Steel with spices
2014-07-10 | Text: Lyudmila Smerkovich | Photo ©: Valeriy Lebedev, Laurentiu Iordache /; Konstantin Milenin / | 4452

If you consider historical periods from the point of view of the materials of the tools used, e.g. Stone Age, Bronze Age and so on, then it appears to be that we are still living in era that should be called the Steel Age, because the majority of modern production means and ready-made products are made of  steel. The Iron Age has left us the problem of corrosion, but this problem can be solved by means of the process called alloying. Today we are going to talk about the history of alloy steel with different additives.

The secrets of ancient times

Iron alloys have been known to mankind ever since the Ancient times, archeologists have found iron adornments in the graves and burial sites that date back to the beginning of the Bronze Age. The interesting fact is that pure iron was quarried and used much later, and the first iron items were made by humans from the meteoric iron that, according to classification, refers to steel alloy. Around 5.7% of meteorites which fall to Earth are iron and consist of an iron-nickel alloy that comprises 8.5% nickel. Ancient people probably used the celestial metal for more practical purposes than adornments, but it was a very rare metal. 

In about 1500 BC, in Asia Minor, the secret of obtaining hotter flames was discovered. It was hotter than that used for melting of cuprum and bronze. It was found out that if you blow air through ore mixed with charcoal, the temperature will increase considerably. The technology of bellows enabled the melting of iron and laid the foundation of the arms race. Iron, in its pure form, is not very hard, but during the treatment process the metal’s surface absorbs carbon and steel is formed. The ancient tools had only thin surface layers steel, but it was enough to make the iron-tipped spears and arrows harder and sharper than the bronze ones. 

In Isaac Asimov’s History of Chemistry we find, “The Dorians, a barbaric Greek tribe equipped with some iron weapons, invaded the Balkan peninsular in about 1100 BC and gradually overcame the more civilized but only bronze-armed Mycenaean Greeks. Some Greeks penetrated as far as Canaan and brought iron weapons with them. These were Philistines, who played such an important role in the Old Testament. Against them the Israelites were helpless until they obtained iron weapons for themselves under King Saul. The Assyrian army was the first army that was fully equipped with good iron weapons. Due to this superiority in armament, the Assyrians conquered many neighboring countries and by 900 BC had built a mighty empire for themselves.”

Until the New Age, the main material for arms and labor production were iron alloys that were found by means of accidental additives as iron ore occurs rarely in its pure form. The famous Damascus steel is considered an exception, and its peculiarity is the absence of alloy elements. The technology of its treatment was aimed at burning off all the additives, so that metal would attain a unique quality. However  it would suffer from corrosion and have a weakness as well.

For a hundred years, the technology of iron’s treatment in Europe didn’t undergo any substantial transformation, and only in 14th century did the method of iron smelting appeared, as well as the so-called bloomer process, the process of iron’s purification, i.e. getting rid of unnecessary carbon additives and silica with manganese to obtain malleable bloomer iron. But in 18th century the need for metal was increasing, and that is why the new methods of steel production were researched, simultaneously studying and changing its qualities.

Blades made of famous Damascus steel.

The Recipes of New Age

Puddling, which replaced the bloomery process, was the first step in steel’s industrial production. The new technology was characterized by a higher productivity rate, as expensive and rare charcoal could be replaced by the harder coal or other types of fuel. The reverberatory furnace for malleable iron was first used with hard coal as a fuel by the Granage brothers in 1766. In 1784, the method was improved by Henry Cort, who played a large role in the expansion of puddling.

By the middle of the 19th century, a method was developed that ensured mass-production of cast steel. A big contribution belongs to English metallurgist, Henry Bessemer (1813 – 1898). When Bessemer was working on the creation of the artillery shell that would rotate in a flight and fly on the desired path, he faced the need to use stronger steel than was used at that time. The talk was about weapons with the gun’s barrel having rifling in the wall. There was a need for strong steel, while the bore had to withstand high pressure that would be needed to press in the expansion of the shell through its rifling. High-grade steel production was very expensive at that time, which was why there was a need for a new type of tool and a new approach to steel was needed.

