Influence of Chemical Composition on the Quality of Microstructure of Steel 4130

The article presents the results of production development of steel 4130 with an optimum chemical composition and quality characteristics that meet the requirements of consumers in the oil and gas industry. Studies of the chemical composition and morphology of nonmetallic inclusions have established the nature of their formation, and technological parameters for melting and casting steel have been developed to produce finished hot-rolled seamless pipes with the required mechanical and technological properties. By maintaining optimum ranges of residual calcium content in the steel, erosion of the refractory materials in the intermediate ladle has been minimized, as well as the occurrence of pre-crystallization and crystallization endogenous inclusions. Microdoping of steel with niobium at the final stage of ladle processing ensured compliance with the requirements for austenitic grain size, taking into account the minimum aluminum content in the steel.