How many Spring Steel grades do you know? Here, let us make an article for Spring Steel.

Spring steel is a type of steel used to make springs or other elastic elements. Spring steel should have excellent comprehensive properties. Such as mechanical properties (especially elastic limit, strength limit, yield ratio), elastic reduction properties (ie resistance to elastic reduction, also known as relaxation resistance), fatigue properties, and hardenability.Physical and chemical properties (heat resistance, low-temperature resistance, oxidation resistance, corrosion resistance, etc.)

In order to meet the above performance requirements, spring steel needs to have excellent metallurgical quality (high purity and uniformity). good surface quality (strictly control surface defects and decarburization). precise shape and size.

Spring Steel grades

There are many types and models of spring steel. For commonly used spring steel, please review the following.

65 Steel

65 steel is a medium-high carbon spring steel. The steel has high strength after heat treatment or cold work hardening. Hardness and elasticity, low cold deformation plasticity, and poor weldability. Oil quenching is generally used. Large cross-section parts are hardened by water quenching oil cooling or normalizing treatment.

70 Steel

The performance of 70 spring steel is similar to that of No. 65 steel. 70 steel has slightly higher elasticity and strength. It is suitable for manufacturing products with small cross-sections and low strength requirements. Round and square spiral springs on general machines. Flat leaf springs and circular coil springs are subject to vibration on machinery. Such as automobiles, tractors or trains.

85 Steel

The performance of 85 spring steel is similar to that of 65 and 70 steel. The strength of 85 steel is higher.
85 steel is suitable for the manufacture of vibration springs with small cross-sectional dimensions and low strength. Such as flat springs and circular spiral springs on railway vehicles. Automobiles, tractors and general machinery. Spring steel wires and steel belts.


The chemical composition of 65Mn contains manganese. It improves hardenability. 65Mn steel has higher strength, hardness, elasticity, and hardenability than 65 steel. But it has overheating sensitivity and temper brittleness. Water quenching is easy to form cracks. The annealed state has good machinability, low cold deformation plasticity and poor weldability.
65Mn steel can be used to make leaf springs under medium load. Coil springs and spring washers with diameters up to 7-20mm. Spring rings. It can also be used for parts with high wear resistance. Such as grinding machine spindles, spring chucks, precision machine tool screws, cutters, collars on spiral roller bearings, and railway rails.


55Si2Mn spring steel contains silicon and manganese. These elements can increase the elastic strength and yield ratio. Improve hardenability, anti-tempering stability, and anti-relaxation stability. The sensitivity to overheating is also small. But, the tendency of decarburization is greater. Especially when the content of silicon and carbon is high, carbon is easy to graphitize, making steel brittle.
55Si2Mn spring steel is used as damping leaf spring and coil spring on automobiles, tractors, and locomotives. Cylinder safety valve spring. It can also be used as heat-resistant springs below 250°C.


The performance of 55Si2MnB spring steel is like that of 55Si2Mn steel. Due to the boron content, its hardenability is improved. The critical hardening diameter in oil is about 90~180mm. Fatigue strength is also improved.

55Si2MnB steel is suitable for the manufacture of leaf springs with medium and small cross-sections. For example, the front and rear leaf springs on automobiles. It can also be used to manufacture other medium-sized leaf springs and coil springs.


60Si2Mn spring steel has high hardenability. The density is 7.85g/cm3. It is a widely used silico-manganese spring steel. It is also the most widely used alloy spring steel. The strength, elasticity and hardenability of 60Si2Mn spring steel are higher than 55Si2Mn.

60Si2Mn spring steel is suitable for the production of flat springs with large loads in railway vehicles, automobile and tractor industries. Coil spring with wire diameter below 30mm. It can also be used to make heat-resistant springs with a working temperature below 250 ℃ in non-corrosive media. As well as large important coiled springs that bear alternating loads and work under high stress. And car shock absorption system.