Influence of welding parameters on fracture toughness and fatigue crack growth rate in friction stir welded nugget of 2024-T351 aluminum alloy joints

2016 ◽  
Vol 26 (10) ◽  
pp. 2567-2585 ◽  
Author(s):  
Danial GHAHREMANI MOGHADAM ◽  
Khalil FARHANGDOOST
Keyword(s):  
Fracture Toughness ◽  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Welding Parameters ◽  
Friction Stir

Fatigue Crack Growth Rate and Fracture Toughness of API5L X65 in Sweet Environments

2013 ◽  
Author(s):  
Michael A. Tognarelli ◽  
Ramgopal Thodla ◽  
Steven Shademan
Keyword(s):  
Fracture Toughness ◽  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Environmental Conditions ◽  
Initiation Toughness ◽  
Diffusible Hydrogen

Corrosion fatigue and fracture toughness in sour environments of APIX65 5L have typically been studied in relatively severe environments like NACE A and NACE B solutions. There are very limited data in sweet and mildly sour environments that are of interest in various applications. This paper presents fatigue crack growth frequency scans in a range of sweet and mildly sour environments as well as on different microstructures: Parent Pipe, Heat Affected Zone (HAZ) and Weld Center Line (WCL). The fatigue crack growth rate (FCGR) increased with decreasing frequency and reached a plateau value at low frequencies. FCGR in the sweet environments that were investigated did exhibit a frequency dependence (increasing with decreasing frequency) and had plateau FCGR in the range of 10–20× the in-air values. In the mildly sour environments that were investigated, FCGR was found to be about 25 to 30× higher than the in-air values. By comparison, in NACE A environments the FCGR is typically about 50× higher than the in-air values. The FCGRs of parent pipe and HAZ were found to be similar over a range of environments, whereas the WCL FCGR data were consistently lower by about a factor of 2×. The lower FCGR of the WCL is likely due to the lower concentration of diffusible hydrogen in the weld. FCGRs as a function of ΔK (stress integrity factor range) were measured on parent pipe at the plateau frequency. The measured Paris law curves were consistent with the frequency scan data. Rising displacement fracture toughness tests were performed in a range of sweet and sour environments to determine the R-curve behavior. Tests were performed in-situ at a slow K-rate of 0.05Nmm−3/2/s over a range of environmental conditions on parent pipe. The initiation toughness and the slope of the R-curve decreased sharply in the sour environments. The initiation toughness and slopes were largely independent of the notch location as well as environmental conditions. Typical values of initiation toughness were in the range of 90–110N/mm.

Determining the Scatter in Fatigue Crack Growth Rate Based on Variations in Bulk Property Data

2009 ◽  
Author(s):  
Jeremy S. Daily ◽  
Nathan W. Klingbeil
Keyword(s):  
Fracture Toughness ◽  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Bulk Property ◽  
Plastic Dissipation ◽  
Hardening Modulus

A technique to predict the variability of the Paris regime fatigue crack growth rates in ductile materials based on bulk property (yield strength, hardening modulus, and fracture toughness) variation is presented. The prediction, based on the plastic dissipation in the reversed plastic zone ahead of the crack tip, is carried out for Ti-6Al-4V. The empirical distributions of the bulk properties of Ti-6Al-4V are characterized and directly used in the probabilistic assessment of the fatigue crack growth rate. Since computing the plastic dissipation is a computationally intensive procedure, a novel sampling scheme based on confidence interval minimization was used to generate the empirical distribution of fatigue crack growth rate. This technique also predicts correlation between fatigue crack growth rate and fracture toughness, which may be useful in probabilistic design of turbines.

Reliability Analysis of Corrosion Fatigue Crack Growth for 2024-T3 Aluminum Alloy

2008 ◽  
Vol 44-46 ◽  
pp. 105-110
Author(s):  
Sen Ge ◽  
Zhong Li ◽  
J.G. Zhang ◽  
Y.C. Xiao ◽  
G.Q. Liu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Reliability Analysis ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Loading Frequency ◽  
Corrosive Environment

Fatigue crack growth rate experiments of center-cracked tension (CCT) specimens of the 2024-T3 aluminum alloy under constant-amplitude load in corrosive environment are carried out with 3 kinds of loading frequency. The fatigue crack growth rates in 3.5% NaCl solution are obtained by using seven-point incremental polynomial method. A probabilistic approach is presented for fatigue crack growth rate in corrosive environment with log-normal random variable model. The reliability analysis of crack propagation is conducted based on the experimental data. The crack exceedance probability at given service time and the distribution of the service time at given crack size are obtained by using the reliability analysis approach. The effect of loading frequency on crack propagation is studied. It is shown that the fatigue crack growth rate is increasing with loading frequency decreasing in corrosive environment. The predicted results by the presented method match the experimental results very well.

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