scholarly journals Tensile Deformation and Fracture Behavior of API-5L X70 Line Pipe Steel

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 501
Author(s):  
Mikhail L. Lobanov ◽  
Vladislav A. Khotinov ◽  
Vladimir N. Urtsev ◽  
Sergey V. Danilov ◽  
Nikolay V. Urtsev ◽  
...  

Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary HSLA steel plates utilized for gas and oil pipeline production. The strength and crack resistance of pipeline steels are mainly determined by its microstructure and crystallographic texture. In this study, the influence of the structural and textural states of industrially produced API-5L X70-X80 pipeline steels on tensile mechanical properties was analyzed. TMCP routes with different hot rolling temperatures and cooling rates were employed. The texture of steel was assessed using the Taylor factor, which was calculated based on electron backscatter diffraction (EBSD). The decrease in rolling temperature resulted in the sharper texture characterized by {001} planes banding (cleavage planes in the bcc lattice) parallel to rolling direction. The tensile deformation behavior at the stage of necking was determined by the crystallographic and morphological texture of the material and demonstrated significant anisotropy. Rupture of all investigated samples was accompanied by the development of splitting on the fracture surface. The splitting was localized in the rolling plane similar to the splitting in standard Charpy tests of pipeline steels.

Author(s):  
Martin Hukle ◽  
Brian Newbury ◽  
Dan Lillig ◽  
Jonathan Regina ◽  
Agnes Marie Horn

The intelligent design of a given pipeline system intended for operation beyond the elastic limit should incorporate specific features into both the base material (line pipe) and girth weld that enable the affected system to deform safely into the plastic regime within the intended strain demand limits. The current paper focuses on the mechanical properties known to influence the strain capacity of the base material (i.e., line pipe steel independent of the girth weld). Line pipe mechanical properties of interest include: longitudinal yield strength, tensile strength, yield to tensile strength ratio, reduction of area, elongation and uniform elongation. Of particular interest (in consideration of the conventional thermally applied corrosion protection coating systems to be employed), are the longitudinal mechanical properties in the “aged” condition. The present study investigates six (6) different pipeline steels encompassing grades X60 (415 MPa) to X100 (690 MPa), and includes both UOE Submerged Arc Welded - Longitudinal (SAW-L) and seamless (SMLS) forming methods.


2011 ◽  
Vol 197-198 ◽  
pp. 724-729 ◽  
Author(s):  
Yue Yue Hu ◽  
Xiu Rong Zuo ◽  
Ru Tao Li ◽  
Zhen Wei Wang

The microstructure and mechanical properties of ferrite-bainite dual-phase pipeline steels respectively produced by thermomechanical control process (TMCP) and intercritical annealing were studied using optical microscope, scanning electron microscope (SEM), Vickers hardness tester and MTS 810 servo-hydraulic machine. The results show that these two processes obtain different morphology and distribution of microstructure, but the mechanical properties of them are similar and superior, especially the yield ratios are low. It is found that for TMCP steel, the grains of ferrite are large and the average ferrite grain size is approximately 6.1µm. The bainite structures are lump-shaped with concentrated distribution in the ferrite matrix and the band structure is obvious. For steels produced by intercritical annealing process, the grains are finer and the distribution of bainite is uniform on the ferrite grain boundaries. From the rolling plane to the centre, the grain sizes of ferrite in these two microstructures increase obviously, and the volume fraction of bainite first increases significantly, then decreases slightly in the TMCP steel and the average volume fraction is approximately 60.1%. However, the bainite volume fraction in the intercritical annealing steel decreases gradually and the average volume fraction is approximately 35.4%. Moreover, hardness values in through-thickness direction are uniform in the TMCP steel and these values are also similar in the intercritical annealing steel except the values in the region near the rolling plane are much larger.


Author(s):  
Jingjing Li ◽  
S. Jack Hu ◽  
John E. Carsley ◽  
Theresa M. Lee ◽  
Louis G. Hector ◽  
...  

The effects of different prestrain levels, paths, and subsequent annealing on the postannealing mechanical properties of AA5182-O were investigated. Aluminum sheet specimens were prestrained in uniaxial, plane strain, and equibiaxial tension to several equivalent strain levels, annealed at 350 °C for short (10 s) and long (20 min) durations and then tested for postannealing mechanical properties, including tensile properties, anisotropy, and forming limits. The tensile properties, R-values at 0, 45, and 90 deg relative to the sheet rolling direction, and forming limit diagrams (FLDs) exhibited dependencies on prestrain and annealing history. The importance of the process variables and their effects were identified via designed experiments and analysis of variance. Three-dimensional digital image correlation, which captured the onset of local necking, was employed in the FLD development. Texture in the as-received and deformed sheets was investigated with electron backscatter diffraction and provided a means for linking prestrain and static recovery or recrystallization with microstructure. This guided the understanding of the mechanical property changes observed after preforming and annealing. Ultimately, the expanded forming limit curve demonstrated the advantage of annealing in extending the formability of strained AA5182-O.


