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Decohesions

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Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001816
EISBN: 978-1-62708-241-9
... Abstract This paper describes the superplastic characteristics of shipbuilding steel deformed at 800 °C and a strain rate less than 0.001/s. After the superplastic deformation, the steel presents mixed fractures: by decohesion of the hard (pearlite and carbides) and ductile (ferrite) phases and...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001838
EISBN: 978-1-62708-241-9
... Abstract Stainless steel pipe (273-mm OD x 8-mm wall thickness) used in the fabrication of large manifolds developed crack-like decohesions during a routine inductive bending procedure. The imperfections, which were found near the outside diameter, were around 3 mm in length oriented in the...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001380
EISBN: 978-1-62708-215-0
... crack origins which assumed a “thumbnail” shape and displayed surface morphologies which resulted from intergranular decohesion. Many of the crack sites initiated from corrosion pits. Energy dispersive spectroscope performed on areas within the crack initiation site showed the presence of chlorides. The...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001383
EISBN: 978-1-62708-215-0
... either a fatigue mechanism or ductile overload failure. SEM analysis revealed that the mode of fracture was intergranular decohesion, which indicates an environmental influence in the fracture mechanism. The primary fracture initiated at a thread root and propagated by environmentally-assisted slow crack...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.chem.c9001534
EISBN: 978-1-62708-220-4
... crack initiation zone, cracking was intergranular. This region also exhibited blisters around inclusions. Microcracks emanating from inclusion sites and decohesion of inclusion/matrix interfaces were also noticed. These features are characteristic of hydrogen embrittlement ( Ref 9 , 10 ). According...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001837
EISBN: 978-1-62708-241-9
... micrographs of capping face of cracked specimen showing ( a ) weld zone, ( b ) HAZ, ( c ) base metal, ( d ) CGHAZ and ( e ) intergranular cracks in CGHAZ and ( f ) intergranular cracks and grain boundary decohesion in CGHAZ (magnification 200×) Figure 10 shows the high magnification (1000×) optical...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006777
EISBN: 978-1-62708-295-2
... cracking steam generator tubes INTERGRANULAR FRACTURE is decohesion that occurs along a grain boundary. Intergranular fracture is often associated with the presence of an embrittlement mechanism or the presence of precipitates and segregates at the grain boundary, which make the grain boundary the...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001107
EISBN: 978-1-62708-214-3
... graphite. Stresses generated by phase transformations promote decohesion of metal particles and graphite, and gross metal wastage (dusting) occurs. Fig. 6 Reactivity of sever air representative alloys reacted in Co. Once this mechanism was initiated, reaction rates probably accelerated when...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001801
EISBN: 978-1-62708-241-9
... section of Rod “B”; surface is rough, but no apparent cracks Fig. 17 Surface morphology of SEM sample holder The fractured surface morphology for both rods was shown in Figs. 10 and 11 ; both samples revealed grain boundary fractures, akin to grain boundary decohesion. The general...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001293
EISBN: 978-1-62708-215-0
... representative of the morphology found on approximately 90% of the total fracture surface. The mode of fracture was intergranular decohesion, indicative of a brittle fracture. No evidence of fatigue striations were observed, but since these features are difficult to resolve in such high-strength materials...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001839
EISBN: 978-1-62708-241-9
... a result of dislocation pile ups against the grain boundaries. The presence of mobile hydrogen essentially facilitates the formation of an intergranular microcrack that initiates brittle fracture. This type of brittle cracking is a stress-controlled intergranular decohesion phenomenon [ 10...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001812
EISBN: 978-1-62708-241-9
... embrittling atoms ahead of crack-tips in many systems, it is generally accepted [ 4 – 8 ] that LME results from adsorption-induced weakening of interatomic bonds at surfaces and crack tips, which facilitates dislocationemission or decohesion. There are, however, a few systems, such as the Al–Ga and Ni–Bi...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001031
EISBN: 978-1-62708-214-3
... condition susceptible to grain-boundary separation at elevated temperatures. Grain-boundary decohesion occurred as oxides formed at grain boundaries, reducing interfacial energy ( Ref 5 , 6 ). The failure mode changed from ductile transgranular to brittle intergranular. Void formation was enhanced in the...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001294
EISBN: 978-1-62708-215-0
... ×. (b) Porosity determined to be missing grains dislodged during polishing. 65× Fig. 4 SEM micrographs of an AM-355 poppet valve sealing surface. (a) A dislodged grain. 570×. (b) Sensitized grain boundaries result in grain boundary decohesion. 1140× Optical photographs and SEM...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.chem.c9001687
EISBN: 978-1-62708-220-4
...-like carbide that precipitated at the grain interior, indicating that the interfaces between the carbide and the matrix have become weaker, enhancing the formation of voids by precipitate-matrix decohesion. Inter-dendritic type of fracture was also detected at the outer region of the tube and shows a...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.power.c9001004
EISBN: 978-1-62708-229-7
... ), can be subjected to impurity induced or assisted grain boundary decohesion. However, the influence of grain boundary segregation, i.e., RTE, on creep is unclear. This probably is the result of the differences between the mechanisms of low and high temperature (creep) fracture, viz., in low temperature...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006784
EISBN: 978-1-62708-295-2
.... Hydrogen damage is a complex phenomenon that takes on several forms, and many mechanisms have been proposed, which include ( Ref 1 ): Hydrogen pressure theory Reduced surface energy (surface adsorption) theory Decohesion theory Enhanced plastic flow theory Decarburization (hydrogen attack...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006775
EISBN: 978-1-62708-295-2
...., carbides in steel) require development of substantial stress for decohesion to start at the particle-matrix interface. Careful work using steels containing small, spheroidized carbides and (typical) MnS inclusions shows that debonding occurs first around the larger and more weakly bonded MnS inclusions and...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006778
EISBN: 978-1-62708-295-2
..., cavities (or microvoids) nucleate at small particles (such as inclusions and second-phase particles) when the matrix material separates from the particle by interfacial decohesion and when the inclusion or second phase fractures. The level of extensional growth of the microvoids is dependent on the level...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001780
EISBN: 978-1-62708-241-9
.... The SL orientation (see Table 3 ) had the fastest propagation rate, where the cracks propagated along the long axis of the inclusions. Decohesion between the inclusions and the matrix was observed. Meanwhile, the TS and LS orientations (see Table 3 ) had slower propagation rates, where the cracks...