Дата публикации: 30 сентября 2021
Автор(ы): Vadim SCHASTLIVTSEV, Dmitry RODIONOV, Yulia KHLEBNIKOVA →
Публикатор: Научная библиотека Порталус
Рубрика: ТУРИЗМ И ПУТЕШЕСТВИЯ →
Источник: (c) Science in Russia, №2, 2012, C.97-105 →
Номер публикации: №1633009089
Vadim SCHASTLIVTSEV, Dmitry RODIONOV, Yulia KHLEBNIKOVA, (c)
by Acad. Vadim SCHASTLIVTSEV, Chief Researcher; Dmitry RODIONOV, Dr. (Phys. & Math.), Chief Researcher; Yulia KHLEBNIKOVA, Cand. Sc. (Tech.), Senior Researcher, Institute of Physics of Metals, Ural Branch, Russian Academy of Sciences, (Yekaterinburg)
The first thing to catch your eye when approaching the town of Nevyansk, one of the oldest here in Russia, is a leaning tower next to a church belfry. Even though nearly five centuries younger than the famous Leaning Tower of Pisa (1174-1372) and Notre Dame de Paris (1211-1311), it has witnessed many a fitful event as the Mid-Ural backwoods were turning into a major industrial area. Only the Moscow Kremlin (1700) and the St. Trinity Cathedral (1703-1704) at Verkhoturye are older than that tower.
The Cathedral of the Transfiguration of the Savior and Nevyansk leaning tower. 19th cent.
The first permanent Slav settlements in the Mid-Urals came up in the late 16th century in the wake of the daring march of Yermak, a bold and enterprising Cossack chieftain. Five years thereafter ground was broken for the Tyumen ostrog* that grew into a town of the same name. In 1587 another stronghold, Tobolsk, was founded--a town that had long been the capital of this area, its military, administrative, political and church center. There followed other towns, Berezov for one. It rose at a crossroads of ancient waterways where political exiles were banished. Permanent population centers were needed for keeping regular and reliable communications between old towns in European Russia--like Cherdyn, Solikamsk and Usolye--and the new-founded Siberian strongholds.
Lozvinsky, a settlement that appeared in the Mid-Urals in 1589 on the site on what is now the town of Ivdel, could hardly measure up for this role: the land route along the Cherdyn road was pretty hard and not linked to waterways leading to Tyumen. This problem was solved by the Babinov highway opened in 1597 and named so for Artemy Babinov, a pathfinder. It went as far as the Nerom-Kar settlement saddling the upper reaches of the Tura where, near its inflow into the Tobol, there stood Tyumen. The following year ground was cleared for Verkhoturye, a town that soon after grew into a major administrative and trans-shipping center in our country's east. The Turin ostrog, the second biggest population center in the Middle Urals, followed next (1600) to boost the reliability of connections of European Russia with Siberia. This fort stemmed the onslaughts of nomadic tribes on the Urals. Many other towns sprung up: Tomsk (1604), Turuk-hansk (1607), the Yenisei ostrog (1618), Krasnoyarsk (1628), Yakutsk (1632), Zhigansk (1632), Verkhoyansk (1638), Okhotsk (1648), Anadyr (1649)... In a mere fifty years or so Russian servicemen and Cossacks pushed through to the coasts of the Sea of Okhotsk and the Pacific.
The population of the Mid-Urals grew fast, both in small villages, 3 to 5 households each, and in larger settlements that evolved into towns. Like Irbit (1631), for instance, where annual fairs became regular as of 1633; or Shadrinsk (1644), Tsarev Kurgan (1662), Kamyshlov (1668), Kamensk-Uralsky (1682). Our Nevyansk dates back to about the same time.
Old Russian Registers* tell us: the Verkhoturye uyezd (administrative district) alone numbered over 360 settlements, twelve large villages among them, their residents engaged for the most part in farming, trade and hunting. Large numbers of iron tools--axes and scythes as well as nails and clamps--were needed for local industries such as home-building, hay-making, firewood storing and the like. These things brought in from European Russia were short in supply and costly.
