Search Results for graphitizing annealing

Gray irons are a group of cast irons that form flake graphite during solidification, in contrast to the spheroidal graphite morphology of ductile irons. This article describes surface hardening of gray irons by flame and induction heating. It provides information on the classification of the gray irons in ASTM specification. The article presents examples that illustrate the use of stress relieving to eliminate distortion and cracking. It describes the three annealing treatments of gray iron: ferritizing annealing, medium (or full) annealing, and graphitizing annealing. The article discusses the parameters of the tensile strength and hardness of a normalized gray iron casting. These include combined carbon content, pearlite spacing, and graphite morphology. The article concludes with a discussion on the induction hardening of gray iron castings.

This article presents fractographs that show evidence of overload in a ferritic malleable cast iron. The images illustrate crack initiation and propagation, as well as regions of dimpled rupture.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of pearlitic malleable and ferritic malleable white irons, and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the fracture sequence, localized plastic deformation, and microcrack initiation and propagation of these irons.

Gray irons are a group of cast irons that form flake graphite during solidification, in contrast to the spheroidal graphite morphology of ductile irons. The heat treatment of gray irons can considerably alter the matrix microstructure with little or no effect on the size and shape of the graphite achieved during casting. This article provides a detailed account of classes of gray iron, and heat treating methods of gray irons with examples. These methods include stress relieving, annealing, normalizing, transformation hardening, austenitizing, quenching, austempering, martempering, flame hardening, induction hardening, and nitriding.

Cast irons may be compared with steels in their reactions to hardening. However, because cast irons (except white iron) contain graphite and substantially higher percentages of silicon, they require higher austenitizing temperatures. This article describes the effect of heat treatment processes such as annealing, normalizing, surface hardening, tempering, stress relieving, quenching, and austempering, on hardness and tensile properties of cast irons, namely gray irons, ductile irons, malleable irons, and austenitic irons.

Malleable iron possesses considerable ductility and toughness because of its combination of nodular graphite and a low-carbon metallic matrix. The desired formation of temper carbon in malleable irons has two basic requirements. First, graphite should not form during the solidification of the white cast iron, and second, graphite must also be readily formed during the annealing heat treatment. These two metallurgical requirements influence the useful compositions of malleable irons and the melting, solidification, and annealing procedures. There are two basic types of malleable iron: blackheart and whiteheart. This article considers only the blackheart type and describes the metallurgical factors of malleable iron. It discusses the mechanical properties of pearlitic and martensitic malleable irons. The article provides additional information on the properties and heat treatment of ferritic, pearlitic, and martensitic malleable irons. The article lists some of the typical applications of malleable iron castings.

Malleable iron is a type of cast iron that has most of its carbon in the form of irregularly shaped graphite nodules instead of flakes, as in gray iron, or small graphite spherulites, as in ductile iron. This article discusses the production of malleable iron based on the metallurgical criteria: to produce solidified white iron throughout the section thickness; and to produce the desired graphite distribution (nodule count) upon annealing. It describes the induction heating and quenching or flame heating and quenching for surface hardening of fully pearlitic malleable iron. Laser and electron beam techniques also have been used for hardening selected areas on the surface of pearlitic and ferritic malleable iron castings that are free from decarburization.

The term cast iron designates a group of materials that contain more than one constituent in their microstructure due to excess carbon that result in unique characteristics such as the fracture appearance and graphite morphology. This article discusses the classification of cast iron and the various metallurgical aspects, such as the composition, alloying element, solidification, and graphite morphologies, of different types of cast iron. It describes the physical properties for various cast irons and the influence of microstructure and chemical composition on each property. The article provides a detailed account on thermal properties, conductive properties, magnetic properties, and acoustic properties of cast iron. It also examines heat treatment, namely, stress relieving, annealing, normalizing, through hardening, and surface hardening. The article presents a discussion on the welding, machining and grinding, and coating of the types of cast iron.

This article discusses criteria that can be used for the classification of cast iron: fracture aspect, graphite shape, microstructure of the matrix, commercial designation, and mechanical properties. It addresses the main factors of influence on the structure of cast iron, including chemical composition, cooling rate, and heat treatment. The article describes some basic principles of cast iron metallurgy. It discusses the main effects of the chemical composition of ductile iron and compacted graphite (CG) iron. The composition of malleable irons must be selected in such a way as to produce a white as-cast structure and to allow for fast annealing times. Some typical compositions of malleable irons are presented in a table. The article concludes with information on special cast irons.

Malleable iron is a type of cast iron that has most of its carbon in the form of irregularly shaped graphite nodules. This article tabulates the typical composition of malleable iron and specifications, and applications of malleable iron castings. It discusses the metallurgical control of malleable irons with emphasis on its composition and heat treatment. The article provides information on the specifications and mechanical properties of different types of malleable irons, such as ferritic, pearlitic, and martensitic malleable irons.

This article introduces the general principles and applications of heat treatment to iron castings. It provides a detailed discussion on the heat treatment processes, namely, stress relieving, annealing, normalizing, throughhardening, and surface hardening for various types of cast irons. These include gray iron, ductile iron, compacted graphite iron, white iron, malleable iron, and high-alloy iron. The article describes how to control temperature and atmosphere during the heat treatment of the iron castings.

Malleable iron, like ductile iron, possesses considerable ductility and toughness because of its combination of nodular graphite and low-carbon metallic matrix. This article discusses melting practices such as batch cold melting and duplexing, and their control mechanisms. It schematically illustrates the microstructure of annealed ferritic malleable iron, which is characterized by microstructures consisting of uniformly dispersed fine particles of free carbon in a matrix of ferrite or tempered martensite. The article describes the digital solidification analysis technology, simulation technologies, and smart engineering for the production of malleable iron. It provides information on the applications of ferritic and pearlitic malleable irons.

This article focuses on heat treatment of malleable and compacted-graphite irons to produce ferritic and pearlitic malleable irons. It describes the heat treatment cycles of malleable iron, including martempering, tempering, bainitic heat treatment, and surface hardening. The article provides information on the mechanical and physical properties of compacted-graphite irons, which are determined by the graphite shape and the pearlite/ferrite ratio.

Malleable iron is a cast ferrous metal that is initially produced as white cast iron and is then heat treated to convert the carbon-containing phase from iron carbide to a nodular form of graphite called temper carbon. This article provides a discussion on the melting practices, heat treatment, microstructure, production technologies, mechanical properties, and applications of ferritic, pearlitic, and martensitic malleable irons.