Super-strength sucker rod steel

Abstract

The invention relates to super-strength sucker rod steel which is characterized by comprising the following chemical components in percentage by weight: 0.23-0.46 percent of carbon (C), 0.1-0.3 percent of silicon (Si), 1.25-1.55 percent of manganese (Mn), less than 0.02 percent of phosphorus (P), less than 0.015 percent of sulphur (S), 0.05-0.15 percent of vanadium (V), 0.025-0.032 percent of chromium (Cr), 0.05-0.13 percent of rare earth (Re) and the balance of iron (Fe), wherein the rare earth is a mixture of lanthanum (La) and cerium (Ce). The invention has the advantages of high comprehensive mechanical property, overall consistent corrosion resistance, super strength and anti-corrosion, breaks the limits of technical means of shot blasting strengthening or electroplating chemical treatment, and the like to the strengthening or the anti-corrosion of the sucker rod and is a brand-new low-cost sucker rod material.

Description

technical field [0001] The invention relates to an ultra-high-strength sucker rod steel, which belongs to the field of alloy steel materials. Background technique [0002] According to the SY / T5029 "Sucker Rod" standard, conventional sucker rods are divided into three grades according to their mechanical properties: K, C, and D. The bearing capacity exceeds D grade, that is, the minimum stress is 0-102Mpa, and the allowable stress value exceeds Sucker rods with 35% mechanical properties of grade D are ultra-high-strength sucker rods, and ultra-high-strength sucker rods are divided into two types: material type (code name HL) and process type (code name HY) sucker rod. Its common specifications, that is, the diameter of the rod body are: 5 / 8in (Φ15.9), 3 / 4in (Φ19.1), 7 / 8in (Φ22.2) and 1in (Φ25.4). [0003] In addition to the selection of raw materials to meet the YB / T054 standard, the HY-type sucker rod must also undergo surface strengthening and coating treatment, and is pr...

AI Technical Summary

Problems solved by technology

However, the prices of alloying elements such as Mo, W, and Cr are relatively high, resulting in relatively expensive raw materials for products.

[0005] However, when the two ultra-high-strength HY and HL sucker rods encounter oil well fluid rich in H 2 In the case of corrosive media such as S, it is easy to cause corrosion fatigue fracture failure, and the oil production conditions of each oilfield are quite different, and the well fluid is rich in various corrosive media, which makes the corrosion degree of the sucker rod very different, such as: Shengli Well fluids in oilfields such as China, Zhongyuan, and Xinjiang all contain a large amount of corrosive media, which shortens the service life of sucker rods, and the number of deep wells, ultra-deep wells, and oil wells with large pumps is gradually increasing. Oilfields urgently need ultra-high strength and corrosion-resistant Sucker rods with strong performance and dual performance appear

[0006] HL type ultra-high strength sucker rod relies on the material itself to meet the mechanical performance requirements, but the anti-corrosion and cracking performance is not good

HY-type ultra-high-strength sucker rods meet the mechanical performance requirements by means of surface strengthening or heat treatment, but after pitting corrosion occurs on the surface coating, the corrosion phenomenon is rapidly aggravated, and the corrosion resistance is not perfect.

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