Search Results for UNS S41000

Stainless steels are characterized as having relatively poor wear resistance and tribological properties, but they are often required for a particular application because of their corrosion resistance. This article describes the classification of stainless steels and wear. Stainless steels have been classified by microstructure and are categorized as austenitic, martensitic, ferritic, or duplex. The main categories of wear are related to abrasion, erosion, adhesive wear, and surface fatigue. The article presents a list that proposes the alloy family that could be the optimal selection for a particular wear mode. The corrosion modes include dry sliding, tribocorrosion, erosion, erosion-corrosion, cavitation, dry erosion, erosion-oxidation, galling and fretting.

This article describes general welding characteristics such as weld microstructure and weldability. The correlations of preheating and postweld heat treatment practices with carbon contents and welding characteristics of martensitic stainless steels are reviewed. The article contains a table that lists the electrodes and welding rods suitable for use as filler metals in the welding of martensitic stainless steels. It provides specific arc welding procedural recommendations for the commonly welded martensitic stainless steels. Martensitic stainless steel joining methods such as laser-and electron-beam welding, resistance welding, flash welding, and friction welding, are discussed.

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.

The machinability of stainless steels varies from low to very high, depending on the final choice of the alloy. This article discusses general material and machining characteristics of stainless steel. It briefly describes the classes of stainless steel, such as ferritic, martensitic, austenitic, duplex, and precipitation-hardenable alloys. The article examines the role of additives, such as sulfur, selenium, tellurium, lead, bismuth, and certain oxides, in improving machining performance. It provides ways to minimize difficulties involved in the traditional machining of stainless steels. The article describes turning, drilling, tapping, milling, broaching, reaming, and grinding operations on stainless steel. It concludes with information on some of the nontraditional machining techniques, including abrasive jet machining, abrasive waterjet machining electrochemical machining, electron beam machining, and plasma arc machining.

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.

Stainless steels are used for medical implants and surgical tools due to the excellent combination of properties, such as cost, strength, corrosion resistance, and ease of cleaning. This article describes the classifications of stainless steels, such as austenitic stainless steels, martensitic stainless steels, ferritic stainless steels, precipitation-hardening stainless steels, and duplex stainless steels. It contains a table that lists common medical device applications for stainless steels. The article discusses the physical metallurgy and physical and mechanical properties of stainless steels. Medical device considerations for stainless steels, such as fatigue strength, corrosion resistance, and passivation techniques, are reviewed. The article explains the process features of implant-grade stainless steels, including type 316L, type 316LVM, nitrogen-strengthened, ASTM F1314, ASTM F1586, ASTM F2229, and ASTM F2581 stainless steels.

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.

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.

This article provides an overview of the identification systems for various grades of wrought stainless steels, namely, the American Iron and Steel Institute numbering system, the Unified Numbering System, and proprietary designations. It elaborates on five major families of stainless steels, as defined by the crystallographic structure. These include ferritic stainless steels, austenitic stainless steels, martensitic stainless steels, and precipitation-hardening stainless steels. The mechanism of corrosion protection for stainless steels is reviewed. The article examines the effects of composition, processing, design, fabrication, and external treatments on the corrosion of stainless steels. Various forms of corrosion, namely, general, galvanic, pitting, crevice, intergranular, stress-corrosion cracking, erosion-corrosion, and oxidation, are reviewed. Corrosion testing for; corrosion in atmosphere, water, and chemical environments; and the applications of stainless steels in various industries are also discussed.

Martensitic stainless steels are the least corrosion-resistant of all stainless alloys. The traditional martensitic stainless steels are iron/chromium/carbon alloys, sometimes with a small amount of nickel and/or molybdenum. This article provides an overview on the influences of the various possible alloying elements on the key properties of martensitic stainless steels. It describes the various preparation processes, namely, atmosphere selection, cleaning, and preheating, prior to heat treatment for these steels. Common heat treatment methods include annealing, hardening, tempering, and stress relieving. The article lists the compositions of casting alloys and also describes the effect of tempering temperature on the hardness, strength, ductility, and toughness properties of the alloys.

This article summarizes the key mechanical characteristics of various types of stainless steel, including ferritic, austenitic, martensitic, precipitation hardening, and duplex steels. Particular emphasis is on fracture properties and corrosion fatigue. The article tabulates typical room-temperature mechanical properties and fatigue endurance limits of stainless steels. Stainless steels are susceptible to embrittlement during thermal treatment or elevated-temperature service. The article discusses embrittlement in terms of sensitization, 475 deg C embrittlement, and sigma-phase embrittlement. It also describes the effect of environment on fatigue crack growth rate.

