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6, passivation to remove hydrogen parts should be passivation after the removal of hydrogen, passivation before the application of 1%H2SO4 or 1% hydrochloric acid activation 5~15s. Passivation shall be treated with colored chromate unless otherwise specified in the design drawings.

Carbon spring steel wire is made of high carbon and high quality carbon structural steel or carbon tool steel wire rod, and its chemical composition, gas content and non-metallic inclusion must be strictly controlled according to the use of the spring. In order to reduce the surface defects and decarbonization layer, the billet produced wire rod should be ground on the surface and peeled when necessary.

During this process, each time the wire is pulled over, the surface hardens due to the high friction temperature. So basically every time you pull it you have to annealing it in the furnace. On the one hand, it is to reduce the surface hardness. On the other hand, during the process of wire pulling, only the surface is deformed, and the center is unchanged. So there’s a lot of stress inside. Therefore, it is necessary to rely on annealing to eliminate the internal stress, so that the wire becomes soft again to eliminate the stress before being drawn again.