A kind of steel for ultra-high strength sucker rod and its manufacturing method

Abstract

The invention relates to steel for an ultra-high-strength sucker rod and a production method thereof. The steel for an ultra-high-strength sucker rod is prepared from the following components: 0.07-0.13wt% of C, 4.0-7.0wt% of Cr, less than 0.50wt% of Mn, less than 0.50wt% of Si, 0.30-0.60wt% of Mo, 0.05-0.15wt% of V, 0.01-0.03wt% of Ti, less than 0.008wt% of P, less than 0.002wt% of S, 0.01-0.05wt% of Al, and the balance of Fe and unavoidable impurities; the steel also can contain less than 0.50wt% of Ni. For the steel for an ultra-high-strength sucker rod, a high-temperature tempered martensite structure can be obtained by adopting a super-clean steel smelting technology with low cost and a heat treatment process including normalizing and high-temperature tempering, nano Cr, V, Mo composite nanoparticles are used as precipitation strengthening phases, and the yield strength can reach 800MPa grade, and the steel disclosed by the invention has the corrosion resistance prior to that of KD-grade steel 20Cr2MoNiA for a sucker rod and can be used for producing H-grade ultra-high-strength corrosion-resistant steel sucker rods.

Description

technical field [0001] The invention relates to the technical field of alloy steel, in particular to an ultra-high-strength sucker rod steel and a manufacturing method. Background technique [0002] With the continuous development of oil wells, the number of heavy oil wells and corrosive media such as chloride salts and sulfides also increase, and higher requirements are placed on the strength and corrosion resistance of sucker rods, which not only require ultra-high strength, but also have excellent corrosion resistance Corrosion properties, especially resistance to H 2 S corrosion ability. According to the national standard GB / T 26075-2010 round steel for sucker rods, the traditional steel for sucker rods with a yield strength of 800MPa or more has a Cr content of ≤2.00% in composition design, and Ni and Cr alloying are mainly used to meet the requirements of corrosion resistance. properties, wherein the Ni content is 0.72 to 2.00wt%, and the (Cr+Ni) content is ≤3.10wt.%...

AI Technical Summary

Problems solved by technology

However, this design is costly and does not deliberately control the content of impurity elements. For example, the control of the content of impurity elements such as P and S is only required to be below 0.025wt.%, and impurity elements such as P and S will reduce the sulfide cracking ability of steel , so the corrosion resistance of the current steel for sucker rods is insufficient, and it is difficult to meet the requirements of oil wells

In addition, the steel process for sucker rods generally adopts the treatment process of quenching + high temperature tempering. The cooling medium for quenching and tempering needs to use water or oil, and the process cost is relatively high.

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