Misplaced Pages

#527472

48-398: The term is also applied colloquially, but inaccurately, to the garden fork . While similar in appearance, the garden fork is shorter and stockier than the pitchfork, with three or four thicker tines intended for turning or loosening the soil of gardens . In some parts of England , a pitchfork is known as a prong . In parts of Ireland , the term sprong is used to refer specifically to

96-731: A martensitic stainless steel alloy, today known as AISI type 420. The discovery was announced two years later in a January 1915 newspaper article in The New York Times . The metal was later marketed under the "Staybrite" brand by Firth Vickers in England and was used for the new entrance canopy for the Savoy Hotel in London in 1929. Brearley applied for a US patent during 1915 only to find that Haynes had already registered one. Brearley and Haynes pooled their funding and, with

144-575: A body-centered tetragonal crystal structure, and offer a wide range of properties and are used as stainless engineering steels, stainless tool steels, and creep -resistant steels. They are magnetic, and not as corrosion-resistant as ferritic and austenitic stainless steels due to their low chromium content. They fall into four categories (with some overlap): Martensitic stainless steels can be heat treated to provide better mechanical properties. The heat treatment typically involves three steps: Replacing some carbon in martensitic stainless steels by nitrogen

192-599: A four-pronged pitchfork. The typical pitchfork consists of a wooden shaft bearing two to five slightly curved metal tines fixed to one end of a handle. These are typically made of steel , wrought iron , or some other alloy , though historically wood or bamboo were used. Unlike a garden fork , a pitchfork lacks a grab at the end of its handle. Pitchforks with few tines set far apart are typically used for bulky material such as hay or straw ; those with more and more closely spaced are used for looser materials such as silage , manure , leaves, or compost . In Europe ,

240-525: A full-sized handle) is known as a border fork or ladies' fork , and is used for lighter work, such as weeding amongst other plants. Forks with broader, flatter tines are made for lifting potatoes and other root crops from the ground. A pair of forks back-to-back may used to lever apart dense clumps of roots. This tool article is a stub . You can help Misplaced Pages by expanding it . Stainless steel Stainless steel , also known as inox , corrosion-resistant steel ( CRES ), and rustless steel ,

288-627: A group of investors, formed the American Stainless Steel Corporation, with headquarters in Pittsburgh , Pennsylvania. Brearley initially called his new alloy "rustless steel". The alloy was sold in the US under different brand names like "Allegheny metal" and "Nirosta steel". Even within the metallurgy industry, the name remained unsettled; in 1921, one trade journal called it "unstainable steel". Brearley worked with

336-519: A local cutlery manufacturer, who gave it the name "stainless steel". As late as 1932, Ford Motor Company continued calling the alloy "rustless steel" in automobile promotional materials. In 1929, before the Great Depression, over 25,000 tons of stainless steel were manufactured and sold in the US annually. Major technological advances in the 1950s and 1960s allowed the production of large tonnages at an affordable cost: Stainless steel

384-451: A lower design criteria and corrosion resistance is required, for example in high temperatures and oxidizing environments. Martensitic , duplex and ferritic stainless steels are magnetic , while austenitic stainless steel is usually non-magnetic. Ferritic steel owes its magnetism to its body-centered cubic crystal structure , in which iron atoms are arranged in cubes (with one iron atom at each corner) and an additional iron atom in

432-469: A protective oxide surface film, such as aluminum and titanium, are also susceptible. Under high contact-force sliding, this oxide can be deformed, broken, and removed from parts of the component, exposing the bare reactive metal. When the two surfaces are of the same material, these exposed surfaces can easily fuse. Separation of the two surfaces can result in surface tearing and even complete seizure of metal components or fasteners. Galling can be mitigated by

480-506: A two-pronged weapon similar in form to a pitchfork but actually related to the trident in design and purpose. Garden fork A garden fork , spading fork , or digging fork (in the past also an asparagus fork , the same name as a very different utensil) is a gardening implement, with a handle and a square-shouldered head featuring several (usually four) short, sturdy tines . It is used for loosening, lifting and turning over soil in gardening and farming, and not to be confused with

528-406: A useful interchange table. Although stainless steel does rust, this only affects the outer few layers of atoms, its chromium content shielding deeper layers from oxidation. The addition of nitrogen also improves resistance to pitting corrosion and increases mechanical strength. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment

SECTION 10

#1732765057528

576-406: Is a recent development. The limited solubility of nitrogen is increased by the pressure electroslag refining (PESR) process, in which melting is carried out under high nitrogen pressure. Steel containing up to 0.4% nitrogen has been achieved, leading to higher hardness and strength and higher corrosion resistance. As PESR is expensive, lower but significant nitrogen contents have been achieved using

624-996: Is an alloy of iron that is resistant to rusting and corrosion . It contains iron with chromium and other elements such as molybdenum , carbon , nickel and nitrogen depending on its specific use and cost. Stainless steel's resistance to corrosion results from the 10.5%, or more, chromium content which forms a passive film that can protect the material and self-heal in the presence of oxygen. The alloy's properties, such as luster and resistance to corrosion, are useful in many applications. Stainless steel can be rolled into sheets , plates, bars, wire, and tubing. These can be used in cookware , cutlery , surgical instruments , major appliances , vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills , chemical plants , water treatment ), and storage tanks and tankers for chemicals and food products. Some grades are also suitable for forging and casting . The biological cleanability of stainless steel

672-532: Is an extension of the heating- quenching - tempering cycle, where the final temperature of the material before full-load use is taken down to a cryogenic temperature range. This can remove residual stresses and improve wear resistance. Austenitic stainless steel sub-groups, 200 series and 300 series: Ferritic stainless steels possess a ferrite microstructure like carbon steel, which is a body-centered cubic crystal structure, and contain between 10.5% and 27% chromium with very little or no nickel. This microstructure

720-426: Is bent or cut, magnetism occurs along the edge of the stainless steel because the crystal structure rearranges itself. Galling , sometimes called cold welding, is a form of severe adhesive wear, which can occur when two metal surfaces are in relative motion to each other and under heavy pressure. Austenitic stainless steel fasteners are particularly susceptible to thread galling, though other alloys that self-generate

768-510: Is classified into five main families that are primarily differentiated by their crystalline structure : Austenitic stainless steel is the largest family of stainless steels, making up about two-thirds of all stainless steel production. They possess an austenitic microstructure, which is a face-centered cubic crystal structure. This microstructure is achieved by alloying steel with sufficient nickel, manganese, or nitrogen to maintain an austenitic microstructure at all temperatures, ranging from

816-409: Is near that of ordinary steel, and much higher than the melting points of aluminium or copper. As with most alloys, the melting point of stainless steel is expressed in the form of a range of temperatures, and not a single temperature. This temperature range goes from 1,400 to 1,530 °C (2,550 to 2,790 °F; 1,670 to 1,800 K; 3,010 to 3,250 °R) depending on the specific consistency of

864-409: Is often used in lieu of the visually similar weapon, the trident , in popular portrayals and satire of Christian demonology . Many humorous cartoons, both animated and otherwise, feature a caricature of a demon ostensibly wielding a "pitchfork" (often actually a trident) sitting on one shoulder of a protagonist, opposite an angel on the other. The Hellenistic deity Hades wields a bident ,

912-1421: Is one of the most-produced industrial chemicals. At room temperature, type 304 stainless steel is only resistant to 3% acid, while type 316 is resistant to 3% acid up to 50 °C (120 °F) and 20% acid at room temperature. Thus type 304 SS is rarely used in contact with sulfuric acid. Type 904L and Alloy 20 are resistant to sulfuric acid at even higher concentrations above room temperature. Concentrated sulfuric acid possesses oxidizing characteristics like nitric acid, and thus silicon-bearing stainless steels are also useful. Hydrochloric acid damages any kind of stainless steel and should be avoided. All types of stainless steel resist attack from phosphoric acid and nitric acid at room temperature. At high concentrations and elevated temperatures, attack will occur, and higher-alloy stainless steels are required. In general, organic acids are less corrosive than mineral acids such as hydrochloric and sulfuric acid. Type 304 and type 316 stainless steels are unaffected by weak bases such as ammonium hydroxide , even in high concentrations and at high temperatures. The same grades exposed to stronger bases such as sodium hydroxide at high concentrations and high temperatures will likely experience some etching and cracking. Increasing chromium and nickel contents provide increased resistance. All grades resist damage from aldehydes and amines , though in

