Georg Agricola, author of De re metallica, an important early work on metal extraction
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use. Metallurgy is distinguished from the craft of metalworking.
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1 Etymology and pronunciation 2 History 3 Extraction 4 Alloys 5 Production 5.1 Metalworking processes 5.2 Heat treatment 5.3 Plating 5.4 Thermal spraying
6 Microstructure 7 See also
The word was originally (1593) an alchemist's term for the extraction of metals from minerals: the ending -urgy signifying a process, especially manufacturing: it was in this sense it was used by the 1797 Encyclopedia Britannica. In the late 19th century it was extended to the more general scientific study of metals and alloys and related processes.  The roots are borrowed from Ancient Greek: μεταλλουργός, matallourgos, "worker in metal", from μέταλλον, metallon, "metal" + ἔργον, ergon, "work". In English, the /meˈtælədʒi/pronunciation is the more common one in the UK and Commonwealth. The /ˈmetələrdʒi/ pronunciation is the more common one in the USA, and is the first-listed variant in various American dictionaries (e.g., Merriam-Webster Collegiate, American Heritage).
Gold headband from Thebes 750-700 BC
Main article: History of ferrous metallurgy See also: Chalcolithic, Bronze Age, Iron Age, Metallurgy in Pre-Columbian America, Metallurgy in preColumbian Mesoamerica, and History of metallurgy in the Indian subcontinent The first evidence of human metallurgy dates from the 5th and 6th millennium BC, and was found in the archaeological sites of Majdanpek, Yarmovac and Plocnik all three in Serbia. To date, the earliest copper smelting is found at the Belovode site, these examples include a copper axe from 5500 BC belonging to the Vinča culture. Other signs of human metallurgy are found from the third millennium BC in places like Palmela (Portugal), Cortes de Navarra (Spain), and Stonehenge (United Kingdom). However, as often happens with the study of prehistoric times, the ultimate beginnings cannot be clearly defined and new discoveries are continuous and ongoing.
Mining areas of the ancient Middle East. Boxes colors: arsenic is in brown, copper in red, tin in grey, iron in reddish brown, gold in yellow, silver in white and lead in black. Yellow area stands for arsenic bronze, while grey area stands for tin bronze.
Silver, copper, tin and meteoric iron can also be found native, allowing a limited amount of metalworking in early cultures. Egyptian weapons made from meteoric iron in about 3000 BC were highly prized as "Daggers from Heaven".  However, by learning to get copper and tin by heating rocks and combining those two metals to make an alloy called bronze, the technology of metallurgy began about 3500 BC with the Bronze Age. The extraction of iron from its ore into a workable metal is much more difficult. It appears to have been invented by the Hittites in about 1200 BC, beginning the Iron Age. The secret of extracting and working iron was a key factor in the success of the Philistines. Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the Middle East and Near East, ancient Iran, ancient Egypt, ancient Nubia, and Anatolia (Turkey), Ancient Nok, Carthage, the Greeks and Romans of ancient Europe, medieval Europe, ancient and medieval China, ancient and medieval India, ancient and medieval Japan, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China, such as the innovation of theblast furnace, cast iron, hydraulic-powered trip hammers, and double acting piston bellows. A 16th century book by Georg Agricola called De re metallica describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time. Agricola has been described as the "father of metallurgy".
Furnace bellows operated by waterwheels, Yuan Dynasty, China.
Extractive metallurgy is the practice of removing valuable metals from an ore and refining the extracted raw metals into a purer form. In order to convert a metal oxide or sulfide to a purer metal, the ore must be reduced physically, chemically, or electrolytically. Extractive metallurgists are interested in three primary streams: feed, concentrate (valuable metal oxide/sulfide), and tailings (waste). After mining, large pieces of the ore feed are broken through crushing and/or grinding in order to obtain particles small enough where each particle is either mostly valuable or mostly waste. Concentrating the particles of value in a form supporting separation enables the desired metal to be removed from waste products. Mining may not be necessary if the ore body and physical environment are conducive to leaching. Leaching dissolves minerals in an ore body and results in an enriched solution. The solution is collected and processed to extract valuable metals. Ore bodies often contain more than one valuable metal. Tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal. That concentrate would then be processed to separate the valuable metals into individual constituents.
Common engineering metals include aluminium, chromium, copper, iron, magnesium, nickel, titanium and zinc. These are most often used as alloys. Much effort has been placed on understanding the iron-carbon alloy system, which includes steels and cast irons. Plain carbon steels are used in low cost, high strength applications where weight and corrosion are not a problem. Cast irons, including ductile iron are also part of the iron-carbon system. Stainless steel or galvanized steel are used where resistance to corrosion is important. Aluminium alloys and magnesium alloys are used for applications where strength and lightness are required.