Bessemer was looking for a method of steel production that would allow steel to be obtained directly from the raw iron - skipping the expensive stage of obtaining wrought iron that was usual in the production of steel those days. In order to remove the surplus carbon from the raw iron, he let air stream through the metal. The metal, at the same time, was didn’t cool off or harden; on the contrary, as a result of the carbon’s reaction with oxygen the heat  increased, and the alloy’s temperature also increased. Consequently Bessemer could obtain steel stopping the process at exactly the right moment. In 1856, Bessemer published an article about the conveyor. The first attempts by Bessemer to repeat the experiments were unsuccessful, as he could obtain steel by this method only from phosphor-free ore. But as soon as this problem was solved, the production became dramatically cheaper.

When this main technical barrier was overcome, the question on the steel’s added qualities by means of alloy additives arose. The first successful experiment of directional alloying was the invention of steel by Robert Mushet, which included 1.8% oxygen, 9% tungsten and 2.5% manganese.  In 1871,  Mushet’s industrial production of steel began. His alloy steel was, specifically, used for the production of the corner teeth for the metal-working machinery. Moreover, this steel later typified the modern line of high-speed steel.

The English metallurgist Robert Abbot Hadfield (1858-1940) studied the influence of other metal additives on steel’s quality. It was already known that manganese additives can make steel more brittle, so Hadfield decided to add more manganese than other metallurgists did. When the manganese content reached 12%, the frailty of the material decreased. Furthermore, it was found that when this steel was heated up to 1000°С, and then quenched, it becomes harder the than initial metal. Hadfield patented manganese steel in 1882, and from that moment the mass production of steel alloy began.

In 1900, during the World Exhibition, the specialists heard about Frederick Winslow Taylor’s rapid steel for the first time. Frederick Taylor and his friend, Moncel White, who held a degree in chemistry, had worked at the steel mill at the Bethlehem Steel Corporation, Philadelphia, USA. Taylor and White decided to try and create an alloy with tungsten steel and chrome. The new steel contained not less than 18% tungsten and 4% chrome. The red-hot teeth from this steel didn’t lose their resistance during bar treatment of other steel. The cutting speed was 4 times quicker than usual. It was on this the basis of high-speed steel was formed.

By 1919, the American inventor, Elwood Haynes (1857-1925) patented stainless steel, which comprised chrome and nickel as additives. In 1916, the Japanese metallurgist, Kotaro Honda (1870-1954) found out that magnets made from the tungsten steel and cobalt had a stronger capacity, than those made from the ordinary steel. This invention paved the way to the development of the stronger magnetic alloys.

Today and tomorrow in numbers

The 20th century brought new methods of obtaining alloy steel, particularly, electric-arc melting, and the development of powder metallurgy. But generally speaking, the iron industry hasn’t changed much over the last one and half centuries and the basic oxygen steelmaking and open furnace technology, first implemented at the middle to end of the century before last, are still used.

21st century metals are left as the main constructing material, while their qualities, production and consumption efficiency has no equal in the majority of fields. About one third of the iron produced is used in mechanical engineering, and approximately one fourth goes into construction. Nowadays, the production ratio of iron and basic metal consumption comprises 72 - 74% of a states’ gross domestic product. Annually, more than 90% of steel is used of the gross mass of consumable metals. During the economic crisis of 2008 it was recorded and confirmed in that the traffic volume of iron production is the most important indicator of the state of economy.

In recent years, because of different crisis notions, the consumption of steel has been varied, and the tendency of decrease in demand for iron is noticeable. Nowadays, 600 million tons of the world’s iron is considered as overcapacity. However, in the next few years the forecasts of analysts are more optimistic. According to the estimates of the WSA (World Steel Association) in 2013 the apparent consumption of steel on a global scale will increase to 3.1% to 1.475 billion tons in comparison to growth of the previous year of 2%. According to their forecasts, in 2014, the global demand for steel will increase further to 3.3% and will reach 1.523 billion tons. Hans Jürgen Kerkoff, the head of the WSA Economic Committee, says that except China, for the last one and a half years steel consumption in a global scale has been lower than was forecast. According to today’s estimates, the demand for steel production in 2013 in the People’s Republic of China will increase by 6%.

The easing of the situation is also expected in our country as well. The CIS region even received a more optimistic forecast from WSA than Europe.  The growth of commercial construction activity and the set of expansionary measures in the auto industry development adopted by Russian government has influenced the growth of metal’s consumption in Russia. According to the estimates of the WSA analysts, the demand for steel in Russia will increase on 3.8% to 43.6 million tons in 2013, and in 2014 – by 4.6% to 45.6%.

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