115-642: Birmingham Steel Corporation was a steel producer in the United States, which made steel merchant and rebar products. The company was formed in 1983 by AEA Investors , Inc. and managed by CEO James Todd. It bought steel mini-mills in Kankakee , Illinois and the mills previously run by Todd at Birmingham Bolt . They then bought the Jackson, Mississippi-based Mississippi Steel Division of Magna Corp . The company went public on NYSE in 1985. In 1993,
230-412: A BOS process is manufactured in one-twelfth the time. Today, electric arc furnaces (EAF) are a common method of reprocessing scrap metal to create new steel. They can also be used for converting pig iron to steel, but they use a lot of electrical energy (about 440 kWh per metric ton), and are thus generally only economical when there is a plentiful supply of cheap electricity. The steel industry
345-535: A C grade, and improving from the 46th to 54th most polluted by ozone smog. According to daily ozone air quality data provided by the EPA, from 2021 to 2024, Pittsburgh had good or moderate air quality most of the time. Then-Allegheny County executive Rich Fitzgerald said in December 2023 that they’d seen an "80 % drop in hazardous air pollutants" and that they made EPA attainment at all eight county air monitors for
460-713: A carbon-intermediate steel by the 1st century AD. There is evidence that carbon steel was made in Western Tanzania by the ancestors of the Haya people as early as 2,000 years ago by a complex process of "pre-heating" allowing temperatures inside a furnace to reach 1300 to 1400 °C. Evidence of the earliest production of high carbon steel in South Asia is found in Kodumanal in Tamil Nadu ,
575-444: A change of volume. In this case, expansion occurs. Internal stresses from this expansion generally take the form of compression on the crystals of martensite and tension on the remaining ferrite, with a fair amount of shear on both constituents. If quenching is done improperly, the internal stresses can cause a part to shatter as it cools. At the very least, they cause internal work hardening and other microscopic imperfections. It
690-484: A decrease in city population, even as the metropolitan area population increased again. During the late 2000s recession , Pittsburgh was economically strong, adding jobs when most cities were losing them. It was one of the few cities in the United States to see housing property values rise. Between 2006 and 2011, the Pittsburgh metropolitan statistical area (MSA) experienced over 10% appreciation in housing prices,
805-428: A ferrite BCC crystal form, but at higher carbon content it takes a body-centred tetragonal (BCT) structure. There is no thermal activation energy for the transformation from austenite to martensite. There is no compositional change so the atoms generally retain their same neighbours. Martensite has a lower density (it expands during the cooling) than does austenite, so that the transformation between them results in
920-613: A free state after the Revolution, enslaved African Americans sought freedom here through escape as refugees from the South, or occasionally fleeing from travelers they were serving who stayed in the city. There were active stations of the Underground Railroad in the city, and numerous refugees were documented as getting help from station agents and African-American workers in city hotels. The Drennen Slave Girl walked out of
1035-685: A growing residential segment. Most significantly, the Pittsburgh Cultural Trust is embarking on RiverParc, a four-block mixed-use "green" community, featuring 700 residential units and multiple towers of between 20 and 30 stories. The Firstside portion of Downtown borders the Monongahela River, the historic Mon Wharf and hosts the distinctive PPG Place Gothic-style glass skyscraper complex. New condo towers have been constructed and historic office towers are converted to residential use, increasing 24-hour residents. Downtown
1150-445: A hard but brittle martensitic structure. The steel is then tempered, which is just a specialized type of annealing, to reduce brittleness. In this application the annealing (tempering) process transforms some of the martensite into cementite, or spheroidite and hence it reduces the internal stresses and defects. The result is a more ductile and fracture-resistant steel. When iron is smelted from its ore, it contains more carbon than
1265-412: A narrow range of concentrations of mixtures of carbon and iron that make steel, several different metallurgical structures, with very different properties can form. Understanding such properties is essential to making quality steel. At room temperature , the most stable form of pure iron is the body-centred cubic (BCC) structure called alpha iron or α-iron. It is a fairly soft metal that can dissolve only
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#17327974293401380-539: A quarter of neighborhood names make reference to "hills," "heights," or similar features. The steps of Pittsburgh consist of 800 sets of outdoor public stairways with 44,645 treads and 24,090 vertical feet. They include hundreds of streets composed entirely of stairs, and many other steep streets with stairs for sidewalks. Many provide vistas of the Pittsburgh area while attracting hikers and fitness walkers. Bike and walking trails have been built to border many of
1495-534: A small concentration of carbon, no more than 0.005% at 0 °C (32 °F) and 0.021 wt% at 723 °C (1,333 °F). The inclusion of carbon in alpha iron is called ferrite . At 910 °C, pure iron transforms into a face-centred cubic (FCC) structure, called gamma iron or γ-iron. The inclusion of carbon in gamma iron is called austenite. The more open FCC structure of austenite can dissolve considerably more carbon, as much as 2.1%, (38 times that of ferrite) carbon at 1,148 °C (2,098 °F), which reflects
1610-453: A steel's final rolling, it is heat treated for strength; however, this is relatively rare. Steel was known in antiquity and was produced in bloomeries and crucibles . The earliest known production of steel is seen in pieces of ironware excavated from an archaeological site in Anatolia ( Kaman-Kalehöyük ) which are nearly 4,000 years old, dating from 1800 BC. Wootz steel
