Recent Development in High Strength Linepipe for Sour Environment

2003 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Toyohisa Shinmiya ◽  
Shigeru Endo ◽  
Tsunemi Wada ◽  
Joe Kondo
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Controlled Rolling ◽  
Accelerated Cooling ◽  
Optimum Conditions ◽  
Microstructural Characteristics ◽  
Design Concepts ◽  
Bainitic Microstructure ◽  
Linepipe Steels ◽  
Sour Gas

This paper firstly summarizes the design concepts for controlling crack resistant property and mechanical properties of high strength linepipe steels for sour gas service. Optimum conditions of controlled rolling and accelerated cooling that balances crack resistant property and toughness were investigated. It was demonstrated that higher cooling rate in accelerated cooling process brings tremendous advantages for balancing toughness and strength by fine bainitic microstructure even for heavy wall thick pipes. Production results of high strength sour resistant linepipes were introduced. In order to increase strength grade of sour linepipes, further investigation was made using the steels with different microstructures. It was found that precipitation hardened ferrite-bainite steels have extremely high resistance against HIC even for Grade X80. Mechanical properties and microstructural characteristics of this newly developed steel were introduced in this paper.

Recent Developments of Oil and Gas Transmission Pipeline Steels: Microstructure, Mechanical Properties and Sour Gas Resistance

2008 ◽  
Author(s):  
Navid Pourkia ◽  
Morteza Abedini
Keyword(s):  
Mechanical Properties ◽  
Acicular Ferrite ◽  
Oil And Gas ◽  
High Strength ◽  
Accelerated Cooling ◽  
Low Carbon ◽  
Pipeline Steels ◽  
Bainitic Microstructure ◽  
Transmission Pipeline ◽  
Sour Gas

In modern oil and gas transmission pipeline steels technology, a suitable microstructure is an important factor for improvement of strength, toughness and sour gas resistance. Therefore, thermo-mechanically controlled rolling processes have been developed and their microstructures have been changed from ferrite-pearlite to acicular ferrite. Moreover in the recent years extensive attempts have been made to improve pipeline steels properties, which include: i) Ultra fine-grained steels, which are produced by optimized usage of dynamic recrystallization and strain-induced transformation with about 1μm equiaxed ferrite grain size. ii) Ultra low carbon steels with less than 0.025 wt% carbon and significant amount of Mo and Nb microalloying elements. iii) Ultra fine acicular ferrite steels, which are produced by application of more accurate controlled thermo mechanical processes and accelerated cooling. iv) Ultra high strength X100 and X120 grade steels, which are produced by thermo-mechanically controlled processes and heavy accelerated cooling. The former is without special technological changes and mainly consist of low carbon upper bainitic microstructure while the latter needs more technological developments with very little amount of boron and mainly consists of lower bainitic microstructure. This paper gives an overview of these new pipeline steels in viewpoint of microstructure, mechanical properties and sour gas resistance. The studies show that ultra fine acicular ferrite is the best alternative microstructure for nowadays ordinary pipeline steels, but because of numerous advantages of ultra high strength pipelines steels which finally reduce the cost of pipeline projects, the trend of the investigations is focused on further development of these steels. Moreover, acicular ferrite microstructure which is generally accepted by pipeline engineers and it is just in doubt because of its differences with acicular ferrite microstructure of weld metal and numerous offered definitions, is completely described.

scholarly journals Study of the thermal treatment modes influence on the forming of microstructure and specified complex of mechanical properties of high-strength sheet product with guaranteed level of hardness (400–450 HB) of low-alloyed steel

2019 ◽  
Vol 75 (4) ◽  
pp. 480-487
Author(s):  
M. Yu. Matrosov ◽  
P. G. Martynov ◽  
A. V. Mitrofanov ◽  
K. Yu. Barabash ◽  
T. V. Goroshko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fine Structure ◽  
Thermal Treatment ◽  
Hot Rolling ◽  
High Strength ◽  
Controlled Rolling ◽  
Alloyed Steel ◽  
Accelerated Cooling ◽  
Cold Forming ◽  
Low Alloyed Steel