Passivation; pickling, that is, acid descaling; electropolishing; and mechanical cleaning are important surface treatments for the successful performance of stainless steel used for piping, pressure vessels, tanks, and machined parts in a wide variety of applications. This article provides an overview of the various types of stainless steels and describes the commonly used cleaning methods, namely, alkaline cleaning, emulsion cleaning, solvent cleaning, vapor degreasing, ultrasonic cleaning, and acid cleaning. Finishing operations of stainless steels, such as grinding, polishing, and buffing, are reviewed. The article also explains the procedures of electrocleaning, electropolishing, electroplating, painting, surface blackening, coloring, terne coatings, and thermal spraying. It includes useful information on the surface modification of stainless steels, namely, ion implantation and laser surface processing. Surface hardening techniques, namely, nitriding, carburizing, boriding, and flame hardening, performed to improve the resistance of stainless steel alloys are also reviewed.

Fabrication of wrought stainless steels requires use of greater power, more frequent repair or replacement of processing equipment, and application of procedures to minimize or correct surface contamination because of its greater strength, hardness, ductility, work hardenability and corrosion resistance. This article provides a detailed account of such difficulties encountered in the fabrication of wrought stainless steel by forming, forging, cold working, machining, heat treating, and joining processes. Stainless steels are subjected to various heat treatments such as annealing, hardening, and stress relieving. Stainless steels are commonly joined by welding, brazing, and soldering. The article lists the procedures and precautions that should be instituted during welding to ensure optimum corrosion resistance and mechanical properties in the completed assembly.

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.

Stainless steels are widely used at elevated temperatures when carbon and low-alloy steels do not provide adequate corrosion resistance and/or sufficient strength at these temperatures. This article deals with the wrought stainless steels used for high temperature applications. It gives some typical compositions of wrought heat-resistant stainless steels, which are grouped into ferritic, martensitic, austenitic, and precipitation-hardening (PH) grades. Quenched and tempered martensitic stainless steels are essentially martensitic and harden when air cooled from the austenitizing temperature. These alloys offer good combinations of mechanical properties. The article focuses on mechanical property considerations and corrosion resistance considerations of stainless steels. The corrosion and oxidation resistance of wrought stainless steels is similar to that of cast stainless steels with comparable compositions.

This article presents the primary considerations and mechanisms for corrosion and explains how they are involved in the selection of materials for process equipment in refineries and petrochemical plants. It discusses the material selection criteria for a number of ferrous and nonferrous alloys used in petroleum refining and petrochemical applications. The article reviews the mechanical properties, fabricability, and corrosion resistance of refinery steels. It describes low- and high-temperature corrosion, hydrogen embrittlement, and cracking such as stress-corrosion, sulfide stress, and stress-oriented hydrogen-induced cracking. The article considers hydrogen attack, corrosion fatigue, and liquid metal embrittlement and the methods of combating them. It explains the causes of velocity-accelerated corrosion and erosion-corrosion. The article summarizes some corrective measures that can be implemented to control corrosion. The applicable standards for materials used in corrosive service conditions in upstream and downstream petroleum service are presented in a tabular form.

This article describes metallographic preparation and examination techniques for stainless steels and maraging steels. It presents a series of micrographs demonstrating microstructural features of these alloys. Procedures used to prepare stainless steels for macroscopic and microscopic examination are similar to those used for carbon, alloy, and tool steels. Cutting and grinding must be carefully executed to minimize deformation because the austenitic grades work harden readily. The high-hardness martensitic grades that contain substantial undissolved chromium carbide are difficult to polish while fully retaining the carbides. Unlike carbon, alloy, and tool steels, etching techniques are more difficult due to the high corrosion resistance of stainless steels and the various second phases that may be encountered. The microstructures of stainless steels can be quite complex. Matrix structures vary according to the type of steel, such as ferritic, austenitic, martensitic, precipitation hardenable, or duplex.

The properties of irons and steels are linked to the chemical composition, processing path, and resulting microstructure of the material. Processing is a means to develop and control microstructure by hot rolling, quenching, and so forth. This article describes the role of these factors in both theoretical and practical terms, with particular focus on the role of microstructure in various irons. These include bainite, pearlite, ferfite, martensite, austenite, ferrite-pearlite, ferrite-cementite, ferrite-martensite, graphite, and cementite. The article discusses the evolution of microstructural change in rail steels, cast iron, and steel sheet. It contains tables that list the mechanical properties and compositions of selected steels. The article also discusses the basis of material selection of irons and steels.