1725-672: Is continuously cast into long slabs, cut and shaped into bars and extrusions and heat treated to produce a final product. Today, approximately 96% of steel is continuously cast, while only 4% is produced as ingots. The ingots are then heated in a soaking pit and hot rolled into slabs, billets , or blooms . Slabs are hot or cold rolled into sheet metal or plates. Billets are hot or cold rolled into bars, rods, and wire. Blooms are hot or cold rolled into structural steel , such as I-beams and rails . In modern steel mills these processes often occur in one assembly line , with ore coming in and finished steel products coming out. Sometimes after
1840-578: Is 39.61 inches (1,006 mm) and precipitation is greatest in May while least in October; annual precipitation has historically ranged from 22.65 in (575 mm) in 1930 to 57.83 in (1,469 mm) in 2018. On average, December and January have the greatest number of precipitation days. Snowfall averages 44.1 inches (112 cm) per season, but has historically ranged from 8.8 in (22 cm) in 1918–19 to 80 in (200 cm) in 1950–51. There
1955-486: Is an average of 59 clear days and 103 partly cloudy days per year, while 203 days are cloudy. In terms of annual percent-average possible sunshine received, Pittsburgh (45%) is similar to Seattle (49%). The American Lung Association's (ALA) 2023 "State of the Air" report (which included data from 2019 to 2021) showed air quality in Pittsburgh improving. The city received a passing grade for ozone pollution, going from an F to
2070-403: Is common for quench cracks to form when steel is water quenched, although they may not always be visible. There are many types of heat treating processes available to steel. The most common are annealing , quenching , and tempering . Annealing is the process of heating the steel to a sufficiently high temperature to relieve local internal stresses. It does not create a general softening of
2185-403: Is desirable. To become steel, it must be reprocessed to reduce the carbon to the correct amount, at which point other elements can be added. In the past, steel facilities would cast the raw steel product into ingots which would be stored until use in further refinement processes that resulted in the finished product. In modern facilities, the initial product is close to the final composition and
2300-453: Is distinguishable from wrought iron (now largely obsolete), which may contain a small amount of carbon but large amounts of slag . Iron is commonly found in the Earth's crust in the form of an ore , usually an iron oxide, such as magnetite or hematite . Iron is extracted from iron ore by removing the oxygen through its combination with a preferred chemical partner such as carbon which
2415-408: Is heat treated to contain both a ferritic and martensitic microstructure to produce a formable, high strength steel. Transformation Induced Plasticity (TRIP) steel involves special alloying and heat treatments to stabilize amounts of austenite at room temperature in normally austenite-free low-alloy ferritic steels. By applying strain, the austenite undergoes a phase transition to martensite without
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#17327974293402530-471: Is home to the University of Pittsburgh , Carnegie Mellon University , Carlow University , Chatham University , The Carnegie Institute's Museums of Art and Natural History , Phipps Conservatory , and Soldiers and Sailors Memorial Hall . It is also home to many parks and public spaces including Mellon Park , Westinghouse Park , Schenley Park , Frick Park , The Frick Pittsburgh , Bakery Square , and
2645-535: Is known as stainless steel . Tungsten slows the formation of cementite , keeping carbon in the iron matrix and allowing martensite to preferentially form at slower quench rates, resulting in high-speed steel . The addition of lead and sulphur decrease grain size, thereby making the steel easier to turn , but also more brittle and prone to corrosion. Such alloys are nevertheless frequently used for components such as nuts, bolts, and washers in applications where toughness and corrosion resistance are not paramount. For
2760-574: Is now known as Washington's Landing, formerly Herr's Island , in what is now the Lawrenceville neighborhood. The first known European to enter the region was the French explorer Robert de La Salle from Quebec during his 1669 expedition down the Ohio River . European pioneers, primarily Dutch, followed in the early 18th century. Michael Bezallion was the first to describe the forks of
2875-691: Is often considered an indicator of economic progress, because of the critical role played by steel in infrastructural and overall economic development . In 1980, there were more than 500,000 U.S. steelworkers. By 2000, the number of steelworkers had fallen to 224,000. The economic boom in China and India caused a massive increase in the demand for steel. Between 2000 and 2005, world steel demand increased by 6%. Since 2000, several Indian and Chinese steel firms have expanded to meet demand, such as Tata Steel (which bought Corus Group in 2007), Baosteel Group and Shagang Group . As of 2017 , though, ArcelorMittal
2990-514: Is one of the largest manufacturing industries in the world, but also one of the most energy and greenhouse gas emission intense industries, contributing 8% of global emissions. However, steel is also very reusable: it is one of the world's most-recycled materials, with a recycling rate of over 60% globally . The noun steel originates from the Proto-Germanic adjective * * stahliją or * * stakhlijan 'made of steel', which
3105-463: Is one of the most commonly manufactured materials in the world. Steel is used in buildings, as concrete reinforcing rods, in bridges, infrastructure, tools, ships, trains, cars, bicycles, machines, electrical appliances, furniture, and weapons. Iron is always the main element in steel, but many other elements may be present or added. Stainless steels , which are resistant to corrosion and oxidation , typically need an additional 11% chromium . Iron
3220-488: Is one of the world's most-recycled materials, with a recycling rate of over 60% globally; in the United States alone, over 82,000,000 metric tons (81,000,000 long tons; 90,000,000 short tons) were recycled in the year 2008, for an overall recycling rate of 83%. As more steel is produced than is scrapped, the amount of recycled raw materials is about 40% of the total of steel produced - in 2016, 1,628,000,000 tonnes (1.602 × 10 long tons; 1.795 × 10 short tons) of crude steel
