The effect of heat treatment parameters on mechanical characteristics of 10CrMo9-10 steel tube bends

The purpose of the paper was to analyse the effect of diverse heat treatment parameters (normalising and tempering) on mechanical characteristics of the material used to develop.508x20 tube bends made of the 10CrMo9-10 steel by application of induction heating. The research conducted included tests of basic mechanical properties as well as low cycle fatigue and creep at the temperature of 500°C. With reference to the results thus obtained, it has been established that there is a relationship between mechanical properties of bends and individual features of their microstructure conditional to the heat treatment parameters. Among other conclusions drawn in the research, it has been found that the main structural factor conditioning the mechanical properties of bends was the grain size. Heat treatment parameters characterised by lower temperature and shorter tempering time triggered changes in the material microstructure, such as increased grain comminution. The effects of the said changes included improvement of strength characteristics (R_m, R_p0,2) as well as increased material durability under conditions of fatigue and creep. Main criterion-specific mechanical properties and geometric features of the bends developed conformed with the relevant requirements of reference standards (Pn-en10216-2, Pn-en 12952).