The Influence of Chemical Composition and Pre-strain on Impact Toughness Transition Behaviour of 18%Mn-18%Cr-N Austenitic Steels

Transition behaviour of impact absorbed energy is well known for 18%Mn-18%Cr-N steel. The cleavage-like transgranular facets are detected on fracture surface of impact specimens tested at low temperature. Impact absorbed energy decrease when these cleavage-like facets are found on fracture surface of test specimen. The ductile-brittle transition temperature of the materials shifted to lower temperature by increased of nickel content, decrease of nitrogen content or pre-straining at high temperature. The relationship between cleavage-like fracture and plastic deformation stracture at the crack tip of impact test specimen has been investigated.