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microcrack nucleation

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Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005415
EISBN: 978-1-62708-196-2
...) for dislocations, martensitic particles and microcracks, and magnetization and polarization for ferromagnetic and ferroelectric transitions. These order parameters are continuous fields (functions of position, r , e.g., ϕ( r , t )) and are referred to as phase fields in the phase-field method. A...
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
... Abstract This article focuses on characterizing the fracture-surface appearance at the microscale and contains some discussion on both crack nucleation and propagation mechanisms that cause the fracture appearance. It begins with a discussion on microscale models and mechanisms for deformation...
Series: ASM Handbook
Volume: 12
Publisher: ASM International
Published: 01 January 1987
DOI: 10.31399/asm.hb.v12.a0000603
EISBN: 978-1-62708-181-8
...; and microcrack initiation and propagation. brittle fracture cleavage fracture fatigue cracks fatigue fracture ferritic ductile iron fractographs microcracking pearlitic ductile iron Brittle cleavage fracture of ductile iron spur gear (ASTM A536, grade 100-70-03) due to improper heat...
Series: ASM Handbook
Volume: 4B
Publisher: ASM International
Published: 30 September 2014
DOI: 10.31399/asm.hb.v04b.a0005967
EISBN: 978-1-62708-166-5
... article illustrates the use of carbon restoration on decarburized spring steels. Different geometric models for carbide formation are shown schematically. The article also describes the different microstructural features such as grain size, microcracks, microsegregation, and banding. carbides...
Series: ASM Handbook
Volume: 12
Publisher: ASM International
Published: 01 January 1987
DOI: 10.31399/asm.hb.v12.a0000610
EISBN: 978-1-62708-181-8
... intersection of deformation bands with coherent twin boundaries. SEM, 2000×. Fig. 643 : Microcracking along coherent annealing twin boundaries on longitudinal section of fractured type 304L sample. Twin-boundary traces lie at an angle of 60° to 90° from the tensile axis (vertical in photomicrograph). 1000...
Series: ASM Handbook
Volume: 5
Publisher: ASM International
Published: 01 January 1994
DOI: 10.31399/asm.hb.v05.a0001286
EISBN: 978-1-62708-170-2
... stresses produce microcracking of the film. The cracks tend to meet orthogonally and form polygon “islands” or “chips” such as are seen in dried “mudflats” ( Ref 65 ). Because the interface is constrained, the mudflat islands will tend to curl at the edges. If the compressive stresses are highly...
Series: ASM Handbook
Volume: 4A
Publisher: ASM International
Published: 01 August 2013
DOI: 10.31399/asm.hb.v04a.a0005773
EISBN: 978-1-62708-165-8
... details the growth process and nucleation process of carbide and nitride coatings formed on the metal surface. The article discusses the advantages, disadvantages, and characteristics of the various coating processes, including high-temperature salt bath carbide coating, high-temperature fluidized-bed...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006793
EISBN: 978-1-62708-295-2
... In the case of impacting bodies, the white layer builds up on the wear surface as impacts progress and becomes intensely work hardened. As a result, microcracks are easily nucleated within the white layer material ( Fig. 8a ). The path of least resistance along which the cracks can propagate is the...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006779
EISBN: 978-1-62708-295-2
... stage I in a highly stressed region of a component subjected to cyclic stresses of sufficient magnitude. On the microscopic scale, the most important feature of the fatigue process is the nucleation of one or more cracks under the influence of cyclic stresses, followed by the development of microcracks...
Series: ASM Handbook
Volume: 12
Publisher: ASM International
Published: 01 January 1987
DOI: 10.31399/asm.hb.v12.a0001834
EISBN: 978-1-62708-181-8
... failures occur through a mechanism known as microvoid coalescence ( Ref 41 , 42 , 43 ). The microvoids are nucleated at any discontinuity where a strain discontinuity exists—for example, grain of subgrain boundaries, second-phase particles, and inclusions. These microvoids, shown in Fig. 10 and 11...
