Search Results for gas content

Gas porosity is a major factor in the quality and reliability of castings. The major cause of gas porosity in castings is the evolution of dissolved gases from melting and dross or slag containing gas porosity. Degassing is the process of removing these gases. This article describes the methods of degassing aluminum, magnesium, and copper alloys. It provides information on the sources of hydrogen in aluminum and gases in copper.

Inert gas fusion is a method of determining the quantitative content of gases in ferrous and nonferrous materials where gases, such as hydrogen, nitrogen, and oxygen, are physically and chemically adsorbed by the materials and later removed and swept by from the fusion area by an inert carrier gas. This article describes the operating principles and sample selection of inert gas fusion. It explains the mechanisms involved in the introduction of fusion gas, separation and detection of fusion gas by thermal-conductive and infrared detection methods. Additionally, the article explains the methods used for analyzing trace amounts of nitrogen, oxygen, and hydrogen in the carrier mediums, providing examples that aid in solving several problems.

This article describes the effects of furnace atmospheric elements on steels. These elements are air, water vapor, molecular nitrogen, carbon dioxide, and carbon monoxide. The article provides useful information on six groups of commercially important prepared atmospheres classified by the American Gas Association on the basis of method of preparation or on the original constituents employed. These groups are designated and defined as follows: Class 100, exothermic base; Class 200, prepared nitrogen base; Class 300, endothermic base; Class 400, charcoal base; Class 500, exothermic-endothermic base; and Class 600, ammonia base. These are subclassified and numerically designated to indicate variations in the method by which they are prepared. The article also contains a table that lists significant furnace atmospheres and their typical applications.

Interplays of metallurgical factors, such as dissolved oxygen, carbon, and silicon content, that control the molten metal from melting to pouring, have a decisive influence on the quality of the castings. This article focuses on the magnesium treatment and desulfurization carried out during inoculation and nucleation of molten cast iron, assisting in the formation of cast iron. The different types of cast irons are gray cast iron, nodular cast iron, compacted graphite iron, malleable cast iron, and alloyed cast iron. The article provides an overview of the melt treatment processes carried out in cast steel, wrought and cast aluminum, and copper materials.

This article illustrates the simulation procedure of casting process. It describes important elements and points of the simulations. These include the setting of clear simulation objectives, selection of proper simulation code, hints in modeling of shape and phenomena, initial and boundary conditions, physical properties, enmeshing, and evaluation of simulation results. The article also provides some insights into the application of models to real world problem for foundry process engineers.

This article focuses on aspects that are important for the commercial production of castings. It discusses the modification process in hypoeutectic and eutectic alloys that differ only in the relative volume fraction of primary aluminum and aluminum-silicon eutectic. The article explains how modification changes porosity formation in a casting. It describes the mechanisms responsible for silicon modification, as well as the modifications and changes in eutectic nucleation and the eutectic grain structure. The article reviews the usage of strontium in foundry practices. The growth of silicon eutectic is described to explain effects ancillary to silicon modification. The article also examines the effects of elements, such as phosphorus, antimony, bismuth, magnesium, boron, and calcium, on the silicon structure.

This article discusses the most common methods of melting steels, namely, electric arc and induction melting. It describes the classification of refractories by an index of the “basicity” of the slag formed on the steel surface. The article provides a discussion on the converter metallurgy, which includes melt refinement in argon oxygen decarburization (AOD) vessels and vacuum oxygen decarburization (VODC) in a converter vessel. It also discusses ladle metallurgy, which includes vacuum induction degassing, vacuum oxygen decarburization, and vacuum ladle degassing.

This article focuses on the construction, operation of electric arc furnaces (EAF), and their auxiliary equipment in the steel foundry industry. It provides information on the power supply of EAF and discusses the components of the EAF, including the roof, furnace shell, spout and tap hole, water-cooling system, preheat and furnace scrap burners, and ladles. The article describes the acid and basic steelmaking practices. It discusses the raw materials used, oxidation process, methods of heat reduction, and deoxidation process in the practices. The article provides a discussion on the arc melting of iron and EAF steelmaking.

Nickel-base alloy castings are widely used in corrosive-media and high-temperature applications. This article begins with a discussion on the compositions of corrosion-resistant nickel-base casting alloys and heat-resistant nickel-base casting alloys. It describes the effects of aluminum and titanium on the structure and properties of nickel-base alloys. The article provides information on the melting, foundry, and pouring practices for nickel-base alloys. It explains the welding and heat treatment of the nickel-base casting alloys. The article concludes with an overview of the numerous applications of cast heat-resistant nickel-base alloys.

Sand mold and permanent mold casting are the major methods for shape casting of steels, with production closely split among green sand, chemically bonded sand, and permanent mold processes. This article describes key aspects of the steel casting process, including steel solidification characteristics, melting practices, melt treatment, and feeding of the molten steel into the mold used in steel foundries. It discusses the features of melting furnaces used in direct arc melting and induction melting. It reviews factors such as wall thickness and designing for avoidance of hot spots. The article explains the sand casting and permanent mold casting of steel. The process design and casting of thin sections are also discussed.

The properties of carbon and alloy steels are dependent on the relationships between chemical composition, processing, and microstructure. This article discusses the effects of alloying and residual elements on the mechanical properties of carbon and alloy steels. Tables listing values for the mechanical properties of selected carbon and alloy steels in the hot-rolled, normalized, annealed, and quenched-and tempered condition are provided.

Vacuum induction melting (VIM) is often done as a primary melting operation followed by secondary melting (remelting) operations. This article presents the process description of VIM and illustrates potential processing routes for products, which are cast from VIM ingots or electrodes. It describes the VIM refinement process, which includes the removal of trace elements, nitrogen and hydrogen degassing, and deoxidation. The article concludes with information on the production of nonferrous materials by VIM.