High-strength alloy structural steel for hydraulic cylinder of fracturing pump and preparation method thereof

Abstract

The invention provides high-strength alloy structural steel for a hydraulic cylinder of a fracturing pump. The steel comprises the following chemical elements in percentage by weight: 0.30-0.36% of C,0.23-0.28% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.05-0.10% of Si, 3.20-3.30% of Ni, 1.40-1.50% of Cr, 0.55-0.60% of Mo, 0.11-0.15% of V, less than or equal to1.5 ppm of H, less than or equal to 112 ppm of O, less than or equal to 70-120 ppm of N and the balance Fe. Meanwhile, the invention further provides a preparation method of the structural steel, thestructural steel obtained through the preparation method is used for manufacturing a hydraulic cylinder of a fracturing pump, under the severe working condition of shale gas exploitation, the servicelife of the product can be prolonged, the use cost can be reduced, the quality is stable and reliable, unpredictable cracking failure and production accidents in the operation process are avoided, andthe requirements of oil-gas field deep well fracturing and shale gas exploitation are met.

Description

technical field [0001] The invention belongs to the field of mechanical manufacturing equipment for oil and gas field stimulation operations and shale gas exploitation fracturing operations, and particularly relates to a high-strength alloy structural steel for fracturing pump cylinders and a preparation method thereof. Background technique [0002] At present, most domestic fracturing pump cylinders use 34CrNi 3 MoE, 34CrNi 3 Mo is a high-strength alloy structural steel, which is widely used in the whole forging low-pressure rotor steel of large steam turbines. It has good comprehensive mechanical properties and process properties, and has been widely used in the production of engine rotors and steam turbine impellers. During the fracturing process, especially the fracturing operation of shale gas exploitation, it is subjected to high pressure of 80-105MPa and repeated actions every 100-200 times per minute, which is prone to fatigue, resulting in fatigue damage to the hyd...

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Problems solved by technology

[0002] At present, most domestic fracturing pump cylinders use 34CrNi 3 MoE, 34CrNi 3 Mo is a high-strength alloy structural steel, which is widely used in the whole forging low-pressure rotor steel of large steam turbines. It has good comprehensive mechanical properties and process properties, and has been widely used in the production of engine rotors and steam turbine impellers. During the fracturing process, especially the fracturing operation of shale gas exploitation, it is subjected to high pressure of 80-105MPa and repeated actions every 100-200 times per minute, which is prone to fatigue, resulting in fatigue damage to the hydraulic cylinder, cracking and failure of the inner cavity , the hydraulic cylinder made of this material has low service life and poor reliability. The average life span is about 100-200 hours under medium and low pressure (60-80MPa) conditions; under high pressure (80-105MPa), it cannot even complete a mouthful The operation of the well (about 10 hours) needs to be shut down for replacement. If it cracks and fails during the operation, it may even lead to a production accident and seriously affect the shale gas exploitation operation

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