat treatment performance, which can resist repeated shocks and wear, and can make springs with complex shapes for its excellent malleability. Therefore, carbon spring steel wires are widely used in various industries, such as automobiles, engineering machinery, agricultural machinery, ships, aerospace and military industry.
