Shot Peening and Fatigue Crack Growth in 7075-T7351 Aluminum

2005 ◽  
Vol 297-300 ◽  
pp. 72-77 ◽  
Author(s):  
Takashi Honda ◽  
Mamidala Ramulu ◽  
Albert S. Kobayshi
Keyword(s):  
Crack Growth ◽  
Shot Peening ◽  
Stress Ratio ◽  
Life Cycles ◽  
X Ray Diffraction ◽  
Compressive Stresses ◽  
The Difference ◽  
Crack Growth Rates ◽  
Severe Shot Peening ◽  
Subsurface Microstructure

Thirty three SENB and nine TPB specimens, which were machined from an 8.1mm thick 7075-T7351 aluminum stock plate, were fatigued in the as-received or shot peened conditions. The SENB specimens were then fractured by overload and were recorded. The crack growth rate of the tunneling crack profiles were measured by fractography at various life cycles. SN curves of the as received and shot peened TPB specimens were also constructed. Peened surface roughness, subsurface microstructure and micro-hardness profiles were examined. X-ray diffraction technique was used to measure the residual stresses in selected shot peened SENB and TPB specimens. The fatigue life under a severe shot peening intensity (Almen scale 0.016A) of the SENB specimens was slightly larger than that of the as received SENB specimens at low stress ratio of R = 0.1 but the difference was found to be smaller at R = 0.8. The SN curves of the as received and severely shot peened TPB specimens were nearly identical. Grain distortion due to peening was observed to a depth of 410µm and was correlated with the measured residual compressive stresses. The compressive residual stress had little effect on the crack growth rates in shot peened SENB and TPB specimens.

scholarly journals Effects of Shot-Peening and Stress Ratio on the Fatigue Crack Propagation of AL 7475-T7351 Specimens

2018 ◽  
Author(s):  
Natália Ferreira ◽  
Pedro Antunes ◽  
José A. M. Ferreira ◽  
José D. M. Costa ◽  
Carlos Capela
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Shot Peening ◽  
Stress Ratio ◽  
Stress Ratios ◽  
Crack Growth Rates ◽  
Hardness Values

Shot peening is an attractive technique for fatigue enhanced performance of metallic components, because it promotes crack initiation retardation and later crack growth. Engineering design based on fatigue crack propagation predictions applying the principles of fracture mechanics is commonly used in aluminum structures for aerospace engineering. The main purpose of present work was to analyze the effect of shot peening on the fatigue crack propagation of the 7475 aluminum alloy, under both constant amplitude loading and periodical overload blocks. The tests were performed on 4 and 8 mm thickness specimen's with stress ratios of 0.05 and 0.4. The analysis of the shot-peened surface showed a small increase of the micro-hardness values, due to the plastic deformations imposed by shot peening. The beneficial effect of surface peening on fatigue crack growth rates is quite limited to an increasing near the threshold. The specimens’ thickness has only marginal influence on the crack propagation, in opposite to the stress ratio. Periodic overload blocks of 300 cycles promotes a reduction of the fatigue crack growth rate for both intervals of 7,500 and 15,000 cycles.

Effect of Surface Recrystallization on the Low Cycle Fatigue Behavior of Directionally Solidified Superalloy DZ4 by In Situ SEM Studies

2012 ◽  
Vol 706-709 ◽  
pp. 2456-2461
Author(s):  
Xian Feng Ma ◽  
Hui Ji Shi
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Shot Peening ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Directionally Solidified ◽  
Annealing Heat Treatment ◽  
Crack Growth Rates

The effect of recrystallization on the low cycle fatigue life of DZ4 directionally solidified superalloy was investigated for specimens with three different recrystallized layers, which were generated by shot peening (0.1MPa, 0.3MPa and 0.5MPa respectively) and a subsequent annealing heat treatment. The fatigue life showed a decrease for recrystallized specimens with shot-peening of 0.1 MPa and 0.3 MPa, and an unusual increase for that of 0.5MPa, in comparison with the original DZ4 specimen. In-situ SEM observations were performed on the short crack growth behaviors for both original and recrystallized specimens, which revealed the fracture mechanism and the interaction with microstructure. Quantitative analysis of fatigue crack growth rates rationalized the influence of recrystallization on the low-cycle fatigue life of DZ4.

scholarly journals Influence of Layer Removal Methods in Residual Stress Profiling of a Shot Peened Steel Using X-Ray Diffraction

2014 ◽  
Vol 996 ◽  
pp. 175-180 ◽  
Author(s):  
Rasha Alkaisee ◽  
Ru Lin Peng
Keyword(s):  
Residual Stress ◽  
Chemical Etching ◽  
Stress Measurement ◽  
Diffraction Measurement ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Removal ◽  
Compressive Stresses ◽  
The Difference

For X-Ray Diffraction Measurement of Depth Profiles of Residual Stress, Step-Wise Removal of Materials has to be Done to Expose the Underneath Layers to the X-Rays. this Paper Investigates the Influence of Layer Removal Methods, Including Electro-Polishing in Two Different Electrolytes and Chemical Etching, on the Accuracy of Residual Stress Measurement. Measurements on Two Shot-Peened Steels Revealed Large Discrepancy in Subsurface Distributions of Residual Stress Obtained with the Respective Methods. Especially, the Chemical Etching Yielded much Lower Subsurface Compressive Stresses than the Electro-Polishing Using a so Called AII Electrolyte. the Difference was Explained by the Influence of the Different Layer Removal Methods on the Microscopic Roughness.

scholarly journals Fatigue crack growth rates of 10CrNi3MoV steel welded joints considering the stress ratio

2021 ◽  
Vol 33 ◽  
pp. 802-808
Author(s):  
Wei Song ◽  
Jingjing Li ◽  
Xuesong Liu ◽  
Ping Wang ◽  
Di Wan ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Welded Joints ◽  
Stress Ratio ◽  
Crack Growth Rates

A New Model for Predicting Small Crack Growth Rates

2004 ◽  
Vol 471-472 ◽  
pp. 330-334 ◽  
Author(s):  
Hong Cai Zhang ◽  
K.Z. Huang ◽  
J.H. Cheng
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Stress Ratio ◽  
Characteristic Parameter ◽  
Small Crack ◽  
Constant Amplitude ◽  
New Model ◽  
Small Crack Growth ◽  
Crack Growth Rates ◽  
Barrier Characteristic

A new model for predicting the small-crack growth rates is proposed under the constant amplitude loading. With the use of two important parameters, the transition crack length a0 and the barrier characteristic parameter d*, the new model can reflect the abnormal feature of small-crack growth. The effect of crack closure is considered in the model as well. The model is shown to provide a better correlation to the experimental results for the Ti-6Al-4V alloy under various stress levels at a stress ratio of R = 0.4.

Reliability Study on Crack Growth Rate of ADB610 Steel

2013 ◽  
Vol 690-693 ◽  
pp. 1741-1745
Author(s):  
Long Wei ◽  
Shi Yue Wang ◽  
Guo Shou Liu ◽  
Xi Jie Yang
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Rates ◽  
Stress Ratio ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Reliability Study ◽  
A Value ◽  
Crack Growth Rates

The test on fatigue crack growth rate of ADB610 steel is completed. The standard compact tension specimen is loaded by cyclic loading, whose stress ratio is constant at a value of R=0.1. Crack growth rates in the form of Paris formula at different survival levels are obtained by using three methods. After a simple comparison it is clear that crack growth rates obtained by three methods are generally same and the method based on (da/dN, delta K) has better effects on data analysis.

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