X100 Linepipe With Excellent HAZ Toughness and Deformability

2003 ◽  
Author(s):  
Yoshio Terada ◽  
Hiroshi Tamehiro ◽  
Hiroshi Morimoto ◽  
Takuya Hara ◽  
Eiji Tsuru ◽  
...  
Keyword(s):  
Low Temperature ◽  
Carbon Content ◽  
Heat Affected Zone ◽  
Uniform Elongation ◽  
Base Material ◽  
Controlled Rolling ◽  
Accelerated Cooling ◽  
Low Temperature Toughness ◽  
Sufficient Strength ◽  
Haz Toughness

Good low-temperature toughness of the base material (BM) and weld heat-affected zone (HAZ), and good deformability of the pipe body together with good field weldability are required for X100 linepipe to ensure the safety of pipelines and to facilitate field welding. It is, however, very difficult to attain these properties simultaneously because of the large addition of alloys. The technology of improving HAZ toughness by reducing carbon content through the reduction of M-A constituents harmful to low-temperature toughness was developed, and accelerated cooling after controlled rolling was applied to attain good low-temperature toughness of BM and high uniform elongation together with sufficient strength corresponding to X100. Two newly developed types of X100 linepipe, a “high HAZ toughness type” and a “high uniform elongation type”, exhibited excellent low-temperature toughness of the HAZ and high uniform elongation together with sufficient strength, respectively.

Offshore Structural Steel Plates for Extreme Low Temperature Service With Excellent HAZ Toughness

2014 ◽  
Author(s):  
Katsuyuki Ichimiya ◽  
Kazukuni Hase ◽  
Shigeru Endo ◽  
Yusuke Terazawa ◽  
Takaki Fujiwara ◽  
...  
Keyword(s):  
Low Temperature ◽  
Main Property ◽  
Offshore Structures ◽  
Nucleation Site ◽  
Steel Plates ◽  
Crack Tip Opening Displacement ◽  
Offshore Structure ◽  
Opening Displacement ◽  
Low Temperature Toughness ◽  
Haz Toughness

The strength and the toughness required for steel plates used for offshore structures became higher as the installation areas move into arctic areas. The main property of offshore structure steel is the crack tip opening displacement (CTOD) property of weld joint, and CTOD testing is performed at the minimum design temperature of the structure. Thus, the demand for satisfying −40°C of CTOD test temperature specification has increased. For the improvement of HAZ toughness, coarse austenite grain is suppressed by TiN, and low-C, Ceq, Si, P, Nb design is adopted to decrease the formation of M-A constituents. Furthermore, by using Ca inclusion, which works as a pinning particle and a bainite nucleation site, very fine bainite microstructure are formed in HAZ and excellent low temperature toughness are achieved. The YP420 class plate with excellent low temperature toughness has been developed using these technology.

Development of Offshore X65/70 Steels for Deep Water Application

2012 ◽  
Author(s):  
Yun-Jo Ro ◽  
Seung-Hwan Chon ◽  
Jang-Yong Yoo ◽  
Ki-Bong Kang
Keyword(s):  
Low Temperature ◽  
Deep Water ◽  
Processing Parameters ◽  
Alloying Elements ◽  
Accelerated Cooling ◽  
Dual Phase ◽  
Effective Grain Size ◽  
Low Temperature Toughness ◽  
Shear Area ◽  
Linepipe Steels

Heavy gauge X65/70 steels have been developed for deep-water offshore application. As the thickness of linepipe steels is increased, Mo, Ni, V alloying elements are generally employed to improve the low temperature toughness and strength balance. However, the price of such alloying element has been rapidly increased. Hence, in the present work, a lean composition is designed to achieve thick X65/70 grade steels with better strength and toughness balance. To prevent the degradation of toughness or strength due to a lean alloying composition, the authors optimize processing parameters, such as a rolling stop temperature or accelerated cooling patterns. By in large, two strategies have been applied to develop linepipe steels; i) cooling starts in γ + α region, and iii) rolling stops in γ + α region. These strategies promote ferrite+bainite dual phase microstructures exhibiting a good low temperature toughness and strength balance. Such dual phase microstructures are characterized by using EBSD (electron back scattered diffraction) technique. The result shows a percentage of DWTT shear area is strongly correlated with effective grain size (misorientation ≥ 15°). As a result, the present work demonstrates that heavy gauge API steels grade X65/70 can be achieved with Mo+V free or small addition of Mo alloying elements.

High Strength Heavy Plate Optimised for Application in Remote Areas and Low-Temperature Service

2010 ◽  
Author(s):  
Charles Stallybrass ◽  
Joachim Konrad ◽  
Heike Meuser ◽  
Fabian Grimpe
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
High Strength ◽  
Alternative Methods ◽  
Accelerated Cooling ◽  
Processing Conditions ◽  
Remote Areas ◽  
Heavy Plate ◽  
Low Temperature Toughness ◽  
Ebsd Method

