scholarly journals Effect of sheet thickness on fatigue crack retardation in high tensile strength steel and validity of crack closure concept.

1985 ◽  
Vol 51 (462) ◽  
pp. 318-325
Author(s):  
Keiro TOKAJI ◽  
Zenji ANDO ◽  
Koshi NAGAE ◽  
Toshio IMAI
Keyword(s):  
Tensile Strength ◽  
Fatigue Crack ◽  
Crack Closure ◽  
Sheet Thickness ◽  
High Tensile Strength ◽  
Crack Retardation

The Effect of Sheet Thickness on Near-Threshold Fatigue Crack Propagation and Oxide and Roughness-Induced Crack Closure

1987 ◽  
Vol 109 (1) ◽  
pp. 86-91 ◽  
Author(s):  
K. Tokaji ◽  
Z. Ando ◽  
K. Nagae
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Crack Closure ◽  
Growth Rates ◽  
Sheet Thickness ◽  
Specimen Thickness ◽  
Low Carbon ◽  
Wide Range ◽  
Near Threshold

Characteristics of fatigue crack propagation have been investigated in a low carbon steel and a high tensile strength steel to evaluate the effect of sheet thickness. Crack propagation data are generated over a wide range of growth rates, from 10−8 to 10−3 mm/cycle, for load ratios of 0.05 and 0.70 at room temperature in laboratory air. Particular emphasis is placed on behavior at near-threshold growth rates. Near-threshold fatigue crack propagation behavior is found to show a marked sensitivity to sheet thickness, and near-threshold growth rates decrease and threshold values increase with increasing sheet thickness. Oxide and roughness-induced crack closure models are proposed as a mechanism for the effect of sheet thickness on near-threshold fatigue crack propagation. It is also shown that the requirement for specimen thickness recommended by ASTM, W/20≤B≤W/4, is not always valid for near-threshold fatigue crack propagation.

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