Search Results for aluminum nitride embrittlement

This article examines the embrittlement of iron and carbon steels. It describes compositional, processing, and service conditions that contribute to the problem and presents examples of how embrittlement influences mechanical properties. Embrittlement due to hydrogen is the most common form of embrittlement and influences the behavior and properties of nearly all ferrous alloys and many metals. The article explains why hydrogen embrittlement is so widespread and reviews the many types of damage it can cause. It also explores other forms of embrittlement, including metal-induced embrittlement, strain-age and aluminum nitride embrittlement, thermal embrittlement, quench cracking, 475 deg C and sigma phase embrittlement (in FeCr alloys), temper embrittlement, and embrittlement caused by neutron irradiation. In addition, the article covers stress-corrosion cracking along with properties and conditions that affect it, and the procedures to detect and evaluate it.

In this article, a basic summary of fracture mechanisms in carbon and alloy steels is presented, along with numerous examples of these fractures. These examples include ductile fracture, brittle cleavage fracture, intergranular fracture, fatigue fracture, and environmentally assisted failure mechanisms.

This article briefly reviews the various metallurgical or environmental factors that cause a weakening of the grain boundaries and, in turn, influence the occurrence of intergranular (IG) fractures. It discusses the mechanisms of IG fractures, including the dimpled IG fracture, the IG brittle fracture, and the IG fatigue fracture. The article describes some typical embrittlement mechanisms that cause the IG fracture of steels.

This article briefly reviews the factors that influence the occurrence of intergranular (IG) fractures. Because the appearance of IG fractures is often very similar, the principal focus is placed on the various metallurgical or environmental factors that cause grain boundaries to become the preferred path of crack growth. The article describes in more detail some typical mechanisms that cause IG fracture. It discusses the causes and effects of IG brittle cracking, dimpled IG fracture, IG fatigue, hydrogen embrittlement, and IG stress-corrosion cracking. The article presents a case history on IG fracture of steam generator tubes, where a lowering of the operating temperature was proposed to reduce failures.

This article introduces some of the general sources of heat treating problems with particular emphasis on problems caused by the actual heat treating process and the significant thermal and transformation stresses within a heat treated part. It addresses the design and material factors that cause a part to fail during heat treatment. The article discusses the problems associated with heating and furnaces, quenching media, quenching stresses, hardenability, tempering, carburizing, carbonitriding, and nitriding as well as potential stainless steel problems and problems associated with nonferrous heat treatments. The processes involved in cold working of certain ferrous and nonferrous alloys are also covered.

Notch toughness is an indication of the capacity of a steel to absorb energy when a stress concentrator or notch is present. The notch toughness of a steel product is the result of a number of interactive effects, including composition, deoxidation and steelmaking practices, solidification, and rolling practices, as well as the resulting microstructure. All carbon and high-strength low-alloy (HSLA) steels undergo a ductile-to-brittle transition as the temperature is lowered. The composition of a steel, as well as its microstructure and processing history, significantly affects both the ductile-to-brittle transition temperature range and the energy absorbed during fracture at any particular temperature.. Th article focuses on various aspects of notch toughness including the effects of composition and microstructure, general influence of manufacturing practices and the interactive effects that simultaneously influence notch toughness. With the exception of working direction, most of the same chemical, microstructural, and manufacturing factors that influence the notch toughness of wrought steels also apply to cast steels. The Charpy V-notch test is used worldwide to indicate the ductile-to-brittle transition of a steel. While Charpy results cannot be directly applied to structural design requirements, a number of correlations have been made between Charpy results and fracture toughness.

Vapor-deposition processes fall into two major categories, namely, physical vapor deposition (PVD) and chemical vapor deposition (CVD). This article describes major deposition processes such as sputtering, evaporation, ion plating, and CVD. The list of materials that can be vapor deposited is extensive and covers almost any coating requirement. The article provides a table of some corrosion-resistant vapor deposited materials. It concludes with an overview of the applications of CVD and PVD coatings and a discussion on coatings for graphite, the aluminum coating of steel, and alloy coatings for aircraft turbines, marine turbines, and industrial turbines.

Ammonia and ammonium hydroxide are not particularly corrosive in themselves, but corrosion problems can arise with specific materials, particularly when contaminants are present. This article discusses the corrosion resistance of materials used for the manufacture, handling, and storage of ammonia. These materials include aluminum alloys, iron and steel, stainless steels, nickel and its alloys, copper and its alloys, titanium and its alloys, zirconium and its alloys, niobium, tantalum, and nonmetallic materials.

