Dergach T. Heat treatment impact upon the structure and intergranular corrosion resistance in the tubes made of low carbon austenitic steels

This work investigated effect of carbon, boron, alfa-phase, heat treatment regimes and deformation upon the structure, resistance to intergranular corrosion (IGC) and mechanical properties of the tubes made of abovementioned stees. It has been shown that an increased content of alfa-phase (to 15 %) in he tube billets of 03Х18Н11 steel results in a structure-selective corrosion in testing hot rolled tubes made of this steel by the "ДУ" method (Standard 6032). An upper limit of the carbon content in 03Х18Н11 steel has been determined and basic requirements to the tube billet quality limiting the carbon content (not higher than 0,025 %) and alfa-phase content were formulated. Scientifically substantiated regimes of tubes were developed to ensure freedom from a surface carbonization of the tube metal, high and guaranteed resistance to IGC (corrosion rate less 0,5 mm/year) and high mechanical properties. The technology of making 03Х18Н11 steel tubes featuring a high complex of properties and improved regimes of the thermal and vacuum thermal treatments of 02Х17Н15Р steel tubes increasing their resistance to IGC been introduced at "NPTZ" JSC, Ukraine. .