mechanisms of failure m.n. tamin, utm sme 4133 failure of engineering components and structures...
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MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
MODULE 4
MECHANISMS OF FAILURE
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE
Static failure
Tensile fracture
Ductile and brittle fracture
Creep rupture
Morphology of fracture surfaces
Fatigue failure
Stages of fatigue failure
Fatigue fracture characteristics
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Tensile Fracture
Cleavage (brittle) fracture Ductile fracture
Source: Vander Voort, G.F., Metals Engineering Quarterly, Vol. 16, No. 3, 1976, pp. 33.
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Fracture of Bolts in Tensile Overload
(a) Brittle fracture
(Water-quenched to 47 Rockwell C)
(b) Ductile fracture
(Annealed to 15 Rockwell C)
(c) Extensive necking and cup-and-cone fracture of an annealed bolt
(d) Brittle fracture of a quenched bolt. No obvious plastic deformation
(a) (b) (c) (d)
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Fracture of Shaft in Torsion Overload
Dark spiral indicates plastic deformation by
torsion Swirl pattern of fracture surface
Fracture surface is flat and perpendicular to axis of shaft
Ductile failure of 1035 steel drive shaft due to torsion overload
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Fig. 4.3, Callister 7ed.
Burgers vector b
Imperfections in SolidScrew dislocation
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
necking void nucleation
void growth and linkage
shearing at surface
fracture
Particles serve as void
nucleation sites.
50 mm
P. Thornton, J. Mater. Sci., Vol. 6, 1971, pp. 347-56.)
Fracture Process in Ductile Materials
Slip by plastic deformation
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
• Ductile failure: --one piece --large deformation
• Brittle failure: --many pieces --small deformation
Figures from V.J. Colangelo and F.A. Heiser, Analysis of Metallurgical Failures (2nd ed.), Fig. 4.1(a) and (b), p. 66 John Wiley and Sons, Inc., 1987. Used with permission.
Ductile Versus Brittle Fracture
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Ductile Fracture Surface
- Dimples in ductile fracture.
• Transgranular fracture (across grains)
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
• Intergranular fracture (between grains)
304 S. Steel (metal)Reprinted w/permission from "Metals Handbook", 9th ed, Fig. 633, p. 650. Copyright 1985, ASM International, Materials Park, OH. (Micrograph by J.R. Keiser and A.R. Olsen, Oak Ridge National Lab.)
4 mm
Brittle Fracture Surfaces
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Deterioration of a material by initiation and propagation of crack when subjected to repeated load.
FATIGUE FAILURE
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Formation of Fatigue Striations
SKMM 4133 Failure of Engineering Components and Structures
MECHANISMS OF FAILURE M.N. Tamin, UTM
SME 4133 Failure of Engineering Components and Structures
Fatigue Striations
SKMM 4133 Failure of Engineering Components and Structures