Are coil springs high carbon steel?

The spring material is generally high carbon steel.

High carbon steel is often referred to as tool steel, the carbon content from 0.60% to 1.70%, can be quenched and tempered. High carbon steel has a density of 7.81g/cm3.

Spring steel belongs to "structural steel" and is "medium and high" carbon, generally 0.55-0.65%. The real "high carbon steel" can only be "tool steel", which contains 0.65-1.05% carbon.

After proper heat treatment or cold drawing hardening, high carbon steel has high strength, high hardness and high elastic limits. Mainly used in the manufacture of springs and wear parts. Carbon tool steel is a kind of high carbon steel which basically does not add alloying elements, and is also a kind of steel with low cost, good cold and hot processability and wide application. With a carbon content of 0.6511.35%, it is a steel specially used in the manufacture of tools.

Small springs are generally made of high carbon steel in good carbon structural steel, such as shock absorbing springs under bicycle seats and springs in clamps. Medium and large springs are generally made of high-carbon alloy steel, such as automotive shock plate springs made of 60Si2Mn and 50CrVA.

It can be distinguished by looking at the morphological reaction of the two after heat treatment. High carbon steel after proper heat treatment or cold-drawn hardening, with high strength and hardness, high elastic limit and fatigue limit (especially the notch fatigue limit), cutting performance is acceptable, but welding performance and cold plastic deformation ability is poor, due to high carbon content, water quenching is easy to crack, so the use of double liquid quenching (water quenching + oil cooling), small section parts are mostly oil quenching, This kind of steel is generally used in the medium temperature tempering or normalizing after quenching or in the surface quenching state, and the hardness is moderate in the annealing state, and it has good machinability.