Anti-H2S stress corrosion high pressure resistant forgings and method for manufacturing same

Abstract

Disclosed is a sulfureted hydrogen-proof stress corrosion high pressure-resistant forge piece, comprising the compositions, in weight percent: C: 0.26 to 0.30, Mn: 0.80 to 1.00, Cr: 0.80 to 1.00, Si:0.20 to 0.35, Ni: 0.50 to 0.95, Mo: 0.20 to 0.30, P<=0.012, S<=0.010, Cu<=0.20, H<=2ppm, O<=50ppm, N<=85ppm, balance Fe; and a manufacturing method comprises the following steps of: secondary refiningand smelting by an electric furnace, and casting for forming ingot; heating and forging, with a heating speed of 100 to 150DEG C / h to rise the temperature to 1190 to 1230DEG C, and then preserving the heat for over 8 hours; forging steel ingot to have the size of a finished product; forging temperature range: 800DEG C to 1130 DEG C; adopting an upsetting drawing process, with a forging ratio >=6;and air cooling to reach a temperature of between 420 and 470DEG C after the forging and preserving the heat for over 2 hours, normalizing, with a temperature of between 870 and 890DEG C, and annealing, with a temperature of between 670 and 690DEG C. The indexes such as yielding, tensile strength, grain size and non-metallic inclusion of the forge piece meet the designed 105MPa pressure demand, and the forge piece is corrosion resistant.

Description

technical field [0001] The invention relates to a hydrogen sulfide stress corrosion resistant high pressure forging for a large blowout preventer and a manufacturing method thereof. Background technique [0002] During downhole operations, when the formation is open, if effective measures cannot be taken to control the high bottom pressure, bottom fluid (oil, gas and water) may flow into the wellbore uncontrollably and spray to the ground in large quantities. This is a blowout . Blowout accidents have great harm to the life and property safety of personnel near the well site, the environment around oil and gas wells, and underground oil and gas resources. Therefore, a blowout preventer should be installed at the oil well / gas wellhead, and it should be activated urgently to seal the wellhead when a blowout occurs, so as to avoid large economic losses. [0003] The blowout preventer not only bears the huge pressure at the bottom of the oil well, but also bears the H in the o...

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Problems solved by technology

[0004] The blowout preventer made of 30CrMo castings has low bottom pressure (below 70MPa), H 2 Oil wells with low S gas content (crude oil S content less than 0.1%) are more suitable, but with a batch of high hydrogen sulfide gas content (crude oil S content greater than 3%) and high pressure ( 105MPa or less), the blowout preventers produced by this manufacturing method have some disadvantages: 1) The thickness of the blowout preventer shells with design pressure ≥ 105MPa is greater than 350mm, and the hardenability of 30CrMo is small, and the shell The body center retains ferrite and pearlite structures, with a tensile strength of 410-490Mpa, which reduces the overall performance of the blowout preventer

2) Adopting the casting molding process to retain the as-cast structure, the grains are coarse, and the grain size is 3 to 4, which reduces the mechanical properties of the material, and there are defects such as trachoma, looseness, and slag inclusion, and repair welding treatment is required

The material of this invention not only has high tensile strength (1820MPa) and fracture toughness, but also has a low yield ratio and good dynamic mechanical properties. This invention only provides materials, and does not mention thermal processing manufacturing methods, and The Ni content is much higher than that required in the "Petrochemical Pressure Vessel Material Selection Standard" in the wet H 2 Under the S stress corrosion environment, the nickel content of the steel is not more than 1%" requirement, prone to H 2 S stress corrosion cracking (SSC)

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