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fatigue crack nucleation

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Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.design.c9001582
EISBN: 978-1-62708-233-4
... that was engaged in a blind hole in the cylinder block. The failures were caused by loose tolerances on the threads that resulted in a non-uniform distribution of load. The load was concentrated on the last threads to engage, thus causing fatigue crack nucleation at the thread root and propagation until the rod...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c0046981
EISBN: 978-1-62708-218-1
... nucleated exhibited corrosion pits. Such pits act as notches and are likely sites for nucleation of fatigue cracks. The corrosion pits were the result of intergranular attack by the corrosive environment and the depletion of chromium from the grain-boundary areas. Depletion of chromium ultimately resulted...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001800
EISBN: 978-1-62708-241-9
... determined that the fractures stemmed from electric arc damage. Intergranular quench cracks in the transformed untempered martensite on the surface of the spring provided crack initiations that propagated during operation causing fatigue fracture. torsion springs fracture electrical arcing steel...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.rail.c0046238
EISBN: 978-1-62708-231-0
.... Visual examination revealed beach marks typical of fatigue cracks that had nucleated at the base of the longitudinal oil hole. Micrographs of sections revealed a remelt zone and an area of untempered martensite within the region of the cracks. However, review of inspection procedures disclosed the pins...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.design.c0046155
EISBN: 978-1-62708-233-4
... was the primary cause of failure. Rubbing of the faying surfaces worked the interference area on the post until small tears developed. These small tears became stress-concentration points that nucleated fatigue cracks. Recommendations included rounding the edge of the box in the area of contact with the post...
Image
Published: 15 May 2022
Fig. 15 Optical micrographs showing the nucleation and growth of a mode I fatigue crack in the plane of the notch as a result of cyclic compression loading in high-impact polystyrene; (a) crazing before fatigue cycling, (b) nucleation of fatigue crack after 15,000 cycles, (c) crack growth More
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001787
EISBN: 978-1-62708-241-9
... to analysis of the fracture morphology and the spline crack propagation, it is found that the fatigue crack initiates from the chamfers and the tooth profile, where stress is concentrated easily. Inclusions will cause nucleation of crack. Size and location of the inclusions influence the material fatigue...
Book Chapter

Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003544
EISBN: 978-1-62708-180-1
... magnitude. The crack propagates under the applied stress through the material until complete fracture results. On the microscopic scale, the most important feature of the fatigue process is the nucleation of one or more cracks under the influence of reversed stresses that exceed the flow stress locally...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.marine.c9001657
EISBN: 978-1-62708-227-3
... was damaged, examination in the SEM revealed several areas of well-defined fatigue striations and microscopic crack growth bands, Figure 4 . A specific fatigue crack nucleation site could not be readily identified, but the orientation of the crack growth bands and striations in area A, Figure 3 , suggested...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c0048117
EISBN: 978-1-62708-235-8
... and was at a 45° angle to the wire axis, which indicated torsional fracture. Conclusions The spring fractured by fatigue; fatigue cracking was nucleated at a subsurface defect that was longitudinal to the wire axis. The stress-raising effect of the defect was responsible for the fracture. Selected...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.machtools.c0047779
EISBN: 978-1-62708-223-5
... overstress as the smooth-textured fatigue zone was relatively large compared with the crystalline textured coarse final-fracture zone. The fatigue crack was nucleated by the nonmetallic inclusion that intersected the surface and initiated in the 0.25 mm radius fillet at a change in section due to stress...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.usage.c9001672
EISBN: 978-1-62708-236-5
..., and the energetics and probabilities associated with fatigue crack nucleation and propagation. A detail treatment of the last statement is beyond the scope of this paper. The initial stress developed in the spring upon compression 2.22 cm (0.875 in.) was about 400 MPa (58 ksi); after the first fracture this value...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c0047835
EISBN: 978-1-62708-217-4
... of untempered martensite constituted the microstructure of the metal at the origin. Small cracks, caused by the high temperatures developed during electro-etching, were observed in the remelted area. It was concluded that fatigue fracture of the rod was caused by the notch resulting from electroetching and thus...
Image
Published: 01 June 2019
showing origin of fracture (arrow) and beach marks. 2.8×. (c) Bottom of oil hole in fractured pin showing circular crack around the arc burn (arrow at top left, arrow at right). 20×. Arrow at bottom left indicates fatigue fracture that nucleated from the circular crack. (d) Bottom of an oil hole More
Image
Published: 01 January 2002
Fig. 44 Types of alternate microscopic fracture modes in fatigue. (a) Ductile striations triggering cleavage. (b) Cyclic cleavage. (c) Alpha-beta interface fracture. (d) Cleavage of alpha in an alpha-beta phase field. (e) Forked intergranular cracks in a hard matrix. (f) Forked intergranular More
Image
Published: 15 January 2021
Fig. 45 Types of alternate microscopic fracture modes in fatigue. (a) Ductile striations triggering cleavage. (b) Cyclic cleavage. (c) Alpha-beta interface fracture. (d) Cleavage of alpha in an alpha-beta phase field. (e) Forked intergranular cracks in a hard matrix. (f) Forked intergranular More
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
... to the end of life must be defined and limited. The conventional design methods are supplemented by the fracture mechanics methods, in which cracklike flaws in the structure are anticipated and included in the design. These methods have all contributed to a better understanding of fatigue crack nucleation...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006918
EISBN: 978-1-62708-395-9
... failure is a consequence of both crack nucleation and subsequent crack growth to failure. The defect-tolerant approach bases the fatigue life of a component on the number of loading cycles needed to propagate a crack of a predetermined initial size to a critical dimension at which fracture ensues. Both...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c0046972
EISBN: 978-1-62708-217-4
... from closing, and additional stresses are imposed on the crack tip, which may accelerate intergranular cracking or act as a stress raiser for nucleation of a transgranular fatigue crack. None of the blades examined showed evidence of sustained metal temperatures exceeding 1040 °C (1900 °F...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001051
EISBN: 978-1-62708-214-3
... treatment, indicating high residual stresses in the area of the weld. All cracks were transgranular and were associated with pits on the inside surfaces of the vessels. It was concluded that the cracking was caused by a low-cycle corrosion fatigue phenomenon, with cracks initiating at areas of localized...