The last decades have seen a steady increase in the demand for high-strength linepipe steels. These offer the most economical option to transport large gas volumes at high pressures from remote areas to the market. Since the beginning of the 1980’s, high strength heavy plates, pipes and pipe bends were developed and produced at Salzgitter Mannesmann Grobblech GmbH and EUROPIPE. Since these days, these products were steadily improved for example in terms of toughness and weldability. As gas resources in increasingly hostile environments are developed, the requirements with regard to deformability and low-temperature toughness have gained growing significance. This is a strong focus of materials development around the world. Modern high-strength heavy plates used in the production of UOE pipes are generally produced by thermomechanical rolling followed by accelerated cooling (TMCP). If accelerated cooling starts above the ferrite-austenite transformation temperature, this processing route results in a microstructure that consists predominantly of bainite. The combination of high strength and high toughness of these steels are a result of the microstructure realised by TMCP and are strongly influenced by the rolling and cooling conditions. Classical light-optical characterisation of the microstructure of these steels is at its limits because the size of the observed features is too small to allow reliable quantitative results. Therefore alternative methods have to be used to obtain a better understanding of the influence of processing conditions on the microstructure. The mechanical properties of high strength plates produced at Salzgitter Mannesmann Grobblech (MGB) and of material rolled using a laboratory rolling mill at the Salzgitter Mannesmann Forschung (SZMF) was characterised with special emphasis on low-temperature toughness. The microstructure was investigated using the electron backscatter diffraction (EBSD) method. With this method, it is possible to gain quantitative information related to features of the microstructure and relate these to the mechanical properties of the plate material. It was found that a variation of the processing conditions has a direct influence on parameters that are accessible through the EBSD method and correlates with mechanical properties. These results can be used as valuable input for the definition of the processing window for heavy plate production depending on the required plate properties.

Microstructure and Properties of High Performance Steels by Controlled Rolling

2013 ◽  
Vol 459 ◽  
pp. 87-90
Author(s):  
Yue Bin Zhu ◽  
Xue Min Wang
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
High Performance ◽  
Uniform Elongation ◽  
Controlled Rolling ◽  
Similar Performance ◽  
Performance Requirements ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness ◽  
Quenched And Tempered Steel

High performancesteels (HPS) require low yield ratio, high uniform elongation and high low temperature impact toughness in addition to higher strength. In this paper,experimental steelswere produced by controlled rolling and tempering to meet high performance requirements. Itwasconcluded that experimental steels by controlled rolling and tempering had similar performance with quenched and tempered steel (QT).

Microstructure Transformation and Mechanical Properties of X80 Large Diameter Thick Wall Induction Heating Bend for Low Temperature Service

2020 ◽  
Author(s):  
Yu Liu ◽  
Zongbin You ◽  
Lijun Yan
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Weld Metal ◽  
Acicular Ferrite ◽  
Base Material ◽  
Welding Process ◽  
Seam Weld ◽  
Bent Pipe ◽  
Low Temperature Toughness ◽  
Submerged Arc

Abstract For the requirement of pipeline station construction project, Grade X80 Longitudinally Submerged Arc Welded (LSAW) induction bend pipe 1422 mm in diameter and wall thickness greater than 25 mm have been developed for pipeline station service applications at −45 °C. The mother pipe of the bends was welded by Ni-Cr-Cu-Mo-Nb-V micro-alloyed Thermo Mechanical Control Process (TMCP) steel plates. After the heat cycle of the bent pipe manufacturing, the microstructure of the base material of the bent pipe consisted of lath bainite ferrite (LBF) and granular bainite (GB). Therefore, it can obtain high strength and excellent low temperature toughness, which can meet the requirements of the project. On the other hand, the welding of the longitudinal seam-welds of the bend mother pipe uses a typical multi-wire two-pass submerged arc welding (SAW) process, which has a large amount of welding heat input. This results in a coarse columnar weld structure with a large amount of fine acicular ferrite so that the seam weld still has a good low temperature impact toughness. However, after the thermal cycling of the bend, the acicular ferrite in the microstructure of the weld metal was greatly reduced, and the grain size was unevenly distributed, which caused the low temperature toughness of the weld metal to deteriorate significantly. In order to solve this problem, the Gleeble3500 thermal simulation test machine was used to test the phase transition critical point Ac3 of the base material and the seam weld metal of the mother pipe. In order to optimize the induction bend process parameters, the influence of heating temperature, cooling rate and tempering temperature on microstructure and mechanical properties were examined. In addition, on the basis of the existing welding process, the welding wire and flux for pipe-making seam-welding were improved, and the pipe-making welding process of the bent mother pipe was improved.

scholarly journals Development of Heavy Gauge Hot Coils with High Strength and Excellent Low Temperature Toughness by Controlled Rolling

1981 ◽  
Vol 67 (3) ◽  
pp. 557-566 ◽  
Author(s):  
Kazutoshi KUNISHIGE ◽  
Masashi TAKAHASHI ◽  
Seiichi SUGISAWA ◽  
Tadao HAMANAKA
Keyword(s):  
Low Temperature ◽  
High Strength ◽  
Controlled Rolling ◽  
Low Temperature Toughness

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.

scholarly journals Effect of Martensite–Austenite Constituent on Low-Temperature Toughness in YS 500 MPa Grade Steel Welds

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 638 ◽  
Author(s):  
In Kim ◽  
Hyunbin Nam ◽  
Myungjin Lee ◽  
Daegeun Nam ◽  
Yeongdo Park ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Affected Zone ◽  
Coarse Grained ◽  
Fine Grained ◽  
Direct Quenching ◽  
Austenite Grain ◽  
Low Temperature Toughness ◽  
Steel Welds ◽  
Quenching And Tempering ◽  
Grade Steel

The effect of martensite–austenite (M–A) constituents and simulated microstructure on low-temperature toughness was investigated in YS 500 MPa grade structural steel welds. The specimens were fabricated using a direct quenching and tempering process. After simulated weld thermal cycles, the coarse-grained heat-affected zone (CGHAZ) and intercritically reheated coarse-grained heat-affected zone (IRCGHAZ) were produced using a Gleeble tester and real welded joint to support the simulation results. The largest low-temperature toughness was observed in the fine-grained heat-affected zone (FGHAZ) owing to the fine-ferrite microstructure. However, the toughness decreased in the IRCGHAZ because of the slender morphology of the M–A constituents that formed primarily along the prior austenite grain boundaries in the IRCGHAZ.

Sign in / Sign up

Export Citation Format

Share Document