Search Results for nickel-base super alloy

A wide range of flow-formed open- and close-ended shapes are currently available in a variety of difficult-to-form materials, including titanium alloys and nickel-base super alloys. This article describes the two basic methods of flow forming that are characterized by the position of the rolls during the forming process. The flow forming methods include staggered-roll flow forming process and in-line flow-forming process. Typical mechanical properties of flow-formed materials in various conditions are summarized in a table. Proper process controls and subsequent product qualification tests are critical to assure optimal performance of the flow-formed tubular component. The article discusses the most commonly required process control parameters and the effects of forming speed and temperature in the flow forming process.

Penetration-enhanced gas tungsten arc welding (GTAW) processes have been referred to variously as flux tungsten inert gas (TIG), A-TIG, and GTAW with a penetration-enhancing compound. This article provides a discussion on the principles of operation, advantages, disadvantages, procedures, and applications of GTAW. It also includes information on the equipment used and health and safety issues associated with GTAW.

This article is a comprehensive collection of tables that list the values for hardness of plastics, rubber, elastomers, and metals. The tables also list the tensile yield strength and tensile modulus of metals and plastics at room temperature. A comparison of various engineering materials, on the basis of tensile strength, is also provided.

This article provides information on the base material properties of wrought duplex stainless steels (DSS). These properties include microstructure, alloy grades, mechanical and physical properties, and corrosion resistance. The article reviews the applications and microstructural development of DSS. It describes the factors influencing welding and weldability of the DSS. These factors include preheating, postweld heat treatment, interpass temperature control, welding practices, welding procedure qualification, filler metal requirements, cracking behavior, and loss of properties. The article examines the applicable welding processes such as fusion welding and solid-state welding processes.

This article begins with a discussion on the components and importance of flue gas desulfurization (FGD) technology used in power plant for pollution control. It further discusses the corrosion problems encountered in different operating zones of FGD system and the major forms of corrosive attack encountered in those zones, including crevice corrosion, pitting corrosion, and acid attack. The article concludes with information on the materials selection and design features for minimizing the possibility of corrosion.

Low-expansion alloys are characterized by their dimensional stability, suiting them for applications such as geodetic tape, bimetal strip, glass-to-metal seals, and electronic components. This article describes the composition of such alloys along with related properties and behaviors. It explains how humidity and other factors, such as heat treating and cold drawing, influence thermal expansion rates. It also provides machining information on some of the more common low-expansion alloys, and reviews special alloy types including iron-cobalt-chromium alloys, hardenable alloys, and high-strength controlled-expansion alloys.

This article discusses special considerations relative to induction heating of stainless steels and nickel-base superalloys. It focuses on the various industrial and high-temperature applications of induction heating to stainless steel and superalloy components, namely, primary melting processes, preheating for primary and secondary forming processes, heat treatments, brazing, and thermal processing for fusion welds. The article also provides information on computational modeling of induction heating processes for super alloys and stainless steels.

Stainless steel alloys have many unique failure mechanisms, including environmentally assisted cracking, cracking associated with welding, and secondary phase embrittlement. This article describes these failure mechanisms and the fracture modes associated with the different categories of stainless steel. These mechanisms and modes are grouped together because of their similarities across the categories.

This article discusses the general welding characteristics and metallurgical welding considerations that play an important function during the welding of nickel, nickel-copper, nickel-chromium, and nickel-chromium-iron alloys.

This article describes the different types of precipitation and transformation processes and their effects that can occur during heat treatment of various nonferrous alloys. The nonferrous alloys are aluminum alloys, copper alloys, magnesium alloys, nickel alloys, titanium alloys, cobalt alloys, zinc alloys, and heat treatable silver alloys, gold alloys, lead alloys, and tin alloys. It also provides a detailed discussion on the effects due to precipitation and transformation processes in these non-ferrous alloys.

Cobalt finds its use in various applications owing to its magnetic properties, corrosion resistance, wear resistance, and its strength at elevated temperatures. This article discusses the mining and processing of cobalt and cobalt alloys. It describes the types of cobalt alloys, including wear-resistant alloys, high-temperature alloys, corrosion-resistant alloys, and special-purpose alloys. The article provides data on the chemical composition, mechanical properties, and physical properties of these alloys. Further, it provides information on the uses of cobalt in superalloys, cemented carbides, magnetic materials, low-expansion alloys, and high-speed tool steels.

