Effect of charge on the structural steel-30 Khgsna of commercial smelting

Chemical composition and mechanical properties, especially the brittle ones, of the steel 30 KhGSNA were studied. The material was smelted at three enterprises either from primary mixture, i.e. pigs made of metallized scrap or from regular mixture of current process, i.e. common scrap. As evidenced by metallographic studies with an optic microscope, the metal smelted from primary mixture did not differ in structure and in non-metal inclusions contents from that smelted from common mixture. Mechanical properties and impact viscosity of steels after hardening and low tempering were given. Primary-mixture steel with the same strength has somewhat higher viscosity and plasticity than the regular steel after high or low tempering in the range from room temperature to 136 deg C. Changes in embrittlement conditions may considerably increase the steel sensitivity to reversible tempering brittleness