Copper-nickel alloys (such as Monel) are used in highly corrosive environments and for non-magnetic applications. Nickel-based superalloys like Inconel are used in high temperature applications such as turbochargers, pressure vessel, and heat exchangers. For extremely high temperatures, single crystal alloys are used to minimize creep.
In production engineering, metallurgy is concerned with the production of metallic components for use in consumer or engineering products. This involves the production of alloys, the shaping, the heat treatment and the surface treatment of the product. The task of the metallurgist is to achieve balance between material properties such as cost, weight, strength, toughness, hardness, corrosion, fatigue resistance, and performance in temperature extremes. To achieve this goal, the operating environment must be carefully considered. In a saltwater environment, ferrous metals and some aluminium alloys corrode quickly. Metals exposed to cold or cryogenic conditions may endure a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from metal fatigue. Metals under constant stress at elevated temperatures can creep.
Main article: Metalworking Metals are shaped by processes such as:
casting - molten metal is poured into a shaped mold. forging - a red-hot billet is hammered into shape. flow forming rolling - a billet is passed through successively narrower rollers to create a sheet. Laser cladding - metallic powder is blown through a movable laser beam (e.g. mounted on a
NC 5-axis machine). The resulting melted metal reach a substrate to form a melt pool. By moving the laser head, it is possible to stack the tracks and build up a 3D piece.
extrusion - a hot and malleable metal is forced under pressure through a die, which shapes it
before it cools.
sintering - a powdered metal is heated in a non-oxidizing environment after being compressed
into a die.
metalworking machining - lathes, milling machines, and drills cut the cold metal to shape. fabrication - sheets of metal are cut with guillotines or gas cutters and bent and welded into
structural shape. Cold working processes, where the product’s shape is altered by rolling, fabrication or other processes while the product is cold, can increase the strength of the product by a process called work hardening. Work hardening creates microscopic defects in the metal, which resist further changes of shape. Various forms of casting exist in industry and academia. These include sand casting, investment casting (also called the “lost wax process”),die casting and continuous casting.
Main article: Heat treatment
Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. Common heat treatment processes include annealing, precipitation strengthening, quenching, and tempering,. The annealing process softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that when the metal is hit or stressed it dents or perhaps bends, rather than breaking; it is also easier to sand, grind, or cut annealed metal. Quenching is the process of cooling a high-carbon steel very quickly after you have heated it, thus "freezing" the steel's molecules in the very hard martensite form, which makes the metal harder. There is a balance between hardness and toughness in any steel, where the harder it is, the less tough or impactresistant it is, and the more impact-resistant it is, the less hard it is. Tempering relieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking. Often, mechanical and thermal treatments are combined in what is known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high alloy special steels, super alloys and titanium alloys.
Main article: Plating Electroplating is a common surface-treatment technique. It involves bonding a thin layer of another metal such as gold, silver, chromium or zinc to the surface of the product. It is used to reduce corrosion as well as to improve the product's aesthetic appearance.
Main article: Thermal spraying Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings.
Metallography allows the metallurgist to study the microstructure of metals.
Metallurgists study the microscopic and macroscopic properties using metallography, a technique invented by Henry Clifton Sorby. In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal. The sample is then examined in an optical or electron microscope, and the image contrast provides details on the composition, mechanical properties, and processing history. Crystallography, often using diffraction of x-rays or electrons, is another valuable tool available to the modern metallurgist. Crystallography allows identification of unknown materials and reveals the crystal
structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been subjected.
Metallurgical failure analysis
From Wikipedia, the free encyclopedia
Metallurgical failure analysis is the process by which a metallurgist determines the mechanism that has caused a metal component to fail. Typical failure modes involve various types of corrosion and mechanical damage. It has been estimated that the direct annual cost of corrosion alone in the United States is a staggering 276 billion, approximately 3.1% of GDP. Metal components fail as a result of the environmental conditions to which they are exposed to as well as the mechanical stresses that they experience. Often a combination of both environmental conditions and stress will cause failure. Metal components are designed to withstand the environment and stresses that they will be subjected to. The design of a metal component involves not only a specific elemental composition but also specific manufacturing processes such as heat treatments, machining processes, etc.… The huge arrays of different metals that result all have unique physical properties. Specific properties are designed into metal components to make them more robust to various environmental conditions. These differences in physical properties will exhibit unique failure modes. A metallurgical failure analysis takes into account as much of this information as possible during analysis. Analysis of a failed part can be done using destructive testing or non-destructive testing. Destructive testing involves removing a metal component from service and sectioning the component for analysis. Destructive testing gives the failure analyst the ability to conduct the analysis in a laboratory setting and perform tests on the material that will ultimately destroy the component. Non destructive testing is a test method that allows certain physical properties of metal to be examined without taking the samples completely out of service. NDT is generally used to detect failures in components before the component fails catastrophically. There is no standardized list of metallurgical failure modes and different metallurgists might use a different name for the same failure mode. The Failure Mode Terms listed below are those accepted by ASTM, ASM, and/or NACE as distinct metallurgical failure mechanisms.