Hence the felt need to produce iron out there, in the Urals, where numerous primitive mills sprung up a la muzhik, in which local handymen would melt ore, while iron ball** was hammered to wrought iron in smitheries. Local handicraftsmen smelt as much as 550 poods (each pood equal to 36 lb) a year. Another state-owned ironworks was built in 1629, it smelt around 400 poods of pure iron annually.
Yet the real breakthrough that brought world fame to the Urals came decades later, toward the close of the 17th century, when two large ironworks were built at Kamensk and Nevyansk (both commissioned in 1701, in October and December, respectively). The history of Ural metallurgy dates from these months of that year.
At first the Nevyansk mill worked sluggishly, in fits and starts, until Czar Peter I issued an edict handing it into private ownership in 1702 to Nikita Demidov, an arms manufacturer and supplier who provided munitions to the Russian troops during the Great Northern War (1700-1721) fought by Russia against Sweden and
* Ostrog, a Russian stronghold or fort between the 13th and 18th cent.--Ed.
* Registers--books or ledgers current in Russia from the 14th to the mid-17th cent. on the property status of peasant farmers. They itemized the property of estates, villages, monasteries and other legal entities.--Ed.
** Iron ball (bloom), a loose slag-saturated ferrous mass that goes to make bloomery iron and steel.--Ed.
Poland. The Nevyansk plant had to work for Russian artillery--the transfer was made conditional on that. Nikita Demidov had a munitions industry in Tula south of Moscow, and had to travel far and wide all over Russia. Therefore right away, in 1702, he appointed his son, a 24-year-old Akinthy, as its manager. Upon his arrival there work began full tilt--a blast furnace gained full power, and hammeries resumed their work. Demidov Junior did a great deal to make his enterprise a success. The Russian poet Vassily Zhukovsky (1783-1852) described him as a "grandfather of Ural mills". Cast iron and iron obtained there from grade ore and charcoal in the 18th and 19th centuries with the use of a two-phase technology were of model quality second only to metal made in Sweden. Between 1703 and 1718 (that is during the Great Northern War) Nevyansk enterprises turned out about 90 percent of artillery shells and grenades manufactured in the Urals.
Since more metal was needed, the number of ironworks kept expanding. As many as 55 ironworks mushroomed in the region, 24 state-owned and 31 in private ownership, with the Demidovs active in the effort. Demidov Sr. built yet another five giants in addition to those at Nevyansk, and his son, as many as seventeen, including an iron foundry and ironworks in Nizhni Tagil (1725), a focal enterprise of the Demidov business. In 1740 local enterprises melt around 72 percent of Russian cast iron and 75 percent of iron. The Demi-
dov shops accounted for 65 percent and 61 percent of cast iron and iron, respectively, produced in the Urals. The mills proliferated, and so did the cluster of settlements around them. Many grew into large towns, such as Nizhni Tagil, Kamensk-Uralsky, Revda and other centers where even today we may come upon buildings dating back to those days: workshops, churches, residential houses as well as high dams and ponds. Such things are there at Nevyansk, too.
The leaning tower erected in 1722 to 1732 (architect unknown) is one of the most remarkable memorials. Its builders used cast-iron and iron elements typical of Russian multilevel churches of the late sixteen-hundreds. A metal framework, its pivotal structure, is held together by cast-iron washers and iron wedges fixed outside. This was really a revolutionary solution, says a Ural historian Igor Shakinko in his book The Demidovs (Yekaterinburg, 2001), comparable to ferroconcrete. It combined two different materials complementary to each other: stone--for compression, iron--for bending and tension. Initially the tower was to be built within the mill doubling as a fortress. These plans had to be changed, however, since the ground proved unstable.
