Ultrahigh-strength and high-toughness steel for pumping rod and production process thereof

Abstract

The invention discloses ultrahigh-strength and high-toughness steel for a pumping rod, which comprises the following chemical components in percentage by mass: 0.32-0.38% of C, 0.17-0.37% of Si, 1.60-1.80% of Mn, 1.10-1.30% of Cr, 0.20-0.30% of Mo, 0.20-0.30% of V, 0.015-0.035% of Al, no more than 0.020% of P, no more than 0.010% of S, no more than 0.002% of [O], no more than 0.0002% of [H] and the balance of Fe. The production process comprises the following steps: smelting in a conventional converter, refining in a refining device, performing silicon-calcium-barium end deoxidation in the late stage of the refining process, performing RH degasification and inclusion removal after refining, casting molten steel into a continuous casting blank, and rolling into phi19-25mm round steel. The invention is reasonable in component design and advanced in process; compared with ultrahigh-strength steel for a pumping rod available on the existing market, the steel disclosed by the invention has higher strength and toughness, the tensile strength Rm is no less than 1200 MPa, the extension percentage delta5 is no less than 12%, the percentage reduction in area Z is no less than 48%, accidents of pumping rod breakage in a high-load environment can be effectively decreased, and the economic loss can be obviously reduced.

Description

technical field [0001] The invention relates to alloy structural steel in the iron and steel industry, in particular to super-high-strength, high-toughness steel for sucker rods (35Mn2CrMoV) and a production process thereof. Background technique [0002] At present, the mechanical production wells account for more than 90% of the total number of oil production wells, and the rod pump oil production method accounts for more than 90% of the mechanical production wells. Therefore, the rod pump oil production method has occupied an important position in my country's crude oil production. The sucker rod is an important component of the rod pumping equipment, which transmits the power of the pumping unit to the downhole pump. In the process of oil production, the sucker rod string is subjected to asymmetric cyclic load, and the working medium is well fluid (crude oil and mine water), most of which contain corrosive media, so the main failure modes of the sucker rod are fatigue fra...

AI Technical Summary

Problems solved by technology

However, during the process of processing such steel into sucker rods, the rod head and the rod tail need to be heat-treated, resulting in a decrease in strength and a large difference in performance from the rest of the rod, which is prone to rod breakage accidents

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