The Chemical Composition Effect of Medium-Carbon Chromomanganesemolybdenum Steel on the Structure of Drill Pipes

Resumo

Dilatometric studies on medium-carbon Cr–Mn–Mo 40KhGMA steel with various chemical compositions are performed. Thermokinetic diagrams for the transformation of supercooled austenite are plotted, and the temperature-time ranges for the formation of structural components are determined. The metallographic study of the steel microstructure have been carried out after cooling at different rates. Steel hardness depending on the tempering temperature and mechanical properties in the heat-treated state are studied. By using a numerical simulation, cooling paths under heat treatment have been determined for a drill pipe with a wall thickness of 30 mm.