Effect of Trace Impurities on High-Cycle Fatigue Damage of Ultrafine Grained Copper Processed by Equal Channel Angular Pressing

2008 ◽  
Vol 584-586 ◽  
pp. 809-814
Author(s):  
Masahiro Goto ◽  
N. Teshima ◽  
Seung Zeon Han ◽  
T. Yakushiji ◽  
Sang Shik Kim
Keyword(s):  
Equal Channel Angular Pressing ◽  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Surface Damage ◽  
Cycle Fatigue ◽  
Trace Impurities ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Two Samples ◽  
Formation Behavior

In order to study the effect of trace impurities on high-cycle fatigue damage of ultrafine grained (UFG) copper, fatigue tests were carried out for two samples: oxygen-free copper (OFC, 99.99 wt% Cu) and deoxidized low-phosphorous copper (DLP, 99.95 wt% Cu). After the processing by equal channel angular pressing (ECAP) using eight passes, equiaxed grains with an average size of 250 nm were formed for both the samples. Fatigue strength of UFG copper was enhanced by the impurities. The formation behavior of surface damage and the change in surface hardness was monitored. A close relationship was observed between the change in hardness and the formation behavior of surface damage. The physical background of the effect of trace impurities on the fatigue damage was discussed from the viewpoints of surface damage formation behavior.

High-Cycle Fatigue Damage of Oxygen-Free and Deoxidized-Phosphorous Copper Processed by Equal Channel Angular Pressing

2014 ◽  
Vol 627 ◽  
pp. 201-204
Author(s):  
M. Goto ◽  
N. Teshima ◽  
Seung Zeon Han ◽  
J.H. Ahn ◽  
T. Yakushiji
Keyword(s):  
Equal Channel Angular Pressing ◽  
Fatigue Damage ◽  
Surface Hardness ◽  
Surface Damage ◽  
Trace Impurities ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Close Relationship ◽  
Formation Behavior ◽  
Equiaxed Grains

Two Cu samples: oxygen-free copper (99.99 wt% Cu) and deoxidized low-phosphorous copper (99.9 wt% Cu) were processed by equal channel angular pressing (ECAP). After the ECAP processing using 4 passes, equiaxed grains (~300 nm grain size) and elongated grains were formed for both samples. Fatigue strength of ultrafine grained Cu was enhanced by the addition of trace impurities. The formation behavior of surface damage and the change in surface hardness during stressing were monitored. A close relationship was observed between the change in hardness and the formation behavior of damage. The effect of trace impurities on the fatigue damage was discussed from the viewpoints of the grain coarsening and the crack initiation/growth behaviors.

FATIGUE DAMAGE FORMATION PROCESS OF ULTRAFINE GRAINED OXYGEN-FREE AND DEOXIDIZED LOW-PHOSPHOROUS COPPER

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2506-2511
Author(s):  
NORIHIRO TESHIMA ◽  
TERUTOSHI YAKUSHIJI ◽  
MASAHIRO GOTO ◽  
YOSHINORI ANDO ◽  
SEUNG-ZEON HAN ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Formation Process ◽  
Surface Damage ◽  
Fatigue Tests ◽  
Trace Impurities ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Two Samples ◽  
Formation Behavior ◽  
Average Size

In order to study the fatigue damage formation process of ultrafine grained copper, fatigue tests were carried out for two samples: oxygen-free copper and deoxidized low-phosphorous copper. After the processing by equal channel angular pressing (ECAP) using eight passes, equiaxed grains with an average size of 300 nm were formed for both the samples. The formation behavior of surface damage was monitored. The effects of trace impurities on surface damage formation behavior were discussed from the viewpoints of change in surface morphological feature during stressing.

