This standard will be the original "GB5218-85", "GB5219-85 spring steel wire guimeng chromium vanadium spring steel wire" and "GB5221-85 three" Chrome silicon spring steel wire into a standard standard.
The standard is suitable for making alloy spring steel wire for high and medium stress spring, and the steel wire wrapping spring needs to be processed by quenching and tempering after forming.
60Si2MnA, 50CrVA and 55CrSiA standard lists three steel grades, together with the rules according to the needs, can supply other trademark wire.
According to the general situation of cold drawn steel wire products delivery, less than 5.0mm in diameter inspection of the ultimate tensile strength B = 1035Mpa, HB = 302 >5.0mm diameter steel wire inspection, proper to pull the light condition. Production standards (diameter >8.0) products cold drawn area reduction does not exceed 25%, small wire (diameter less than or equal to 5) reduction rate does not exceed 30%. The annealing condition is too soft, the steel wire is too soft, it is easy to bend and survive. The spring is generally not good and the pitch is uneven. When the drawing rate of cold drawing is too large, the steel wire is too hard, and the rebound is large when the spring is wrapped, so the forming of the rough spring is difficult. Therefore, the direct winding spring wire is most suitable for light pulling condition. As for the users who buy steel wires for cold processing (such as flattening, rolling into special-shaped sections, etc.), the annealed steel wire should be recommended.
In order to ensure the function of wrapping spring steel wire products, steel wire wrapping test, diameter less than 5.0mm in the right to 1~2 times the diameter of the steel wire is coiled mandrel 6 laps, not split and broken.
Decarburization and surface defects seriously reduce the fatigue life of spring, it is necessary to strictly control. Especially for 60Si2MnA and 55CrSi, the silicon content is higher, and the annealing is simple decarburization. Low temperature annealing and long time annealing are recommended for spheroidizing annealing of steel wire rod and recrystallization annealing of semi products. As mentioned earlier, fatigue life requires high spring, it is necessary to use the polishing wire, but need to discern is still cold polished polished annealing. 50CrV soft wire grinding swarf is simple adhesion to the surface of steel wire, composed of irregular white spots, so as far as possible to choose the cold polishing skills, reduce the surface of the white spot".
To ensure the surface quality under the condition of mixed content has become the most important influence factors of fatigue life, so the standard rules, the need can be added when non metal mixture, graphite carbon inspection.
