Bulat steel
Encyclopedia
Bulat is a type of steel
alloy
known in Russia from medieval times and regularly mentioned in Russian legends as material of choice for cold steel. The name булат is a Russian
transliteration of the Persian
word پولاد (transliterated pulad), meaning steel. There are no known sources indicating that the origin of bulat is Russian while the name suggests that the immediate source of it was Persia. It is highly possible that bulat steel is made using the same process as wootz steel
.
in 1838, when he completed ten years of study into the nature of Damascus steel
sword
s. Bulat became popular in cannon
manufacturing, until the Bessemer process
was able to make the same quality steels for far less money.
Anosov had entered the Saint Petersburg
Mine Cadet School in 1810, where a Damascus steel sword was stored in a display case. He became enchanted with the sword, and was filled with stories of them slashing through their European counterparts. In November 1817 he was sent to the factories of Zlatoust
mining region in the southern Urals, where he was soon promoted to the inspector of the "weapon decoration department".
Here he again came into contact with Damascus steel of European origin (which was in fact pattern welded
steel, and not at all similar), but quickly found that this steel was quite inferior to the original from the Middle East
. Anosov had been working with various quenching techniques, and decided to attempt to duplicate Damascus steel with quenching. He eventually developed a methodology that greatly increased the hardness of his steels.
, in the form of ferrite
, and cementite
or iron carbide, a compound of iron and carbon
. Cementite is very hard and brittle; its hardness is about 640 by the Brinell hardness test, whereas ferrite is only 200. The amount of the carbon and the cooling regime determine the crystalline and chemical composition of the final steel. In bulat, the slow cooling process allowed the cementite to precipitate as micro particles in between ferrite crystals and arrange in random patterns. The color of the carbide is dark while steel is grey. This mixture is what leads to the famous patterning of Damascus steel
.
Since cementite is essentially a ceramic, this also accounts for the famous sharpness of the Damascus (and bulat) steel. Cementite is unstable and breaks down between 600-1100°C into ferrite and carbon, so working the hot metal must be done very carefully.
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
known in Russia from medieval times and regularly mentioned in Russian legends as material of choice for cold steel. The name булат is a Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...
transliteration of the Persian
Persian language
Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...
word پولاد (transliterated pulad), meaning steel. There are no known sources indicating that the origin of bulat is Russian while the name suggests that the immediate source of it was Persia. It is highly possible that bulat steel is made using the same process as wootz steel
Wootz steel
Wootz steel is a steel characterized by a pattern of bands or sheets of micro carbides within a tempered martensite or pearlite matrix. It was developed in India around 300 BCE...
.
History
The secret of bulat manufacturing was lost by the beginning of the 19th century. Pavel Petrovich Anosov eventually managed to duplicate the qualities of that metalMetal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
in 1838, when he completed ten years of study into the nature of Damascus steel
Damascus steel
Damascus steel was a term used by several Western cultures from the Medieval period onward to describe a type of steel used in swordmaking from about 300 BCE to 1700 CE. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water...
sword
Sword
A sword is a bladed weapon used primarily for cutting or thrusting. The precise definition of the term varies with the historical epoch or the geographical region under consideration...
s. Bulat became popular in cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
manufacturing, until the Bessemer process
Bessemer process
The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron. The process is named after its inventor, Henry Bessemer, who took out a patent on the process in 1855. The process was independently discovered in 1851 by William Kelly...
was able to make the same quality steels for far less money.
Anosov had entered the Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
Mine Cadet School in 1810, where a Damascus steel sword was stored in a display case. He became enchanted with the sword, and was filled with stories of them slashing through their European counterparts. In November 1817 he was sent to the factories of Zlatoust
Zlatoust
Zlatoust is a city in Chelyabinsk Oblast, Russia, located on the Ay River , west of Chelyabinsk. Population: 181,000 ; 161,000 ; 99,000 ; 48,000 ; 21,000 ....
mining region in the southern Urals, where he was soon promoted to the inspector of the "weapon decoration department".
Here he again came into contact with Damascus steel of European origin (which was in fact pattern welded
Pattern welding
Pattern welding is the practice in sword and knife making of forming a blade of several metal pieces of differing composition that are forge-welded together and twisted and manipulated to form a pattern. Often called Damascus steel, blades forged in this manner often display bands of slightly...
steel, and not at all similar), but quickly found that this steel was quite inferior to the original from the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
. Anosov had been working with various quenching techniques, and decided to attempt to duplicate Damascus steel with quenching. He eventually developed a methodology that greatly increased the hardness of his steels.
Structure
Carbon steel consists of two components: pure ironIron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, in the form of ferrite
Ferrite (iron)
Ferrite or alpha iron is a materials science term for iron, or a solid solution with iron as the main constituent, with a body centred cubic crystal structure. It is the component which gives steel and cast iron their magnetic properties, and is the classic example of a ferromagnetic material...
, and cementite
Cementite
Cementite, also known as iron carbide, is a chemical compound of iron and carbon, with the formula Fe3C . By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, though it is more...
or iron carbide, a compound of iron and carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
. Cementite is very hard and brittle; its hardness is about 640 by the Brinell hardness test, whereas ferrite is only 200. The amount of the carbon and the cooling regime determine the crystalline and chemical composition of the final steel. In bulat, the slow cooling process allowed the cementite to precipitate as micro particles in between ferrite crystals and arrange in random patterns. The color of the carbide is dark while steel is grey. This mixture is what leads to the famous patterning of Damascus steel
Damascus steel
Damascus steel was a term used by several Western cultures from the Medieval period onward to describe a type of steel used in swordmaking from about 300 BCE to 1700 CE. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water...
.
Since cementite is essentially a ceramic, this also accounts for the famous sharpness of the Damascus (and bulat) steel. Cementite is unstable and breaks down between 600-1100°C into ferrite and carbon, so working the hot metal must be done very carefully.
See also
- Wootz steelWootz steelWootz steel is a steel characterized by a pattern of bands or sheets of micro carbides within a tempered martensite or pearlite matrix. It was developed in India around 300 BCE...
, an IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n crucible steelCrucible steelCrucible steel describes a number of different techniques for making steel in a crucible. Its manufacture is essentially a refining process which is dependent on preexisting furnace products... - Pattern welded steelPattern weldingPattern welding is the practice in sword and knife making of forming a blade of several metal pieces of differing composition that are forge-welded together and twisted and manipulated to form a pattern. Often called Damascus steel, blades forged in this manner often display bands of slightly...