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1 Metallurgical Failure Modes Caused By Corrosion and Stress 2 Metallurgical Failure Modes Caused By Stress 3 Metallurgical Failure Modes Caused by Corrosion
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Because of its ability to study objects with highly polished surfaces like metals, a metallurgical microscope is different from other microscopes. Due to the various possible applications of a metallurgical microscope, buying one would give you a multipurpose investment. The many metallurgical microscopes will allow them to explore different fields and broaden their knowledge with just one tool. The study of metals and alloys and more specifically metallography, the microscopic examination of metals and alloys, a metallurgical microscope, especially a high end one, is generally equipped to provide great help in other fields of materials science as well. Metallography is the study of metal and alloys. Metallurgical microscope can help in knowing objects through its physical structure and properties. Metallography, in this art and science field, metal surfaces are prepared for microscopic analyses either by etching, polishing, or grinding the object in order to show its microstructure. Identifying properties and processing conditions of a metal or alloy sample with a metallographic analysis is what an expert in metallography can do. Archaeometallurgy, a subfield under metallurgy and archaeology, archaeometallurgy is the study of the history of metal use and production. With proper education and adequate experience, you can study a prehistoric metal object with a metallurgical microscope and be able to determine its processing condition and use. Crystallography, many material scientists use crystallography to help them in various kinds of research. Single crystal provides vital information about the crystalline arrangement of its atoms because a crystal’s natural shape usually reflects its atomic structure. Crystallography also helps in deciphering defects in crystals and developing preventive and rehabilitative measures for them. One of the key in identifying and understanding physical properties of many objects is crystallography. A metallurgical microscope will reveal the plate-like structure of clay and further study will show that its very structure is the cause of its easily moldable characteristic. Phase identification and enumeration of symmetry patterns in a given object can also be achieved with crystallography. A wonderful and interesting field under mineralogy is gemology. Gemology, the art, science, and profession of identifying and evaluating precious stones, may not be one of the primary applications of metallurgical microscopes but the latter is adequately equipped to answer basic questions in gemology. Properly educated and licensed gemologists would need post-graduate training and work experience in order to become a licensed appraiser as well. An appraiser has the ability to attach a monetary value to a certain gemstone or jewelry piece. The specialization is based on the type of gemstones. You can use your metallurgical microscope, for instance, to become adept in studying rubies or diamonds. Just the natural and well known gemstones like diamonds, sapphires and emeralds were studied. The applications of gemology have as well expanded to include them. Now, it’s important for gemologists to identify if a gemstone is natural or synthetic, fracture-filled, treated, and color-enhanced. In determining series of events leading to an accident or a questionable incident and determine the cause of a malfunctioning product or structure, the forensic metallurgy offers a great help. For forensic metallurgy, a special type of compound metallurgical microscope is used to be able to compare two samples or specimens with each other.
Different Parts of a Metallurgical Microscope
The parts of a metallurgical microscope are almost the same with ordinary optical microscopes except for two things: firstly, it uses a different illumination system to enable it to produce clear and sharp magnified images of metals and alloys, even with their shiny surfaces. Secondly, a metallurgical microscope may come with an XY stage similar to those used by measuring and tool maker microscopes.
