Influence of Martensitic Islands on Fracture Behaviour of High Heat-Input Weld HAZ

Suzuki, Shinichi; Kamo, Takahiro; KOMIZO, Yuichi

doi:10.2207/qjjws.25.532

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…During tempering, the evolution of M/ A constituents during tempering becomes one of the most important factors influencing the impact toughness. e M/A constituents are generally regarded as a brittle phase [21], and tempering will weaken the embrittlement effect of the M/A constituents [22]. Hence, the impact energy of the weld metal of hot bends increases after tempering at the low temperature.…”

Section: Discussionmentioning

confidence: 99%

Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends

Qiao

Han

Xiao

et al. 2019

Advances in Materials Science and Engineering

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Impact toughness of the weld metal is one of the important factors affecting the quality of hot bends, which is strongly dependent on the microstructure transformation during hot bending and tempering. In this study, three kinds of weld metals with different Ni contents were selected, and then the effects of tempering temperature on the microstructure impact toughness of weld metals for hot bends were investigated by simulation conducted on a Gleeble-3500 thermal simulator. The results show that the nonmetallic inclusion particles in weld metals can become the nuclear core of acicular ferrite like in as-welded metal. So, the overlapping acicular ferrite microstructure is obtained in the weld metal after direct cooling from the reheating temperature. During tempering, the overlapping acicular ferrite microstructure is degenerated, and martensite/austenite (M/A) constituents in the acicular ferrite microstructure decompose into ferrites and carbides. The resulting carbide particles mainly distribute along the acicular ferrite grain boundaries. With the increase of the tempering temperature, the carbide particles coarsen, which decreases the impact toughness of the weld metal of hot bends. Addition of Ni to weld metals can refine the acicular ferrite and improve the impact toughness.

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Section: Discussionmentioning

confidence: 99%

Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends

Qiao

Han

Xiao

et al. 2019

Advances in Materials Science and Engineering

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“…In addition CGHAZ experience heating in the intercritical region during second thermal cycle. This phenomenon leads to formation of M-A constituents (Suzuki et al , 2009). M-A constituents are secondary phases present in the primary microstructure.…”

Section: Introductionmentioning

confidence: 99%

The structural integrity of high-strength welded pipeline steels: a review

Singh

Shukla

Kumar

et al. 2020

IJSI

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PurposeThe key purpose of conducting this review is to identify the issues that affect the structural integrity of pipeline structures. Heat affected zone (HAZ) has been identified as the weak zone in pipeline welds which is prone to have immature failuresDesign/methodology/approachIn the present work, literature review is conducted on key issues related to the structural integrity of pipeline steel welds. Mechanical and microstructural transformations that take place during welding have been systematically reviewed in the present review paper.FindingsKey findings of the present review underline the role of brittle microstructure phases, and hard secondary particles present in the matrix are responsible for intergranular and intragranular cracks.Research limitations/implicationsThe research limitations of the present review are new material characterization techniques that are not available in developing countries.Practical implicationsThe practical limitations are new test methodologies and associated cost.Social implicationsThe fracture of pipelines significantly affects the surrounding ecology. The continuous spillage of oil pollutes the land and water of the surroundings.Originality/valueThe present review contains recent and past studies conducted on welded pipeline steel structures. The systematic analysis of studies conducted so far highlights various bottlenecks of the welding methods.

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“…Optical micrograph shows granular bainite, ferrite (PF) with dispersed M‐A constituents in the microstructure (Figure 13F). According to Suzuki et al, 33 dispersed M‐A constitutes are hard and brittle particles in the matrix. According to Moeinifar et al, 34 dispersed M‐A islands increase localized stress concentration, which increases the risk of crack propagation in the microstructure.…”

Section: Resultsmentioning

confidence: 99%

Influence of heat input on microstructure and fracture toughness property in different zones of X80 pipeline steel weldments

Singh

Arora

Kumar

et al. 2020

Fatigue Fract Eng Mat Struct

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In this paper, microstructure observations and mechanical behaviour of fusion line and offsetting positions from fusion line by 1, 2 and 3 mm were analysed. For the welding of X80 pipeline steel plates, different magnitudes of heat inputs such as high heat input (HHI) 25 kJ/cm, medium heat input (MHI) 20 kJ/cm and low heat input (LHI) 15 kJ/cm were employed. Critical values of J-integral (J 0.2) and crack tip opening displacement (CTOD 0.2) for predetermined regions in the X80 weldment were determined as per ASTM-E1820a. M-A constituents of different sizes such as small (1-2 μm), large >2 μm and slender (>4 μm) were observed in the microstructure of subzones of weldments for different heat inputs. Formation of granular bainite, M-A constituents and inclusions of Ti, Si, Mo in the microstructure impaired fracture toughness property. In the X80 weldment, the fusion line (FL) for HHI was found weakest in terms of fracture resistance, which subsequently increases the risk of fracture.

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Influence of Martensitic Islands on Fracture Behaviour of High Heat-Input Weld HAZ

Cited by 4 publications

References 6 publications

Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends

Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends

The structural integrity of high-strength welded pipeline steels: a review

Influence of heat input on microstructure and fracture toughness property in different zones of X80 pipeline steel weldments

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