engleski

Influence of two different heat tretment procedures on mechanical and fracture properties of 65 Si 7 steel

This paper deals with the results of investigation of two different heat treatment procedures and their influence on some mechanical properties as well as on the magnitude of some fracture mechanics parameters for a particular type of steel. The exsperimental investigations were performed on the specimens made of 65Si7 steel. The processes occurring by tempering of two different microstructures of the steel, i. e. martensite and lower bainite were investigated. An advantage of austempering over hardening and tempering is in obtaining the bainitic microstructure. Steel of bainite microstructure has a toughness, ductility, contraction, fatigue strength and a better fracture toughness than a tempered martensite of the same type of steel. A bainite microstructure also gives a better resistance to thermal fatigue in comparasion with martensite microstructure. The above mentioned improved values of mechanical properties refer to the untempered state of bainite.

mechanical fracture properties; heat treatment; steel 65Si7

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