Variations in Crack Growth Rate Behavior

2009 ◽  
pp. 54-54-14
Author(s):  
ME Artley ◽  
JP Gallagher ◽  
HD Stalnaker
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Rate Behavior

Fatigue and Static Crack Growth Rate of Alloy 718 Under Cathodic Polarization

CORROSION ◽  
10.5006/3572 ◽  
2021 ◽  
Author(s):  
Ramgopal Thodla ◽  
Anand Venkatesh
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Cathodic Polarization ◽  
Alloy 718 ◽  
Static Crack ◽  
Rate Behavior

Fatigue crack growth rate was developed on three heats of alloy 718 (UNS N07718) under cathodic polarization, over a wide range of loading conditions. Fatigue crack growth rate increased with decreasing frequency over a range of Kmax and K conditions. In most cases, there was no evidence of a plateau in fatigue crack growth rate at low frequencies. The fatigue crack growth rate over the range of conditions evaluated were influenced by static crack growth rate at Kmax. The principle of superposition of fatigue crack growth and static crack growth was used to rationalize the observed crack growth rate response. Static crack growth rate of alloy 718 measured under constant K conditions, was lower than that measured under rising displacement conditions. A crack tip strain rate based model was used to rationalize the fatigue crack growth rate behavior and the static crack growth rate behavior under constant K. However, the formulation of the model for the rising K was not able to rationalize the crack growth rate under rising displacement conditions.

Crack Growth Rate Behavior of a Titanium-Aluminide Alloy During Isothermal and Nonisothermal Conditions

1995 ◽  
Vol 117 (1) ◽  
pp. 118-126 ◽  
Author(s):  
J. J. Pernot ◽  
S. Mall ◽  
T. Nicholas
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Titanium Aluminide ◽  
Hold Time ◽  
Linear Elastic ◽  
Isothermal Fatigue ◽  
Titanium Aluminide Alloy ◽  
Rate Behavior ◽  
Nickel Base

Observations of isothermal fatigue, isothermal fatigue with superimposed load hold times, and thermomechanical fatigue (TMF) crack growth rate behavior of Ti-24Al-11Nb are presented and compared with results from previous studies on titanium and nickel-base superalloys. Elevated-temperature crack growth mechanisms in this alloy, which involve fatigue, oxidation and creep, and the influence of frequency, temperature, and hold-time are discussed. These mechanisms are used to interpret the observations of TMF crack growth. The limitations of current crack growth rate models based on the linear-elastic fracture mechanics parameter, K, are addressed.

Sign in / Sign up

Export Citation Format

Share Document