3335-520: Is possible only by reducing iron's ductility. Steel was produced in bloomery furnaces for thousands of years, but its large-scale, industrial use began only after more efficient production methods were devised in the 17th century, with the introduction of the blast furnace and production of crucible steel . This was followed by the Bessemer process in England in the mid-19th century, and then by
3450-434: Is possible to make very high-carbon (and other alloy material) steels, but such are not common. Cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties. Certain compositions of cast iron, while retaining the economies of melting and casting, can be heat treated after casting to make malleable iron or ductile iron objects. Steel
3565-679: Is primarily composed of residential neighborhoods and is noteworthy for its well-constructed and architecturally interesting homes. Many buildings date from the 19th century and are constructed of brick or stone and adorned with decorative woodwork, ceramic tile, slate roofs and stained glass. The North Side is also home to attractions such as Acrisure Stadium , PNC Park , Kamin Science Center , National Aviary , Andy Warhol Museum , Mattress Factory art museum, Children's Museum of Pittsburgh , Randyland , Penn Brewery , Allegheny Observatory , and Allegheny General Hospital . The South Side
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3680-400: Is quite ductile , or soft and easily formed. In steel, small amounts of carbon, other elements, and inclusions within the iron act as hardening agents that prevent the movement of dislocations . The carbon in typical steel alloys may contribute up to 2.14% of its weight. Varying the amount of carbon and many other alloying elements, as well as controlling their chemical and physical makeup in
3795-573: Is referred to as "the Point." The city extends east to include the Oakland and Shadyside sections, which are home to the University of Pittsburgh , Carnegie Mellon University , Chatham University , Carnegie Museum and Library , and many other educational, medical, and cultural institutions. The southern, western, and northern areas of the city are primarily residential. Many Pittsburgh neighborhoods are steeply sloped with two-lane roads. More than
3910-457: Is related to * * stahlaz or * * stahliją 'standing firm'. The carbon content of steel is between 0.02% and 2.14% by weight for plain carbon steel ( iron - carbon alloys ). Too little carbon content leaves (pure) iron quite soft, ductile, and weak. Carbon contents higher than those of steel make a brittle alloy commonly called pig iron . Alloy steel is steel to which other alloying elements have been intentionally added to modify
4025-513: Is served by the Port Authority 's light rail system and multiple bridges leading north and south. It is also home to Point Park University and Duquesne University which borders Uptown . The North Side is home to various neighborhoods in transition. The area was once known as Allegheny City and operated as its own independent city until 1907, when it was merged with Pittsburgh despite great protest from its citizens. The North Side
4140-441: Is the base metal of steel. Depending on the temperature, it can take two crystalline forms (allotropic forms): body-centred cubic and face-centred cubic . The interaction of the allotropes of iron with the alloying elements, primarily carbon, gives steel and cast iron their range of unique properties. In pure iron, the crystal structure has relatively little resistance to the iron atoms slipping past one another, and so pure iron
4255-547: Is the world's largest steel producer . In 2005, the British Geological Survey stated China was the top steel producer with about one-third of the world share; Japan , Russia , and the United States were second, third, and fourth, respectively, according to the survey. The large production capacity of steel results also in a significant amount of carbon dioxide emissions inherent related to
4370-498: Is then lost to the atmosphere as carbon dioxide. This process, known as smelting , was first applied to metals with lower melting points, such as tin , which melts at about 250 °C (482 °F), and copper , which melts at about 1,100 °C (2,010 °F), and the combination, bronze, which has a melting point lower than 1,083 °C (1,981 °F). In comparison, cast iron melts at about 1,375 °C (2,507 °F). Small quantities of iron were smelted in ancient times, in
4485-754: Is water. The 80th meridian west passes directly through the city's downtown. The city is on the Allegheny Plateau , within the ecoregion of the Western Allegheny Plateau . The Downtown area (also known as the Golden Triangle) sits where the Allegheny River flows from the northeast and the Monongahela River from the southeast to form the Ohio River . The convergence is at Point State Park and
4600-492: The 68th-most populous city in the U.S., with a population of 302,971 as of the 2020 census . The city is located in southwestern Pennsylvania at the confluence of the Allegheny River and the Monongahela River , which combine to form the Ohio River . It anchors the Pittsburgh metropolitan area , which had a population of 2.457 million residents and is the largest metro area in both the Ohio Valley and Appalachia ,
4715-582: The Allegheny Mountains . The Great Fire of Pittsburgh destroyed over a thousand buildings in 1845. The city rebuilt with the aid of Irish immigrants who came to escape the Great Famine . By 1857, Pittsburgh's 1,000 factories were consuming 22 million coal bushels yearly. Coal mining and iron manufacturing attracted waves of European immigrants to the area, with the most coming from Germany . Because Pennsylvania had been established as
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4830-786: The Edgar Thomson Steel Works in North Braddock, Pennsylvania , which evolved into the Carnegie Steel Company . He adopted the Bessemer process to increase production. Manufacturing was key to growth of Pittsburgh and the surrounding region. Railroad lines were built into the city along both rivers, increasing transportation access to important markets. In 1901, J. P. Morgan and attorney Elbert H. Gary merged Carnegie Steel Company and several other companies into U.S. Steel . By 1910, Pittsburgh
4945-655: The Golconda area in Andhra Pradesh and Karnataka , regions of India , as well as in Samanalawewa and Dehigaha Alakanda, regions of Sri Lanka . This came to be known as wootz steel , produced in South India by about the sixth century BC and exported globally. The steel technology existed prior to 326 BC in the region as they are mentioned in literature of Sangam Tamil , Arabic, and Latin as
