Influence of Oxide film filling defects on fatigue properties of cast A1-7Si-Mg Alloy

by Christian Wambura Mwita Nyahumwa

Publisher: University of Birmingham in Birmingham

Written in English
Published: Downloads: 187
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Edition Notes

Thesis (Ph.D) - University of Birmingham, School of Metallurgy and Materials, Faculty of Engineering.

Statementby Christian Wambura Mwita Nyahumwa.
ID Numbers
Open LibraryOL17462402M

This thesis describes the results of a study conducted on cast W aluminum, a commercial Al-Si-Cu alloy used in automotive engine components, and presents a model that effectively predicts fatigue properties in this alloy as a function of material condition. This paper provides a review of the fatigue properties reported in the open literature for die cast magnesium-based alloys. Recently developed fatigue data, in the form of stress versus number of cycles to failure for bending fatigue (R=-1), are presented for die cast AM60B and AZ91D alloy specimens with thicknesses between 1 and 10 mm.   of the defect area as a representation of the dimension of the porosity,[37] this size is approximately 55 lm. Also, for low-alloy steel, fatigue strength reductions from 8 to 30 pct were reported when shrinkage porosity cavities covered 3 to 7 pct of the fracture surface.[22] Recently, for an aluminum alloy, Linder et al.[29] measured a. The fatigue life can be increased by % for the nm-thick film, and % for the 1 µm-thick film, when tested under maximum stress of MPa. The fatigue life at the same stress level and the fatigue-endurance limit of the alloy coated with nm-thick film are slightly higher than those of the alloy coated with 1 µm-thick film.

Flaws observed during growth of thermal oxide films on aluminum 7 Growth of electronically conducting polymers on the insulating barrier layer 8 Pores in SiO% films grown in oxygen 8 Electrochemical detection of flaws or pores in oxide film 9 Dekker and Middlehoek's pore-filling . The aim of this work was to investigate the fatigue life for cast AC4C-T6 alloy with different amounts of inherent porosity. An additional aim was to predict the durability for cast components with defect constrained in a specified volume of components, by using a commercial program MSC. Fatigue. Lost foam casting is a highly versatile metalcasting process that offers significant benefits in terms of design flexibility, energy consumption, and environmental impact. In the present work, the fatigue behavior of lost foam cast aluminum alloy , in conditions T6 and T7, was investigated, under both zero and non-zero mean stress conditions, with either as-cast or machined surface finish.   A reliable and comprehensive database of design properties for cast iron is key to full and efficient utilization of this versatile family of high production-volume engineering materials. A database of strain-life fatigue properties and supporting data for a wide range of structural cast irons representing industry standard quality was developed in this program.

• Quality of Film – Physical and Chemical Properties •Stress • Adhesion • Stoichiometry • Film density, pinhole density • Grain size, boundary property, and orientation • Breakdown voltage • Impurity level • Deposition Directionality • Directional: good for lift-off, trench filling • . Fatigue tests were made to establish the effects of corrosion,. of abrasive blasting, and of corrosion followed by abrasive blasting on the fatigue strength of L93 alloy.' All fatigue tosting was carried out on a rotating beisding machine operated at a frequency of IOU: 5 Ri. Problems of Porosity As the amount of porosity increases in an aluminum or iron casting, it can become inter-connected and cause a leak path. The porosity makes the casting unusable for holding pressure in applications like pumps, compressors, transmissions and plumbing fixtures. Thermal Oxide or SiO2 is one of the "building block" films used in making both simple and complex semiconductor devices. If grown correctly using a high purity low defect Silicon substrate, it can be an excellent dielectric (Insulating) thin film. It is normally found on a device as "field oxide" electrically isolating Polysilicon, metal or other conductive thin film(s) from the Silicon.

Influence of Oxide film filling defects on fatigue properties of cast A1-7Si-Mg Alloy by Christian Wambura Mwita Nyahumwa Download PDF EPUB FB2

Influence of oxide film defects generated in filling on mechanical strength of aluminium alloy castings. Materials Science and Technology: Vol. 20, No. 4, pp. Cited by: Most reported results are for the casting alloy A, which contains about 7%Si [3].

