Effect of surface treatment on oxidation film of 55SiCr spring steel wire

Abstract In this work, the surface pretreatments of 55SiCr spring steel wire rods were conducted using shot blasting and phosphating. After drawing, the steel wire was heated at 950°C × 15 s, followed by oxidation treatment with high-temperature steam or air for 3 seconds, and tempering treatment at 520°C. The effects of different surface treatment methods on the surface oxide film of spring steel wire were studied using stereomicroscopy, SEM, EDS, and XRD. The results showed that the steel wire surface oxide film with phosphating pretreatment was thicker and easy to fall off. The thickness of the oxide film formed by phosphating pretreatment samples increased by 2.1 um (high-temperature steam) and 0.3 um (air) compared to the shot-blasting samples under different oxidation atmospheres. High-temperature steam oxidation treatment significantly increased the thickness of the oxide film by 0.65 um (shot blasting) and 2.45 um (phosphating) under different surface pretreatment conditions. The outer surface of the oxide film turned black with high-temperature steam oxidation treatment and turned yellowish brown with air oxidation treatment. By both above oxidation treatments, the oxide film showed a multilayer structure, with enrichment of Cr and Si on the inner side.