Search Results for equivalent carbon content

Carbon steels have wider usage than any other metal because of their versatility and low cost. Required hardenability is the most important factor influencing a choice between carbon- and alloy steel. By increasing hardenability, alloying elements extend the potential for enhanced properties to the large sections required for many applications. Alloy steels are ordinarily quench hardened and tempered to the level of strength desired for the application. Distortion during heat treatment may occur with almost any hardenable carbon or alloy steel, although distortion is usually more severe for carbon grades than for alloy grades of equivalent carbon content. The relatively low hardenability of carbon steels is a primary reason for choosing them in preference to alloy steels for parts that are to be locally heat treated by flame or induction hardening. Fabrication processes are performed on hardenable carbon and alloy steels in the unhardened condition, that is, prior to heat treating.

Steel castings produced from carbon and alloy steels in any of the various types of molds and wrought steel of equivalent chemical composition respond similarly to heat treatment. They have the same weldability, and similar physical, mechanical, and corrosion properties. This article lists the specification requirements given in ASTM standards and in SAE J435c. Steel castings are classified according to their carbon or alloy composition into four general groups. Carbon steel castings account for three of these groups: low-carbon steel castings with less than 0.20″ carbon, medium-carbon castings with 0.20 to 0.50″ carbon, and high-carbon castings with more than 0.50″ carbon. The fourth group, low-alloy steel castings, is generally limited to grades with a total alloy content of less than 8″. The article presents graphical representations of the mechanical properties of cast carbon steels as a function of carbon content for different heat treatments.

This article presents in-depth metallurgical information about the response of carbon and low-alloy steels to welding conditions and micro-structural evolution in the weld heat-affected zone. It discusses the fabrication weldability and service weldability of carbon and low-alloy steels. The article describes six general classes of the metal: low-carbon steels, high-strength low-alloy steels, quenched-and-tempered steels, heat-treatable low-alloy steels, thermal-mechanical-controlled processing steels, and chromium-molybdenum steels. It concludes with an illustration of steels' susceptibility to hydrogen-assisted cold cracking relative to carbon content and carbon equivalent.

Hardenability of steel is the property that determines the depth and distribution of hardness induced by quenching. Hardenability is usually the single most important factor in the selection of steel for heat-treated parts. The hardenability of a steel is best assessed by studying the hardening response of the steel to cooling in a standardized configuration in which a variety of cooling rates can be easily and consistently reproduced from one test to another. These include the Jominy end-quench test, the carburized hardenability test, and the air hardenability test. Tests that are more suited to very low hardenability steels include the hot-brine test and the surface-area-center test. The article discusses the effects of varying carbon content as well as the influence of different alloying elements. It includes charts and a table that serve as a general steel hardenability selection guide.

Cast irons primarily are iron alloys that contain more than 2% carbon and from 1 to 3% silicon. This article provides a description of iron-iron carbide-silicon system; and discusses the classification, composition, and characteristics of cast irons, such as gray, ductile, malleable, compacted graphite, and white cast iron. A table shows the correspondence between commercial and microstructural classification, as well as final processing stage in obtaining common cast irons.

Hardenability refers to the ability of steel to obtain satisfactory hardening to some desired depth when cooled under prescribed conditions. It is governed almost entirely by the chemical composition (carbon and alloy content) at the austenitizing temperature and the austenite grain size at the moment of quenching. This article describes the Jominy end-quench test, the Grossman method, and the air hardenability test to evaluate hardenability. It also reviews the factors that influence steel hardenability and selection.

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.

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.

The ferrous metals are the most significant class of commercial alloys. This article describes the solidification structures of plain carbon steel, low-alloy steel, high-alloy steel, and cast iron, with illustrations. The formation of nonmetallic inclusions in the liquid before and during solidification is also discussed.

This article discusses the classification schemes for cast irons and describes the characteristics of major categories, including gray iron, white iron, ductile iron, compacted graphite iron, mottled iron, malleable iron, and austempered ductile iron. It also discusses some of the basic principles of cast iron metallurgy. When discussing the metallurgy of cast iron, the main factors of influence on the structure include chemical composition, cooling rate, liquid treatment, and heat treatment. In terms of commercial status, cast irons can be classified as common cast irons and special cast irons. Special cast irons differ from the common cast irons mainly in the higher content of alloying elements. Alloying elements can be added in common cast iron to enhance some mechanical properties. They influence both the graphitization potential and the structure and properties of the matrix.

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.

Hardenability is usually the single most important factor in the selection of steel for heat-treated parts. The hardenability of steel is best assessed by studying the hardening response of the steel to cooling in a standardized configuration in which a variety of cooling rates can be easily and consistently reproduced from one test to another. These include the Jominy end-quench test, the carburized hardenability test, and the surface-area-center hardenability test. This article discusses the effects of varying carbon content as well as the influence of different alloying elements on hardenability of steels. The basic information needed before a steel with adequate hardenability can be specified as the as-quenched hardness required prior to tempering to final hardness that will produce the best stress-resisting microstructure; the depth below the surface to which this hardness must extend; and the quenching medium that should be used in hardening.

This article discusses the metallurgical aspects of underwater welds. It describes the microstructural development, which mainly includes three types of ferrite associated with low carbon steel weld metal: grain-boundary ferrite, sideplate ferrite, and acicular ferrite. The article explains the factors that affect heat-affected zone (HAZ) cracking. These include hydrogen from the weld pool, microstructures that develop in the HAZ, and stress levels that develop in the weld joint. The article describes the welding practices that can reduce residual stresses. It explains the effect of water pressure on the formation of porosity in underwater gravity welding. The article concludes with a discussion on the practical applications of underwater welding.

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.

Stainless steels are primarily alloys of iron and chromium. They are grouped into five families, primarily based on their microstructure: ferritic, austenitic, martensitic, duplex, and precipitation hardening. Three out of the five families of stainless steels, namely, austenitic, ferritic, and martensitic, are well suited for manufacture via conventional powder metallurgy (PM) processes. This article presents the iron-chromium partial phase diagram to illustrate the changes in the temperature range when pure iron is alloyed with chromium. It describes AISI and UNS numbering systems, which are used as an identification system for stainless steels. The article tabulates the material designations of stainless steels in accordance with the Metal Powder Industries Federation. It also details the characteristics and chemical composition of wrought and PM stainless steels.

This article discusses the graphite morphology, chemical composition, mechanical and physical properties, and applications of compacted graphite (CG) irons. It compares the selected properties of gray, ductile and CG irons, and lists their property requirements as per ASTM A 842. A listing of tensile properties of various CG irons produced by different melt treatment methods is also provided.

Hardening and depth of hardening of steel is a critically important material and process design parameter. This article presents a selective overview of experimental and predictive procedures to determine steel hardenability. It also covers the breadth of steel hardenability, ranging from shallow, to very difficult to harden, to air-hardening steels.