5060-744: The Iroquois Confederacy , based in New York, had maintained control of much of the Ohio Valley as hunting grounds by right of conquest after defeating other tribes. By the terms of the 1768 Treaty of Fort Stanwix , the Penns were allowed to purchase the modern region from the Iroquois . A 1769 survey referenced the future city as the "Manor of Pittsburgh". Both the Colony of Virginia and
5175-487: The Köppen climate classification , Pittsburgh falls within either a hot-summer humid continental climate ( Dfa ) if the 0 °C (32 °F) isotherm is used or a humid subtropical climate ( Cfa ) if the −3 °C (27 °F) isotherm is used. Summers are hot and winters are moderately cold with wide variations in temperature. Despite this, it has one of the most pleasant summer climates between medium and large cities in
5290-746: The Pittsburgh Post-Gazette was started, and in 1787, the Pittsburgh Academy was chartered. Unrest during the Whiskey Rebellion of 1794 resulted in federal troops being sent to the area. By 1797, glass manufacture began, while the population grew to around 1,400. Settlers arrived after crossing the Appalachian Mountains or through the Great Lakes . Fort Pitt (now Pittsburgh) at the source of
5405-561: The Pittsburgh Steelers , Pittsburgh Penguins , and Pittsburgh Pirates . Pittsburgh is additionally where Jehovah's Witnesses traces its earliest origins, and was the host of the 2009 G20 Pittsburgh summit . Pittsburgh was named in 1758, by General John Forbes , in honor of British statesman William Pitt, 1st Earl of Chatham . As Forbes was a Scotsman , he probably pronounced the name / ˈ p ɪ t s b ər ə / PITS -bər-ə (similar to Edinburgh ). Pittsburgh
5520-468: The Pittsburgh Zoo and PPG Aquarium. The neighborhoods of Shadyside and Squirrel Hill are large, wealthy neighborhoods with some apartments and condos, and pedestrian-oriented shopping/business districts. Squirrel Hill is also known as the hub of Jewish life in Pittsburgh, home to approximately 20 synagogues. Oakland , heavily populated by undergraduate and graduate students, is home to most of
5635-584: The Province of Pennsylvania claimed the region under their colonial charters until 1780, when they agreed under a federal initiative to extend the Mason–Dixon line westward, placing Pittsburgh in Pennsylvania. On March 8, 1771, Bedford County, Pennsylvania was created to govern the frontier. On April 16, 1771, the city's first civilian local government was created as Pitt Township . William Teagarden
5750-460: The University of Pittsburgh . The area has served as the federal agency headquarters for cyber defense , software engineering , robotics , energy research , and the nuclear navy . In the private sector, Pittsburgh-based PNC is the nation's fifth-largest bank, and the city is home to ten Fortune 500 companies and seven of the largest 300 U.S. law firms. Other corporations that have regional headquarters and offices have helped Pittsburgh become
5865-599: The cementation process was described in a treatise published in Prague in 1574 and was in use in Nuremberg from 1601. A similar process for case hardening armour and files was described in a book published in Naples in 1589. The process was introduced to England in about 1614 and used to produce such steel by Sir Basil Brooke at Coalbrookdale during the 1610s. The raw material for this process were bars of iron. During
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#17327974293405980-549: The open-hearth furnace . With the invention of the Bessemer process, a new era of mass-produced steel began. Mild steel replaced wrought iron . The German states were the major steel producers in Europe in the 19th century. American steel production was centred in Pittsburgh , Bethlehem, Pennsylvania , and Cleveland until the late 20th century. Currently, world steel production is centered in China, which produced 54% of
6095-528: The second-largest in Pennsylvania , and the 26th-largest in the U.S. Pittsburgh is the principal city of the greater Pittsburgh–Weirton–Steubenville combined statistical area which includes parts of Ohio and West Virginia . Pittsburgh is known as "the Steel City" for its dominant role in the history of the U.S. steel industry . It developed as a vital link of the Atlantic coast and Midwest , as
6210-445: The 17th century, it was realized that the best steel came from oregrounds iron of a region north of Stockholm , Sweden. This was still the usual raw material source in the 19th century, almost as long as the process was used. Crucible steel is steel that has been melted in a crucible rather than having been forged , with the result that it is more homogeneous. Most previous furnaces could not reach high enough temperatures to melt
6325-475: The 17th century, the first step in European steel production has been the smelting of iron ore into pig iron in a blast furnace . Originally employing charcoal, modern methods use coke , which has proven more economical. In these processes, pig iron made from raw iron ore was refined (fined) in a finery forge to produce bar iron , which was then used in steel-making. The production of steel by
6440-587: The 1850 Fugitive Slave Act , as it required cooperation from law enforcement even in free states and increased penalties. From 1850 to 1860, the black population in Allegheny County dropped from 3,431 to 2,725 as people headed to more safety in Canada. The American Civil War boosted the city's economy with increased iron and armament demand by the Union. Andrew Carnegie began steel production in 1875 at
6555-608: The Arabs from Persia, who took it from India. It was originally created from several different materials including various trace elements , apparently ultimately from the writings of Zosimos of Panopolis . In 327 BC, Alexander the Great was rewarded by the defeated King Porus , not with gold or silver but with 30 pounds of steel. A recent study has speculated that carbon nanotubes were included in its structure, which might explain some of its legendary qualities, though, given
6670-454: The Central, North Side/North Hills, South Side/South Hills, East End, and West End. Downtown Pittsburgh has 30 skyscrapers, nine of which top 500 feet (150 m). The U.S. Steel Tower is the tallest, at 841 ft (256 m). The Cultural District consists of a 14-block area of downtown along the Allegheny River . This district contains many theaters and arts venues and is home to
