Micro-fracture behaviour induced by M-A constituent (Island Martensite) in simulated welding heat affected zone of HT80 high strength low alloyed steel

Chen, J.H.; Kikuta, Yoneo; Araki, Takao; Yoneda, Masafumi; Matsuda, Yutaka

doi:10.1016/0001-6160(84)90234-7

Cited by 157 publications

(75 citation statements)

References 1 publication

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“…7b) throughout the wall-thickness except within 1 mm to both the inner and outer surfaces. These strings of M-A islands are normally found along the prior austenite grain boundaries [20][21][22] which on the fusion surface do not have much mobility under impact from two abutting edges on both sides.…”

Section: Resultsmentioning

confidence: 99%

Tackling the toughness of steel pipes produced by high frequency induction welding and heat-treatment

Yan

Güngör

Thibaux

et al. 2011

Materials Science and Engineering: A

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Steel linepipes produced by high frequency induction welding can result in a low-toughness zone at the weld junction, even after a heat treatment which reaustenitises the affected region. The possible causes for low toughness are explored, including microstructure, retained austenite, inclusions and crystallographic texture. It is found that the toughness is reduced primarily by the tendency for cleavage planes of ferrite crystals to align and hence create a macroscopic plane on which cleavage can propagate easily with little resistance from grain boundaries. This mechanism suggests that an appropriate heat treatment may alter the texture sufficiently to enhance the toughness of the zone concerned.

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Section: Resultsmentioning

confidence: 99%

Tackling the toughness of steel pipes produced by high frequency induction welding and heat-treatment

Yan

Güngör

Thibaux

et al. 2011

Materials Science and Engineering: A

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“…It is generally accepted that CGHAZ and ICCGHAZ are the most detrimental regions from the point of view of toughness and cleavage fracture may occur in the two regions during impact. [3,[5][6][7][8] Thus, there is a need to understand the correlation of structure-property-cleavage fracture mechanism in the HAZ, especially in CGHAZ and ICCGHAZ.…”

Section: Thermo-mechanically Processed X80-x100mentioning

confidence: 99%

“…In regard to nucleation, at least three possible mechanisms have been suggested and include: (a) crack initiation at grain boundaries caused by pile-up of dislocations, [9,10] (b) cracking of inclusions, large second phase particle or martensiteÀaustenite (MÀA) constituent present within the grains or along the grain boundaries, [5][6][7]11] , and (c) decohesion of inclusions/MÀA from matrix. [6][7][8] Cleavage fracture occurs when (1) the maximum principal stress (r yy ) close to the crack tip exceeds fracture stress (r f ) over a characteristic distance, [12] or (2) the microcracks, nucleated ahead of the main crack tip because of high stress field, [13] interconnect with each other. [14] During propagation, there is competition between the microcracks formed at the crack front.…”

Section: Thermo-mechanically Processed X80-x100mentioning

confidence: 99%

Structure–Property–Fracture Mechanism Correlation in Heat-Affected Zone of X100 Ferrite−Bainite Pipeline Steel

Subramanian

et al. 2015

Metallurgical and Materials Transactions E

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Structural performance of a weld joint primarily depends on the microstructural characteristics of heat-affected zone (HAZ). In this regard, the HAZ in X100 ferriteÀbainite pipeline steel was studied by separating the HAZ into intercritically reheated coarse-grained (ICCG) HAZ containing and non-containing regions. These two regions were individually evaluated for Charpy impact toughness and characterized by electron back-scattered diffraction (EBSD). Low toughness of~50 J was obtained when the notch of impact specimen encountered ICCGHAZ and high toughness of~180 J when the notch did not contain ICCGHAZ. Fracture surface was 60 pct brittle in the absence of ICCGHAZ, and 95 pct brittle (excluding shear lip) in the presence of ICCGHAZ in the impact tested samples. The underlying reason is the microstructure of ICCGHAZ consisted of granular bainite and upper bainite with necklace-type martensiteÀaustenite (MÀA) constituent along grain boundaries. The presence of necklace-type M-A constituent notably increases the susceptibility of cleavage microcrack nucleation. ICCGHAZ was found to be both the initiation site of the whole fracture and cleavage facet initiation site during brittle fracture propagation stage. Furthermore, the study of secondary microcracks beneath CGHAZ and ICCGHAZ through EBSD suggested that the fracture mechanism changes from nucleation-controlled in CGHAZ to propagation-controlled in ICCGHAZ because of the presence of necklace-type M-A constituent in ICCGHAZ. Both fracture mechanisms contribute to the poor toughness of the sample contained ICCGHAZ.

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“…It is generally recognized that cleavage fracturing in welded joints is mainly controlled by the microstructure, such as the M-A constituents. The micro-mechanism of cleavage cracks in simulated HAZs is controlled by the size and volume fraction of the martensite-austenite (M-A) constituent [10,11]. Furthermore, it should be noted that the morphologies of M-A constituents are sensitive to cleavage cracking [12,13].…”

Section: Introductionmentioning

confidence: 99%

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

Kim

Nam

Lee

et al. 2018

Metals

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Abstract: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.

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Micro-fracture behaviour induced by M-A constituent (Island Martensite) in simulated welding heat affected zone of HT80 high strength low alloyed steel

Cited by 157 publications

References 1 publication

Tackling the toughness of steel pipes produced by high frequency induction welding and heat-treatment

Tackling the toughness of steel pipes produced by high frequency induction welding and heat-treatment

Structure–Property–Fracture Mechanism Correlation in Heat-Affected Zone of X100 Ferrite−Bainite Pipeline Steel

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

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