Cold brittleness of Cr−Mn−Si steels with an unstable austenitic structure

1.Type 80G8Kh3 steel, which is stable in cooling all the way to the temperature of liquid nitrogen, has a wide Md-MS temperature range, as the result of which deformation martensite is formed in it during dynamic bend tests in the \t-196 to +150\dgC range. As the result of alloying of 80G8Kh3 steel with up to 3% silicon the temperature of formation of deformation martensite increases to 200\dgC and, in addition, the quantity of it in the fractures of the steels increases. li]2.|Alloying with silicon has no clear influence on the grain size of the steel. Small additions of it (up to 1%) promote grain growth while more significant ones (up to 3%) cause refinement but in alloying with silicon in the investigated limits there is a significant increase in the ductile-to-brittle transition temperature.