6785-518: The Elder , while the settlement was named "Pittsborough". During Pontiac's War , a loose confederation of Native American tribes laid siege to Fort Pitt in 1763; the siege was eventually lifted after Colonel Henry Bouquet defeated a portion of the besieging force at the Battle of Bushy Run . Bouquet strengthened the defenses of Fort Pitt the next year. During this period, the powerful nations of
6900-470: The Linz-Donawitz process of basic oxygen steelmaking (BOS), developed in 1952, and other oxygen steel making methods. Basic oxygen steelmaking is superior to previous steelmaking methods because the oxygen pumped into the furnace limited impurities, primarily nitrogen, that previously had entered from the air used, and because, with respect to the open hearth process, the same quantity of steel from
7015-568: The Monongahela House in 1850, apparently to freedom. The Merchant's Hotel was also a place where African-American workers would advise slaves the state was free and aid them in getting to nearby stations of the Underground Railroad. Sometimes refugee slaves from the South stayed in Pittsburgh, but other times they continued North, including into Canada. Many slaves left the city and county for Canada after Congress passed
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#17327974293407130-522: The North American front of the Seven Years' War , began with the future Pittsburgh as its center. British General Edward Braddock was dispatched with Major George Washington as his aide to take Fort Duquesne. The British and colonial force were defeated at Braddock's Field . General John Forbes finally took the forks in 1758. He began construction on Fort Pitt , named after William Pitt
7245-728: The North Side, and the Golden Triangle are characterized by more density of housing, walking neighborhoods, and a more diverse, urban feel. Pittsburgh falls within the borders of the Northeastern United States as defined by multiple US Government agencies. Pittsburgh is the principal city of the Pittsburgh Combined Statistical Area , a combined statistical area defined by the U.S. Census Bureau . Pittsburgh falls within
7360-692: The Ohio River became the main base for settlers moving into the Northwest Territory . The federal government recognizes Pittsburgh as the starting point for the Lewis and Clark Expedition . Preparations began in Pittsburgh in 1803 when Meriwether Lewis purchased a keelboat that would later be used to ascend the Missouri River . The War of 1812 cut off the supply of British goods, stimulating American industry. By 1815, Pittsburgh
7475-565: The Ohio headwaters was long inhabited by the Shawnee and several other settled groups of Native Americans . Shannopin's Town was an 18th-century Lenape (Delaware) town located roughly from where Penn Avenue is today, below the mouth of Two Mile Run, from 30th Street to 39th Street. According to George Croghan , the town was situated on the south bank of the Allegheny, nearly opposite what
7590-452: The Ohio in a 1717 manuscript, and later that year European fur traders established area posts and settlements. In 1749, French soldiers from Quebec launched an expedition to the forks to unite Canada with French Louisiana via the rivers. During 1753–1754, the British hastily built Fort Prince George before a larger French force drove them off. The French built Fort Duquesne based on LaSalle's 1669 claims. The French and Indian War ,
7705-430: The U.S. The city lies in the USDA plant hardiness zone 6b except along the rivers where the zone is 7a. The area has four distinct seasons: winters are cold and snowy, springs and falls are mild with moderate levels of sunshine, and summers are warm. As measured by percent possible sunshine, summer is by far the sunniest season, though annual sunshine is low among major US cities at well under 50%. The warmest month of
7820-416: The addition of heat. Twinning Induced Plasticity (TWIP) steel uses a specific type of strain to increase the effectiveness of work hardening on the alloy. Pittsburgh Pittsburgh ( / ˈ p ɪ t s b ɜːr ɡ / PITS -burg ) is a city in and the county seat of Allegheny County, Pennsylvania , United States. It is the second-most populous city in Pennsylvania , after Philadelphia , and
7935-399: The air and the rivers. The "Renaissance II" project followed in 1977, focused on cultural and neighborhood development. The industrial base continued to expand through the 1970s, but beginning in the early 1980s both the area's steel and electronics industries imploded during national industrial restructuring. There were massive layoffs from mill and plant closures. In the later 20th century,
8050-425: The area shifted its economic base to education, tourism, and services, largely based on healthcare/medicine, finance, and high technology such as robotics. Although Pittsburgh successfully shifted its economy and remained viable, the city's population has never rebounded to its industrial-era highs. While 680,000 people lived in the city proper in 1950, a combination of suburbanization and economic turbulence resulted in
8165-436: The austenite grain boundaries until the percentage of carbon in the grains has decreased to the eutectoid composition (0.8% carbon), at which point the pearlite structure forms. For steels that have less than 0.8% carbon (hypoeutectoid), ferrite will first form within the grains until the remaining composition rises to 0.8% of carbon, at which point the pearlite structure will form. No large inclusions of cementite will form at
8280-471: The austenite is for it to precipitate out of solution as cementite , leaving behind a surrounding phase of BCC iron called ferrite with a small percentage of carbon in solution. The two, cementite and ferrite, precipitate simultaneously producing a layered structure called pearlite , named for its resemblance to mother of pearl . In a hypereutectoid composition (greater than 0.8% carbon), the carbon will first precipitate out as large inclusions of cementite at
8395-547: The borders of Appalachia as defined by the Appalachian Regional Commission , and has long been characterized as the "northern urban industrial anchor of Appalachia." In its post-industrial state, Pittsburgh has been characterized as the "Paris of Appalachia", recognizing the city's cultural, educational, healthcare, and technological resources, and is the largest city in Appalachia. Under
