Development of Grade X80 High Charpy Energy Linepipe by MA Formation Control

2016 ◽  
Author(s):  
Hideyuki Kimura ◽  
Tomoyuki Yokota ◽  
Nobuyuki Ishikawa ◽  
Shinichi Kakihara ◽  
Joe Kondo
Keyword(s):  
Ductile Fracture ◽  
Formation Control ◽  
Single Phase ◽  
Void Nucleation ◽  
Controlled Rolling ◽  
Accelerated Cooling ◽  
Dual Phase ◽  
Long Distance ◽  
Dual Phase Steels ◽  
Homogeneous Microstructure

Higher grade linepipes such as grade X80 have been developed and applied to long distance pipelines in order to reduce the cost of pipeline construction by using thinner pipes than is possible with conventional grades. Service pressures have also been increased in recent years for efficient gas transportation. In addition to the requirement of higher strength, running ductile fracture should be prevented in long distance and high pressure pipelines. Resistance to ductile fracture, as evaluated by Charpy energy, is an important material property for higher grade linepipes. It has been reported that bainite single-phase steel tends to show higher Charpy energy than ferrite-bainite or bainite-MA (martensite-austenite constituent) dual-phase steels, since void nucleation is suppressed in single-phase steels compared with dual-phase steels. However, in higher grade steels with a bainite single phase, a small amount of MA grains generally remains due to the chemical stability of MA. Therefore, further reduction of MA is key to improving Charpy energy for higher grade linepipe steels. In order to achieve high Charpy energy by MA formation control, the optimum conditions of the plate manufacturing process were investigated. As a result, a high Charpy energy was achieved by the combination of controlled rolling and precise control of the accelerated cooling conditions, by which the MA phase was minimized. Based on the above investigation, grade X80 high Charpy energy linepipes were trial-produced by applying JFE Steel’s optimized accelerated cooling (ACC) system with a high cooling rate and homogeneous temperature profile. Stable higher Charpy energy was achieved by minimizing MA formation and achieving a homogeneous microstructure by advanced cooling control.

Ductile Fracture Behavior of Bainite-MA Dual Phase Steels

2014 ◽  
Author(s):  
Junji Shimamura ◽  
Kyono Yasuda ◽  
Nobuyuki Ishikawa ◽  
Shigeru Endo
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Volume Fraction ◽  
Void Nucleation ◽  
Ground Movement ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Boundary Area ◽  
Strain Capacity ◽  
Shelf Region

In order to achieve safety and reliability of the pipeline installed in seismic region, it is quite important to apply the high-strength linepipes with sufficient strain capacity against buckling and weld fracture by the seismic ground movement. Dual-phase microstructure control is an essential measure for improving strain capacity of linepipe steels. Ferrite-bainite or bainite-MA microstructures are practically applied to the linepipes for the strain-based design to achieve higher deformability which has low Y/T (Yield/Tensile strength) ratio and high uniform elongation even after pipe coating. On the other hand, dual-phase steels tend to show lower Charpy energy in the upper shelf region than single-phase steel. It is considered that void nucleation and growth is enhanced in the dual-phase steels due to the strain concentration at the boundary between two different phases, resulting in early cracking in the specimen that leads to lower Charpy energy. The Charpy energy of the bainite-MA dual-phase steels was strongly affected by the volume fraction and size of MA. In the case of Bainite-MA steels with fewer volume fraction of MA and smaller size of MA, the sample showed higher Charpy energy. Ductile fracture behavior was investigated through several kinds of Charpy impact tests in order to clarify the effect of these microstructure differences on the Charpy energy in the upper shelf region. From the SEM observation, it was found that void nucleation was enhanced in the sample with higher volume fraction of MA and larger size of MA. It is considered that the increase of boundary area that works as void nucleation site affected these results. Experimental results were mainly discussed in this paper.