Already at the foundation laying stage the base sank in unevenly, and the structure tipped to one side. Yet one went ahead with the construction work trying to stabilize the object. Thus one immured open and closed metal braces into 1.8 meter-thick walls so as to keep the
Shorthand of the bloomery furnace.
stonework whole. Furthermore, a system of horizontal cast-iron beams and girders reinforced the bracing effect with the aid of pins and washers fixed at the angles. In shape the beams resemble wooden bars 190x145 across and 6 meters long. A 60x36 mm iron rod welded to the cast-iron base was fixed underneath. In short, the Ural metal-makers created a composite material that stood up well against compressive and tensile loads. Window grates and balcony railings, too, added to the bracing effect for the brickwork. Having no shortage of metal, the Demidovs could afford to be extravagant like that.
Judging by the data cited in the Studies on the History of Culture and Household Life of Old Nevyansk (Yekaterinburg, 2001), the construction of the tower proceeded in two stages, first in quadragons (quadrangular) and then in octagons (octagonal) levels crowned with a metal cupola of original design, the world's first. Only 100 years later a similar design was repeated in the Mainz Cathedral, Germany, in 1826, and then in the dome of the St. Isaac Cathedral in St. Petersburg. A spire furnished with a lightning conductor crowned the Nevyansk tower. Made of 1 mm-thick ball iron*, the conductor was in the shape of a hollow ball ("sun-ball") more than 10 inches in diameter and supplied with spikes ("rays"). Their 40 cm pointed triangles were forged to the outer surface. This lightning conductor was put up two decades before the North American scientist Benjamin Franklin had invented his lightning rod; the one at Nevyansk stood on top of the tower over
200 years and, after repairs in the middle of the nine-teen-hundreds, became a museum exhibit.
Now, how could this lightning rod come to be? As we know, Akinthy Demidov was always on the go, shuttling between St. Petersburg and Moscow, Tula and Nevyansk. And so he was abreast of all developments in his field. He knew that Prince Alexander Menshikov, the czar's favorite, had erected a tall tower in St. Petersburg and had it covered with Nevyansk iron donated by the Demidovs. But a lightning hit its hip roof in a thunderstorm in the summer of 1723 and caused a fire that ravaged the upper levels of wooden tiers. And so to protect the tower of Nevyansk against such accidents its metal roof was furnished with a spire and a crown in the form of a sun. The grounding was passed through the brickwork. The lightning conductor saved the structure many a time, and when the "sun ball" was taken off, its spikes ("rays") happened to be scorched.
A clock and chimes were installed on the lower octagon. Ten bells carried this cast inscription: "Richard Phelps. London. 1730." Placed in the center was a brass ball with the words: "Siberia. Anno 1732 of June the First this here bell weighing 65 poods and 27 pounds was cast in the Nevyansk works of the nobleman Akinthy Demidov." That is, it weighed more than a ton! The chimes sounded every 15 minutes, on the half hour and on the hour; every three hours there came a melody of musical drums.
Built nearly 300 years ago, the tower still keeps its original, virgin look, and this makes many specialists wonder. Metal-makers, for one. We, metal experts, show great interest in many things, particularly, in its
* Ball (wrought, welding) iron, obtained by forging loose porous ferric mass, the iron ball.--Ed.
cast-iron, iron and steel elements manufactured at the local plant. A rare case: the metal produced here, in the fortress-mill of Nevyansk, stayed in the Urals, while most of the metal cast elsewhere was shipped to European Russia and abroad, to England in particular. Topgrade Ural alloys were readily bought in Europe, come as they did from excellent iron ores and charcoal. Topnotch metal-makers took care of the melting.
Ball iron was the main product of local mills. The furnace employed for one heating was a cupola-like pit equipped with air ducts for blasting. Crushed ore and charcoal were fed into the melting chamber of the furnace. Some of the slag was tapped from a side aperture, though a greater part of it stayed in the stock mass. The metal making was in two stages: 1 ) pig iron and cast iron, and 2) iron proper and steel. The spongy conglomerate thus obtained was welded readily in subsequent punching.