8510-494: The boundaries in hypoeutectoid steel. The above assumes that the cooling process is very slow, allowing enough time for the carbon to migrate. As the rate of cooling is increased the carbon will have less time to migrate to form carbide at the grain boundaries but will have increasingly large amounts of pearlite of a finer and finer structure within the grains; hence the carbide is more widely dispersed and acts to prevent slip of defects within those grains, resulting in hardening of
8625-521: The characteristics of steel. Common alloying elements include: manganese , nickel , chromium , molybdenum , boron , titanium , vanadium , tungsten , cobalt , and niobium . Additional elements, most frequently considered undesirable, are also important in steel: phosphorus , sulphur , silicon , and traces of oxygen , nitrogen , and copper . Plain carbon-iron alloys with a higher than 2.1% carbon content are known as cast iron . With modern steelmaking techniques such as powder metal forming, it
8740-494: The city's population. Pittsburgh also became a main destination of the African-American Great Migration from the rural South during the first half of the 20th century. Limited initially by discrimination, some 95% percent of the men became unskilled steel workers. During World War II , demand for steel increased and area mills operated 24 hours a day to produce 95 million tons of steel for
8855-542: The city's rivers and hollows. The Great Allegheny Passage and Chesapeake and Ohio Canal Towpath connect the city directly to downtown Washington, D.C. (some 335 miles [539 km] away) with a continuous bike/running trail. The city consists of the Downtown area, called the Golden Triangle, and four main areas surrounding it. These surrounding areas are subdivided into distinct neighborhoods (Pittsburgh has 90 neighborhoods). Relative to downtown, these areas are known as
8970-413: The city. However, the city divested from steel and, since the 1990s, Pittsburgh has focused its energies on the healthcare, education, and technology industries. Pittsburgh is home to large medical providers, including the University of Pittsburgh Medical Center , Allegheny Health Network , and 68 colleges and universities , including research and development leaders Carnegie Mellon University and
9085-476: The community and various developers to create a master plan for a mixed-use development that included a riverfront park, office space, housing, health-care facilities, and indoor practice fields for the Pittsburgh Steelers and Pitt Panthers . Construction of the development began in 1998. The SouthSide Works has been open since 2005, featuring many stores, restaurants, offices, and the world headquarters for American Eagle Outfitters . The East End of Pittsburgh
9200-567: The company purchased the American Steel and Wire Company . In June 2002, after several consecutive quarters of losses, the company filed for Chapter 11 bankruptcy protection. Its remaining steel mills and other assets were purchased by Nucor in December 2002 for approximately $ 615,000,000. Steel Steel is an alloy of iron and carbon with improved strength and fracture resistance compared to other forms of iron. Because of its high tensile strength and low cost, steel
9315-422: The desired properties. Nickel and manganese in steel add to its tensile strength and make the austenite form of the iron-carbon solution more stable, chromium increases hardness and melting temperature, and vanadium also increases hardness while making it less prone to metal fatigue . To inhibit corrosion, at least 11% chromium can be added to steel so that a hard oxide forms on the metal surface; this
9430-470: The downtown skyline, and numerous other residential neighborhoods such as Sheraden and Elliott . Many of Pittsburgh's patchwork of neighborhoods still retain ethnic characters reflecting the city's settlement history. These include: Several neighborhoods on the edges of the city are less urban, featuring tree-lined streets, yards and garages, with a more suburban character. Oakland, the South Side,
9545-413: The final steel (either as solute elements, or as precipitated phases), impedes the movement of the dislocations that make pure iron ductile, and thus controls and enhances its qualities. These qualities include the hardness , quenching behaviour , need for annealing , tempering behaviour , yield strength , and tensile strength of the resulting steel. The increase in steel's strength compared to pure iron
9660-648: The finest steel in the world exported to the Roman, Egyptian, Chinese and Arab worlds at that time – what they called Seric Iron . A 200 BC Tamil trade guild in Tissamaharama , in the South East of Sri Lanka, brought with them some of the oldest iron and steel artifacts and production processes to the island from the classical period . The Chinese and locals in Anuradhapura , Sri Lanka had also adopted
9775-513: The form of charcoal) in a crucible, was produced in Merv by the 9th to 10th century AD. In the 11th century, there is evidence of the production of steel in Song China using two techniques: a "berganesque" method that produced inferior, inhomogeneous steel, and a precursor to the modern Bessemer process that used partial decarburization via repeated forging under a cold blast . Since
9890-599: The hardenability of thick sections. High strength low alloy steel has small additions (usually < 2% by weight) of other elements, typically 1.5% manganese, to provide additional strength for a modest price increase. Recent corporate average fuel economy (CAFE) regulations have given rise to a new variety of steel known as Advanced High Strength Steel (AHSS). This material is both strong and ductile so that vehicle structures can maintain their current safety levels while using less material. There are several commercially available grades of AHSS, such as dual-phase steel , which
10005-437: The highest appreciation of the largest 25 metropolitan statistical areas in the United States, with 22 of the largest 25 metropolitan statistical areas experiencing depreciations in housing values. In September 2009, the 2009 G20 Pittsburgh summit was held in Pittsburgh. Pittsburgh has an area of 58.3 square miles (151 km ), of which 55.6 square miles (144 km ) is land and 2.8 square miles (7.3 km ), or 4.75%,
