| Abstract: | In order to control the composition, morphology and size distribution of oxide inclusions in spring steel, the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxide inclusion precipitated at different temperatures was determined based on thermodynamic equilibrium for spring steel 60Si2MnA, and has been verified by practice. The size distribution of non-metallic inclusions electrolytically extracted from specimens of hot rolled spring steel was determined by image analyzer. The results show that there are a great deal of large inclusions in spring steel produced by the conventional process, and the quantity and the size of large inclusions in spring steel produced by new process are largely reduced. As a result, the fatigue properties of the spring steel produced by new process are highly improved, and the ratio of σ-1/σb is raised from 0.451 to 0.468. |