High-strength sheet product of low-alloyed steel, used at manufacturing of heavy-loaded structures, must have, apart from wear resistance, high toughness, good weldability, ability to hot and cold forming, machinability and low cost. Combination of these properties based on forming fine grain austenite structure before the martensitic transformation at definite its thermal treatment modes. Results of study of microstructure, fine structure and mechanical properties of high-strength boron-containing low-alloyed steel after different technological methods of the rolled product manufacturing presented: high-temperature hot rolling and twostages controlled rolling with accelerated cooling followed by thermal treatment – quenching with tempering. Variants of optimal modes of thermal treatment determined, providing combination of high level of impact toughness under negative temperatures, hardness and strength properties of sheet product. The two considered in the article technological variants, comprising treatment of low-alloyed steel with boron (hot rolling and two-stages controlled rolling with accelerated cooling) followed by thermal treatment results in forming fine structure of tempered martensite, which provides high mechanical properties, meeting the made requirements. Depending on the heating temperature before quenching in the range 770–950 °С, the morphology of the actual steel grain is changing from elongated to equiaxed, which is connected with the metal recrystallization process during heating after plastic deformation. The study results obtained allow to optimize the thermal treatment processes of sheet product of low-alloyed boron containing steel for particular conditions of application.

Process, Microstructure and Mechanical Properties of X90 Pipeline Steel

2016 ◽  
Vol 850 ◽  
pp. 894-898
Author(s):  
Bin Guo ◽  
Jin Qiao Xu ◽  
Lei Cui ◽  
Qing Feng Wang
Keyword(s):  
Mechanical Properties ◽  
Manufacturing Process ◽  
Pipeline Steel ◽  
Structural Characteristics ◽  
High Strength ◽  
Controlled Rolling ◽  
Accelerated Cooling ◽  
Iron And Steel ◽  
Technical Requirements ◽  
China National Petroleum Corporation

This paper provided a detailed description of X90 pipeline steel developed in Wuhan Iron and Steel Corporation (WISCO), including its metallurgical design, manufacturing process, structural characteristics and mechanical properties. Some key issues such as the cooling rate and rolling parameters were addressed for the development of X90 pipeline steel. The experimental results showed that the manufacturing process of controlled rolling (for austenite refining) + relaxation (for ferrite phase transformation) +ultrafast accelerated cooling could guarantee very fine microstructure and excellent mechanical properties. The X90 pipeline steel developed in WISCO has a good match of high strength and excellent toughness. Mechanical properties of X90 coils, plates and corresponding SSAW and LSAW pipes comprehensively meet the technical requirements of China National Petroleum Corporation (CNPC).

Study on the Microstructure and Mechanical Properties of a High Strength Crack-Free Steel

2012 ◽  
Vol 706-709 ◽  
pp. 2265-2270
Author(s):  
Chun Lin Qiu ◽  
Liang Yun Lan ◽  
De Wen Zhao ◽  
Xiu Hua Gao ◽  
Jing Lin Wen
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Accelerated Cooling ◽  
Strengthening Effect ◽  
Microstructural Characteristics ◽  
Tempering Temperature ◽  
Electron Backscattering Diffraction ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Ebsd Technique

Thermo-mechanical process followed by accelerated cooling and high temperature tempering was applied to investigate the microstructure evolution and mechanical properties of a high strength crack-free steel. Optical microscopy, transmission electron microscopy (TEM) and electron backscattering diffraction (EBSD) technique were employed to analyze the complex microstructural characteristics of the steel. The results indicated that the precipitation strengthening effect played an important role in optimizing the tempered strength. According to EBSD results, the average grain size of as-rolled specimens was about 3.2 μm, and it increased slightly with the tempering temperature. Therefore, the grain refinement wasthe major reason for the good mechanical properties of the crack-free steel.

Spun Steel Pipes for the Offshore Industry

1983 ◽  
Vol 105 (1) ◽  
pp. 97-102 ◽  
Author(s):  
A. Royer ◽  
B. Dumas ◽  
M. Gantois
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Centrifugal Casting ◽  
High Strength ◽  
Controlled Rolling ◽  
Climatic Conditions ◽  
Casting Technique ◽  
Steel Pipes ◽  
Potential Applications ◽  
Offshore Industry