10120-439: The main production route. At the end of 2008, the steel industry faced a sharp downturn that led to many cut-backs. In 2021, it was estimated that around 7% of the global greenhouse gas emissions resulted from the steel industry. Reduction of these emissions are expected to come from a shift in the main production route using cokes, more recycling of steel and the application of carbon capture and storage technology. Steel
10235-610: The mineral-rich Allegheny Mountains led to the region being contested by the French and British Empires, Virginians , Whiskey Rebels , and Civil War raiders . For part of the 20th century, Pittsburgh was behind only New York City and Chicago in corporate headquarters employment; it had the most U.S. stockholders per capita. Deindustrialization in the late 20th century resulted in massive layoffs among blue-collar workers as steel and other heavy industries declined, coinciding with several Pittsburgh-based corporations moving out of
10350-450: The most part, however, p-block elements such as sulphur, nitrogen , phosphorus , and lead are considered contaminants that make steel more brittle and are therefore removed from steel during the melting processing. The density of steel varies based on the alloying constituents but usually ranges between 7,750 and 8,050 kg/m (484 and 503 lb/cu ft), or 7.75 and 8.05 g/cm (4.48 and 4.65 oz/cu in). Even in
10465-436: The oxidation rate of iron increases rapidly beyond 800 °C (1,470 °F), it is important that smelting take place in a low-oxygen environment. Smelting, using carbon to reduce iron oxides, results in an alloy ( pig iron ) that retains too much carbon to be called steel. The excess carbon and other impurities are removed in a subsequent step. Other materials are often added to the iron/carbon mixture to produce steel with
10580-449: The product but only locally relieves strains and stresses locked up within the material. Annealing goes through three phases: recovery , recrystallization , and grain growth . The temperature required to anneal a particular steel depends on the type of annealing to be achieved and the alloying constituents. Quenching involves heating the steel to create the austenite phase then quenching it in water or oil . This rapid cooling results in
10695-759: The production methods of creating wootz steel from the Chera Dynasty Tamils of South India by the 5th century AD. In Sri Lanka, this early steel-making method employed a unique wind furnace, driven by the monsoon winds, capable of producing high-carbon steel. Since the technology was acquired from the Tamilians from South India, the origin of steel technology in India can be conservatively estimated at 400–500 BC. The manufacture of wootz steel and Damascus steel , famous for its durability and ability to hold an edge, may have been taken by
10810-504: The record cold daily maximum is −3 °F (−19 °C), which occurred three times, most recently the day of the all-time record low, while, conversely, the record warm daily minimum is 82 °F (28 °C) on July 1, 1901. Due to elevation and location on the windward side of the Appalachian Mountains, 100 °F (38 °C)+ readings are very rare, and were last seen on July 15, 1995. Average annual precipitation
10925-605: The sixth-best area for U.S. job growth. Pittsburgh is sometimes called the "City of Bridges" for its 446 bridges . Its rich industrial history left the area with renowned cultural institutions, including the Carnegie Museums of Pittsburgh , Pittsburgh Parks Conservancy , Pittsburgh Zoo & Aquarium , Phipps Conservatory and Botanical Gardens , the National Aviary , and a diverse cultural district . The city's major league professional sports teams include
11040-477: The solid-state, by heating the ore in a charcoal fire and then welding the clumps together with a hammer and in the process squeezing out the impurities. With care, the carbon content could be controlled by moving it around in the fire. Unlike copper and tin, liquid or solid iron dissolves carbon quite readily. All of these temperatures could be reached with ancient methods used since the Bronze Age . Since
11155-401: The steel. At the very high cooling rates produced by quenching, the carbon has no time to migrate but is locked within the face-centred austenite and forms martensite . Martensite is a highly strained and stressed, supersaturated form of carbon and iron and is exceedingly hard but brittle. Depending on the carbon content, the martensitic phase takes different forms. Below 0.2% carbon, it takes on
11270-561: The steel. The early modern crucible steel industry resulted from the invention of Benjamin Huntsman in the 1740s. Blister steel (made as above) was melted in a crucible or in a furnace, and cast (usually) into ingots. The modern era in steelmaking began with the introduction of Henry Bessemer 's process in 1855, the raw material for which was pig iron. His method let him produce steel in large quantities cheaply, thus mild steel came to be used for most purposes for which wrought iron
11385-561: The technology of that time, such qualities were produced by chance rather than by design. Natural wind was used where the soil containing iron was heated by the use of wood. The ancient Sinhalese managed to extract a ton of steel for every 2 tons of soil, a remarkable feat at the time. One such furnace was found in Samanalawewa and archaeologists were able to produce steel as the ancients did. Crucible steel , formed by slowly heating and cooling pure iron and carbon (typically in
11500-862: The universities, and the Petersen Events Center . The Strip District to the west along the Allegheny River is an open-air marketplace by day and a clubbing destination by night. Bloomfield is Pittsburgh's Little Italy and is known for its Italian restaurants and grocers. Lawrenceville is a revitalizing rowhouse neighborhood popular with artists and designers. The Hill District was home to photographer Charles Harris as well as various African-American jazz clubs. Other East End neighborhoods include Point Breeze , Regent Square , Highland Park , Homewood , Lincoln-Lemington-Belmar , Larimer , East Hills , East Liberty , Polish Hill , Hazelwood , Garfield, Morningside, and Stanton Heights. The West End includes Mt. Washington , with its famous view of
11615-525: The upper carbon content of steel, beyond which is cast iron. When carbon moves out of solution with iron, it forms a very hard, but brittle material called cementite (Fe 3 C). When steels with exactly 0.8% carbon (known as a eutectoid steel), are cooled, the austenitic phase (FCC) of the mixture attempts to revert to the ferrite phase (BCC). The carbon no longer fits within the FCC austenite structure, resulting in an excess of carbon. One way for carbon to leave