Getting to Know the Different Parts of a Metallurgical Microscope Eyepieces – There are various types of eyepieces used in microscopes but there are those specially built for metallurgical microscopes. Eyepieces are one half of what makes the total magnification of a microscope. They are also what determines the field of view or how much of the image of the sample you can see. The best eyepieces cannot improve low levels or quality of the objective lenses you’re using but a poorly designed eyepiece can reduce the quality of image resolution provided by the microscope’s objectives. Objective – As it is with all types of microscopes, it’s important for you to invest in a good to excellent quality of objective lenses. It’s in fact better if you work with a pair of excellent objectives rather than have various lenses of mediocre quality. There are also various types of objectives sold in the market today and you can use two different types of objectives at the same time in certain occasions. Objectives make the other half of your microscope’s magnification. Multiplying the eyepiece magnification with that of the objectives will give you your microscope’s total magnification. Condenser – In an upright metallurgical microscope, you’ll find it beneath the stage and that’s why it’s often referred to as the substage condenser. In inverted metallurgical microscopes, however, the condenser is located above the stage. A condenser is one of the most important parts of a microscope’s illumination system. When the light source beams off light, it will be collected, concentrated, and controlled by the condenser. It is also partly because of the condenser that a metallurgical microscope is able to use various types of illumination such as polarized light and epi bright field optics. People mistakenly adjust the condenser’s focus knobs to adjust light intensity. If this is the problem, you shouldn’t be adjusting the condenser but rather the aperture iris diaphragm. If field brightness that’s the problem then adjust or change the filter you’re using and not the condenser. The condenser focus knob is simply there to adjust its vertical height and nothing else. Aperture Iris Diaphragm – This is part of your metallurgical microscope’s condenser. Adjusting it enables you to reduce or increase light angle coming from the condenser. Filter and Filter Holder or Carrier – Filters are also the other reason why you can use several illumination systems for your metallurgical microscope. The filter carrier is attached or found right next to the substage condenser. Purchase of additional filters can expand the applications of your microscope and the types of objects it is able to study. Nosepiece – This is also known as the objective changer and it is where the objective lenses of a metallurgical microscope are located. A nosepiece holding five lenses is more than enough but four is good as well. Three is adequate but two or one might be troublesome because you’d then have to manually change lenses when the two currently attached are unsuitable for the object you’re examining. Stage – This is where you place your object. Also known as your microscope’s platform, a stage may be built-in or integrated with the rest of the microscope or mechanical. It may come with a simple plane design or in a XY style for better precision in positioning your object. Interchangeability of stages depends primarily on the model you wish to purchase. Coarse Adjustment Knobs – These are the bigger knobs found on your metallurgical microscope and are there to lift or lower the stage or body tube. Fine Focus Knob – These are the smaller knobs on your metallurgical microscope and are there to adjust focus on the object. Foot – This represents the base of your metallurgical microscope. If possible, look for one with a magnetic base to allow you to study objects at any angle. Eyepiece Tube – This is where the eyepiece is inserted and it’s what connects the eyepiece to the rest of the metallurgical microscope. This is where video and camera accessories may also be attached. And these are the most important parts of a metallurgical microscope. Locating them and understanding their respective functions will help improve your skills and broaden your experience in working with metallurgical microscopes.
Introduction: The discovery of metals was the stepping stone towards civilization. The metal are known to man form the pre biblical times and different civilizations used the metal to make products for religious, hunting, weapon, house hold and ornamental purpose. Now, man is dependent on metal for cooking to traveling. A separate department called the metallurgy studies the entire process of working the metals for various applications. Pure metal are chemical element that cannot be further broken down into other substance. There are hundreds of such substances, of which some are found in the free stare and other are found in combination with silicon or other elements. Metals are generally shiny, strong, hard, brittle and good conductors of electricity. But, they have varying amount of each properties. Some metal like mercury are found in the liquid state on the other hand metals like lithium are very heavy. Each element has its own characteristics according to which they can be used for different purposes. Some are malleable which means they can be stretched and pulled while others are ductile which means that they can be hammered and squeezed. Metallurgy: Metallurgy is the science of metals which deals with the extraction, purification, alloying, heat treatment and working of ore. Since metals plays an important part in all type of activities, metallurgical is an important division of science studies. The metallurgy department has been divided mainly into three branches- extractive metallurgy which deals with the extraction of metals, physical metallurgy which deals with the structure and properties and production metallurgy which deals with designing and finishing the metal into useful products. The entire process of extracting the metal from the ore to shaping them into products is known as metal working. Metalworking Process: The main process involved in extracting the ore is to melt the ore by heating. Some ores are found relatively pure in nature and others are to be extracted from the complex ores. Different methods are used to remove the impurities like pounding the metal to chip of the impurities or by reshaping the raw ores. However, the predominantly used method is of melting the ores and separating the metal from the other elements. The removal of impurities can be done two times. First, when the ingot is made near the mines and the second time when the intro is melted for reworking at the craft production sits away from the source of the ore. When the metal is melted at a high temperature the molten metal gets deposited in the bottom and the impurities better know as slag floats on the top. The process of removing the metal from the impurities is known as smelting. After which the extracted metal is shaped into blocks or bars that is known as ingots so that it is easy for storage, transportation and further processes. E.g., of smelting is when copper or is reduced to copper through mixing carbon with the ore and heating the combination. Casting and forging are the most widely used method for shaping the metals into different products. Forging: Also known as hammering method, forging are of two types hot hammering and cold hammering methods. Softer metals like copper and bronze can be shaped into weapon or other items by just hammering. But metal like irons are to be heated so they are soft enough to be shaped into the required form. When the metal is heated the crystalline structure in weakened, therefore the finished product e.g., sword in plunged into water so that the crystal structure is restored and the product becomes hard. Casting: The most widely used metalworking method, casting can be done only if the metal is completely melt. Therefore, iron came later into use, because iron cannot be melted at ordinary temperature and other sophisticated methods are required to melt it. From the prebiblical time lost wax techniques was prevalently used and even today in some part of India this technique is used to cast bronze product like idols and statues. Alloys: Metals in its pure state generally does not satisfy the properties required for casting. Hence, in most cases metal have to combine with other element so that they acquire favorable qualities for the product like strength, ductility, malleability, etc. In an alloy, two or metal combine to form a new metal that has all the properties required for a particular application. Aluminum for instance is light in weight but soft and ductile. When aluminum is combined with other metals, the alloy formed is still light weight, but stronger, harder and resistant to corrosion. The realization of the wide application of alloys was the main reason for the industrial revolution.
