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70-653: The Latin name means "between-two-rivers", in reference to its location on the confluence of the Nera river ( Ancient Umbrian Nahar , Latin : Nār, Nahar ) and the Serra stream. When disambiguation was needed, it was referred to as Interamna Nahars . Its inhabitants were known in Latin as Interamnātēs Na(ha)rtēs . Interamna was founded as an Ancient Roman town, albeit settlements in the Terni area well precede this occurrence. During

140-547: A Light rail line. Ternana Calcio is the main football club in the city. The club has twice played in Italy's first division Serie A (seasons 1972–1973 and 1974–1975 ). Ternana is currently playing in Serie B ( season 2021–2022 ). The club plays at the 22,000-seat Stadio Libero Liberati , named after Italian motorcycle racer Libero Liberati , who was born in Terni, won the 500cc World Championship in 1957, and died while he

210-731: 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

280-601: A bishop here, and the remains are preserved in the basilica-sanctuary in his honour. The city was founded around the 7th century BC by the Umbrians Nahartes , in a territory inhabited (as testified by archaeological excavations) as early as the Bronze Age . The Iguvine Tablets describe these Nahartes as a strong, numerous people and as the most important enemy of the Umbrian people of Gubbio (Iguvium). In

350-575: 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

420-639: A company listed on STAR segment of Borsa Italiana , that is active in the renewable energy sector, and promotes and develops technological start-ups in the cleantech sector. Terni is connected with the A1 motorway , the European route E45 and National Road Flaminia by the RATO , a motorway junction. Terni railway station is part of the Ancona–Orte railway , and is also a junction station for two secondary lines,

490-627: 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

560-519: 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

630-451: 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

700-820: A number of innovations , some of them shared by its neighbor to the west, Latin. (Below, following convention, bold text for Umbrian and Oscan indicates words written in the native, Etruscan derived script, while italics represents words written in Latin-derived script.) All diphthongs are simplified into monophthongs , a process only partly seen in Latin, and only very rarely in Oscan. So Proto-Italic * ai and * ei become Umbrian low ē : kvestur  : Oscan kvaísstur , Latin quaestor 'official in charge of public revenue and expenditure'; prever 'single' : Oscan preivatud , Latin prīvus ; furthermore, Proto-Italic * oi , * ou and * au become ō (written u in

770-469: 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

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840-399: A term generally replaced by Sabellic in modern scholarship. Since that classification was first formulated, a number of other languages in ancient Italy were discovered to be more closely related to Umbrian. Therefore, a group, the Umbrian languages, was devised to contain them. Umbrian is known from about 30 inscriptions dated from the 7th through 1st centuries BC. The largest cache by far is

910-406: 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

980-406: 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

1050-532: 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

1120-472: Is as follows: Pure: i, e, a, o, u; ā, ē, ī, ō, ū Diphthongs: ai, ei, ou Classes of nouns roughly match those in Latin: long a-stems matching Latin first declension, historical o-stems matching Latin second declension, consonant- and i-stems matching Latin third declension, with some more sparse attestation of u-stem (Latin fourth) and long e-stem (Latin fifth) declensions. There are seven attested cases in

1190-426: 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

1260-510: 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

1330-409: 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

1400-1421: 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

1470-402: 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

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1540-498: 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

1610-452: 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

1680-571: 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

1750-697: The Iguvine Tablets , seven inscribed bronze tablets found in 1444 near the village of Scheggia or, according to another tradition, in an underground chamber at Gubbio (ancient Iguvium ). The seven tablets contain notes on the ceremonies and statutes for priests of the ancient religion in the region. Sometimes they are called the Eugubian tablets after the medieval name of Iguvium/Eugubium. The tablets contain 4000–5000 words. Other minor inscriptions are from Todi , Assisi and Spoleto . The Iguvine tablets were written in two alphabets. The older,

1820-513: The Terni–Sulmona railway (which links Terni with L'Aquila ) and the Terni–Sansepolcro railway ( FCU ) (which serves Perugia ). One of the most important national freight stations is located nearby. The local urban and suburban transport service, ATC, runs 90 bus lines. In the north of the city (Colleluna zone), there are works in progress on the line from Perugia to enable it to be used as

1890-638: 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

1960-528: 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

2030-719: 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

2100-549: 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

2170-549: 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,

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2240-541: The 19th century, steel mills were introduced and led the city to have a role in the Second Industrial Revolution in Italy. Because of its industrial importance, the city was heavily bombed during World War II by the Allies . It remains an industrial hub and has been nicknamed "The Steel City". Terni is also known as the "City of Lovers", as its patron saint, Saint Valentine , was born and became

