Fatigue Crack Growth and Fracture Toughness in Bimodal Al 5083

2003 ◽  
Vol 791 ◽  
Author(s):  
P. S. Pao ◽  
H. N. Jones ◽  
C. R. Feng
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Nanocrystalline Powders ◽  
Coarse Grain ◽  
Nanocrystalline Powder ◽  
Bulk Nanocrystalline ◽  
Crack Growth Rates

ABSTRACTThe fatigue crack growth rates and fracture toughness of bulk nanocrystalline Al 5083 having a bimodal grain size distribution were investigated. The nanocrystalline powders were prepared by mechanically ball milling spray atomized Al 5083 powders in liquid nitrogen. This nanocrystalline powder was blended with 50 wt% spray atomized large grained Al 5083 powders. The blended powder was then cold pressed, degassed, and extruded into rods. The bimodal Al 5083 thus produced consists of nanocrystalline grain bands and coarse grain bands. While the yield strength of the bimodal Al 5083 is about 25% lower than that of the all nanocrystalline Al 5083, its tensile ductility is almost 50% greater. In addition, the fracture toughness of the bimodal material is about 85% higher than that of the all nanocrystalline counterpart. Fatigue crack growth rates of bimodal Al 5083 are about 30% lower than those of all nanocrystalline Al 5083. The lower fatigue crack growth rates are accompanied by more tortuous crack paths when the crack propagated through the coarse grain regions in the bimodal Al 5083.

Fatigue crack growth rates and fracture toughness in electroslag refined En 52 steel

1980 ◽  
Vol 2 (4) ◽  
pp. 147-152 ◽  
Author(s):  
M HEBSUR ◽  
K ABRAHAM ◽  
Y PRASAD
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Growth Rates

Fracture Mechanics Parameters for a 5083-0 Aluminum Alloy at Low Temperatures

1977 ◽  
Vol 99 (4) ◽  
pp. 306-312 ◽  
Author(s):  
R. L. Tobler ◽  
R. P. Reed
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Rolling Direction ◽  
Integral Test ◽  
Alloy Plate ◽  
Crack Growth Rates

The fatigue crack growth and fracture resistance of a 5083-0 aluminum alloy plate were investigated at four temperatures in the ambient-to-cryogenic range—295, 111, 76, and 4 K. J-integral test methods were applied using compact specimens 3.17 cm thick, and the value of J required to initiate crack extension (JIc) is reported as an index of fracture toughness. The fracture toughness was orientation dependent, with anisotropy accounting for JIc variations of up to a factor of 2. For specimens having fracture planes parallel to the rolling direction, JIc increases progressively from 9 to 25 kJm−2 as temperature decreases between 295 and 4 K. In contrast, the fatigue crack growth rates (da/dN) are insensitive to specimen orientation. The fatigue crack growth rates at cryogenic temperatures are up to 10 times lower than in air at room temperature, but are virtually constant between 111 and 4 K.

Fatigue crack growth rates and fracture toughness of rapidly solidified Al-8.5 pct Fe-1.2 pct V-1.7 pct Si alloys

1994 ◽  
Vol 25 (5) ◽  
pp. 1005-1014 ◽  
Author(s):  
S. Hariprasad ◽  
S. M. L. Sastry ◽  
K. L. Jerina ◽  
R. J. Lederich
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Rapidly Solidified ◽  
Crack Growth Rates

Tensile Deformation and Fatigue Crack Growth in Bulk Nanocrystalline Al-7.5Mg

2002 ◽  
Vol 740 ◽  
Author(s):  
P.S. Pao ◽  
H.N. Jones ◽  
S.J. Gill ◽  
C. R. Feng
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Dislocation Density ◽  
Shear Band ◽  
Crack Growth ◽  
Growth Rates ◽  
Tensile Deformation ◽  
Tensile Fracture ◽  
Bulk Nanocrystalline ◽  
Crack Growth Rates

ABSTRACTThe fatigue crack growth kinetics and tensile deformation of bulk nanocrystalline Al-7.5Mg were investigated. Nanocrystalline particulates were first prepared by mechanically ball milling spray atomized Al-7.5Mg powders in liquid nitrogen. These particulates were then degassed, consolidated by hot isostatic pressing, and extruded into rods. Bulk nanocrystalline Al-7.5Mg has significantly higher fatigue crack growth rates and lower fatigue crack growth thresholds than those of ingot-processed 7050-T7451. The fatigue crack growth thresholds exhibit only a weak stress ratio dependency and can be identified as having a Class I behavior when using the fatigue classification proposed by Vasudevan and Sadananda. In 3.5% NaCl solution, fatigue crack growth rates of bulk nanocrystalline Al-7.5Mg are as much as three times higher than those obtained in air. Tensile fracture of bulk nanocrystalline Al-7.5Mg is preceded by the formation of a localized shear band. In contrast to the low dislocation density in the as-extruded material, the gage section and the shear band region both exhibited a high dislocation density and dislocation cell structure.

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