Search Results for solidified cast metal

Analysis of bifilms provides a simple, powerful, and elegant concept to explain many features of the metallurgy of castings. This article describes the effects of bifilms in metals. Mechanisms for the entrainment of bifilms are reviewed. 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. These include gas precipitation, shrinkage, linear contraction, dendrite pushing, and nucleation and growth of intermetallics. The article also describes the role of bifilm defects in fracture.

Metal casting is the manufacturing method in which a metal or an alloy is melted, poured into a mold, and allowed to solidify. Typical uses of castings include municipal hardware, water distribution systems (pipes, pumps, and valves), automotive components (engine blocks, brakes, steering and suspension components, etc.), prosthetics, and gas turbine engine hardware. This introduction explains the steps involved in making a casting using a simplified flow diagram, and discusses the ferrous and nonferrous alloys used for metal casting.

A gating system is the conduit network through which liquid metal enters a mold and flows to fill the mold cavity, where the metal can then solidify to form the desired casting shape. This article discusses various desirable design considerations for the gating system. Proper design of an optimized gating system will be made easier by the application of several fundamental principles of fluid flow. The article illustrates the Bernoulli's theorem, the law of continuity, and the effect of momentum. Most casting alloys are subject to the presence of particles that can deleteriously affect the physical properties and appearance of the casting. The article lists a variety of adverse effects of the particles. Ceramic filters, when correctly applied, can be relied on to trap particles before they can enter the casting cavity. The article concludes with information on the advantages and the types of the ceramic filters.

Metal matrix composites (MMCs) can be synthesized by vapor phase, liquid phase, or solid phase processes. This article emphasizes the liquid phase processing where solid reinforcements are incorporated in the molten metal or alloy melt that is allowed to solidify to form a composite. It illustrates the three broad categories of MMCs depending on the aspect ratio of the reinforcing phase. The categories include continuous fiber-reinforced composites, discontinuous or short fiber-reinforced composites, and particle-reinforced composites. The article discusses the two main classes of solidification processing of composites, namely, stir casting and melt infiltration. It describes the effects of reinforcement present in the liquid alloy on solidification. The article examines the automotive, space, and electronic packaging applications of MMCs. It concludes with information on the development of select cast MMCs.

Semisolid metal (SSM) processing is a special die casting process, where partially solidified metal slurry is injected into a die cavity to form die cast components. This article discusses the flow behavior of an SSM slurry with emphasis on viscosity, rheological behavior, and yield stress. It illustrates the microstructural formation of semisolids under forced convection. The article concludes with an illustration that compares two SSM processes, namely, thixocasting and rheocasting.

Solidification is a comprehensive process of transformation of the melt of metals and alloys into a solid piece, involving formation of dendrites, segregation which involves change in composition, zone formation in final structure of the casting, and microporosity formation during shrinkage. This article describes the imperfections in the solidification process including porosity, inclusions, oxide films, secondary phases, hot tears, and metal penetration. It talks about the purpose of the gating system and the risering system in the casting process.

The role of an engineer in designing risers is to make sure that risers provide the feed metal in the right amount, at the right place, and at the right time. This article addresses feed metal volume, riser location, and duration of liquid feed metal. It discusses the three types of feeding systems used in riser design: riser sleeves, topping compounds, and breaker cores.

Casting offers the cost advantages over other manufacturing methods for most components. This article reviews the aspects of castings with which designers should be familiar, as well as the methods used by foundries to produce high-integrity castings. It discusses the design concepts that designers and foundries can use to obtain maximum performance from cast parts. The article describes the effects of casting discontinuities on properties, including porosity, inclusions, hot tears, metal penetration, and surface defects. A discussion on hot isostatic pressing treatment of castings is also provided. The article concludes with information on solidification simulation and its use in designing castings.

This article provides a general introduction on casting processes and design techniques. It discusses the process steps and methods of the main categories of shape casting methods, namely, expendable molds with permanent patterns, expendable molds with expendable patterns, and metal or permanent mold processes. The article lists the general guidelines of geometry in casting design. It describes the three separate contractions that are a result of cooling: liquid-liquid contraction, solid-solid contraction, and liquid-solid contraction. Factors influencing the solidification sequence of simple shapes, such as T-sections, X-sections, and L-sections, are discussed. The article also presents an overview of geometric factors that influence heat transfer and transport phenomena. It concludes with a description of the structure and properties of castings.