The fatigue resistance of cast aluminum alloys was reported to be controlled by microstructural defects. Abstract. Double oxide film defects consist of doubled-over oxide films containing a gas-filled crevice, and are reported to cause both reductions in mechanical properties and increases in the scatter of properties in Al alloy : Q.

Chen, A. Caden, W. Griffiths. Abstract— The fatigue properties of un‐notched polished specimens of an aluminium casting alloy have been measured for various heat‐treatment conditions and at various mean stresses.

The relation between fatigue life and alternating stress is insensitive to heat‐treatment and, apparently, to mean stress. It was observed that failure initiated at interdendritic shrinkage defects Cited by:   The paper investigates the influence of casting defects on the static and fatigue strength of a high pressure die cast aluminium alloy.

The material is EN ACUNI EN (ex GD-Al Si Cu Fe-UNI ), widely used in load-bearing components in the automotive by:   Cast aluminum alloy ZLA, which is named by Chinese national norm, is a typical cast Al–Cu–Mn–Ti aluminum alloy with primary alloying elements including – wt.% Cu, – wt.% Mn, – wt.% Ti and other minim elements such as Zr, Cd, V.

The bonding possibility of the double oxide film defect was investigated by holding pressure during solidification after holding in liquid A alloy for 13 min. The defect was modeled experimentally through contacting the oxide film layers of the A alloy.

The composition and morphology of the oxide film layers were studied by SEM and EDX. C.W.M. Nyahumwa: “ Influence of Oxide Film Filling Defects on Fatigue Properties of Cast A1 -7Si-Mg Alloy ”, PhD.

Thesis, University of Birmingham, UK, Book Chapter The Oxide Film Defect: The Bifilm By John Campbell The article describes the effect of furling and unfurling on mechanical properties of the solidified cast metal. It provides a discussion on the mechanisms of unfurling to determine the casting properties of the metals.

The Oxide Film Defect: The Bifilm, Casting, Vol The influence of casting defects on fatigue strength of an investment cast Ti-6Al-4V alloy is investigated.

The most common of these defects are: pinhole, linear defect and inclusion. Each of them is currently defined by its size, morphology and position from the surface but is different from each other for a same type.

An experimental campaign. the characteristics of oxide films in vacuum-cast materials. The only previous work about oxide films in vacuum-cast Ni-based alloys was described by Rashid and Campbell in [3].

This study has added to the evidence that oxide film defects do exist in studied Ni-based super-alloy in certain vacuum casting conditions. 1 Experimental methods. 20 years.

More recently, new mechanisms of pore formation based on entrainment of oxide films during the filling of aluminum alloy castings have been identified and documented []. Oxide film defects are formed when the oxidized surface of the liquid metal is folded over.

Influence of casting defects on fatigue behaviour of A aluminium alloy. International Journal of Cast Metals Research: Vol. 27, No. 6, pp. The Relationship Between High-Cycle Fatigue and Tensile Properties in Cast Aluminum Alloys Huseyin Ozdes University of North Florida This Master's Thesis is brought to you for free and open access by the Student Scholarship at UNF Digital Commons.

It has been accepted for inclusion in UNF Graduate Theses and Dissertations by an authorized. Oxide film defects in cast Al-Si-Mg alloys Effect of oxide films on tensile properties of castings Fe-rich intermetallic phase in cast Al-Si-Mg alloy Effect of Fe-rich phases on tensile properties of the castings Porosity defects in cast Al-Si-Mg alloy The fatigue properties of high-pressure die-casting (HPDC) magnesium (Mg) alloys AZ91 exhibit a high variability, due primarily to the porosity that is inherent in the injection process.

In the 94% of the studied samples, the porosity in which crack nucleation originates is at the surface or adjacent to the surface.

In order to study the environmental effect on fatigue properties of die-cast magnesium alloys, several fatigue tests were performed for AM50HP and AZ91HP in ambient air, vacuum, engine oil, deionized water and % NaCl solution.

It is found that the S-N curves are steeper in corrosive environment and AM50HP shows a higher sensitivity to the action of % NaCl solution than AZ91HP.

Abstract Three‐dimensional (3D) images of casting defects present in broken and nonbroken fatigue samples of a cast Al alloy (A–ISO: AlSi8Cu3Fe) have.

