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Steel suitable for drill rod joint in low-temperature environment and heat treatment process of steel

A drill pipe joint, low temperature environment technology, applied in drill pipe, drill pipe, earthwork drilling, etc., can solve problems such as inability to meet the requirements of use

Inactive Publication Date: 2011-08-03
SHANGHAI HILONG DRILL PIPE MATERIALS INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The test results show that commonly used joint materials such as 37CrMnMo, when the yield strength is 900MPa, as the impact test temperature drops from normal temperature to -60°C, the impact energy decreases from 100J to about 40J, and the ductile-brittle transition temperature is about -50°C. Unable to meet the requirements for use in a -60°C environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] The chemical composition designed according to the present invention (for example, take C 0.26, Si 0.28, Mn 0.55, P 0.008, S 0.004, Cr 0.85, Ni 1.27, Mo 0.65, Al 0.02, V0.08). After smelting, continuous casting and rolling into round steel, the hot-rolled round steel is forged into the NC40 male joint specified in API SPEC 7, with an outer diameter of 139.7mm and an inner diameter of 61.9mm, and then put into the pit furnace Heat to 920°C and keep it warm for 1 hour, quench and fully cool, put it into a well-type furnace for tempering, set the tempering temperature at 680°C, hold it for 2 hours, and then leave the furnace. After heat treatment, samples are taken from the threads, and tensile tests, series of low temperature impact tests and metallographic analysis tests are carried out. The results show that the properties of the joint are as follows: the yield strength is 905MPa, -60°C, the average Charpy impact energy (longitudinal, full-scale) is 110J, the average fr...

Embodiment 2

[0026] The chemical composition designed according to the present invention (for example, take C 0.30, Si 0.23, Mn 0.79, P 0.006, S0.003, Cr 1.05, Ni 0.99, Mo 0.20, Ti 0.02, Re 0.02). After smelting, continuous casting and rolling into round steel, the hot-rolled round steel is forged into the NC50 female joint specified in API SPEC 7, with an outer diameter of 168.3mm and an inner diameter of 82.5mm, and then put it into the pit furnace Heat to 940°C and keep it warm for 1.5 hours, quench and fully cool, put it into a pit furnace for tempering, set the tempering temperature at 690°C, keep it warm for 2.5 hours and then come out of the furnace. After heat treatment, samples are taken from the threads for hardness, series of low-temperature impact tests and metallographic analysis tests. The results show that the joint properties are as follows: the average Brinell hardness is 315HB, -60°C, the average Charpy impact energy (longitudinal, full size) is 100J, the average fracture...

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Abstract

The invention relates to steel suitable for a drill rod joint in a low-temperature environment and a heat treatment process of the steel. The steel used for a drill rod joint comprises the following components by weight percent: C 0.25-0.35%, Mn 0.50-1.00%, P<=0.015%, S<=0.008%, Mo 0.15-1.00%, Ni 0.75-1.50%, Cr 0.80-1.50%, two or more of Si<=0.30%, Al<=0.03%, V<=0.10%, Ti<=0.03% and Re<=0.005%, and the balance of Fe and inevitable trace elements. The heat treatment process of the steel suitable for a drill rod joint is as follows: heating the steel in a furnace to 900-960 DEG C; carrying out heat insulation for 1.0-1.5 hours; putting the steel into a quenching medium and cooling down completely; tempering at the temperature of 660-690 DEG C; carrying out heat insulation for about 2.0-2.5 hours; and then taking the steel out of the furnace. After the steel is treated according to the process, when the yield strength of the steel is 905MPa, longitudinal and full-size charpy impact power average value at -60 DEG C is 110J, the fracture fiber rate is 100% on the average, and the ductile-brittle transition temperature is -85 DEG C.

Description

technical field [0001] The invention relates to a steel for drill pipe joints that can be used in a low-temperature environment, and belongs to the technical field of petroleum and natural gas. Background technique [0002] With the development of the global economy, there is an increasing demand and dependence on energy represented by oil and natural gas. Energy plays a pivotal role in the development of the country and people's lives. In order to obtain more energy, oil drilling has shifted from conventional drilling to harsher environments, such as ultra-deep wells, deep sea, and ultra-low temperature environments. The investigation report shows that the Arctic Circle is rich in oil and gas resources. Some countries have successively allowed the exploitation of oil and gas resources in this alpine environment, but the temperature is as low as -60°C. If you want to work in these alpine areas, the drill pipe must have good Low-temperature toughness (including two indicator...

Claims

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Application Information

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IPC IPC(8): C22C38/44C22C38/50C21D1/18E21B17/02
Inventor 袁鹏斌欧阳志英余世杰
Owner SHANGHAI HILONG DRILL PIPE MATERIALS INST
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