Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

Ki, D. Schwam: J.F. Wallace: Y. Zhu: J.W.

Case Western Reserve University

关键词: Aluminium;    Mechanical Properties;    Alloys;    Sand;    Fragmentation;   

RP-ID  :  DE-FC36-01ID13980
RP-ID  :  FC36-01ID13980
RP-ID  :  882786

美国|英语

来源: UNT Digital Library

【 摘 要 】

The utilization of aluminum die casting as enclosures where internal equipment is rotating inside of the casting and could fracture requires a strong housing to restrain the fractured parts. A typical example would be a supercharger. In case of a failure, unless adequately contained, fractured parts could injure people operating the equipment. A number of potential reinforcement materials were investigated. The initial work was conducted in sand molds to create experimental conditions that promote prolonged contact of the reinforcing material with molten aluminum. Bonding of Aluminum bronze, Cast iron, and Ni-resist inserts with various electroplated coatings and surface treatments were analyzed. Also toughening of A354 aluminum cast alloy by steel and stainless steel wire mesh with various conditions was analyzed. A practical approach to reinforcement of die cast aluminum components is to use a reinforcing steel preform. Such performs can be fabricated from steel wire mesh or perforated metal sheet by stamping or deep drawing. A hemispherical, dome shaped casting was selected in this investigation. A deep drawing die was used to fabricate the reinforcing performs. The tendency of aluminum cast enclosures to fracture could be significantly reduced by installing a wire mesh of austenitic stainless steel or a punched austenitic stainless steel sheet within the casting. The use of reinforcements made of austenitic stainless steel wire mesh or punched austenitic stainless steel sheet provided marked improvement in reducing the fragmentation of the casting. The best strengthening was obtained with austenitic stainless steel wire and with a punched stainless steel sheet without annealing this material. Somewhat lower results were obtained with the annealed punched stainless steel sheet. When the annealed 1020 steel wire mesh was used, the results were only slightly improved because of the lower mechanical properties of this unalloyed steel. The lowest results were obtained with unreinforced 356 aluminum casting. Good strength can be obtained with a sound die casting without any defects produced by squeeze casting. The use of higher pressure to produce the squeeze casting has been shown to increase the strength of a hemispherical dome casting. This dome shape casting has been produced both with and without reinforcement and tested to determine its pressure resistance under internal pressure of water. Only a slight improvement in strength could be determined because of water leaks at the seal between hemispherical dome and its flat supporting side. However, when the ability of the casting was tested under the compressive force of a plunger, the strengthening effect of wire mesh or sheet was evident. Higher loads to failure were obtained because of the reinforcement of the stainless steel wire and punched sheet. Rather than a sudden failure occurring, the reinforcement of the stainless steel wire or the punched hard stainless steel sheet held the material together and prevented any loss of the fractured casting to the surroundings. Unalloyed steel did not have the required strength or mechanical properties to increase the properties of the casting.