THE EFFECTS OF THE WAVY GRAIN BOUNDARIES ON THE CREEP FRACTURE BEHAVIOR IN UDIMET-700 ALLOY

AbstractWe have observed that a change in the bulk sulfur content of oxygen-free electronic copper markedly affects its high temperature (400–1000°C), high strain-rate (> 103 s−1) deformation and fracture behavior. These conditions are typical of those found in "jets" formed from the explosive deformation of copper shaped-charge liners. Specifically, an increase in the bulk sulfur concentration from 4 ppm to 8 ppm shortens the breakup time, tb, of the copper jets by nearly 20% as measured using flash x-ray radiographs recorded during breakup of the jets. At bulk concentrations of 4 ppm, the jet was observed to be uniform and axisymmetric with a breakup time of 186 µs. Jet particles exhibited length-to-diameter ratios of roughly 8:1. The addition of sulfur transformed the jet breakup behavior to non-uniform, non-axisymmetric rupture and reduced the breakup time to 147 µs. The length-to-diameter ratios decreased to roughly 5:1 in the sulfurdoped samples. Previously measured sulfur solubilities and diffusivities in copper at the temperatures where this material was processed indicates nearly all of the sulfur was localized to grain boundaries. Therefore, we infer that the increase in sulfur content at grain boundaries is directly responsible for the change in breakup performance of the shaped-charge jets.

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Understanding the creep fracture behavior of aluminum alloys and aluminum alloy metal matrix composites

Materials Science and Engineering A ◽

10.1016/j.msea.2011.07.027 ◽

2011 ◽

Vol 528 (28) ◽

pp. 8218-8225 ◽

Cited By ~ 9

Author(s):

R. Fernández ◽

G. González-Doncel

Keyword(s):

Aluminum Alloy ◽

Aluminum Alloys ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Fracture Behavior ◽

Matrix Composites ◽

Creep Fracture ◽

Alloy Metal

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Creep fracture behavior of Cr1Mo welds from a 31-year-old fossil power plant

Materials Science and Engineering A ◽

10.1016/0921-5093(91)90395-4 ◽

1991 ◽

Vol 131 (2) ◽

pp. 187-201 ◽

Cited By ~ 16

Author(s):

P.K. Liaw ◽

G.V. Rao ◽

M.G. Burke

Keyword(s):

Power Plant ◽

Fracture Behavior ◽

Creep Fracture ◽

Fossil Power Plant

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Strength and fracture behavior of graphene grain boundaries: effects of temperature, inflection, and symmetry from molecular dynamics

Physical Chemistry Chemical Physics ◽

10.1039/c3cp44716b ◽

2013 ◽

Vol 15 (28) ◽

pp. 11794 ◽

Cited By ~ 31

Author(s):

Han Zhang ◽

Zheng Duan ◽

Xiaonan Zhang ◽

Chao Liu ◽

Junfeng Zhang ◽

...

Keyword(s):

Molecular Dynamics ◽

Grain Boundaries ◽

Fracture Behavior ◽

Effects Of Temperature

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The Investigation of Creep Behavior for NiAl-28Cr-5.5Mo-0.5Hf-0.02wt.%P Alloy at High Temperature

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.279.28 ◽

2011 ◽

Vol 279 ◽

pp. 28-32

Author(s):

Guang Ye Zhang ◽

Dong Wen Ye ◽

Jin Lin Wang ◽

You Ming Chen ◽

Long Fei Liu ◽

...

Keyword(s):

Steady State ◽

High Temperature ◽

Creep Behavior ◽

Fracture Behavior ◽

Primary Creep ◽

Dislocation Climb ◽

Steady State Creep ◽

Creep Fracture ◽

Creep Mechanisms ◽

Higher Temperature

The Microstructure and creep behavior for NiAl-28Cr-5.5Mo-0.5Hf-0.02wt.%P alloy at high temperature have been investigated in this paper. The results reveal that the high temperature creep behavior of the NiAl-28Cr-5.5Mo-0.5Hf-0.02wt.%P alloy is characterized by transient primary creep and dominant steady-state creep as well as ternary creep behavior. The primary creep can be described by Garofalo equation and the steady-state creep can be depicted by Dorn equation. The creep mechanisms are viscous glide of dislocations at lower and middle testing temperatures and dislocation climb at higher temperature. No change of the microstructure for the testing alloy indicates that the creep fracture is controlled by the formation and propagation of cavities and cracks, and the creep fracture behavior obeys Monk man-Grant relationship.

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Sulfur Effects on High-Temperature Creep and Fracture Behavior of 25Cr35Ni-Nb Alloys

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2013-97322 ◽

2013 ◽

Cited By ~ 1

Author(s):

Tao Chen ◽

Xuedong Chen ◽

Juan Ye ◽

Xiyun Hao

Keyword(s):

Elevated Temperature ◽

Grain Boundaries ◽

Fracture Behavior ◽

Elevated Temperatures ◽

Rupture Life ◽

Local Stress ◽

Tensile Tests ◽

Creep Rupture ◽

Scanning Electron Micrographs ◽

Nucleation Sites

Centrifugal cast 25Cr35Ni-Nb alloy furnace tubes with different contents of S are selected to investigate effects of S addition on creep and fracture behavior. Rupture tests in air at 1100 °C and 17 MPa and slow rate tensile tests at 850 °C showed that the presence of S decreased the creep rupture life and elevated temperature ductility of 25Cr35Ni-Nb alloy obviously. Scanning electron micrographs (SEM) of the fracture and energy dispersive X-ray spectroscopy (EDS) analysis results indicated that S was the important element to control creep rupture life and elevated temperature ductility. S segregated to grain boundaries at elevated temperatures, blocky fine sulfide particles with smooth surface distribute on the grain boundaries. The presence of sulfides became effective nucleation sites for intergranular creep cavities. Micro cracks occurred by linking up cavities at elevated temperatures due to local stress concentration. Eventually, early failure happened.

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