Guidelines for the use of spring steel wires (for high-carbon steel springs, for reference only)
1 Tempering treatment of spring
The purpose of spring tempering is as follows:
1) Increase the yield strength of the material to about 90% of the tensile strength to improve the creep resistance of the spring;
2) Releasing the residual stress caused by the process of drawing and coiling spring, improving fatigue performance and creep performance.
3) Stable spring shape (the outer ring of the spring will shrink to a stable level after 15-30 minutes of tempering).
Precautions :
1) Avoid spring tempering by increasing the temperature and shortening the time;
2) Hardness: As the tempering temperature increases, the hardness decreases after a slight increase. The temperature with the best fatigue performance is slightly lower than the temperature with the highest hardness;
3) Reduced diameter: The outer diameter of the carbon steel spring will shrink when tempered, so some dimensions should be reserved when coiling the spring;
4) Spring tempering color: tempering color is related to temperature and residue on the surface of steel wire, uneven color is related to temperature distribution or air flow in the furnace.
If the color is expected to be uniform, the furnace and charging method must be managed; if there is oil or fingerprints on the part, the color will change after tempering;
5) Tempering temperature: generally used tempering temperature is 250-280 ℃, if 200-250 ℃ is used to treat steel wire, although the strength can be improved,
Plastic toughness will also be lost, which can cause breakage when the tension spring is used as a hook or a torsion spring is bent;
6) Compression spring: mild low temperature tempering after hammering can reduce deformation;
7) Tension spring: there will be loss of initial stress after tempering, the allowable loss should be considered when setting deviation;
8) Torsion spring: After coiling the spring, it should be tempered at 280 ℃. If the spring is reworked after coiling, the low-temperature tempering temperature is 250 ℃;
9) The hook of the tension spring and the arm of the torsion spring: the position will change after tempering. If there is an accurate position requirement, the amount of change should be mastered.
Tempering process:
The tempering process is related to the working conditions of the spring, spring characteristic requirements and the type of tempering furnace. The following are the common tempering processes for carbon steel springs:
Classification requires good fatigue performance, static load or slight dynamic load application
Dynamic load spring 300-350 degrees/20-30 minutes 200-350 degrees/15-20 minutes
Static load spring 200-250 degrees /20-30 minutes
2 Mechanical properties
Tensile modulus of elasticity: 205GPa
Torsional modulus of elasticity: 79GPa
Design torsion stress level: 40% (wire not suitable for dynamic load spring) and 45% (wire for dynamic load spring)
Rockwell hardness: HRC31-60 (approximately corresponding to strength)
3 Safety and product protection
Pay attention to safety when handling, stacking and uncoiling to avoid crushing, stab and bullet injuries.
During handling and storage, care should be taken to prevent the product from friction damage, deformation and rust, and keep it dry.
4 Environmental protection
Please properly dispose of waste packaging, support waste regeneration and reduce resource waste, and reduce environmental impact.
2020-08-26