A crystal plasticity based finite element framework for RVE calculations of two-phase materials: Void nucleation in dual-phase steels

2021 ◽  
Vol 187 ◽  
pp. 103510
Author(s):  
Tuncay Yalçinkaya ◽  
Serhat Onur Çakmak ◽  
Cihan Tekoğlu
Keyword(s):  
Finite Element ◽  
Crystal Plasticity ◽  
Void Nucleation ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Two Phase

scholarly journals Ductile Fracture Behavior of Bainite-MA Dual Phase Steels

2016 ◽  
Vol 56 (12) ◽  
pp. 2304-2312 ◽  
Author(s):  
Junji Shimamura ◽  
Shusaku Ota ◽  
Kyono Yasuda ◽  
Nobuyuki Ishikawa
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Dual Phase ◽  
Dual Phase Steels

Mesoscale simulation of the early evolution of ductile fracture in dual-phase steels

2015 ◽  
Vol 74 ◽  
pp. 17-34 ◽  
Author(s):  
Takashi Matsuno ◽  
Cristian Teodosiu ◽  
Daisuke Maeda ◽  
Akihiro Uenishi
Keyword(s):  
Ductile Fracture ◽  
Early Evolution ◽  
Dual Phase ◽  
Mesoscale Simulation ◽  
Dual Phase Steels

scholarly journals Effect of Martensite Volume Fraction on Void Formation Leading to Ductile Fracture in Dual Phase Steels

2014 ◽  
Vol 54 (4) ◽  
pp. 938-944 ◽  
Author(s):  
Takashi Matsuno ◽  
Daisuke Maeda ◽  
Hiroshi Shutoh ◽  
Akihiro Uenishi ◽  
Masayoshi Suehiro
Keyword(s):  
Ductile Fracture ◽  
Volume Fraction ◽  
Void Formation ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Martensite Volume Fraction

scholarly journals Steel for gas and oil pipelines resistant to destruction in hydrogen sulphide-containing media

2019 ◽  
Vol 121 ◽  
pp. 04008
Author(s):  
Yury Matrosov ◽  
Ivan Shabalov ◽  
Alexey Kholodnyi ◽  
Valery Velikodnev
Keyword(s):  
High Resistance ◽  
Thermomechanical Processing ◽  
Large Diameter ◽  
Controlled Rolling ◽  
Accelerated Cooling ◽  
Homogeneous Microstructure ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Hydrocarbon Fields ◽  
Large Diameter Pipes

About a third reserves of the natural gas and oil contain H2S impurities, which, in the presence of moisture, form an acidic medium and can lead to pipeline destruction by the mechanisms of hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC). With the growing number of hydrocarbon fields being developed with a high content of H2S, the demand for gas and oil large diameter pipes grade from ВМS to Х70MS with high resistance to HIC and SSC increases. Comprehensive studies have been carried out in laboratory and industrial conditions to determine the effect of the chemical composition and thermomechanical processing on the microstructure, mechanical properties and resistance to HIC of rolled plates from low-alloy pipe steels. Optimal concentration of segregating elements (С ≤ 0.06%, Mn ≤ 1.00%), and schedules of accelerated cooling after controlled rolling (Тsc ≥ Ar3; Тfc = 520±30°C; Vc ≥ 20°C/с) provide the high resistance to destruction in H2S-containing media due the formation of a homogeneous microstructure without developed central segregation heterogeneity was determined. According to the research results, the technology for manufacturing of plates for large-diameter pipes grade X52MS, X56MS, X60MS, and X65MS ordered for sour service was developed.

