Search Results for magnesium assemblies

This article discusses the effects of heavy metal impurities, environmental factors, the surface condition (such as as-cast, treated, and painted), and the assembly practice on the corrosion resistance of a magnesium or a magnesium alloy part. It provides information on stress-corrosion cracking and galvanic corrosion of magnesium alloys, as well as the surface protection of magnesium assemblies achieved by inorganic surface treatments.

This article begins with a discussion on the environmental factors that induce corrosion in magnesium alloys. It reviews the factors that determine the severity of different forms of localized corrosion, namely, galvanic corrosion, corrosion fatigue, and stress-corrosion. The article discusses corrosion protection in magnesium assemblies and the protective coating systems used in corrosion protection practices. Protection schemes for specific applications and the production of novel magnesium alloys with improved corrosion resistance are also reviewed. The article concludes with a discussion on the corrosion of bulk vapor-deposited alloys and magnesium-matrix composites.

Aluminum, a commonly used base material for brazing, can be easily fabricated by most manufacturing methods, such as machining, forming, and stamping. This article outlines non-heat-treatable wrought alloys typically used as base metals for the brazing process. It highlights chloride-active and fluoride-active types of fluxes that are used for torch, furnace, or dip brazing processes. The article explains the steps to be performed, including the designing of joints, preblaze cleaning, assembling, brazing techniques (dip brazing, furnace and torch brazing, fluxless vacuum brazing), flux removal techniques, and postbraze heat treatment processes. It concludes with information on the safety precautions to be followed during the brazing process.

Brazing technology is continually advancing for a variety of metals including aluminum and its alloys and nonmetals. This article discusses the key physical phenomena in aluminum brazing and the materials for aluminum brazing, including base metals, filler metals, brazing sheet, and brazing flux. It describes various aluminum brazing methods, such as furnace, vacuum, dip, and torch brazing. Friction, flow, induction, resistance, and diffusion brazing are some alternate brazing methods discussed. The article reviews the brazing of aluminum to ferrous alloys, aluminum to copper, and aluminum to other nonferrous metals. It also discusses post-braze processes in terms of post-braze heat treatment and finishing. The article concludes with information on the safety precautions considered in brazing aluminum alloys.

Mechanical joining by forming includes all processes where parts being joined are formed locally and sometimes fully. This article focuses on the types, advantages, disadvantages, and applications of the various mechanical joining methods, namely, riveting, crimping, clinching, and self-pierce riveting.

Magnesium and magnesium alloys have been employed in a wide variety of structural applications because of their favorable combination of tensile strength, elastic modulus, and low density. Providing a brief section on occurrence, production, and uses of magnesium, this article describes alloy and temper designations of cast and wrought magnesium alloys. The role of mechanical properties and fabrication characteristics in selection of product forms for structural applications is covered. The article explores the use of magnesium alloys as a substitution for heavier metals such as steel and aluminum alloys to reduce weight in structural parts.

Most magnesium alloys can be joined by gas-tungsten arc welding (GTAW) and gas-metal arc welding (GMAW). This article describes relative weldability ratings and provides information on joint design and surface preparation and the use of filler metals and shielding gases suitable to arc welding of magnesium alloys. The article describes the repair welding of castings, with examples. It concludes with a discussion on heat treatment of castings after welding.

Magnesium and magnesium alloys are used in a wide variety of structural and nonstructural applications. This article provides information on selection and application of magnesium and magnesium alloys, mainly, casting alloys and wrought alloys. It also provides tabulated data for the composition, properties of these alloys, including compressive strength, bearing strength, shear strength, hardness, wear resistance, and fatigue strength. The article describes the selection of product forms (castings, extrusions, forgings) for structural applications which is based on mechanical property requirements, cost, availability, and fabricability. It also discusses the types of inserts used in magnesium. The article also deals with the joining of magnesium alloys by welding, adhesive bonding, and riveting. It concludes by describing the formability and machinability of magnesium and magnesium alloys, and explains the role of magnesium in design and weight reduction.

This article describes the influences of the operational environments of U.S. Navy aircraft during corrosion-control process. The most widely used materials in airframe structures and components, such as aluminum, steel, titanium, and magnesium alloy systems, are reviewed. The article provides information on the inspections steps, corrosion-control issues, and corrosion-prevention strategies for naval aircraft. It contains a table that lists typical locations of corrosion on the aircraft. The article also provides examples of aircraft corrosion damage.

Copper, copper alloys, and precious metals are probably the most easily brazed metals because of their resistance to oxidation at high temperatures. This article provides a brief discussion on the metallurgy of copper, copper alloys, and precious metals and discusses the filler metals, brazing fluxes, joint clearance and design, and different brazing processes used in brazing of copper, copper alloys, and precious metals.

This article describes the process and advantages of no-bond methods of vacuum molding and magnetic molding, with schematic illustrations. It also discusses the characteristics of plastic film and dimensional specifications of vacuum molding.

This article begins with a discussion on the corrosion characteristics of unalloyed magnesium and two major magnesium alloy systems. It shows the effects of iron and 13 other elements on the saltwater corrosion performance of magnesium in binary alloys with increasing levels of the individual elements. The article illustrates the effect of increasing iron, nickel, and copper contamination on the standard ASTM B 117 salt-spray performance of the die-cast AZ91 test specimens as compared to the range of performance observed for cold-rolled steel and die-cast aluminum alloy 380 samples. It discusses the effect of heat treating and cold working on the corrosion rates of the die-cast AZ91 alloy. The article concludes with a description on the causes of corrosion failures in magnesium alloys.

This article focuses on the various criteria considered in the selection of product forms, joint types, solders, and filler metals for brazing and soldering of base material components.

This article provides information about the selection of brazing processes and filler metals and describes the brazing (heating) methods, including manual torch brazing, furnace brazing, induction brazing, dip brazing, resistance brazing and specialized brazing processes such as diffusion and exothermic brazing. The article explains joint design, filler materials, fuel gases, equipment, and fluxes in the brazing methods. The article also describes the brazing of steels, stainless steels, cast irons, heat-resistant alloys, aluminum alloys, copper and copper alloys, and titanium and titanium alloys.

This article focuses on the variety of alloys, furnaces, and associated melting equipment as well as the casting methods available for manufacturing magnesium castings. These methods include sand casting, permanent mold casting, die casting, thixomolding, and direct chill casting. The article discusses the flux process and fluxless process for the melting and pouring of magnesium alloys. It describes the advantages and disadvantages of green sand molding and tabulates typical compositions and properties of magnesium molding sands. The article provides information on the machining characteristics of magnesium and the applications of magnesium alloys.

The morphology of the graphite particles in compacted graphite iron (CGI) is intermediate to the graphite particles found in gray iron or ductile iron. This article discusses the castability and product design of compacted graphite iron. The introduction of modern measurement and control technologies has made CGI a viable material for high-volume series production. The article describes the production of compacted graphite iron castings and the process control that depends on the production volume of components made from compacted graphite iron. It also discusses the process control for high-volume CGI commonly based on thermal analysis.