Casting can be done with either expendable molds for one-time use or permanent molds for reuse many times. This article lists the various methods used to fabricate expendable molds from permanent patterns. The methods include molding of sand with clay, inorganic binders, or organic resins; shell molding of sand with a thin resin-bonded shell; no-bond vacuum molding of sand; plaster-mold casting; ceramic-mold casting; rammed graphite molding; and magnetic (no-bond) molding of ferrous shot. The article tabulates a general comparison of casting methods and discusses the basic requirements of foundry molds.

This article discusses the general principles and advantages of countergravity mold filling. It details several production implementations that use differential pressure countergravity mold filling methods, namely the countergravity low-pressure air process, countergravity low-pressure vacuum process, countergravity low-pressure inert atmosphere process, countergravity pressure vacuum process, supported shell technique, loose sand vacuum process, and countergravity centrifugal casting process.

This article provides general guidelines for casting design to provide progressive solidification, minimize heat concentration, eliminate cores, and prevent distortion. Casting design also affects tolerances. Casting tolerances depend on the alloy being poured, the size of the casting, and the molding method used. Designers can predict the effect of the design on the structure of the final part using solidification simulation models, namely finite element and finite difference models, and rapid prototyping. The article concludes with a short note on how the quality is assured in the foundry.

Ingot casting is the vital conduit between molten metal provided by primary production and recycling and the manufacture of aluminum and aluminum alloy products. A number of ingot casting processes have been developed to ensure the soundness, integrity, and homogeneity required by downstream manufacturing processes. This article starts with a review of the different forms of ingot and the molten-metal processing techniques involved in ingot casting. It then describes the open-mold casting and direct chill (DC) ingot casting processes. The process variations and solidification in the DC process are summarized. The article explains continuous processes, namely, twin-roll strip casting, slab casting, and wheel-belt processes. It concludes with information on postsolidification processes, including stress relief and scalping, and a discussion of safety practices for ingot casting.

Ingot casting is the vital conduit between molten metal provided by primary production and recycling, and the manufacture of aluminum and aluminum alloy products. This article discusses various ingot forms, such as remelt ingot, billets, ingots for rolling, fabricating ingot, and particle ingot and powder. It describes the molten metal processing and ingot casting process in terms of open-mold casting and direct chill process. The article examines the continuous processes that provide commercial alternatives to conventional ingot casting. It reviews the postsolidification processes in terms of stress relief, homogenization, and scalping. The article concludes with a discussion on safety limited to ingot casting.

Semisolid metal (SSM) processing, also known as semisolid metal casting, semisolid forming, or semisolid metal forging, is a special die casting process. This article discusses the origin and advantages of the SSM processing. It describes three major semisolid processing routes: thixocasting, rheocasting, and thixomolding.

The ferrous metals are the most significant class of commercial alloys. This article describes the solidification structures of plain carbon steel, low-alloy steel, high-alloy steel, and cast iron, with illustrations. The formation of nonmetallic inclusions in the liquid before and during solidification is also discussed.

This article reviews the history and methods of copper alloy continuous casting. These methods include vertical continuous casting and horizontal continuous casting. The article discusses the upcasting methods used in vertical continuous casting and strip casting used in horizontal continuous casting. The article also describes the methods and processes of wheel casting and the Ohno continuous casting method.

This article discusses the solidification of a matrix alloy in cast metal matrix composites (MMCs). It begins with a discussion on the mixing techniques in reinforcement incorporation and wettability of reinforcement. It describes the solidification processes, such as stir mixing and melt infiltration, used in the synthesis of MMCs. The article also considers the fundamentals of the process and presents a computational modeling of particle/solidification front interactions in metal-ceramic systems. The article concludes with information on nanocomposites.

This article provides information on four different length scales at which surface morphology can be viewed: macro, meso, micro and nanoscale. Elementary thermodynamics demonstrates that a liquid cannot solidify unless some undercooling below the equilibrium (melting) temperature occurs. The article details five types of solidification undercooling, namely, kinetic, thermal, constitutional (solutal), curvature, and pressure undercooling. It explains the types of nucleation which occur in the melt during solidification. The effects of local instabilities at the solid/liquid interface during growth are illustrated. The article also describes the solidification structures of pure metals, solid solutions, eutectics, peritectics, and monotectics.