Explanation

steel with higher control requirements for sulfur, water and other impurities and trace residual element content than high-quality steel. The sulfur and phosphorus content of special quality non alloy tool steel in China shall not be greater than 0.020% and 0.030% respectively; The sulfur and phosphorus content of special quality structural steel shall not be greater than 0.030% and 0.035% respectively; At the same time, the fluctuation range of carbon content and the content of residual elements such as nickel, chromium, copper and non-metallic inclusions are also more stringent than those of high-quality steel.

Classification