2310-718: The 3rd century BC, Terni was conquered by the Romans and soon became an important municipium lying on the Via Flaminia and known under the name Interamna , meaning "between-two-rivers". In 271 BC the Roman consul Manius Curius Dentatus ordered the construction of a canal (the Curiano Trench) to divert the water from the marshes in the Rieti Valley and from Lake Velino over the natural cliff at Marmore , creating

2380-580: The 3rd person: singular primary -ter , singular secondary -(n)tur , plural -endi . Perfect stems are derived from the present stem in different ways. Latin -vī- perfects are not attested in Umbrian. Instead, Umbrian uses its own set of forms, including reduplicated perfects such as dede 'gave', the -s- suffix, as in sesu-s-t 'will have sat', and the -nçi- suffix, as in purdi-nçi-ust 'will have presented'. Some verbs also use suppletive forms. Other tenses are formed by suffixation: The following non-finite forms are attested (all of them are based on

2450-418: The Latin alphabet is represented by a single character in the native script (generally transcribed as ř ; this represents an unknown sound that developed regularly from intervocalic *-d- in most cases). To clearly distinguish them, the native script is generally transcribed in bold, the Latin in italics. The exact phonetics of much of what follows are not completely clear. The consonant inventory of Umbrian

2520-469: The Latin alphabet on the tablet): In Latin: In English: Stainless steel Stainless steel , also known as inox , corrosion-resistant steel ( CRES ), and rustless steel , 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

2590-690: The Umbrian alphabet, like other Old Italic script , was derived from the Etruscan alphabet , and was written right-to-left, essentially equivalent to the Neo-Etruscan, but using a letter shaped like a 'P' from the Archaic Etruscan alphabet for the unique Umbrian sound discussed below. The newer was written in the Latin script . The texts are sometimes called Old Umbrian and New Umbrian. The differences are mainly orthographic. For example, rs in

2660-667: 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

2730-441: 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

2800-587: 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

2870-610: 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

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2940-706: 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

3010-580: 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

3080-544: 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

3150-477: The city" (note that Umbrian continues the PIE case, while Latin innovates here to -ae); Dat. tute "to the city"; Abl. asa "from the altar"; Loc. tote "in the city"; Voc. Prestota "Oh, Prestota" Plural: Nom. fameřias "families"; Acc. porca "pigs"; Gen. pracatarum "of the ramparts"?; Dat.-Abl. plenasier "for the annual festival" (with final rhotacism from -s; thought to be related to Latin plenus "full" with

3220-432: The initial syllable of words as a stress accent, since non-initial syllables are regularly lost or weakened. Since the same pattern occurs in the history of Etruscan , this must be assumed to be an areal feature. (By the time of classical Latin, the accent had shifted in that language to more of an Ancient Greek pattern--on the third syllable from the end (antepenult) unless the last syllable was long, in which case it fell on

3290-460: The language, final -s also becomes -r (a change not seen in Latin). For example, the genitive plural ending of -ā stems: Umbrian -arum , Latin -arum vs Oscan -asúm (compare Sanskrit - āsām ). While initial * d- is preserved (spelled t in the native alphabet), earlier intervocalic *-d- (and sometimes *-l-) show up in the native alphabet as a character generally transliterated as ř , but as

3360-506: 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

3430-637: The native script) in initial syllables: unu 'one' : Old Latin oinus ; ute 'or' : Oscan auti , Latin aut ; tuta 'city' : Oscan touto . Velars are palatalized and spirantized before front vowels and the front glide /j/ to probably a palatalized sibilant (perhaps the postalveolar /ʃ/), written ç , ś or simply s . (A similar change happened later in most Romance languages.) For example: Umbrian śesna 'dinner' : Oscan kersnu , Latin cēna ; Umbrian façiu 'I do, I make' : Latin faciō . Like Latin, but unlike Oscan, intervocalic -s- rhotacized to -r- in Umbrian. In late forms of

3500-421: The present stem): Umbrian shares some phonological changes with its sister language Oscan. This change is shared with Umbrian, and so is a common Sabellic change, reminiscent of the k/p split between Goidellic (Irish, etc) and Cymric (Welsh, etc). piře , pirse "what"; Oscan pídum vs Latin quid. At some point early in the history of all Indo-European Italic languages, the accent seems to have shifted to

