Effect of Micro-porosities on Fatigue Behavior in Aluminum Die Castings by 3D X-ray Tomography Inspection

Abstract

In this investigation, porosities in fatigue specimens obtained from practical ADC12 high pressure die castings were detected and reconstructed with high resolution X-ray computed tomography technology. Three dimensional (3D) characterizations of the porosities were analyzed. The high cycle fatigue tests were carried out at five stress amplitudes on seven groups of the specimens with different porosity contents. The Weibull analysis suggested less scatter of the fatigue life at larger stress condition. With the SEM observation on the fatigue fractured surfaces, the porosities initializing the fatigue cracks were identified. A pore-fatigue life prediction equation was deduced with the pore characteristics from the fracture surface and 3D X-ray tomography inspection. With 3D reconstruction of tomography data and FEA method, the simulation of the stress distribution around the actual 3D pores were carried out and analyzed further.KEY WORDS: high pressure die casting; porosity; fatigue; three dimensional tomography; finite element analysis.

Continuum damage mechanics based approach to the fatigue life prediction of cast aluminium alloy with considering the effect of porosity

“…Then, a dimensionless quantity related to the diameter of pore is introduced to the damage evolution equations to reflect the effect of stress concentration induced by a pore. It is found that the calculated fatigue lives are in accordance with the experimental results [7]. materials, can be represented by the deterioration ratio of the stiffness of representative volume element (RVE): …”

“…The fractured surfaces of all specimens were observed with a scanning electron microscope (SEM). Part of the results [7] are shown in Table 2. …”

“…The specimens for the X-ray tomography scan and fatigue test were machined from a practical high pressure die casting (HPDC) ADC12 aluminium alloy [7]. During the die casting process, the melt pouring temperature was 680°C, and the shot speeds were 0.1 to 0.8 and 4.0 m/s during the slow and high injection periods, respectively.…”

Detection of Periodic Defects Using Dual-Light Switching Lighting Method on the Surface of Thick Plates

“…In steel manufacturing conditions, many methods have been developed to improve the quality of steel and achieve automatic inspection. In this introduction, we briefly mention the various inspection techniques that have been developed for steel manufacturing environments, which include ultrasonic detection methods for stainless steel spot welds 2) and ductile iron, 3) quality monitoring using voltage signals for small-scale resistance spot welding, 4) 3D X-ray tomography inspection for fatigue in aluminum die castings, 5) and optical inspection techniques for slabs, 6,7) steel bar, 8,9) billets, 10) and silicon steel. 11) Although the several studies mentioned above have achieved good performance and can effectively detect their respective defects, it is difficult to apply them directly to defect detection in thick plate surfaces because each of these methods is optimized for a…”

Using X-ray computed tomography analysis tools to compare the skeletal element morphology of fossil and modern frog (Anura) species

“…Though initially CT scans were used mainly for industrial, engineering, and medical purposes (McColl et al, 2006;Kuwazuru et al, 2008;Nicoletto et al, 2010Nicoletto et al, , 2012Wan et al, 2014) X-ray micro computed tomography from micro-CT scanners and X-ray synchrotron imaging has become increasingly popular as a diagnostic and analytical tool for palaeontologists, archaeologists, and other Natural Science disciplines as it is entirely nondestructive and provides detailed 3D images of the structure of whole animals or plants, the remains of fossils buried in amber, rock, or hard substrate, and the interior of fossil bones and teeth (Tafforeau et al, 2006;Kearney et al, 2005;Lak et al, 2008;Sutton, 2008;Jasinoski et al, 2010;Jasinoski and Chinsamy, 2012;Huttenlocker et al, 2013;Holloway et al, 2014;Dollion et al, 2015;Wichura et al, 2015).…”