960-402: Is porous and fragile. In addition, as iron oxide occupies a larger volume than the original steel, this layer expands and tends to flake and fall away, exposing the underlying steel to further attack. In comparison, stainless steels contain sufficient chromium to undergo passivation , spontaneously forming a microscopically thin inert surface film of chromium oxide by reaction with the oxygen in

1008-498: Is present at all temperatures due to the chromium addition, so they are not capable of being hardened by heat treatment. They cannot be strengthened by cold work to the same degree as austenitic stainless steels. They are magnetic. Additions of niobium (Nb), titanium (Ti), and zirconium (Zr) to type 430 allow good weldability. Due to the near-absence of nickel, they are less expensive than austenitic steels and are present in many products, which include: Martensitic stainless steels have

SECTION 20

#1732765057528

1056-452: Is superior to both aluminium and copper, and comparable to glass. Its cleanability, strength, and corrosion resistance have prompted the use of stainless steel in pharmaceutical and food processing plants. Different types of stainless steel are labeled with an AISI three-digit number. The ISO 15510 standard lists the chemical compositions of stainless steels of the specifications in existing ISO, ASTM , EN , JIS , and GB standards in

1104-571: The Essen firm Friedrich Krupp Germaniawerft built the 366-ton sailing yacht Germania featuring a chrome-nickel steel hull, in Germany. In 1911, Philip Monnartz reported on the relationship between chromium content and corrosion resistance. On 17 October 1912, Krupp engineers Benno Strauss and Eduard Maurer patented as Nirosta the austenitic stainless steel known today as 18/8 or AISI type 304. Similar developments were taking place in

1152-638: The cryogenic region to the melting point. Thus, austenitic stainless steels are not hardenable by heat treatment since they possess the same microstructure at all temperatures. However, "forming temperature is an essential factor for metastable austenitic stainless steel (M-ASS) products to accommodate microstructures and cryogenic mechanical performance. ... Metastable austenitic stainless steels (M-ASSs) are widely used in manufacturing cryogenic pressure vessels (CPVs), owing to their high cryogenic toughness, ductility, strength, corrosion-resistance, and economy." Cryogenic cold-forming of austenitic stainless steel

1200-475: The pitchfork , a similar tined tool used for moving (or throwing) loose materials such as hay , straw , silage , and manure . A garden fork is used similarly to a spade in loosening and turning over soil. Its tines allow it to be pushed more easily into the ground, and it can rake out stones and weeds and break up clods, it is not so easily stopped by stones, and it does not cut through weed roots or root-crops. Garden forks were originally made of wood, but

1248-528: The water industry . Precipitation hardening stainless steels have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than other martensitic grades. There are three types of precipitation hardening stainless steels: Solution treatment at about 1,040 °C (1,900 °F) followed by quenching results in a relatively ductile martensitic structure. Subsequent aging treatment at 475 °C (887 °F) precipitates Nb and Cu-rich phases that increase

1296-549: The 1840s, both Britain's Sheffield steelmakers and then Krupp of Germany were producing chromium steel with the latter employing it for cannons in the 1850s. In 1861, Robert Forester Mushet took out a patent on chromium steel in Britain. These events led to the first American production of chromium-containing steel by J. Baur of the Chrome Steel Works of Brooklyn for the construction of bridges. A US patent for

1344-549: The 19th century didn't pay attention to the amount of carbon in the alloyed steels they were testing until in 1898 Adolphe Carnot and E. Goutal noted that chromium steels better resist to oxidation with acids the less carbon they contain. Also in the late 1890s, German chemist Hans Goldschmidt developed an aluminothermic ( thermite ) process for producing carbon-free chromium. Between 1904 and 1911, several researchers, particularly Leon Guillet of France, prepared alloys that would be considered stainless steel today. In 1908,

1392-667: The United States, where Christian Dantsizen of General Electric and Frederick Becket (1875–1942) at Union Carbide were industrializing ferritic stainless steel. In 1912, Elwood Haynes applied for a US patent on a martensitic stainless steel alloy, which was not granted until 1919. While seeking a corrosion-resistant alloy for gun barrels in 1913, Harry Brearley of the Brown-Firth research laboratory in Sheffield, England, discovered and subsequently industrialized