2021 ◽  
Vol 890 ◽  
pp. 25-32
Author(s):  
Alin Constantin Murariu ◽  
Aurel Valentin Bîrdeanu

In all industrial fields, the product requirements are more and more demanding. HSLA steels are designed to provide higher atmospheric corrosion resistance and improved mechanical properties than structural steels. The paper presents the results of an experimental program based on factorial design, applied to predict the mechanical properties of butt-welded joints of S420MC and S460MC hot-rolled, high-strength low-alloy (HSLA) steel plates with 2mm, 4mm and 8mm thickness. Gas Metal Arc Welding (GMAW) was used and correlations between the main process parameters and the related mechanical properties of the welded joints were found. Obtained mathematical correlations can be exploited to provide optimal combination of welding parameters to fit the quality requirements of the end-users for envisaged welded product.


2015 ◽  
Vol 816 ◽  
pp. 381-386
Author(s):  
H. Yan ◽  
R.S. Chen ◽  
E.H. Han

Mg-2.0Zn-xGd sheets with non-basal texture were fabricated by common rolling process, which showed excellent ductility and formability at room temperature. In this paper, tensile tests were carried out at moderate temperature along the rolling direction and transverse direction to evaluate the influences of tensile temperature on mechanical properties and formability of the sheet. The microstructural evolution during tensile deformation was also investigated to analysis deformation mechanisms. The results showed that the elongation of the sheets increased from 57% at 373K to 253% at 573°C along the rolling direction, while the yield strength decreased with the increase of tensile temperature. The microstructure observation indicated that twining was one of the deformation modes and no dynamic recrytallization took place during deformation at 373K. With temperature increasing up to 473K, dynamic recrystallization took place and led to finer microstructure. This suggests that the formability of the Mg-Zn-Gd sheets with high ductility at room temperature could be further improved by increasing temperature up to 473K, which could refine the microstructure leading to higher strength during second forming process.


Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 860 ◽  
Author(s):  
Qiang Liu ◽  
Jiangfeng Song ◽  
Fusheng Pan ◽  
Jia She ◽  
Shuo Zhang ◽  
...  

A series of Mg-1Al-1Sn-Mn magnesium alloy sheets were rolled from 3 mm to 1 mm under temperatures of 150 °C, 200 °C, and 250 °C in four rolling passes using on-line heating rolling. The conventional rolling was also performed for comparison. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) technologies were utilized to characterize the edge cracks as well as the microstructure of rolled thin sheets. The result revealed that the number of edge cracks decreased dramatically with the increase of rolling temperature. No visible edge cracks were found on the surface of sheets rolled at 250 °C by on-line heating rolling, while the conventional rolling at the same temperature still resulted in severe edge cracks. The intensity of the basal texture for on-line rolled sheets increased from 4.982 to 9.596 as the rolling temperature increased from 150 °C to 250 °C, which was related to the reorientation of new grains and deformation grains remained after rolling. The direction of the basal pole slightly tilted towards the rolling direction (RD), which may be mainly attributed to the activation of a pyramidal slip, as well as the tension imposed on the samples. Moreover, mechanical properties were improved after rolling on the basis of the strong texture and grain refinement. The highest yield strength (YS), ultimate tensile strength (UTS), and the maximum elongation of the rolled sheets were 148 MPa, 298 MPa, and 14.6% along the RD, respectively.


2011 ◽  
Vol 197-198 ◽  
pp. 757-761
Author(s):  
Gui Zhi Xiao ◽  
Kuai She Wang ◽  
Fu Xian Zhu ◽  
Hong Shuang Di

SPV490Q steel is a low alloy high strength structural steel plate used in the manufacture of oil storage tank. To improve the comprehensive performance of SPV490Q steel plate and reduce manufacturing costs, direct quenching technology has been developed as revolutionary plate manufacturing technologies in recent years. Effect of direct quenching on microstructure and mechanical properties of high performance SPV490Q steel plate has been studied. The direct quenched (DQ) steel plates are rolled at different finish rolling temperatures, and their microstructures and mechanical properties are compared with those of reheat quenched (RQ) steel plate. The optical microstructure of the DQ steel shows deformed grains elongated parallel to the rolling direction, while complete equiaxed grains are visible in RQ steel. The transmission electron microscope (TEM) microstructure of the DQ steel shows refined lath martensite with high density of dislocations. The findings indicate that the application of the direct quenching process to low-carbon alloy steels contributes to the production of steel plates with excellent strength and toughness.


Author(s):  
Taylor R. Jacobs ◽  
David K. Matlock ◽  
Kip O. Findley ◽  
Laurie Collins

The mechanical properties of six industrially produced pipeline steels equivalent to API X52, X60, and X70 specifications were evaluated in the temperature range of 200–350 °C. The steels were tested in uniaxial tension at strain rates of 10−4 and 8 × 10−4 s−1 in the as-received condition and after a low temperature 100 h aging process under a 419 MPa tensile stress. Dynamic strain aging was identified in the tensile data with the observation of serrated yielding, minima in ductility and maxima in ultimate tensile strength with respect to temperature. In addition to minima in ductility, higher strength grade steels exhibited maxima in ductility at high temperatures and greater amounts of strengthening compared to the lower strength grade, both which could be attributed to the precipitation of carbides or nitrides during tensile deformation. The low temperature aging process resulted in increased yield strength due to static strain aging, slight changes to ultimate tensile stress and, no observable change in ductility. Thus, based on the results discussed it is suggested that pipeline steels can be designed based on room temperature tensile properties, using established corrections for such properties at elevated temperatures.


2005 ◽  
Vol 38 (1) ◽  
pp. 56
Author(s):  
P. K. Ghosh ◽  
A. K. Saxena ◽  
K. Devakumaran
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document