Microstructure and Mechanical Properties of Intercritical Heat-affected Zone of X80 Pipeline Steel in Simulated In-Service Welding

Di, Xinjie; Cai, Lin; Xing, Xi-Xue; Chen, Cuixin; Xue, Zhen-Kui

doi:10.1007/s40195-015-0272-2

Cited by 25 publications

(13 citation statements)

References 23 publications

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“…This subregion needs more attention to be known as the local brittle zone [5,8] (LBZ). The temperature range between A c1 and A c3 , is favorable to MA microconstituent formation in multipass weldments [2,5,8], as it can deteriorate the steel toughness, depending on its size and distribution in the ferritic matrix [9,10]. The following sub-region is reheated in the subcritical temperature range: it arises the SC-CGHAZ.…”

Section: Introductionmentioning

confidence: 99%

A New Approach to Simulate HSLA Steel Multipass Welding through Distributed Point Heat Sources Model

Ferreira

Alves

Neto

et al. 2018

Metals

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Mechanical properties of welded joints depend on the way heat flows through the welding passes. In multipass welding the reheating of the heat affected zone (HAZ) can form local brittle zones that need to be delimited for evaluation. The difficulty lies in the choice of a model that can simulate multipass welding. This study evaluated Rosenthal’s Medium Thick Plate (MTP) and the Distributed heat Sources (DHS) of Mhyr and Gröng models. Two assumptions were considered for both models: constant and temperature-dependent physical properties. It was carried out on a multipass welding of an API 5L X80 tube, with 1016 mm (42″) external diameter, 16 mm thick and half V-groove bevel, in the 3G up position. The root pass was welded with Gas Metal Arc Welding (GMAW) process with controlled short-circuit transfer. The Flux Cored Arc Welding (FCAW) process was used in the filling and finishing passes, using filler metal E111T1-K3M-JH4. The evaluation criteria used were overlapping the simulated isotherms on the marks revealed in the macrographs and the comparison between the experimental thermal cycle and those simulated by the proposed models. The DHS model with the temperature-dependent properties presented the best results and simulated with accuracy the HAZ of root and second welding passes. In this way, it was possible to delimit the HAZ heated sub-regions.

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Section: Introductionmentioning

confidence: 99%

A New Approach to Simulate HSLA Steel Multipass Welding through Distributed Point Heat Sources Model

Ferreira

Alves

Neto

et al. 2018

Metals

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“…The Multiphysics Object-Oriented Simulation Environment (MOOSE), which is an open-source finite-element analysis software framework developed and maintained by Idaho National Laboratory, was used for the X100 pipeline steel laser-welding temperature field simulation. To compare the laser-welding temperature field simulation results with the actual working conditions of the welding process, a two-dimensional finite-element model consistent with the actual welding joint size was established through reasonable model abstraction and reliable data for the material thermophysical parameters that were calculated by JmatPro [31][32][33][34][35]. The material thermophysical parameters are shown in Table 3.…”

Section: Establishment and Solution Of The Finite-element Modelmentioning

confidence: 99%

“…According to the shape parameters of the weld seam and the welding heat-affected zone (HAZ), the heat-source model for a Gaussian-distributed rotating body is proposed (Equations (1)-(3)). Heat convection, heat conduction, and heat radiation are taken into account in the boundary conditions (Equations 4and 5) [32,34,[36][37][38][39][40]. The model was solved by the Preconditioned Jacobian-Free Newton-Krylov algorithm (PJFNK).…”

Section: Establishment and Solution Of The Finite-element Modelmentioning

confidence: 99%

Quantitative Correlation between Thermal Cycling and the Microstructures of X100 Pipeline Steel Laser-Welded Joints

Wang

Wang²,

Yin

et al. 2019

Materials

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Due to the limitations of the energy density and penetration ability of arc welding technology for long-distance pipelines, the deterioration of the microstructures in the coarse-grained heat-affected zone (HAZ) in welded joints in large-diameter, thick-walled pipeline steel leads to insufficient strength and toughness in these joints, which strongly affect the service reliability and durability of oil and gas pipelines. Therefore, high-energy-beam welding is introduced for pipeline steel welding to reduce pipeline construction costs and improve the efficiency and safety of oil and gas transportation. In the present work, two pieces of X100 pipeline steel plates with thicknesses of 12.8 mm were welded by a high-power robot laser-welding platform. The quantitative correlation between thermal cycling and the microstructure of the welded joint was studied using numerical simulation of the welding temperature field, optical microscopy (OM), and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The results show that the heat-source model of a Gaussian-distributed rotating body and the austenitization degree parameters are highly accurate in simulating the welding temperature field and characterizing the austenitization degree. The effects of austenitization are more significant than those of the cooling rate on the final microstructures of the laser-welded joint. The microstructure of the X100 pipeline steel in the HAZ is mainly composed of acicular ferrite (AF), granular bainite (GB), and bainitic ferrite (BF). However, small amounts of lath martensite (LM), upper bainite (UB), and the bulk microstructure are found in the columnar zone of the weld. The aim of this paper is to provide scientific guidance and a reference for the simulation of the temperature field during high-energy-beam laser welding and to study and formulate the laser-welding process for X100 pipeline steel.

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“…Considering the effect of effective grain size on the toughness, it is suggested that both M-A constitutions and effective grain size are the key factors to determine the absorbed energy when t 8/5 is larger than 60 s. However, at high heat input, M-A constitutions plays more dominant role on the toughness than effective grain size owing to severe damage of M-A constitutions on the toughness. 3,[26][27][28][29][30][31] Coarse austenite grain size increases the size of M-A constituents and lowers the CGHAZ impact energy. Li et al 26) have elucidated the role of the fraction, size, shape, distribution of M-A constituents on impact toughness and concluded that the size of M-A constituent was influenced by the prior austenite grain size, consequently, which governed impact energy.…”

Section: M-a Constitutionsmentioning

confidence: 99%

Effect of Heat Input on Microstructure and Toughness of Coarse Grained Heat Affected Zone of Q890 Steel

et al. 2016

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Microstructure evolution and impact toughness measurement on a coarse grained heat affected zone (CGHAZ) of Q890steel have been investigated in this study by Gleeble 1 500 simulation technique. The results indicate that a relevant mediate energy input is recommended for welding of Q890 steel, according to a fact that an impact energy as high as 83 J is attained in the CGHAZ with t 8/5 of 20 s. It is related to the cumulative contribution of prior-phase bainitic ferrite separated martensite comprises interlocking structure of laths that can promote a sufficient subdivision of the block and finer effective grain size and the highest density of high angle boundaries. Higher heat input can result in brittle fracture in the CGHAZ since the stress concentration and triaxiality of the neighboring matrix are increased by the hard phase particles such as M-A constituents.KEY WORDS: microstructure; M-A constituents; impact toughness; electron backscattered diffraction (EBSD).

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Microstructure and Mechanical Properties of Intercritical Heat-affected Zone of X80 Pipeline Steel in Simulated In-Service Welding

Cited by 25 publications

References 23 publications

A New Approach to Simulate HSLA Steel Multipass Welding through Distributed Point Heat Sources Model

A New Approach to Simulate HSLA Steel Multipass Welding through Distributed Point Heat Sources Model

Quantitative Correlation between Thermal Cycling and the Microstructures of X100 Pipeline Steel Laser-Welded Joints

Effect of Heat Input on Microstructure and Toughness of Coarse Grained Heat Affected Zone of Q890 Steel

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