(Summary description)Generally, spring steel can be produced by electric furnace, open hearth or oxygen converter; high-quality spring steel with good quality or special properties can be made by electroslag furnace or vacuum furnace. The specified content range of carbon, manganese, silicon and other main elements in spring steel is narrow, and the chemical composition must be strictly controlled during smelting. When the silicon content is high, it is easy to form defects such as bubbles, and white spots are easy to occur when the ingot is not cooled properly after forging and rolling. Therefore, the raw materials for smelting must be dried to remove gas and inclusions as much as possible, and to avoid overheating of molten steel.
Spring steel must pay special attention to decarburization and surface quality during rolling. When the steel surface is severely decarburized, it will significantly reduce the fatigue limit of the steel. For high silicon spring steel such as 70Si3MnA, care should be taken to avoid graphitization. Therefore, the stop rolling temperature during hot working should not be too low (≥850°C), to avoid staying too long in the temperature range (650-800°C) where graphitization is easier to form.
After the spring is made, shot peening can generate residual compressive stress on the surface of the spring to offset part of the working stress on the surface and inhibit the formation of surface cracks, which can significantly improve the fatigue limit of the spring.

• Time of issue:2019-12-30
• Views:0