Promotion of the impact toughness of A333Gr.3 cryogenic seamless tubes

For improving the impact toughness of A333Gr. 3 cryogenic seamless tubes, the chemical composition, hazardous element, gas content, rolling state mechanical properties, metallographic structure and mechanical properties of three kinds of cryogenic seamless steel tubes after heat treatment were analyzed and compared. Carbon content has obvious influence on the low-temperature impact toughness of the steel tubes. The lower the carbon content is, the higher the impact toughness is. The brittle transition temperature can be obviously improved by the phosphorus content of the steel, so the phosphorus content of the steel should be reduced. At the same time, the rolling temperature of the steel tubes should be controlled, the finishing rolling temperature of the steel tubes should be reduced, the cooling velocity should be enhanced, and the grain size should be refined. These measures are beneficial to enhance the low-temperature impact toughness of the steel tubes.