The alloying process: The process of alloying helps in bettering the physical properties of the main metal that is used like iron and steel. During the alloying process the main changes happens in the engineering properties like ductility and malleability and to some extent in physical properties like density, reactivity, etc. The scientific reason behind the change is properties in because the smaller atoms are tightly compressed by the forces of the larger atoms. Since the alloy is a mixture of two or more metals it does not have a single melting point. There is a melting range, which is known as the liquidus point in the metal melts. Metals used for alloying: Alloys can be made of one or more metals. The main metals used are aluminum, copper, iron etc. and the alloying metals used with them are tin, zinc, molybdenum, etc. In many cased the alloy is better known by the main material metal that it constitutes of. For eg. an iron rod is made from an alloy but it is known by the name of its main component iron. The metals and alloys used for metal casting are broadly divided into ferrous metals and alloy that contain iron, and non ferrous metals and alloys that does not contain iron. Ferrous: The word ferrous is used generally to indicate the presence of iron in the metal sor in alloys. Iron in its pure state is soft but with the addition of carbon it becomes stron. Pig iron and steel have some percentage of carbon present. Other metals are also added to form alloys. All ferrous metals are magnetic and give little resistance to corrosion. Ferrous metal and alloys are used in a wide range of applications. carbon steel, allloy steel, tool steel etc. Non-Ferrous: These are metal or alloys that does not cotain iron, or has iron is an neligible quantity. They are non magnetic and more resistant to corrosion than ferrous metals. Nonferrous metals pplay an important role in the overall sustainable development of society. Therefore, many countries give prime importance to the study of the minining, production and recycling of non -ferrous metals. Examples are aluminium, copper, lead. zinc and tin. Structure of metals: The structure of a metal and its metallic porperties are determined by the bonding that is formed betweem the the atoms. This is known as metallic bonding. Properties like ductility, malleability and surface finish are determined by the metallic bonding and the presence of free electrons in the crystal lattice.
Bi-valve Breakdown powder
A simple two part mould. An additive that helps in the easy degradaon of the bond between sand and binder after the casting is over. This is useful especially in removing the waste of sand formed by cores. Core These are molds made of sand or other aggregates that is placed inside the mold cavity to design the internal features. Core are usually inserted after the pattetrn is removed from casting box. Chaplets A metal device used to support the core. Die A device made of rubber or metal that is used for shaping metal while casting jewellery, gear, etc. Size tolerance The variation which may be permitted on a given casting dimension is called its tolerance, and is equal t the difference between the minimum and maximum limits, for any special dimension. Feeders a vent that is provdided in a sand mould through which molten metal can be feed to the cast as it cools. Draft Also called draw, is the taper that is provided to the on the pattern that allow the pattern to be withdrawn from the mold. Flask A frame that is used to hold the mold of sand, plaster, etc for metal casting. Shaped in any convenient form like square, round, rectangular, etc. flasks have only sides and no top and bottom. Bulk The manufacturing of heavy metal for the autombile and other heavy manufacturing metal industry in large scale for making the production process cost effective. Methods mostly used for bulk manufacturing are permanent, die, centrifugal, and continuous casting.
Sprue Runner Mold Cavity Solidification Choke
Leads the molten metal from the ladle to the spruce well. Takes the metal from the sprue to the mold cavity The cavity formed in the shaped of the pattern, when the pattern is removed from the molding materials. The process of tranfsormation of molten metal in a solid piece of alloy. Smallest portion of the gating system that is uded to control the flow of molten metal from the ladle to the sprue well.