3570-414: 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

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3640-547: The province. The presence of important industries made the city a favorite target for the Allied bombardments in World War II . On August 11, 1943, a raid by 44 USAAF bombers, which dropped 213 tons of bombs, devastated the city, killing 564 people. It was the first of the 57 airstrikes that destroyed or damaged 40% of Terni's buildings and killed 1,018 civilians. Despite this, industrial environment increased quickly after

3710-429: 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

3780-526: The same for centuries. After the Lombard conquest in 755, Terni lost prominence when it was reduced to a secondary town in the Duchy of Spoleto . In 1174, it was sacked by Frederick Barbarossa 's general, Archbishop Christian of Mainz . In the following century, Terni was one of the sites visited frequently by St. Francis to give sermons. In the 14th century Terni issued its own constitution, and from 1353

3850-603: The second to last syllable (the penult).) The degree to which these shifts can be connected to similar shifts to initial stress in Celtic and Germanic is unclear; for discussion see J. Salmons' Accentual Change and Language Contact . Examples: Loss of unstressed short -e-: * onse "shoulder" < * omesei , compare Latin umerus ; destre "on the right" < * deksiterer ; ostendu "present" (imperative) < * obs-tendetōd , compare Latin ostendito . But compared to its highly conservative sister language Oscan, Umbrian exhibits

3920-405: The semantic development > "of the full (year)"). Verbs in Umbrian are inflected for the following categories: Present, future and future perfect forms in the active voice use the following set of personal endings (primary): Imperfect, perfect indicative and all tenses of the subjunctive in the active voice use a different set of endings (secondary): Passive endings are attested only for

3990-443: The sequence rs in Umbrian texts using the Latin alphabet. The exact pronunciation is unknown: piře , pirse "what" vs. Oscan pídum , Latin quid. Proto-italic *ū became /i/, sim (accusative singular) <PI *sūm "pig" Taken from the Iguvine Tablets , tablet Va, lines 6–10 (written in the native alphabet on the tablet): In Latin: In English: Taken from the Iguvine Tablets , tablet VIa, lines 25–31 (written in

4060-603: The singular: nominative , accusative (along with the nom-acc neuter case), genitive , dative , ablative , locative , and vocative . In the plural, there are only four distinct cases: nominative; accusative; genitive; and dative-and-ablative combined into one form. There are no attested locative or vocative plurals. Examples from long a-stems (for use of bold versus italic script, see above under "Alphabet"): Singular: Nom. muta/mutu "fine" (related to Latin molta "fine"); Acc. tuta / totam "city, state"; Gen. tutas / totar (the later with rhotacism, on which see below) "of

4130-574: 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

4200-949: 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

4270-536: 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,

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4340-698: 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

4410-472: The traditional industrial connotation of the city. In the 17th century, however, the population of Terni declined further due to plagues and famines. In the 19th century, Terni took advantage of the Industrial Revolution and of plentiful water sources in the area. New industries included a steelworks, a foundry , as well as weapons, jute and wool factories. In 1927, Terni became capital of

4480-487: 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

4550-826: The walls were enlarged, and new channels were opened. As with many of the Italian communes of the Late Middle Ages, it was beset by civil unrest between the partisans of the Guelphs and Ghibellines , and later between the Nobili and Banderari (Terni's bourgeoisie). It later joined the Papal States . In 1580, an ironwork , the Ferriera, was introduced to work the iron ore mined in Monteleone di Spoleto , starting

4620-470: The war. The city has three important industrial hubs: the first one is the Stainless Steel Area, called AST (part of the group ThyssenKrupp ) and is a wide area located in the east part of Terni. West of the town, there is a second industrial hub, known as "Area Polymer", with four different chemical multinational industries. The third industrial hub is Italeaf, which controls TerniEnergia,

4690-480: The waterfall. This caused flooding in the valley around Terni below. For a long time this became the cause of interminable quarrels between the cities of Rieti and Terni. The issue was so contentious between the two cities that the Roman Senate was forced to address it in 54 BC. Aulus Pompeius represented Terni, and Cicero represented Rieti. The Senate did nothing about the problem, and the problem remained

4760-415: 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

4830-476: 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

4900-611: Was training with his Gilera Saturno along the Valnerina road near Terni. Terni is twinned with: Umbrian language Umbrian is an extinct Italic language formerly spoken by the Umbri in the ancient Italian region of Umbria . Within the Italic languages it is closely related to the Oscan group and is therefore associated with it in the group of Osco-Umbrian languages ,

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