High-velocity oxyfuel (HVOF)-applied thermal spray coatings are viable candidates for replacement of hard chrome in numerous applications. HVOF thermal spraying can be used to deposit both metal alloy and cermet coatings that are dense and highly adherent to all the commonly used base metals in airframe structures. This article summarizes the results of materials and component testing. It also presents a cost/benefit analysis of HVOF WC/17Co and WC/10Co4Cr coatings on aircraft landing gear components.

Flash welding (FW) is a resistance welding process in which a butt joint weld is produced by a flashing action and by the application of pressure. Flash welding is used to join metallic parts that have similar cross sections in terms of size and shape. This article discusses flash-welding applications, including chain links, transmission bands, automotive flywheel ring gears, aircraft landing gear, band-saw blades, and crankshaft counter weights. It describes the components of a typical flash-welding machine. The article provides information on the electrical controls of flash-welding equipment. These include programmable controllers, welding current controllers, and either motor or servo-valve controllers.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of wrought aluminum alloys and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the corrosion-fatigue fracture, fatigue striations, tension-overload fracture surface, ductile fracture, cone-shaped fracture surface, intergranular crack propagation, transgranular crack propagation, stress-corrosion cracking, hydrogen damage, and grain-boundary separation of these alloys. Fractographs are also provided for a forged aircraft main-landing gear wheel and actuator beam, an aircraft wing spar, a fractured aircraft propeller blade, shot peened fillet, an aircraft lower-bulkhead cap, and clevis-attachment lugs.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of precipitation-hardening stainless steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the cup-and-cone tension-overload fracture, low-cycle and high-cycle fatigue fracture, fracture surface, brittle intergranular fracture, hydrogen embrittlement, and intergranular stress-corrosion cracking of stainless steel components of these steels. The components include high-pressure compressor parts, springs, deflector yokes of aircraft main landing gears, and aircraft engine mount beams.

This article reviews forge welding and illustrates the typical joint configurations used for manual and automatic forge welding applications.

This article presents an overview of the use of mechanism analysis (kinematics and dynamics) and simulation. It provides indications of the directions in which mechanism simulation is growing and how it is integrated in the evolving computer aided design and computer aided engineering (CAD/CAE) fields. Mechanism simulation is best used as part of a concurrent CAD/CAE approach to design. The article discusses the state, evolution, and direction of application for these techniques in a variety of fields.

This article focuses on failure analyses of aircraft components from a metallurgical and materials engineering standpoint, which considers the interdependence of processing, structure, properties, and performance of materials. It discusses methodologies for conducting aircraft investigations and inspections and emphasizes cases where metallurgical or materials contributions were causal to an accident event. The article highlights how the failure of a component or system can affect the associated systems and the overall aircraft. The case studies in this article provide examples of aircraft component and system-level failures that resulted from various factors, including operational stresses, environmental effects, improper maintenance/inspection/repair, construction and installation issues, manufacturing issues, and inadequate design.

This article summarizes some general alloy groupings by application or major characteristics. The groupings include cast rotor, general-purpose, elevated-temperature, wear-resistant, moderate-strength, high-strength, and high-integrity die casting alloys and cast aluminum alloys bearings. A table lists selected applications for aluminum casting alloys.

This article reviews corrosion problems in the U.S. Department of Defense (DoD) and discusses management and maintenance aspects of the practices that address the cost and readiness. It describes the plans to institute corrosion prevention and control strategies under DoD directives in engineering design, material selection, and fabrication processes for new acquisitions. The article also suggests a long-term strategy to reduce the cost of corrosion control.

Ultrahigh-strength steels are designed to be used in structural applications where very high loads are applied and often high strength-to-weight ratios are required. This article discusses the composition, mechanical properties, processing, product forms, and applications of commercial structural steels capable of a minimum yield strength of 1380 MPa (200 ksi). These include medium-carbon low-alloy steels, such as 4340, 300M, D-6a and D-6ac steels; medium-alloy air-hardening steels, such as HI1 modified steel and H13 steel; high fracture toughness steels, such as HP-9-4-30, AF1410, and AerMet 100 steels; and maraging steels.

This article describes the process of selecting an optimum coating and material system for a specific application. It reviews critical coating functions that influence the coating selection process, and presents some application success stories. The article explores the benefits of thermal spray coatings and functions they provide. It also presents key references from various National Thermal Spray Conference, United Thermal Spray Conference, and International Thermal Spray Conference Proceedings from 2006 through 2012.

Selective plating, also known as brush plating, differs from traditional tank or bath plating in that the workpiece is not immersed in a plating solution (electrolyte). Instead, the electrolyte is brought to the part and applied by a handheld anode or stylus, which incorporates an absorbent wrapping for applying the solution to the workpiece (cathode). This article focuses on the selective plating systems that include a power pack, plating tools, anode covers, specially formulated plating solutions, and any auxiliary equipment required for the particular application. It provides a detailed account of the applications of selective plating, with examples. The article describes the advantages, limitations, key process elements, and health and safety considerations of selective plating. It also includes the most important industrial, government, and military specifications.

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.

This article discusses coating products available for use in the aerospace industry that are compliant with regulations requiring reductions in emissions from organic solvents. The coating products addressed include primers, topcoats, and chemical milling maskants. It describes their characteristics and limitations compared to conventional noncompliant materials. The article addresses the methods and products commonly used achieve regulatory compliance: waterborne coatings, exempt-solvent-based coatings, high-solids coatings, powder coating, and electro-deposition.

Forge welding is a solid-state joining process in which the workpieces are heated to the welding temperature and then sufficient blows or force are applied to cause permanent deformation and bonding at the faying surfaces. Coextrusion welding is a solid-state process that produces a weld by heating two or more workpieces to the welding temperature and forcing them through an extrusion die. This article illustrates typical joint configurations used for manual and automatic forge welding applications. It provides information on the common metals welded by coextrusion welding, such as low-carbon steel, aluminum, copper, and copper alloys. The article also explains the common coextrusion behaviors.

This article summarizes the various kinds of gear wear, including fatigue, impact fracture, wear, and stress rupture, describes how gear life in service is estimated. It presents the rules concerning lubricants in designing gearing and analyzing failures of gears. The article presents the equations for determining surface durability and life of gears. It tabulates the situations and concepts of pitting failures in gears. The article analyzes some of the more common flaws that affect the life of gear teeth. It reviews the components in the design and structure of each gear and/or gear train that must be considered in conjunction with the teeth.

This article discusses the fundamental variables involved in fatigue-life assessment, which describe the effects and interaction of material behavior, geometry, and stress history on the life of a component. It compares the safe-life approach with the damage-tolerance approach, which employs the stress-life method of fatigue life assessment. The article examines the behavior of three different metallic materials used in the design and manufacture of structural components: steel, aluminum, and titanium. It also reviews the effects of retardation and spectrum load on component life. The article concludes with case studies of fatigue life assessment from the aerospace industry.

This article provides information on the applications of fiber-reinforced composites in commercial and military aircrafts. It tabulates the composite components in various types of aircraft. The applications of the composites in the components of Boeing 727, 737, 757, 767, 777, and 777-200 are schematically illustrated.