Ferritic stainless steels are essentially chromium containing steel alloys with at least 10.5% Cr. They can be grouped based on their chromium content: low chromium (10.5 to 12.0%), medium chromium (16 to 19%), and high chromium (greater than 25%). This article provides general information on the metallurgy of ferritic stainless steels. It describes two types of heat treatments to avoid sensitization and embrittlement. They are annealing and stress relieving. The article also provides information on casting and stabilization of ferritic stainless steels to avoid precipitation of grain boundary carbides.

This article presents examples of the visual fracture examination that illustrate the procedure as it applies to failure analysis and quality determination. It describes the techniques and procedures for the visual and light microscopic examination of fracture surfaces with illustrations. The article also describes microscopic and macroscopic features of the different fracture mechanisms with illustrations with emphasis on visual and light microscopy examination. The types of fractures considered include ductile fractures, tensile-test fractures, brittle fractures, fatigue fractures, and high-temperature fractures.

This article aims to identify and illustrate the types of overload failures, which are categorized as failures due to insufficient material strength and underdesign, failures due to stress concentration and material defects, and failures due to material alteration. It describes the general aspects of fracture modes and mechanisms. The article briefly reviews some mechanistic aspects of ductile and brittle crack propagation, including discussion on mixed-mode cracking. Factors associated with overload failures are discussed, and, where appropriate, preventive steps for reducing the likelihood of overload fractures are included. The article focuses primarily on the contribution of embrittlement to overload failure. The embrittling phenomena are described and differentiated by their causes, effects, and remedial methods, so that failure characteristics can be directly compared during practical failure investigation. The article describes the effects of mechanical loading on a part in service and provides information on laboratory fracture examination.

The selection of material for a drawing die is aimed at the production of the desired quality and quantity of parts with the least possible tooling cost per part. This article discusses the performance of a drawing die. It contains tables that list the lubricants used for deep drawing, and the typical materials for punches and blank holders. The article describes the typical causes of wear (galling) of deep-drawing tooling. It analyzes the selection of a harder and more wear-resistant material, the application of a surface coating such as chromium plating to the finished tools, and surface treatments such as carburizing or carbonitriding for low-alloy steels or nitriding or physical vapor deposition coating for tool steels.

This article describes the factors considered in the analysis of brazeability and solderability of engineering materials. These are the wetting and spreading behavior, joint mechanical properties, corrosion resistance, metallurgical considerations, and residual stress levels. It discusses the application of brazed and soldered joints in sophisticated mechanical assemblies, such as aerospace equipment, chemical reactors, electronic packaging, nuclear applications, and heat exchangers. The article also provides a detailed discussion on the joining process characteristics of different types of engineering materials considered in the selection of a brazing process. The engineering materials include low-carbon steels, low-alloy steels, and tool steels; cast irons; aluminum alloys; copper and copper alloys; nickel-base alloys; heat-resistant alloys; titanium and titanium alloys; refractory metals; cobalt-base alloys; and ceramic materials.

Overload failures refer to the ductile or brittle fracture of a material when stresses exceed the load-bearing capacity of a material. This article reviews some mechanistic aspects of ductile and brittle crack propagation, including a discussion on mixed-mode cracking, which may also occur when an overload failure is caused by a combination of ductile and brittle cracking mechanisms. It describes the general aspects of fracture modes and mechanisms. The article discusses some of the material, mechanical, and environmental factors that may be involved in determining the root cause of an overload failure. It also presents examples of thermally and environmentally induced embrittlement effects that can alter the overload fracture behavior of metals.

This article is a compilation of terms related to surface engineering of irons, steels, and nonferrous metals.

This article describes the general factors that can influence fracture appearances. The focus is on the general practical relationships of fracture appearances, with factors presented in some broad categories, including: material conditions (e.g., crystal structure and microstructure); loading conditions (stress state, strain rate, and fatigue); manufacturing conditions (casting, metal-working, machining, heat treatment, etc.); and service and environmental factors (hydrogen embrittlement, stress corrosion, temperature, and corrosion fatigue).

The surface of irons and steels can be hardened by introducing nitrogen (nitriding), nitrogen and carbon (nitrocarburizing), or nitrogen and sulfur (sulfonitriding) into the surface. This article lists the principal reasons for nitriding and nitrocarburizing, and summarizes the typical characteristics of nitriding processes along with a general comparison of carburizing processes in a table. It describes the two most common nitriding methods: gas nitriding and ion (plasma) nitriding. The article discusses the wear behavior of nitrided layers and the wear resistance of selected steels. Rolling-contact fatigue (RCF) occurs in rolling contacts such as bearings, rolls, and gears. The article provides a discussion on rolling-contact fatigue of nitrided steels for aerospace bearing components.