Search Results for UNS N08800

This article focuses on high-temperature corrosion in synthetic gas (syngas) coolers. Extensive laboratory corrosion studies on both model and commercial alloys are summarized. The article describes the material selection criteria for long-term performance of materials in service. It provides information on the fuels with chlorine contents used in gasification plants.

This article outlines the processes by which materials are selected to prevent or control localized corrosion, galvanic corrosion, and intergranular corrosion. It reviews the operating conditions and the design of candidate materials for material selection. The article discusses various corrosion-resistant materials, including ferrous and nonferrous metals and alloys, thermoplastics, reinforced thermosetting plastics, nonmetallic linings, glass, carbon and graphite, and catalyzed resin coatings. It examines an unusual form of intergranular corrosion known as exfoliation, which occurs in aluminum-copper alloys. The article also describes three types of erosion-corrosion: liquid erosion-corrosion, cavitation, and fretting. It concludes with information on the various factors to be considered for material selection, including minimum cost or economic design, minimum corrosion, minimum investment, and minimum maintenance.

Stainless steels and nickel-base alloys are recognized for their resistance to general corrosion and other categories of corrosion. This article examines the effects of specific alloying elements, metallurgical structure, and mechanical conditioning on corrosion resistance of these materials. It provides information on the compositions of selected stainless steels, copper-nickel, and nickel-base alloys in a tabular form. The article also illustrates the compositional and property linkages for stainless steels and nickel-base alloys.

This article provides a discussion on forging methods, melting procedures, forging equipment, forging practices, grain refinement, and critical factors considered in forging process. It describes the different types of solid-solution-strengthened and precipitation-strengthened superalloys, namely, iron-nickel superalloys, nickel-base alloys, cobalt-base alloys, and powder alloys. The article discusses the microstructural mechanisms during hot deformation and presents processing maps for various superalloys. It concludes with a discussion on heat treatment of wrought heat-resistant alloy forgings.

Molten salts, or fused salts, can cause corrosion by the solution of constituents of the container material, selective attack, pitting, electrochemical reactions, mass transport due to thermal gradients, and reaction of constituents and impurities of the molten salt with the container material. This article describes a test method performed using thermal convection loop for corrosion studies of molten salts. It discusses the purification of salts that are used in the Oak Ridge molten salt reactor experiment. The article also reviews the corrosion characteristics of nitrates/nitrites and fluoride salts with the aid of illustrations and equations.

Several factors contribute to marine-atmospheric corrosion with the local environment being the single most important factor. Therefore, assessing a local environment, which is essential to reduce the gross expenditure, is assisted by modeling of the local environment and by a set of corrosion standards proposed by the International Standards Organization (ISO). This article focuses on the important variables associated with atmospheric corrosion in marine atmospheres, namely, moisture, temperature, winds, airborne contaminants, alloy content, location, and biological organisms along with their corresponding assessing methods. It also examines the ISO CORRAG program for modeling the corrosion rate of atmospheric corrosion that is represented as equations modeling.

Austenitic stainless steels exhibit a single-phase, face-centered cubic structure that is maintained over a wide range of temperatures. This article reviews the compositions of standard and nonstandard austenitic stainless steels. It summarizes the important aspects of solidification behavior and microstructural evolution that dictate weld-metal ferrite content and morphology. The article describes weld defect formation, namely, solidification cracking, heat-affected zone liquation cracking, weld-metal liquation cracking, copper contamination cracking, ductility dip cracking, and weld porosity. It discusses four general types of corrosive attack: intergranular attack, stress-corrosion cracking, pitting and crevice corrosion, and microbiologically influenced corrosion. The article concludes with information on weld thermal treatments such as preheat and interpass heat treatments and postweld heat treatment.

This article reviews the corrosion behavior in various environments for seven important nickel alloy families: commercially pure nickel, Ni-Cu, Ni-Mo, Ni-Cr, Ni-Cr-Mo, Ni-Cr-Fe, and Ni-Fe-Cr. It examines the behavior of nickel alloys in corrosive media found in industrial settings. The corrosive media include: hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid, nitric acid, organic acids, salts, seawater, and alkalis. The modes of high-temperature corrosion include oxidation, carburization, metal dusting, sulfidation, nitridation, corrosion by halogens, and corrosion by molten salts. Applications where the corrosion properties of nickel alloys are important factors in materials selection include the petroleum, chemical, and electrical power industries. Most nickel alloys are much more resistant than the stainless steels to reducing acids, such as hydrochloric, and some are extremely resistant to the chloride-induced phenomena of pitting, crevice attack, and stress-corrosion cracking (to which the stainless steels are susceptible). Nickel alloys are also among the few metallic materials able to cope with hot hydrofluoric acid. The conditions where nickel alloys suffer environmentally assisted cracking are highly specific and therefore avoidable by proper design of the industrial components.

This article tabulates the nominal compositions for nickel and cobalt alloys. It illustrates the comparison of strain-hardening rates of a number of alloys in terms of the increase in hardness with increasing cold reduction. The forming practice for age-hardenable alloys and the lubricants used in the forming processes of nickel and cobalt alloys are also discussed. The article summarizes the modification of tools and dies used for cold forming other metals, as the physical and mechanical properties of nickel and cobalt alloys frequently necessitate it. It discusses forming techniques for these alloys and provides several examples of these techniques, which include shearing, blanking, piercing, deep drawing, spinning, explosive forming, bending, and expanding/tube forming.