11730-572: The value of homes in the South Side had increased in value by about 10% annually for the 10 years leading up to 2014. East Carson Street has developed as one of the most vibrant areas of the city, packed with diverse shopping, ethnic eateries, vibrant nightlife, and live music venues. In 1993, the Urban Redevelopment Authority of Pittsburgh purchased the South Side Works steel mill property. It collaborated with
11845-400: The war effort. This resulted in the highest levels of air pollution in the city's almost century of industry. The city's reputation as the "arsenal of democracy" was being overshadowed by James Parton 's 1868 observation of Pittsburgh being "hell with the lid off." Following World War II, the city launched a clean air and civic revitalization project known as the "Renaissance," cleaning up
11960-428: The world's steel in 2023. Further refinements in the process, such as basic oxygen steelmaking (BOS), largely replaced earlier methods by further lowering the cost of production and increasing the quality of the final product. Today more than 1.6 billion tons of steel is produced annually. Modern steel is generally identified by various grades defined by assorted standards organizations . The modern steel industry
12075-604: The year in Pittsburgh is July, with a 24-hour average of 73.2 °F (22.9 °C). Conditions are often humid, and combined with highs reaching 90 °F (32 °C) on an average 9.5 days a year, a considerable heat index arises. The coolest month is January, when the 24-hour average is 28.8 °F (−1.8 °C), and lows of 0 °F (−18 °C) or below can be expected on an average 2.6 nights per year. Officially, record temperatures range from −22 °F (−30 °C), on January 19, 1994 to 103 °F (39 °C), which occurred three times, most recently on July 16, 1988;
12190-718: Was developed in Southern India and Sri Lanka in the 1st millennium BCE. Metal production sites in Sri Lanka employed wind furnaces driven by the monsoon winds, capable of producing high-carbon steel. Large-scale wootz steel production in India using crucibles occurred by the sixth century BC, the pioneering precursor to modern steel production and metallurgy. High-carbon steel was produced in Britain at Broxmouth Hillfort from 490–375 BC, and ultrahigh-carbon steel
12305-486: Was federally recognized as "Pittsburg", though use of the final h was retained during this period by the city government and other local organizations. After a public campaign, the federal decision to drop the h was reversed. The Pittsburg Press continued spelling the city without an h until 1921. [REDACTED] Kingdom of France 1690s–1763 [REDACTED] Great Britain 1681–1781 [REDACTED] United States 1776–present The area of
12420-509: Was formerly used. The Gilchrist-Thomas process (or basic Bessemer process ) was an improvement to the Bessemer process, made by lining the converter with a basic material to remove phosphorus. Another 19th-century steelmaking process was the Siemens-Martin process , which complemented the Bessemer process. It consisted of co-melting bar iron (or steel scrap) with pig iron. These methods of steel production were rendered obsolete by
12535-545: Was incorporated as a borough on April 22, 1794, with the following Act: "Be it enacted by the Pennsylvania State Senate and Pennsylvania House of Representatives of the Commonwealth of Pennsylvania ... by the authority of the same, that the said town of Pittsburgh shall be ... erected into a borough, which shall be called the borough of Pittsburgh for ever." From 1891 to 1911, the city's name
12650-517: Was once the site of railyards and associated dense, inexpensive housing for mill and railroad workers. Starting in the late 20th century, the city undertook a Main Street program in cooperation with the National Trust for Historic Preservation , encouraging design and landscape improvements on East Carson Street, and supporting new retail. The area has become a local Pittsburgher destination, and
12765-438: Was produced globally, with 630,000,000 tonnes (620,000,000 long tons; 690,000,000 short tons) recycled. Modern steels are made with varying combinations of alloy metals to fulfil many purposes. Carbon steel , composed simply of iron and carbon, accounts for 90% of steel production. Low alloy steel is alloyed with other elements, usually molybdenum , manganese, chromium, or nickel, in amounts of up to 10% by weight to improve
12880-757: Was produced in the Netherlands from the 2nd-4th centuries AD. The Roman author Horace identifies steel weapons such as the falcata in the Iberian Peninsula , while Noric steel was used by the Roman military . The Chinese of the Warring States period (403–221 BC) had quench-hardened steel, while Chinese of the Han dynasty (202 BC—AD 220) created steel by melting together wrought iron with cast iron, thus producing
12995-542: Was producing significant quantities of iron, brass, tin, and glass. On March 18, 1816, the 46-year-old local government became a city. It was served by numerous river steamboats that increased trading traffic on the rivers. In the 1830s, many Welsh people from the Merthyr steelworks immigrated to the city following the aftermath of the Merthyr Rising . By the 1840s, Pittsburgh was one of the largest cities west of
13110-625: Was the nation's eighth-largest city , accounting for between one-third and one-half of national steel output. The Pittsburgh Agreement was subscribed in May 1918 between the Czech and Slovak nationalities, as envisioned by T. G. Masaryk , concerning the future foundation of Czechoslovakia . The city suffered severe flooding in March 1936. The city's population swelled to more than a half million, attracting numerous European immigrants to its industrial jobs. By 1940, non-Hispanic whites were 90.6% of
13225-584: Was the first constable, and William Troop was the first clerk. Following the American Revolution , the village of Pittsburgh continued to grow. One of its earliest industries was boat building for settlers of the Ohio Country . In 1784, Thomas Vickroy completed a town plan which was approved by the Penn family attorney. Pittsburgh became a possession of Pennsylvania in 1785. The following year,
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