Effect of second phase on the fatigue crack growth in AlSl 4340 steel

1996 ◽  
Vol 15 (3) ◽  
pp. 192-196 ◽  
Author(s):  
Jiun-Ren Hwang ◽  
Kan-Ping Peng ◽  
Chien-Chun Wang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Second Phase ◽  
4340 Steel

Interfacial Composition Measurements in Complex Ni-Base Superalloys

1996 ◽  
Vol 458 ◽  
Author(s):  
E. L. Hall ◽  
J. Bentley
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Grain Boundary ◽  
Crack Growth ◽  
Time Dependent ◽  
Alloying Elements ◽  
Second Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Boundary Composition

ABSTRACTIn this study, three different Ni-base superalloy / heat treatment combinations are studied in an attempt to assess the role of grain boundary morphology, composition, and phase distribution on mechanical properties, particularly time-dependent fatigue crack growth. The alloys chosen include one in which crack growth can be slowed by slow-cooling, and one in which crack growth is slow in the fast-cooled state. Both x-ray spectroscopy and energy-filtered imaging in the analytical electron microscope were used to measure grain boundary composition. The x-ray spectroscopy showed some enhancement of Cr, Mo, and W in the γ matrix at grain boundaries in the fast-cooled state, which was not present after slow cooling. Energy-filtered imaging showed no significant enhancement in alloying elements at interfaces in any of the samples studied. The results did show the tendency for the γ matrix to quickly equilibrate by second-phase precipitation, and a preference to avoid γ ‘- γ’ interfaces. The conclusions of this study are that time-dependent fatigue crack growth behavior in these alloys cannot be completely explained on the basis of grain boundary composition of major alloying elements.

Fracture and Fatigue Crack Growth of Bulk Metallic Glass Alloys and their Composites

2000 ◽  
Vol 644 ◽  
Author(s):  
Katharine M. Flores ◽  
Reinhold H. Dauskardt
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Metallic Glass ◽  
Crack Growth ◽  
Bulk Metallic Glass ◽  
Damage Zone ◽  
Stable Crack Growth ◽  
Second Phase ◽  
Glass Matrix Composite ◽  
Metallic Glass Matrix Composite

AbstractBulk metallic glasses exhibit extraordinary strength and elastic properties, but the lack of extensive plastic deformation and the catastrophic nature of failure limit the usefulness of the monolithic alloy. This work presents an overview of the results of fracture and fatigue crack growth experiments for a bulk metallic glass matrix composite with a Zr-Ti-Nb reinforcement phase precipitated in situ. The composite exhibits stable crack growth at stress intensities nearly double the fracture toughness of the monolithic glass. This is associated with the formation of a distributed damage zone at the crack tip. While the second phase had a marked effect on the fracture behavior, there was very little change to the fatigue crack growth results. Fractography suggests that the second phase particles are too small to cause crack bridging or significantly change the crack path.

Effect of Hardness of Second Phase Particle on Fatigue Crack Growth Behavior of Steels with Hard Second Phase Particle in Soft Ferrite Matrix

2010 ◽  
Vol 129-131 ◽  
pp. 775-779 ◽  
Author(s):  
Mohammad Sukri Mustapa ◽  
Yoshiharu Mutoh
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Phase Particle ◽  
Stress Shielding ◽  
Ferrite Matrix ◽  
Carbon Steels ◽  
Shielding Effect ◽  
Second Phase ◽  
Soft Ferrite

K-constant fatigue crack growth (FCG) tests were conducted on low carbon steels with uniformly distributed hard particle with different of pearlite, bainite and martensite in a soft ferrite matrix. The FCG tests by using a single edge cracked tension (SECT) type was performed inside a scanning electron microscope chamber equipped with a servo-hydraulic fatigue machine. During the test, in-situ crack path observation was carried out to identify the crack tip stress shielding phenomena. From the results, influence of hardness of second phase particle on the FCG behavior in Paris regime was systematically investigated. The results revealed that the ferrite-martensite (FM) steel showed significantly higher FCG resistance compared to that of ferrite-pearlite (FP) and ferrite-bainite (FB) steels. The harder second phase particle would be more difficult to be plastically deformed, which would induce higher plastic constrain. This higher plastic constrain may result in significant crack closure effect and stress shielding effect, thereby increasing higher FCG resistance.

Fatigue Crack Growth Process in CPVC Pipe Couplings

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Z. Khan ◽  
N. Merah ◽  
F. Saghi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Process ◽  
Stress Raiser ◽  
Fatigue Loading ◽  
Second Phase ◽  
Shear Yielding ◽  
Different Temperatures ◽  
Crack Growth Process

AbstractAn investigation of the influence of temperature and loading frequencies on the morphological features found on the fatigue fractured surface of chlorinated polyvinyl chloride (CPVC) has been conducted. Single edge notched rectangular coupons obtained by flattening schedule 80 CPVC pipe couplings were subjected to fatigue loading at different temperatures of 0, 23, 40, and 70 °C and frequencies of 0.1, 1, and 50 Hz. Crack growth in CPVC, involved a combination of shear yielding and crazing processes. At the test temperature of 0 °C and 23 °C, the fatigue crack growth was noted to occur predominantly by shear yielding while crazing played a secondary role. On the other hand at 40 °C and 70 °C, the fatigue crack growth process appeared to predominantly involve a crazing process while shear yielding played a less significant role. Filler material particles played a major role as brittle second phase stress-raiser particles and facilitated craze initiation. iDiscontinuous crack growth bands (DGBs) indicating repeated crack arrests were also noted on the fracture surface.

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