Topic
Paris' law
About: Paris' law is a research topic. Over the lifetime, 13815 publications have been published within this topic receiving 224818 citations. The topic is also known as: Paris-Erdogan law.
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20 Jan 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of heat-treatment on the fatigue crack growth and fracture paths in lost foam sand cast B319 and A356 Al has been examined by in situ testing in a scanning electron microscope.
Abstract: The effect of heat-treatment on the fatigue crack growth and fracture paths in lost foam sand cast B319 and A356 Al has been examined by in situ testing in a scanning electron microscope. Fatigue crack growth and fracture toughness experiments were performed at ambient temperature on B319 Al in T5, T6, and T7 conditions and on A356 in the T6 condition to characterize the crack path and the interaction of the crack-tip with the microstructure. High-resolution micrographs of the near-tip region were analyzed using a machined-vision-based stereoimaging technique, known as DISMAP, to determine the crack-tip displacement and strain fields. Selected-area energy dispersive spectroscopy was used to identify the particles in the wake of the fatigue cracks, as well as the alloy content of the Al-matrix ahead of the crack-tip. Microhardness tests revealed the presence of hard and soft zones in B319-T6 that the fatigue cracks tended to follow. The fatigue crack growth rate was reduced and the crack path altered when the crack-tip interacted with (1) localized shear bands, (2) interdendritic boundaries, (3) particle/matrix interface, (4) shrinkage pores, and (5) fractured particles. The decrease in the fatigue crack growth rate can be attributed to increasing crack-tip shielding due to crack branching and deflection. The fracture toughness of A356-T6 is higher than the B319 materials because of the absence of shear localization in the matrix.
111 citations
TL;DR: In this article, the effects of stress ratio on fatigue-crack growth were analyzed using Paris' stress-intensity analysis, and the results from the R = 0 tests on a plot of rate against stressintensity range.
110 citations
TL;DR: In this article, a number of modifications are introduced to the linear elastic approach to establish a new parameter which is capable of correlating both long crack and short crack fatigue crack growth data.
110 citations
TL;DR: In this paper, Fatigue crack growth and threshold behavior have been examined in three commercial aluminium alloys in both air and vacuum environments, and it was observed that, in air, the threshold stress intensity range ΔKt, varied linearly with the ΔKT ratio.
Abstract: — Fatigue crack growth and threshold behaviour have been examined in three commercial aluminium alloys in both air and vacuum environments. It was observed that, in air, the threshold stress intensity range ΔKt, varied linearly with the ΔKt ratio. In contrast ΔK, in vacuum was found to be independent of R. Over the whole growth rate range examined fatigue crack growth in vacuum was ΔK controlled and failure occurred by a dimple and ductile striation mechanism. This also applied to failure in the intermediate growth rate ranges in air. However, at slow growth rates in air, fatigue crack growth was structure sensitive and crystallographic facets were formed during the crack propagation process.
110 citations
25 Jan 2011-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the effect of laser shock processing on some mechanical properties of 2205 duplex stainless steel was evaluated using a Q-switched Nd:YAG laser, operating at 10 Hz with infrared (1064nm) radiation.
Abstract: Duplex stainless steels have wide application in different fields like the ship, petrochemical and chemical industries that is due to their high strength and excellent toughness properties as well as their high corrosion resistance. In this work an investigation is performed to evaluate the effect of laser shock processing on some mechanical properties of 2205 duplex stainless steel. Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switched Nd:YAG laser, operating at 10 Hz with infrared (1064 nm) radiation. The pulses are focused to a diameter of 1.5 mm. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is determined by the contour method. It is observed that the higher the pulse density the greater the compressive residual stress. Pulse densities of 900, 1600 and 2500 pul/cm2 are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness if this steel.
110 citations