This article provides the corrosion data for materials in hydrofluoric acid (HF) and anhydrous hydrogen fluoride (AHF). These materials include carbon and low-alloy steels, austenitic stainless steels, nickel-rich austenitic stainless steels, nickel and nickel-base alloys, copper alloys, precious metals, and non-metals. The article also discusses the hydrogen blistering and stress-corrosion cracking of carbon steels in high-temperature HF and AHF.

Stainless steels are iron-base alloys containing minimum of approximately 11% Cr, and owing to its excellent corrosion resistance, are used for wide range of applications. These applications include nuclear reactor vessels, heat exchangers, oil industry tubular, chemical processing components, pulp and paper industries, furnace parts, and boilers used in fossil fuel electric power plants. The article provides a brief introduction on corrosion resistance of wrought stainless steel and its designations. It lists the chemical composition and describes the physical and mechanical properties of five major stainless steel families, of which four are based on the crystallographic structure of the alloys, including martensitic, ferritic, austenitic, or duplex. The fifth is precipitation-hardenable alloys, based on the type of heat treatment used. The article further discusses the factors in the selection of stainless steel, namely corrosion resistance, fabrication characteristics, product forms, thermally induced embrittlement, mechanical properties in specific temperature ranges, and product cost.

The process of making assemblies of solid-solution and precipitation hardening groups of alloys and superalloys often requires welding of dissimilar metals, welding of diffusion-bonded materials, and sometimes weld overlay cladding and even thermal spraying that in turn requires special knowledge and treatments developed specifically for each material. This article emphasizes the special metallurgical welding considerations for welding solid-solution and precipitation hardening nickel alloys, cobalt alloys, and superalloys.

This article discusses the composition, characteristics, and properties of the five groups of wrought stainless steels: martensitic stainless steels, ferritic stainless steels, austenitic stainless steels, duplex stainless steels, and precipitation-hardening stainless steels. The selection of stainless steels may be based on corrosion resistance, fabrication characteristics, availability, mechanical properties in specific temperature ranges and product cost. The fabrication characteristics of stainless steels include formability, forgeability, machinability, and weldability. The product forms of wrought stainless steels are plate, sheet, strip, foil, bar, wire, semifinished products, pipes, tubes, and tubing. The article describes tensile properties, elevated-temperature properties, subzero-temperature properties, physical properties, corrosion properties, and fatigue strength of stainless steels. It characterizes the experience of a few industrial sectors according to the corrosion problems most frequently encountered and suggests appropriate grade selections. Corrosion testing, surface finishing, mill finishes, and interim surface protection of stainless steels are also discussed.

Density allows for the conversion of uniform corrosion rates from units of weight (or mass) loss per unit area per time to thickness per unit time. This article contains a table that lists the density of metals, such as aluminum, copper, iron, stainless steel, magnesium, and lead, and their alloys.

Nickel and nickel-base alloys are vitally important to modern industry because of their ability to withstand a wide variety of severe operating conditions involving corrosive environments, high temperatures, high stresses, and combinations of these factors. This article discusses the mining and extraction of nickel and describes the uses of nickel. It discusses the categories of nickel-base alloys, including wrought corrosion-resistant alloys, cast corrosion-resistant alloys, heat-resistant alloys (superalloys), and special-purpose alloys. The article covers the corrosion resistance of nickel with the inclusion of varying alloying elements. It provides useful information on the behavior of nickel and nickel alloys in specific environments describes its corrosion resistance in certain acids, alkalis, and salts.

This article describes the eight chemical cleaning methods, namely, circulation, fill and soak, cascade, foam, vapor-phase organic, steam-injected, on-line chemical, and mechanical cleaning. It presents information on deposit types, solvents used to remove them, and construction material incompatibilities in a table. The article summarizes the uses of chemical cleaning solutions, including hydrochloric acid, phosphoric acid, and sulfamic acid, as well as the additives used to neutralize their impact on corrosion. It discusses the chemical cleaning procedures, including selection of cleaning method and solvent, documentation of cleaning, and corrosion monitoring in chemical cleaning.

True alkaline chemicals include caustic soda or sodium hydroxide (NaOH), caustic potash or potassium hydroxide (KOH), and soda ash or sodium carbonate (Na2CO3). This article reviews alkaline chemicals and provides a basis for a general discussion on various alkaline exposures. It describes the corrosion effects of caustic soda on aluminum and aluminum alloys, iron and steel, carbon and low-alloy steels, stainless steels, high-performance austenitic alloys, nickel and nickel alloys, copper and copper alloys, titanium and titanium alloys, and zirconium and zirconium alloys. The article discusses the corrosion effects of caustic soda on nonmetallic materials: plastics, thermoplastics, thermosetting resin materials, carbon and graphite, and ceramics. It concludes with information on the effects of contamination of and by caustic and of admixtures of caustic with other chemicals, including chlorates, chlorides, chlorine/hypochlorite, mercury, sulfur, and iron.

This article focuses on the mechanisms of microbially induced or influenced corrosion (MIC) of metallic materials as an introduction to the recognition, management, and prevention of microbiological corrosion failures in piping, tanks, heat exchangers, and cooling towers. It discusses the degradation of various protective systems, such as corrosion inhibitors and lubricants. The article describes the failure analysis of steel, iron, copper, aluminum, and their alloys. It also discusses the probes available to monitor conditions relevant to MIC in industrial systems and the sampling and analysis of conditions usually achieved by the installation of removable coupons in the target system. The article also explains the prevention and control strategies of MIC in industrial systems.