STRUCTURE AND PHASE TRANSFORMATIONS DURING COLD DEFORMATION OF AUSTENITIC HIGH-NITROGEN STEELS

摘要

Structure and phase transformations during cold and hot deformation of nitrogen-and carbon-containing Fe-based alloys have been studied by optical and electron microscopy, X-ray diffractometry and mechanical testing. It has been shown that nitrogen decreases the stacking fault energy, increases the stacking fault concentration as well as the density of annealing twins formed during heating. Nitrogen and alloying elements affect martensitic transformation and grain refinement during deformation due to the decrease of stacking fault energy. The probability of deformation through martensitic transformation and transformation induced plasticity (TRIP), simultaneously is enhanced, with the maximum strength achieved in a steel with nitrogen and manganese addition. Chromium and Cr-Mn-N steels can be recommended as high-strength non-magnetic corrosion resistance steel.