With an alloy content as high as 80%or more,Ni-based OCTG is a strategic products related to the state energy security,mainly applied in the exploitation and development of sour gas fields with complicate geological f...With an alloy content as high as 80%or more,Ni-based OCTG is a strategic products related to the state energy security,mainly applied in the exploitation and development of sour gas fields with complicate geological formation,high temperature,high pressure and severe corrosive well conditions.Ni-based OCTG is regarded as the pipe product with most high technologies due to the complexity and great difficulty in manufacturing and rigorous requirements in quality control.In this paper,the technical features and quality requirements of Ni-based OCTG are summarized,and the quality and properties of the Ni-based OCTG products of Baosteel are introduced in detail.With the help of SEM,XPS and TEM,the corrosion mechanism of Nickle-based OCTG in the environments containing H_2S,CO_2,Cl^- and elementary suifur are also analyzed.展开更多
The mechanical and corrosion performance of low alloy steel tubular goods depends on the microstructure obtained as a result of the combination of alloying elements and manufacturing process parameters. The basic desi...The mechanical and corrosion performance of low alloy steel tubular goods depends on the microstructure obtained as a result of the combination of alloying elements and manufacturing process parameters. The basic design philosophy for the selection of the alloying elements is ruled by the balance between the steel cost and the material performance.Following this approach the alloying sequence for the manufacturing of tubular components in oil country tubular goods(OCTG) application is generally Mn,C,r and Mo,used as substitutional elements in a total added weight concentration around 1%up to 3%.Other elements such as B,Ti,Nb and V are applied as strengthening microalloying elements forming fine precipitates. A lack of experience is found related to the use of Tungsten(W) on OCTG applications,although W is also a substitutional element that belongs to group 6 of the periodic table together with Cr and Mo.On the other hand W is widely added for steel pipes working in high temperature services such as power plant boilers,where creep resistance is needed.It is also applied for tool steels enhancing the hardness,wear resistance and cutting performance. Taken into consideration the similarity between Cr,Mo and W and the applications where W has been proven it was decided to analyze the feasibility of using W as an alternative alloying element for some OCTG applications. Another factor that drives this study is the fact that W could be a cost effective substitute of Mo,depending on the alloy market price. This paper is based on literature review and experimental activity done on laboratory steels in which 0.1%Mo was replaced by 0.2%and 0.4%W.The different findings in regards with manufacturing process considerations, material performance and the possible use of W alloyed steel for OCTG applications are summarized. (1 ) Opposed to the susceptibility shown by low carbon with high Cr-W content,hot cracks are not expected in medium C steels(0.2%-0.3%) with W addition up to 1%. (2) Microporosity-related defects could form if W <<0.4%. (3) An improvement in the oxidation resistance for typical rolling furnace atmospheres in the temperature range 1 200 - 1 340℃was detected if Mo is substituted by W. (4) Theoretically W is one half less efficient in regards with hardenability. (5) No differences were found in the grain size after austenitizing in the temperature range 920 - 1 050℃, independently on Mo and W contents. (6) Tempering resistance was similar to Mo steels and there was no effect on the cementite shape factor,which affects the performance in sour environments. (7) Both pitting and general corrosion resistance are improved by W addition.But W effectiveness in improving pitting resistance is about one half. (8) The use of W as a substitute of Mo has been proven to be feasible and it could be applied for the manufacturing of N80 or L80 OCTG steel grades as per ISO 11960/API 5CT.展开更多
The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that wh...The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that when the tool has a fine and uniform microstructure,the main failure mode is wear failure.Furthermore,observed phenomena including large chip bonding,coating peeling,cracks demonstrate that the main wear mechanisms of the tool are adhesive wear,abrasive wear,coating flaking,and microchipping.展开更多
文摘With an alloy content as high as 80%or more,Ni-based OCTG is a strategic products related to the state energy security,mainly applied in the exploitation and development of sour gas fields with complicate geological formation,high temperature,high pressure and severe corrosive well conditions.Ni-based OCTG is regarded as the pipe product with most high technologies due to the complexity and great difficulty in manufacturing and rigorous requirements in quality control.In this paper,the technical features and quality requirements of Ni-based OCTG are summarized,and the quality and properties of the Ni-based OCTG products of Baosteel are introduced in detail.With the help of SEM,XPS and TEM,the corrosion mechanism of Nickle-based OCTG in the environments containing H_2S,CO_2,Cl^- and elementary suifur are also analyzed.
文摘The mechanical and corrosion performance of low alloy steel tubular goods depends on the microstructure obtained as a result of the combination of alloying elements and manufacturing process parameters. The basic design philosophy for the selection of the alloying elements is ruled by the balance between the steel cost and the material performance.Following this approach the alloying sequence for the manufacturing of tubular components in oil country tubular goods(OCTG) application is generally Mn,C,r and Mo,used as substitutional elements in a total added weight concentration around 1%up to 3%.Other elements such as B,Ti,Nb and V are applied as strengthening microalloying elements forming fine precipitates. A lack of experience is found related to the use of Tungsten(W) on OCTG applications,although W is also a substitutional element that belongs to group 6 of the periodic table together with Cr and Mo.On the other hand W is widely added for steel pipes working in high temperature services such as power plant boilers,where creep resistance is needed.It is also applied for tool steels enhancing the hardness,wear resistance and cutting performance. Taken into consideration the similarity between Cr,Mo and W and the applications where W has been proven it was decided to analyze the feasibility of using W as an alternative alloying element for some OCTG applications. Another factor that drives this study is the fact that W could be a cost effective substitute of Mo,depending on the alloy market price. This paper is based on literature review and experimental activity done on laboratory steels in which 0.1%Mo was replaced by 0.2%and 0.4%W.The different findings in regards with manufacturing process considerations, material performance and the possible use of W alloyed steel for OCTG applications are summarized. (1 ) Opposed to the susceptibility shown by low carbon with high Cr-W content,hot cracks are not expected in medium C steels(0.2%-0.3%) with W addition up to 1%. (2) Microporosity-related defects could form if W <<0.4%. (3) An improvement in the oxidation resistance for typical rolling furnace atmospheres in the temperature range 1 200 - 1 340℃was detected if Mo is substituted by W. (4) Theoretically W is one half less efficient in regards with hardenability. (5) No differences were found in the grain size after austenitizing in the temperature range 920 - 1 050℃, independently on Mo and W contents. (6) Tempering resistance was similar to Mo steels and there was no effect on the cementite shape factor,which affects the performance in sour environments. (7) Both pitting and general corrosion resistance are improved by W addition.But W effectiveness in improving pitting resistance is about one half. (8) The use of W as a substitute of Mo has been proven to be feasible and it could be applied for the manufacturing of N80 or L80 OCTG steel grades as per ISO 11960/API 5CT.
文摘The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that when the tool has a fine and uniform microstructure,the main failure mode is wear failure.Furthermore,observed phenomena including large chip bonding,coating peeling,cracks demonstrate that the main wear mechanisms of the tool are adhesive wear,abrasive wear,coating flaking,and microchipping.