Many parts either for sea-line pipes as “buckle” or “crack arrestor,” or for structures may require the use of wall tubular products with high mechanical properties. Such heavy-wall pipes may be produced by centrifugal casting. Two Mn-Mo steels have been developed for medium-wall pipes (e≤35 mm) to be used under very severe climatic conditions: an acicular ferritic steel, a pearlite reduced steel produced by controlled rolling techniques [1, 2, 3]. More alloyed chemical composition and heat-treatments are needed to produce heavy-wall pipes. Then, production of such pipes is more difficult and sometimes impossible. Observations made on controlled-rolled Mn-Mo steel led to a better understanding of the influence of metallurgical structures and chemical composition on steel characteristics. Similar metallurgical structures can only be reached via other routes, for example centrifugal-casting of steel associated with heat-treatment, lead to the production of heavy-wall pipes with high strength and suitable transition temperature. After a brief description of the centrifugal casting technique, we introduce the grades developed for heavy-wall pipes with yield strength up to 100,000 psi. The mechanical properties, Battelle, fatigue, static bending, C.O.D., weldability, etc., of Centrishore II are given and compared to other materials. Possible offshore applications and other potential applications of parts produced by centrifugal casting are described.

Effect of Processing Route on Mechanical Behavior of C-Mn Multiphase High Strength Cold Rolled Steel

2007 ◽  
Vol 539-543 ◽  
pp. 4375-4380
Author(s):  
Dagoberto Brandão Santos ◽  
Élida G. Neves ◽  
Elena V. Pereloma
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Quantitative Relationship ◽  
High Strength ◽  
Microstructural Characterization ◽  
Processing Route ◽  
Accelerated Cooling ◽  
Microstructural Parameters ◽  
Transmission Electron

The multiphase steels have complex microstructures containing polygonal ferrite, martensite, bainite, carbide and a small amount of retained austenite. This microstructure provides these steels with a high mechanical strength and good ductility. Different thermal cycles were simulated in the laboratory in order to create the microstructures with improved mechanical properties. The samples were heated to various annealing temperatures (740, 760 or 780°C), held for 300 s, and then quickly cooled to 600 or 500°C, where they were soaked for another 300 s and then submitted to the accelerated cooling process, with the rates in the range of 12-30°C/s. The microstructure was examined at the end of each processing route. The mechanical behavior evaluation was made by microhardness testing. The microstructural characterization involved optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The use of multiple regression analysis allowed the establishment of quantitative relationship between the microstructural parameters, cooling rates and mechanical properties of the steel.

scholarly journals Mechanical properties of wire and arc additively manufactured high-strength steel structures

2021 ◽  
Author(s):  
Johanna Müller ◽  
Jonas Hensel ◽  
Klaus Dilger
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Yield Strength ◽  
High Strength Steel ◽  
Energy Input ◽  
High Strength ◽  
Accelerated Cooling ◽  
Active Cooling ◽  
Wire Arc Additive Manufacturing ◽  
Interpass Temperature

AbstractAdditive manufacturing with steel opens up new possibilities for the construction sector. Especially direct energy deposition processes like DED-arc, also known as wire arc additive manufacturing (WAAM), is capable of manufacturing large structures with a high degree of geometric freedom, which makes the process suitable for the manufacturing of force flow-optimized steel nodes and spaceframes. By the use of high strength steel, the manufacturing times can be reduced since less material needs to be deposited. To keep the advantages of the high strength steel, the effect of thermal cycling during WAAM needs to be understood, since it influences the phase transformation, the resulting microstructure, and hence the mechanical properties of the material. In this study, the influences of energy input, interpass temperature, and cooling rate were investigated by welding thin walled samples. From each sample, microsections were analyzed, and tensile test and Charpy-V specimens were extracted and tested. The specimens with an interpass temperature of 200 °C, low energy input and applied active cooling showed a tensile strength of ~ 860–900 MPa, a yield strength of 700–780 MPa, and an elongation at fracture between 17 and 22%. The results showed the formation of martensite for specimens with high interpass temperatures which led to low yield and high tensile strengths (Rp0.2 = 520–590 MPa, Rm = 780–940 MPa) for the specimens without active cooling. At low interpass temperatures, the increase of the energy input led to a decrease of the tensile and the yield strength while the elongation at fracture as well as the Charpy impact energy increased. The formation of upper bainite due to the higher energy input can be avoided by accelerated cooling while martensite caused by high interpass temperatures need to be counteracted by heat treatment.

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