Series: ASM Handbook
Volume: 4A
Publisher: ASM International
Published: 01 August 2013
DOI: 10.31399/asm.hb.v04a.a0005774
EISBN: 978-1-62708-165-8
... quenchant nucleate boiling heat-transfer conditions on the part surface, slow cooling in air, and convection cooling in the quench tank. The IQ-2 process is usually applied to batch quenching. The IQ-3 process is a one-step intensive cooling method (referred to as an IQ-3 technique), where cooling at the...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006792
EISBN: 978-1-62708-295-2
... selection. In general, a harder surface is more resistant to wear, fatigue, and so on. At the same time, compressive residual stresses near the surface of the component will slow crack growth such that any microcracks that form propagate more slowly, thereby increasing the time until failure. Therefore...
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
... austenitic stainless steels). High-nitrogen austenitic stainless may also be less ductile during rapid crack growth. Fig. 4 Cleavage fracture in a carbon steel component. Scanning electron micrograph. Original magnification: 593× Cleavage initiates via microcrack nucleation at the leading edge...
Series: ASM Handbook
Volume: 5
Publisher: ASM International
Published: 01 January 1994
DOI: 10.31399/asm.hb.v05.a0001300
EISBN: 978-1-62708-170-2
... used for tribological applications (such as hard chromium) is equiaxed, and extremely finely grained, and it contains some oxide inclusions and microcracks, which give the coating some porosity ( Fig. 3 ). Tensile residual stresses can be produced in the coating during plating and can lead to a network...
Series: ASM Handbook
Volume: 4A
Publisher: ASM International
Published: 01 August 2013
DOI: 10.31399/asm.hb.v04a.a0005819
EISBN: 978-1-62708-165-8
... is rapid or slow, because nonequilibrium conditions can have marked effects on the nucleation and growth rates of the constituents created during austenite decomposition and the resultant microstructure. To characterize the conditions that produce the various microstructures, two types of...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 November 1995
DOI: 10.31399/asm.hb.emde.a0003066
EISBN: 978-1-62708-200-6
... is dependent on the composition of the different components and hence on these components' properties, including bulk modulus and density ( Ref 13 ). Grain size and other microstructural features play a secondary role in determining composite thermal expansion. Because microcracking can result from...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006277
EISBN: 978-1-62708-169-6
... nucleation and growth of α precipitates from supersaturated β matrix ( Ref 5 ) or defect-mediated nucleation and growth by intermediate phases (such as martensite α′, or α″, and metastable ω phase) ( Ref 5 , 6 ), precursory concentration modulation within the β-phase matrix ( Ref 7 , 8 , 9...
Series: ASM Handbook
Volume: 5
Publisher: ASM International
Published: 01 January 1994
DOI: 10.31399/asm.hb.v05.a0001287
EISBN: 978-1-62708-170-2
... brittle and causes microcracks, which create local hot spots that result in burnout. On burnout, the tungsten is vaporized and can contaminate the film. In general, it is better to replace tungsten wire heaters after each deposition if such contamination poses a problem. When large masses of material that...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 November 1995
DOI: 10.31399/asm.hb.emde.a0003063
EISBN: 978-1-62708-200-6
.... 2 ). A fine-grained α-Al 2 O 3 fiber is obtained by seeding the high-temperature α-Al 2 O 3 with a very fine hydrous colloidal iron oxide. The iron oxide improves the nucleation rate of α-Al 2 O 3 so that a high-density, ultrafine, homogeneous α-Al 2 O 3 fiber is obtained. α-iron oxide is...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005342
EISBN: 978-1-62708-187-0
... features with fine microcracks. It should be noted that fracture features are often only discernible at the crack-tip region, or at secondary cracks, as the fracture surface is typically coated with oxidation products caused by the corrosive environment. Other alloys, such as ductile iron and steel, can...