Impossible as it was to secure specimens of exported Ural metal of the 18th century so as to identify and describe its structure, we seized at the lucky opportunity of studying Nevyansk tower samples kindly provided by Nina Medovshchikova of the local museum of architecture and by the museum of the Nevyansk metallurgical plant. It was important to assess the grade of Demidov alloys (chemical composition, structure as well as the mechanical properties of cast and wrought iron) and make comparative studies with foreign analogs of that time.
The presence of carbon was assessed by metal structure, for the small dimensions of museum samples ruled out the gravimetric chemical method (by dissolving metal chips in special chemical agents), while X-ray microanalysis proved much in error. Yet this method was found fairly accurate for measuring the concentration of other dopes.
We got two cast-iron fragments--one from a balcony grate, a copybook example of art (ornamental) castings of the 18th century, and the other, a piece of a memorial metal plaque (plate) dated 1725. The exact date was
of special importance to us. Both samples belong to eutectic* white cast irons containing about 4.3 percent carbon. Hard and brittle, they are silvery-white in fracture. The melting point of such metal is around 1,150 °C. It is composed predominantly of ledeburite eutectic** and excess cementite. Cementite crystals are seen in a white background in microphotographs. We could also make out spots of pearlite as dark areas of irregular form.
A chemical study of the samples attests to their sufficiently high purity thanks to the use of grade ore and charcoal. Both cast irons contain copper inclusions typical of Ural iron ores. They might have been made from minerals mined at the Vysokaya Gora deposit near what is now the city of Nizhni Tagil tapped around 1725. Its ore contained about 1.5 percent manganese and 0.35 percent copper.
We found a significant amount of phosphorus (~0.2 percent) in the metal. The use of white cast iron for making balcony grates in particular, is most unusual. Today gray cast iron remarkable for its good melting and casting characteristics (good fluidity) is employed for like purposes. It contains a greater part of carbon in graphite, not cementite, admixtures. Usually from 2.4 to 3.8 percent of C and from 1.2 to 3.55 percent of Si is present in such metal. The high presence of Si is conducive to graphite formation. Manganese, contrariwise, impedes this process and leads to bleaching (chilling of iron casting), and one tries to limit its use therefore. In white cast iron carbon (C) is present as cementite (Fe3C) making it quite hard and brittle. Yet it is second to gray cast iron in casting characteristics, and therefore it is processed into iron or steel, the conversion material.
The chemical composition of our two samples enables us to assume that both the plate (plaque) and
* Eutectic, a melt of two and more components whose quantitative proportions correspond to the lowest melting temperature of the mix.--Ed.
** Ledeburite eutectic: obtained as a mosaic ornament is formed from cementite crystals (Fe3C carbide) and austenite inclusions capable of turning to pearlite or bainite in cooling).--Ed.
the balcony grate were cast from the same melt meant for a subsequent conversion into ball (wrought) iron. As a matter of fact, even today conversion pig iron melt produced in the foundry of the Nizhni Tagil integrated works is of similar composition containing 4-4.3 percent C, 0.15-0.25 percent Si, 0.20-0.25 percent Mn, and not more than 0.10 percent P and 0.035 percent S. This iron may also include vanadium (as much as 0.48 percent) and titanium (up to 0.25 percent) that are present in the ores of Kachkanar, not of Mount Vysokaya, as it was in the 18th and 19th centuries.
Welding (wrought) iron as well as steel obtained in the bloomery process was used in the leaning tower. Wrought iron--in the sheet material of the lightning rod, in the forged braces and in the fixing wedge. The steel went into the making of strip bars (rafters) of the porch, one fragment of which carries a remarkable brand: "Nevyansk works, nobleman Akinthy Demidov, Siberia, H:S, DAD". A fragment taken from the frame of the clockwork of the tower chimes of bells is dated anno 1730, the year as the clock was set. This is a good chance to compare the Demidov material with the European (Swedish or British) metal. Some experts question the fact of the metal of the frame being made in England. Say, research workers of the Nevyansk State Museum of History and Architecture think it could have been made in Sweden.