1440-441: The air and even the small amount of dissolved oxygen in the water. This passive film prevents further corrosion by blocking oxygen diffusion to the steel surface and thus prevents corrosion from spreading into the bulk of the metal. This film is self-repairing, even when scratched or temporarily disturbed by conditions that exceed the inherent corrosion resistance of that grade. The resistance of this film to corrosion depends upon

1488-587: The alloy in question. Like steel , stainless steels are relatively poor conductors of electricity, with significantly lower electrical conductivities than copper. In particular, the non-electrical contact resistance (ECR) of stainless steel arises as a result of the dense protective oxide layer and limits its functionality in applications as electrical connectors. Copper alloys and nickel-coated connectors tend to exhibit lower ECR values and are preferred materials for such applications. Nevertheless, stainless steel connectors are employed in situations where ECR poses

Pitchfork - Misplaced Pages Continue

1536-610: The alloy must endure. Corrosion resistance can be increased further by the following means: The most common type of stainless steel, 304, has a tensile yield strength around 210 MPa (30,000 psi) in the annealed condition. It can be strengthened by cold working to a strength of 1,050 MPa (153,000 psi) in the full-hard condition. The strongest commonly available stainless steels are precipitation hardening alloys such as 17-4 PH and Custom 465. These can be heat treated to have tensile yield strengths up to 1,730 MPa (251,000 psi). Melting point of stainless steel

1584-706: The alloy. The invention of stainless steel followed a series of scientific developments, starting in 1798 when chromium was first shown to the French Academy by Louis Vauquelin . In the early 1800s, British scientists James Stoddart, Michael Faraday , and Robert Mallet observed the resistance of chromium-iron alloys ("chromium steels") to oxidizing agents . Robert Bunsen discovered chromium's resistance to strong acids. The corrosion resistance of iron-chromium alloys may have been first recognized in 1821 by Pierre Berthier , who noted their resistance against attack by some acids and suggested their use in cutlery. In

1632-580: The center. This central iron atom is responsible for ferritic steel's magnetic properties. This arrangement also limits the amount of carbon the steel can absorb to around 0.025%. Grades with low coercive field have been developed for electro-valves used in household appliances and for injection systems in internal combustion engines. Some applications require non-magnetic materials, such as magnetic resonance imaging . Austenitic stainless steels, which are usually non-magnetic , can be made slightly magnetic through work hardening . Sometimes, if austenitic steel

1680-544: The chemical composition of the stainless steel, chiefly the chromium content. It is customary to distinguish between four forms of corrosion: uniform, localized (pitting), galvanic, and SCC (stress corrosion cracking). Any of these forms of corrosion can occur when the grade of stainless steel is not suited for the working environment. The designation "CRES" refers to corrosion-resistant (stainless) steel. Uniform corrosion takes place in very aggressive environments, typically where chemicals are produced or heavily used, such as in

1728-402: The majority are now made of forged carbon steel or stainless steel . Reflecting their differing uses, garden forks have shorter, flatter, thicker, and more closely spaced tines than pitchforks. They have comparatively a fairly short, stout, usually wooden handle, typically with a D- or T-shaped grab at the end. A smaller version of such forks with shorter, closer-spaced, thinner tines (but

1776-506: The most widely used. Many grading systems are in use, including US SAE steel grades . The Unified Numbering System for Metals and Alloys (UNS) was developed by the ASTM in 1970. Europe has adopted EN 10088 . Unlike carbon steel , stainless steels do not suffer uniform corrosion when exposed to wet environments. Unprotected carbon steel rusts readily when exposed to a combination of air and moisture. The resulting iron oxide surface layer

1824-502: The pitchfork has been used as a populist symbol and appended as a nickname for certain leading populist figures, such as "Pitchfork" Ben Tillman and "Pitchfork" Pat Buchanan . The Gangster Disciples, a street gang in the Midwestern United States, use a three-pointed pitchfork as one of their symbols. Venezuelan far-right political party, New Order use three-pointed pitchforks as their symbol. The pitchfork

1872-538: The pitchfork was first used in the Early Middle Ages , at about the same time as the harrow . These were made entirely of wood. The pitchfork is occasionally employed as an improvised weapon , as in a mob or riot. Paintings by various artists depict a wide variety of pitchforks in use and at rest. A notable American work is American Gothic (1930) by Grant Wood , which features a three-pronged tool. Because of its association with peasantry and farming,

