Effect of cyclic plastic deformation on microstructure and mechanical properties of weld metals used for reel-lay pipeline steels

Lin, Shuang Ping; Wang, Dongpo; Li, Chengning; Liu, Xiuguo; Di, Xinjie; Jiang, Yuhong

doi:10.1016/j.msea.2018.09.036

Cited by 27 publications

(11 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figures 8(a), (d), and g show the microstructure of the girth weld at 0% pre-strain, which is similar and consists of lath bainite (LB), granular bainite (GB), polygonal ferrite (PF), and M-A island. It has been confirmed in some literatures [24,25] that the effect of small pre-strain on weld microstructure is not significant. Nevertheless, dislocation slip and lattice rotation lead plastic deformation of girth welds in tensile process [26].…”

Section: Strain Distribution and Microstructure Evolution Of Girth-we...mentioning

confidence: 62%

Effect of pre-strain on microstructure evolution and fracture behavior of undermatching X80 pipeline steel girth weld

Dai,

Jia,

Yang

et al. 2024

Mater. Res. Express

View full text Add to dashboard Cite

This work aims to study the effect of pre-strain on the fracture behavior of X80 pipeline girth weld joint, a comprehensive analysis was conducted on the microstructure and mechanical properties of the girth weld before and after pre-strain treatment. The mechanical properties were evaluated through tensile testing, Charpy impact testing, and digital image correlation (DIC) strain analysis. Furthermore, the microstructure and fracture morphology of the girth weld were observed using optical electron microscopy (OM) and scanning electron microscopy (SEM). The results show that the application of pre-strain treatment leads to dislocation accumulation at the grain boundary of X80 pipeline girth weld, resulting in stress concentration and subsequent formation of damage holes. This process disrupts the continuity of chain M-A island and initiates small cracks at the grain boundary, ultimately causing a significant decrease in impact toughness and impact work from 177 J to about 10 J.

show abstract

Section: Strain Distribution and Microstructure Evolution Of Girth-we...mentioning

confidence: 62%

Effect of pre-strain on microstructure evolution and fracture behavior of undermatching X80 pipeline steel girth weld

Dai,

Jia,

Yang

et al. 2024

Mater. Res. Express

View full text Add to dashboard Cite

show abstract

“…Combining the CTOD results listed in Table 4 , it can be seen that there is a clear positive correlation between the CTOD fracture toughness and the fracture contour map at the front the prefabricated fatigue crack, especially in high brittle materials and their structures with low CTOD performance. Excellent fracture toughness must be accompanied by larger plastic deformation [ 30 ], which is reflected in the macroscopic height cloud map. For a given sample size, the greater the height difference at the crack front, the better the fracture toughness and the higher the CTOD value.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Liu

et al. 2022

Materials

Self Cite

View full text Add to dashboard Cite

The coarse-grain heat-affected zones (CGHAZs) of X80 girth-welded steel pipelines are prone to embrittlement, which has an extremely adverse effect on their structural integrity. In the present work, the fracture behavior of the CGHAZs of X80 girth welds under the conditions of conventional and ultra-low heat input was studied. The fracture toughness of CGHAZs was evaluated using the crack tip opening displacement (CTOD) test at −10 °C, and the fracture behavior mechanism of CGHAZs were clarified by analyzing microstructural characteristics at prefabricated fatigue cracks containing fracture cloud image, scanning electron microscopy (SEM), and electron back-scatter diffraction (EBSD) figures. The results illustrate that the average fracture toughness (CTOD) value of the ultra-low heat input CGHAZ is 0.6 mm, and the dispersion of CTOD values is small, while the CTOD value of conventional heat input is only 0.04 mm. The ultra-low heat input makes the high-temperature residence time of the coarse-grained region short, reduces the proportion of prior austenite grain boundaries, and inhibits the formation of strip-like bainite and island-like M-A components. The reduction of these deleterious ductile microstructures increases the plastic reserve and deformation capacity of the CGHAZ.

show abstract

“…It is known that XRD peak profiles are the result of the instrument and tested samples. Hence, before calculating the dislocation density, the instrumental contribution to the peak broadening has subtracted from the row date [ 28 , 29 , 30 ]. Then, the dislocation density, ρ , was quantitatively calculated by the modified Williamson–Hall method, which can be expressed as the following Equation (1):

where ε represents the non-uniform strain, and b represents the Burst’s vector of the dislocation in α-Fe (b = 0.248 nm) can be determined as the slope which was obtained by performing a linear regression of Δθ·cos θ/λ and 2 sin θ/λ of the first three peaks in XRD patterns.…”

Section: Resultsmentioning

confidence: 99%

Effect of Tempering Treatment on Microstructural Evolution and Mechanical Behavior of Heavy-Wall Heat Induction Seamless Bend Pipe

Liu

Wang

et al. 2021

Materials

View full text Add to dashboard Cite

In this paper, the microstructure and mechanical properties of heavy-wall seamless bend pipe after quenching at different tempering temperatures, including 550 °C, 600 °C, 650 °C, and 700 °C, were studied. Microstructure and dislocations observations were characterized by means of an optical microscope, a scanning electron microscope, a transmission electron microscope, and X-ray diffraction. As the tempering temperature increases, the dislocation density in the test steel gradually decreases, and the precipitation behavior of (Nb, V)(C, N) increases. The sample tempered at 650 °C exhibits a granular bainite structure with a dislocation cell structure and a large number of smaller precipitates. The yield platforms of tempered samples at 650 °C and 700 °C are attributed to the pinning effect of the Cottrell atmosphere on dislocations. The sample tempered at 650 °C not only presents the highest strength, but also the highest uniform elongation, which is attributed to the higher strain-hardening rate and instantaneous work-hardening index. This is closely related to the multiplication of dislocations, the interaction between dislocations and dislocations, and the interaction between dislocations and precipitates during plastic deformation of the 650 °C-tempered samples with low dislocation density, which delays the occurrence of necking.

show abstract

Effect of cyclic plastic deformation on microstructure and mechanical properties of weld metals used for reel-lay pipeline steels

Cited by 27 publications

References 28 publications

Effect of pre-strain on microstructure evolution and fracture behavior of undermatching X80 pipeline steel girth weld

Effect of pre-strain on microstructure evolution and fracture behavior of undermatching X80 pipeline steel girth weld

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Effect of Tempering Treatment on Microstructural Evolution and Mechanical Behavior of Heavy-Wall Heat Induction Seamless Bend Pipe

Contact Info

Product

Resources

About