Environment-tensile property relationship in AISI 1018 steel

A characterization of strain rate and environment influences on the tensile properties of a steel 1018 having a fully spheroidized microstructure is presented. It is part of a larger study which investigates the influence of ion implantation on the tensile properties, fracture behaviour, cyclic stress response and fatigue properties of a high strength steel. The influence of environment on tensile properties at the test temperature (ambient temperature) is rationalized on the basis of test time. At the strain rate of 10 exp --5 s exp --1 the time of exposure of the specimen to the environment is ten times more than at the strain rate of 10 exp --4 s exp --1 . The slower strain rate provides for increased test time which allows for greater interaction between the environment and the material. Consequently, effect of the inert gaseous nitrogen environment on mechanical properties is felt at the slower strain rate (10 exp --5 s exp --1 ) than at a higher strain rate (10 exp --4 s exp --1 ). Photomicrographs, Graphs. 25 ref.--J.H.