Surface Damage and Fatigue Strength of Ultrafine Grained Copper Treated by Mild Annealing

2013 ◽  
Vol 577-578 ◽  
pp. 145-148
Author(s):  
N. Teshima ◽  
M. Goto ◽  
Seung Zeon Han ◽  
Kwang Jun Euh ◽  
K. Yamauchi ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Thermal Instability ◽  
High Cycle Fatigue ◽  
Surface Damage ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Improved Stability ◽  
Long Life

Fatigue tests of ultrafine grained (UFG) copper produced by equal channel angular pressing (ECAP) showed negligible enhancement of fatigue strength in high-cycle fatigue regime. This was attributed to the thermal instability of UFG microstructure; a grain coarsening occurred during a large number of stress repetitions. Aiming at an enhancement of fatigue strength in the long-life field in excess of 107cycles, post-ECAP mild-annealing for improving thermal stability was conducted. Grains with sizes up to a few tens of micrometers surrounded by fine grains were formed after the annealing as a result of discontinuous recrystallization. The improved stability of post-ECAP annealed micrstrucvture was related to the 9% increased fatigue strength in long life fields. The effect of bimodal microstructure on surface damage formation and fatigue strength was discussed.

GS0302 Surface Damage and Crack Growth Behavior of Ultrafine Grained Copper in High-Cycle Fatigue

2008 ◽  
Vol 2008 (0) ◽  
pp. _GS0302-1_-_GS0302-2_
Author(s):  
Yoshinori ANDO ◽  
Masahiro GOTO ◽  
Seung-Zeon HAN ◽  
Norihiro TESHIMA ◽  
Takamasa HIMENO ◽  
...  
Keyword(s):  
Crack Growth ◽  
High Cycle Fatigue ◽  
Surface Damage ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Cycle Fatigue ◽  
Ultrafine Grained

High cycle fatigue behavior of Al1070 alloy severely deformed by equal channel angular pressing process

2016 ◽  
Vol 232 (6) ◽  
pp. 514-519 ◽  
Author(s):  
Mohammad Bagher Limooei ◽  
Morteza Zandrahimi ◽  
Ramin Ebrahimi
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Equal Channel Angular Pressing ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Pure Aluminum ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Angular Pressing ◽  
Pressing Process

In the present work, equal channel angular pressing of commercial pure aluminum 1070 was performed up to 4 passes using route Bc. For equal channel angular pressing operation, a suitable die set was designed and manufactured. X-ray diffraction analysis was used to determine the microstructure of the equal channel angular pressing-ed material. The fracture surface morphology and microstructure after fatigue were investigated by scanning electron microscopy. Mechanical properties of the equal channel angular pressing-ed material were evaluated by hardness and tension tests. Also, cyclic deformation behavior of severe plastic deformation Al1070 has been studied and results show a significant variation in hardness, ultimate strength and fatigue properties in high cycle fatigue life. Coefficient of fatigue strength σ′f and Bridgman correction factor have been obtained by S-N curve and tension test specimens, respectively, and compared before and after equal channel angular pressing process. Also an useful relation has been derived between fatigue life ( Nf) and stress amplitude ( σa) in high cycle fatigue region. Results indicated that there was not clear relation between fatigue strength coefficient and true corrected fracture stress in this case.

Relationship between Grain Growth and Formation of Fracture Surface of Ultrafine Grained Cu in High-Cycle Fatigue

2016 ◽  
Vol 713 ◽  
pp. 147-150
Author(s):  
M. Goto ◽  
Seung Zeon Han ◽  
Takaei Yamamoto ◽  
J. Kitamura ◽  
Kamil Kusno ◽  
...  
Keyword(s):  
Fracture Surface ◽  
High Cycle Fatigue ◽  
Crack Tip ◽  
Plastic Zone Size ◽  
Fatigue Tests ◽  
Growth Behavior ◽  
Cycle Fatigue ◽  
Zone Size ◽  
Angular Pressing ◽  
Ultrafine Grained

Fatigue tests were conducted on specimens of ultrafine grained copper produced by equal channel angular pressing. The growth behavior of a fatal crack was monitored successively. The morphological features of the crack growth paths and fracture surfaces were influenced by variation of grain size and damaged areas of the crack tip, depending on the stage of progress of the fatigue damage. The change in fracture surface was discussed by considering the interrelation between the reversible plastic zone size at the crack tip and the microstructure evolved during cyclic stressing.

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