The chemical composition of the lightning conductor points to the high grade of material both according to metal admixtures and according to sulfur and phosphorus as well, a characteristic feature of ball iron produced at Nevyansk. The presence of carbon, judging by the structure of the sample, is under 0.1 percent. In more than two hundred years of service, its surface suffered from significant atmospheric corrosion, as shown by multiple black dots in a microphotograph.
A sample taken from the strip covering (brace) around the brickwork was found to contain 0.3 percent carbon. The main component of its structure is represented by Widmanstatten ferrite remarkable for spiny crystals. Such kind of structure was typical of early 18th-century metal produced at Nevyansk and else-
where. This fact was cited in one of the first metal science books published in Russia (St. Petersburg, 1905).
In our work on the structure and mechanical characteristics of Ural welding iron (published in the Russian language journal Fizika metallov i metallovedenie, No. 1, Vol. 97, 2004) we made a detailed study of the tower's fixing wedge. We found the concentration of carbon varying in the 0.1 to 0.4 percent range in different parts of the wedge. The yield point (strength) of ball iron objects was equal to 250 M Pa, ultimate strength 350 M Pa, elongation--10 percent, reduction of area--17 percent, impact strength* at room temperature--11 J/cm2, and 7 J/cm2 at t= - 40 °C.
We compared these mechanical characteristics with those of present-day alloys. In carbon (0.1-0.4 percent) and silicon (~0.01 percent) the metal of the wedge is comparable to the present low-carbon rimmed steels, e.g. of the St3 kp brand, containing 0.14-0.22 percent of C and less than 0.05 percent of Si in small cross sections. The Moscow-published list of steel and alloy grades (2001) shows that in strength and hardness our object is close to present alloys but inferior in plasticity (elongation value) and impact strength at room temperature. It showed no cold shortness** (brittleness) characteristics. On the other hand, at negative temperatures its impact strength was not second to modern grades of steel of similar chemical composition. The low plasticity values are due to the presence of significant slag impurities in ball iron and steel.
Steel samples cut off from the bars (rafters) of the tower's porch also caught our attention. The Nevyansk plant had been making bloomery steel from the very start. We have no data on the process specifics since every steel-maker stuck to his own technology. But we have good reasons to suppose that this method was based on ball iron remelting, for it had been employed at the neighboring Kamensk state-owned works in the early 18th century. The sample sawn off from porch bars contains 0.5 to 0.6 percent carbon, and its structure composed of pearlite (possibly with some inclusions of bainite) and of a well-developed ferrite net. This sample was subjected to tensile testing. Its yield strength (point) was equal to 300 MPa, ultimate strength-540 M Pa, and elongation--8 percent.
The chemical assay of the clockwork frame shows it was made of high-grade iron with small impurities of sulfur and phosphorus. Carbon is in the 0.1 to 0.4 percent range, with slag inclusions in the metal structure, a typical sign of the bloomery process. In his book on the metallurgy of cast iron, iron and steel published in St. Petersburg and Moscow in 1911 Vyacheslav Lipin cites data on the chemical composition of high-grade Swedish metal. Collating these data with those on Ural iron and on the clockwork frame metal, we see that local metal was quite on a par with European specimens. At the same time we may allow for the possibility of the tower bells manufactured in Sweden after all.
We might as well note that the Nevyansk mill kept in the lead almost all through the 18th century. Its brand of iron, Sibir (Siberia), was valued both in Russia and in Europe. According to the Yekaterinburg-published encyclopedia on the metallurgical plants of the Urals in the 18th through 20th centuries (2001) nearly the entire annual output of forge iron in the 1730s and 1740s was shipped to the Admiralty for the needs of the Russian navy and artillery.
* Impact strength (elasticity), capacity of material to absorb mechanical energy in the process of deformation and destruction under the action of impact loads.--Ed.
** Cold shortness (brittleness), greater brittleness of metal at lower temperatures.--Ed.
Опубликовано на Порталусе 30 сентября 2021 года
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