Eisenmann, David Jon, "Effects of alloying elements on the microstructure and fatigue properties of cast iron for internal combustion engine exhaust manifolds" (). Graduate Theses and Dissertations. deformation resistance of the alloy. Fatigue life behavior The total strain amplitude (Δe t /2) versus fatigue life (N f) curves for both die-cast and permanent mold cast Al-Si-Cu-Mg alloys are shown in Fig.

It is noted that the fatigue life of the die-cast alloy is higher than that of the permanent mold cast alloy. THE INFLUENCE OF MATERIALS PROCESSING ON THE HIGH TEMPERATURE LOW CYCLE FATIGUE PROPERTIES OF THE CAST ALLOY INLC 1 1 2Jr.

and e Westinghouse Electric Corporation 1. Research and Development Center Pittsburgh Pa. U.S.A. tion Turbine Systems Division Concordville Pa. U.S.A. Some of the defects produced may be neglected or tolerated and some are not acceptable, it must be eliminated for better functioning of the parts.

Types. Casting defects can be categorized into 5 types. Gas Porosity: Blowholes, open holes, pinholes 2. Shrinkage defects: shrinkage cavity 3. Cast parts usually inherit internal defects such as micro shrinkage pores due to the manufacturing process.

In order to assess the fatigue behaviour in both finite-life and long-life fatigue regions, this paper scientifically contributes towards a defect-based fatigue design model. Extensive fatigue and fracture mechanical tests were conducted whereby the crack initiating defect size.

Title: Oxide Film and Porosity Defects in Magnesium Alloy AZ91 Author: L. Wang, H. Rhee, S. Felicelli, A. Sabau, J. Berry Subject: Shape Casting: Third International. Cast Iron. The fatigue performance of a particular cast iron depends on the quantity, size, and shape of the free graphite constituent as well as its interaction with the matrix.

Tensile and compressive behavior of cast iron can be different. Compressive strength and. Casting Defects - Sand Mold, Metal Casting. Introducing various metal casting defects with many pictures by Dandong Foundry in China.

These are the common sand casting defects on the surface and inside of cast iron and cast steel parts. Blowhole and Pinhole This is a kind of cavities defect, which is also divided into pinhole and subsurface blowhole. FATIGUE BEHAVIOR OF VARIOUS GRADES OF STEEL CASTINGS AND THE INFLUENCE OF CAST SURFACES.

This investigation evaluated the fatigue properties of three commercial grades of cast steel utilized by the railroad industry. The tests were conducted using a 3/8 inch thick cm) ten inch ( cm) long flat plate specimen tested in reversed bending. Therefore, tensile properties, fatigue, and corrosion-fatigue behavior of automotive die cast AlMg5Si2Mn alloy are studied in the current work.

The results indicate that the tensile strength and yield strength of the as-cast specimens are obviously lower than those of the age-treated specimens, while the elongation decreases with increasing. In this study, the effects of surface oxide film formation on the fatigue behavior of T6 aluminum alloy were analyzed in terms of the corrosion time of the alloy.

The aluminum material used is known to have high corrosion resistance due to the passivation phenomenon that prevents corrosion.

The AM60 Mg alloy has been used in the automotive industry to help achieve higher fuel efficiency. However, its products, mostly fabricated via high pressure die casting process, are inherently plagued with porosity issues. The presence of porosity impairs mechanical properties, especially fatigue properties, and thus.

effect on casting properties. Ductility and fatigue strength are especially sensitive to inclusions. In addition, almost Inclusion defects in die cast alloys: a) oxide inclu- dling when filling casting furnaces with this treated metal.free materials. Porosity is more detrimental to fatigue life than oxide films.

3. There exists a critical defect size for fatigue crack initiation, below which fatigue crack initiates from other competing initiators such as eutectic particles and slip bands.

In Sr modified cast A alloy, the critical defect size is in the range of 25 to 50 m. 4.A study was conducted to determine how the fatigue life of a aluminum alloy (W) was affected by pore size.

To perform this study, two sets of microstructurally similar castings with differing levels of microporosity were created. Following room temperature fatigue testing, the pores that init.