1920-414: The product was issued in 1869. This was followed with recognition of the corrosion resistance of chromium alloys by Englishmen John T. Woods and John Clark, who noted ranges of chromium from 5–30%, with added tungsten and "medium carbon". They pursued the commercial value of the innovation via a British patent for "Weather-Resistant Alloys". Scientists researching steel corrosion in the second half of

1968-429: The pulp and paper industries. The entire surface of the steel is attacked, and the corrosion is expressed as corrosion rate in mm/year (usually less than 0.1 mm/year is acceptable for such cases). Corrosion tables provide guidelines. This is typically the case when stainless steels are exposed to acidic or basic solutions. Whether stainless steel corrodes depends on the kind and concentration of acid or base and

Pitchfork - Misplaced Pages Continue

2016-574: The solution temperature. Uniform corrosion is typically easy to avoid because of extensive published corrosion data or easily performed laboratory corrosion testing. Acidic solutions can be put into two general categories: reducing acids, such as hydrochloric acid and dilute sulfuric acid , and oxidizing acids , such as nitric acid and concentrated sulfuric acid. Increasing chromium and molybdenum content provides increased resistance to reducing acids while increasing chromium and silicon content provides increased resistance to oxidizing acids. Sulfuric acid

2064-949: The standard AOD process. Duplex stainless steels have a mixed microstructure of austenite and ferrite, the ideal ratio being a 50:50 mix, though commercial alloys may have ratios of 40:60. They are characterized by higher chromium (19–32%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. Duplex stainless steels have roughly twice the yield strength of austenitic stainless steel. Their mixed microstructure provides improved resistance to chloride stress corrosion cracking in comparison to austenitic stainless steel types 304 and 316. Duplex grades are usually divided into three sub-groups based on their corrosion resistance: lean duplex, standard duplex, and super duplex. The properties of duplex stainless steels are achieved with an overall lower alloy content than similar-performing super-austenitic grades, making their use cost-effective for many applications. The pulp and paper industry

2112-536: The strength up to above 1,000 MPa (150,000 psi) yield strength. This outstanding strength level is used in high-tech applications such as aerospace (usually after remelting to eliminate non-metallic inclusions, which increases fatigue life). Another major advantage of this steel is that aging, unlike tempering treatments, is carried out at a temperature that can be applied to (nearly) finished parts without distortion and discoloration. Typical heat treatment involves solution treatment and quenching . At this point,

2160-698: The structure remains austenitic. Martensitic transformation is then obtained either by a cryogenic treatment at −75 °C (−103 °F) or by severe cold work (over 70% deformation, usually by cold rolling or wire drawing). Aging at 510 °C (950 °F) — which precipitates the Ni 3 Al intermetallic phase—is carried out as above on nearly finished parts. Yield stress levels above 1400   MPa are then reached. The structure remains austenitic at all temperatures. Typical heat treatment involves solution treatment and quenching, followed by aging at 715 °C (1,319 °F). Aging forms Ni 3 Ti precipitates and increases

2208-487: The use of dissimilar materials (bronze against stainless steel) or using different stainless steels (martensitic against austenitic). Additionally, threaded joints may be lubricated to provide a film between the two parts and prevent galling. Nitronic 60, made by selective alloying with manganese, silicon, and nitrogen, has demonstrated a reduced tendency to gall. The density of stainless steel ranges from 7.5 to 8.0 g/cm (0.27 to 0.29 lb/cu in) depending on

2256-415: The yield strength to about 650 MPa (94,000 psi) at room temperature. Unlike the above grades, the mechanical properties and creep resistance of this steel remain very good at temperatures up to 700 °C (1,300 °F). As a result, A286 is classified as an Fe-based superalloy , used in jet engines, gas turbines, and turbo parts. Over 150 grades of stainless steel are recognized, of which 15 are

2304-476: Was one of the first to extensively use duplex stainless steel. Today, the oil and gas industry is the largest user and has pushed for more corrosion resistant grades, leading to the development of super duplex and hyper duplex grades. More recently, the less expensive (and slightly less corrosion-resistant) lean duplex has been developed, chiefly for structural applications in building and construction (concrete reinforcing bars, plates for bridges, coastal works) and in

#527472