Search Results for ambient temperature

The constitutive relations for metalworking include elements of behavior at ambient temperature as well as high-temperature response. This article presents equations for strain hardening and strain-rate-sensitive flow, with alternate sections on empirically determined properties, followed by the models of constitutive behavior. It provides a discussion on creep mechanisms involving dislocation and diffusional flow, such as the Nabarro-Herring creep and the Coble creep. The equations for the several creep rates are also presented. Research on the mechanism of the superplastic flow in fine-grain metals has encompassed many ideas, such as the diffusional creep, dislocation creep with diffusional accommodation at grain boundaries, and concepts of grain-mantle deformation. The article concludes with information on the kinetics of superplastic deformation processes, including low stress behavior, concurrent grain growth, and high stress behavior.

Constitutive relations for metal-working include elements of behavior at ambient temperature as well as high-temperature response. This article presents the equations for the strain hardening and strain-rate-sensitive flow, with alternate sections on empirically determined properties, followed by models of constitutive behavior. These models include the isothermal constitutive model and the physical model for superplastic flow. A formal description of the superposition of the operative mechanisms for dynamic recovery at hot-working strain rates is also provided. The article describes creep mechanisms that are useful for illustrating the strong stress dependence of dislocation and diffusional flow.

This article discusses the applications of high-strength aluminum powder metallurgy (P/M) alloys, detailing the advantages, properties, and the various steps involved in P/M technology, including powder production, powder processing, and degassing and consolidation. Three areas of design efforts to push the inherent advantages of aluminum alloys to new limits are also covered: high ambient-temperature strength with improved corrosion and stress corrosion cracking resistance; improved elevated-temperature properties so aluminum alloys can more effectively compete with titanium alloys; and increased stiffness and/or reduced density for aluminum alloys to compete with organic composites. An appendix provides a detailed account of the properties, processing, and applications of conventionally pressed and sintered aluminum P/M alloys.

This article focuses on the temperature requirements of typical nonferrous metals and their alloys of commercial importance. These include aluminum, copper, magnesium, and titanium. The article describes the thermoelectricity, photoelectricity, and capacity of aluminum alloys. In addition, it provides information on the electrical properties of copper and its alloys. The article also lists typical physical and mechanical properties of aluminum alloys at ambient temperature.

This article discusses the classification of wear based on the presence or absence of effective lubricants, namely, lubricated and nonlubricated wear. Variations in ambient temperature, atmosphere, load, and sliding speed, as well as variations in material bulk composition, microstructure, surface treatment, and surface finish of steel are also considered. The article discusses the types, wear testing, wear evaluation, and hardness evaluation of abrasive wear. It describes the selection criteria of steels for wear resistance. The article also describes the importance of hardness and microstructure as factors in resistance to wear. It provides a discussion on the resistance of various materials to wear in specific applications. The wear resistance of austenitic manganese steels is also discussed. The article discusses the applications of phosphate coatings, wear-resistant coatings, and ion implantation. It concludes with information on interaction of wear and corrosion.

This article contains a table that lists the electrical conductivity and resistivity of selected metals, alloys, and materials at ambient temperature. These include aluminum and aluminum alloys; copper and copper alloys; electrical heating alloys; instrument and control alloys; relay steels and alloys; thermostat metals; electrical contact materials; and magnetically soft materials.

This article addresses the important variables in erosion, such as particle impact velocity; particle impact angle; particle size, shape, and material; and ambient temperature. It describes four erosion test methods: the gas-blast method, a method using a centrifugal accelerator test rig, the wind-tunnel test, and the whirling arm test. The article also details the various test methods used to measure impact velocity of particle and data analysis and interpretation of these four methods.

Catastrophic failure best typifies the characteristic behavior of brittle solids in the presence of cracks or crack-like flaws under ambient conditions. This article provides a description of the concepts of fracture mechanics of brittle solids and focuses on the various testing methods developed to characterize the fracture behavior of brittle solids with examples. These include the fracture toughness test method and R-curve test method at ambient and elevated temperatures. The article also includes information on the evaluation of fracture-toughness test results and the behavior of R-curve.