Effects of Microstructure and Texture on DWTT Properties for High Strength Line Pipe Steels

2006 ◽  
Author(s):  
Takuya Hara ◽  
Yasuhiro Shinohara ◽  
Hitoshi Asahi ◽  
Yoshio Terada
Keyword(s):  
Tensile Strength ◽  
High Intensity ◽  
Single Phase ◽  
High Strength ◽  
Rolling Plane ◽  
Dual Phase ◽  
Pipe Steels ◽  
Dual Phase Steels ◽  
Line Pipe ◽  
Plane Parallel

The crack arrestability for high strength line pipe steels with tensile strength of 650 to 850 MPa was evaluated using precrack DWTT (pc-DWTT). Moreover, the effects of microstructure and texture on pc-DWTT energy were investigated. The pc-DWTT energy was remarkably affected by tensile strength. The pc-DWTT energy of ferrite and bainite/martensite dual phase steels was much higher than that of bainite single phase steels in comparison with the same tensile strength. The {100} plane is a cleavage plane in iron, so the brittle crack mainly propagates along the {100} plane. Bainte single phase steels indicated a high intensity of the {100} on the plane rotated 40° from the rolling plane with the axis of the rolling direction. On the other hand, ferrite and bainite/martensite dual phase steels indicated not only a high intensity of the {100} plane rotated 40° from the rolling plane, but also a high intensity of the {100} plane parallel to the rolling plane. Slant fracture could be easily formed by the high intensity of the {100} on the plane rotated 40° from the rolling plane if local brittle areas such as martensite and austenite constituent (M-A constituent), which became the initiation point of brittle fracture, existed. In contrast, separation tended to be formed by the high intensity of the {100} plane parallel to the rolling plane that was caused by the formation of ferrite and bainte/martensite dual phase microstructure. Thus, pc-DWTT energy and shear area were remarkably affected by microstructure and texture. Therefore, to control microstructure and texture is vay important for the improvement of pc-DWTT properties.

Effect of Martensite Fraction on Void Nucleation Behavior and Ductility in DP Steels

2014 ◽  
Vol 783-786 ◽  
pp. 875-879 ◽  
Author(s):  
Daisuke Maeda ◽  
Osamu Kawano
Keyword(s):  
Ductile Fracture ◽  
Void Fraction ◽  
Void Nucleation ◽  
Small Strain ◽  
The Other ◽  
Dual Phase ◽  
Nucleation Behavior ◽  
Martensite Fraction ◽  
Effective Factor ◽  
Dp Steels

Void nucleation behavior of ferrite/martensite dual phase steels varying martensite fraction was investigated. As easily recognized, void fraction was increased with strain induced, and more voids were nucleated in the sample with higher martensite fraction. On the other hands, void fraction at ductile fracture was decreased with increasing martensite fraction. Void nucleation was observed to occur due to the fracture of martensite in DP steels. In the sample with high martensite fraction, many micro voids were nucleated at initial deformation with small strain and lead to ductile fracture. Inter-voids distance at the fracture was almost same among the DP steels with various martensite fractions. It is considered that the most effective factor on ductile fracture of DP steels was not 2nd phase fraction but the distance between 2nd phases which caused micro voids.

Development and Production of Ultra-High Strength Linepipes With Dual-Phase Microstructure for High Strain Application

2007 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Mitsuru Okatsu ◽  
Junji Shimamura ◽  
Shigeru Endo ◽  
Nobuo Shikanai ◽  
...  
Keyword(s):  
Base Material ◽  
High Strength ◽  
Controlled Rolling ◽  
Accelerated Cooling ◽  
Heating Process ◽  
Dual Phase ◽  
Low Carbon ◽  
Cooling Process ◽  
Bainite Microstructure ◽  
Microstructural Control

Extensive studies to develop high strength linepipes with higher deformability have been conducted. One of the key technologies for improving deformability is dual-phase microstructural control. Steel plate with ferrite-bainite microstructure can be obtained by applying Thermo-mechanical controlled processing, TMCP, made up with controlled rolling and accelerated cooling process. Low carbon-boron free steels were used to enable the ferrite formation during cooling after controlled rolling, and the accelerated cooling process with ultimate cooling rate enabled to achieve high strength of up to X120 grade. On-line heating process by induction device was also applied subsequently after accelerated cooling in order to improve Charpy energy of the base material and homogeneity of material properties in the plate. Trial production of X120 high deformability linepipe was also conducted by applying dual-phase microstructural control. Microstructural and mechanical properties of X120 linepipe are introduced in this paper.

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