This article covers the current state of materials development of nickel-base superalloys for additive manufacturing (AM) processes and the associated challenges. The discussion focuses on nickel-base superalloy fusion AM processes, providing information on typically encountered cracking mechanisms in AM nickel-base superalloys, such as solid-solution-strengthened nickel-base superalloys and precipitate-strengthened nickel-base superalloys. The mechanisms include solidification cracking, strain-age cracking, liquation cracking, and ductility-dip cracking. The article also provides a short discussion on binder jet AM and powder recyclability.

This article provides a review of metallographic procedures and techniques for analyzing the microstructure of fusion welded joints. It discusses sample preparation, the use of backing plates, and common sectioning methods. It identifies the various types of defects that can occur in arc welded metals, organizing them according to the sectioning method by which they are observed. It describes the relationship between weld bead morphology and sectioning direction and its effect on measurement error. The article examines micrographs from stainless steel, aluminum, and titanium alloy joints, highlighting important details such as solidification and solid-state transformation structures and what they reveal about the welding process. Besides arc welding, it also discusses laser and electron beam welding methods, resistance and spot welding, and the welding of dissimilar metals.

Superalloys are nickel, iron-nickel, and cobalt-base alloys generally used for high-temperature applications. Superalloys are used in aircraft, industrial, marine gas turbines, nuclear reactors, spacecraft structures, petrochemical production, orthopedic and dental prostheses, and environmental protection applications. This article discusses the material characteristics, phases, structures, and systems of superalloys. It describes the processing of superalloys, including primary and secondary melting, deformation processing (conversion), powder processing, investment casting, and joining methods. The article also describes the properties, microstructure, and thermal exposure of superalloys. It further discusses the effects of environmental factors on superalloys, including oxidation and hot corrosion. Protective coatings are also discussed. The article provides information on the mechanical properties and chemical composition of nickel, iron, and cobalt-base superalloys in both the cast and wrought forms.

This article focuses on the properties of conventional wrought superalloys based on nickel, iron, and cobalt, as well as on the properties of alloys produced from powder. The powder metallurgy (P/M) category includes alloys that were originally developed as casting alloys; new alloy compositions developed specifically to benefit from powder processing; and oxide dispersion strengthened alloys (particularly those produced by mechanical alloying). The article discusses some of the applications of superalloys and emphazises the interplay between chemical composition, microstructure, consolidation method, mechanical properties and surface stability of wrought nickel alloys. Vacuum melting processes are a necessity for many nickel- and iron-nickel-base alloys because of the presence of aluminum and titanium as solutes. Cobalt-base alloys do not usually contain these elements and may be melted in air. An appendix to this article presents the property data and corresponding information on a family of cobalt-chromium-tungsten-carbon alloys that use P/M processing.

This article describes the corrosion modes in a waste-to-energy boiler. It discusses the corrosion protection and alloy performance with an emphasis on two main areas of the boiler: furnace water walls and super heaters.

Phosphoric acid is less corrosive than sulfuric and hydrochloric acids. This article discusses the corrosion rates of metal alloys in phosphoric acid, including aluminum, carbon steel and cast irons, stainless steels, nickel-rich G-type alloys, copper and copper alloys, nickel alloys, lead, titanium alloys, and zirconium alloys. Nonmetallic materials may be chemically attacked in some corrosive environments, which can result in swelling, hardening, or softening phenomena; extraction of ingredients; chemical conversion of the nonmetallic constituents; cross-linking oxidation; and/or substitution reactions. The article also describes the corrosion resistance of nonmetallic materials such as rubber and elastomeric materials, plastics, carbon and graphite, and ceramic materials.

This article provides a basic introduction to the various aspects of full density powder metallurgy, including properties, applications, processing methods, and process parameters.

Dissimilar metal welding applications require careful control over the welding parameters and corresponding dilution level in order to produce welds with proper microstructure and properties for the intended service. This article reviews the relation between the dilution and bulk fusion-zone compositions and describes the effect of fusion welding parameters on dilution. It also provides typical examples of the microstructure and property control in dissimilar weld applications.

This article addresses consumable selection and procedure development for the welding of stainless steels. The WRC-1992 diagram and the Schaeffier diagram, are used to illustrate the rationale behind many filler-metal choices. The article discusses the basic metallurgy and base metals of five major families of stainless steels: martensitic stainless steels, ferritic stainless steels, austenitic stainless steels, precipitation-hardening (PH) stainless steels, and duplex ferritic-austenitic stainless steels. Stainless steels of all types are weldable by virtually all welding processes. The article describes the common arc welding processes with regard to procedure and technique errors that can lead to loss of ferrite control with the common austenitic stainless steel weld metals that are designed to contain a small amount of ferrite for protection from hot cracking. The arc welding processes include shielded-metal arc welding, gas-tungsten arc welding, and gas-metal arc welding.