Development of Production of High-Strength Locks for Drill Pipes

A comparative study of steels promising for the production of high-strength welded tool joints (hereinafter referred to as tool joints) for connecting drill pipes into columns was conducted. A rational chemical composition of chromium–nickel–molybdenum steel containing ~0.35% carbon and microalloyed with vanadium and niobium was proposed. It was shown that the proposed steel grade has a superior mechanical properties compared to well-known 38KhNZMFA and 07KhZGNMYuA steels according to State Standard 4543–2016, which are widely used in mechanical engineering for the production of critical components. The study confirmed the high hardenability of the experimental steel and its suitability for the production of tool joints, including large-volume steels with increased wall thickness in the cylindrical section.