With the introduction of the Bessemer process in 1858 the modern steel making era began. The Bessemer process allowed for large quantities of steel to be produced cheaply, effectively replacing wrought iron with steel, however this was just the first of many production methods used in modern steel making most were just improvements on the Bessemer process one of these was the Gilchrist-Thomas process created by Sidney Gilchrist Thomas and cousinPercy Gilchrist devised in 1876-77 this process was widely used in Europe there after.
The Gilchrist-Thomas process of manufacturing in Bessemer converters a kind of low-phosphorus steel known as Thomas steel. In the Thomas – Gilchrist process the lining used in the converter is basic rather than acidic, and it captures the acidic phosphorus oxides formed upon blowing air through molten iron. the Gilchrist-Thomas process was an improvement on the Bessemer process.
Another improvement on the Bessemer process was the Siemens-Martin process, In 1865, the french engineer Pierre-Emile Martin took out a licence from Carl Wilhelm Siemens and first applied his furnace for making steel. Their process was known as the Siemens-Martin process, and the furnace as an "open-hearth" furnace. The most appealing characteristic of the Siemens regenerative furnace is the rapid production of large quantities of basic steel, used for example to construct high-rise buildings. The usual size of furnaces is 50 to 100 tons, but for some special processes they may have a capacity of 250 or even 500 tons. The Siemens-Martin process complemented rather than replaced the Bessemer process. It is slower and thus easier to control.
Both the Gilchrist-Thomas process and Siemens-Martin process complemented, rather than replaced the original Bessemer process
Siemens-Martin Oven below
The Bessemer process was rendered obsolete by the Linz-Donawitz process of basic oxygen steel making developed in the 1950’s, by 1968 most all commercial steel producers stopped using the Bessemer process and replaced it with the Linz-Donawitz process which offered better control of final chemistry. The Bessemer process was so fast (10-20 minutes for a heat) that it allowed little time for chemical analysis or adjustment of the alloying elements in the steel. Bessemer converters did not remove phosphorus efficiently from the molten steel; as low-phosphorus ores became more expensive, conversion costs increased. The process only permitted a limited amount of scrap steel to be charged, further increasing costs, especially when scrap was inexpensive. Certain grades of steel were sensitive to the nitrogen which was part of the air blast passing through the steel.
For the first post on this site it will not be about steel buildings, but about the history of steel it’s self. No one really knows exactly when and where steel was first produced however some of the first steel that we know of comes from East Africa dating all the way back to 1400 BC , in the 4th century steel weapons we produced in the Iberian peninsula. Under the Han Dynasty in china in 202 BC to 220 AD steel was created by melting together Cast Iron with Wrought Iron to make a Carbon - Intermediate - Steel.
Another type of steel was produced in India and Sri Lanka around 300 BC. called Wootz Steel and Damascus Steel, Wootz Steel is Characterized by a pattern of bands and or sheets of micro carbides with in a tempered martensite or pearlite matrix. Wootz Steel was widely exported throughout the region and became famous in the Middle East, where it became known as Damascus Steel. Damascus Steel is a hot forged steel used in Middle Eastern Sword making around 1100 -1700 AD. Damascus Swords were legendary for there strength and sharpness, legend has it they could cut through rock and cut through European swords that were of lesser strength. The formula to create Damascus Steel has been lost in history.
Before the advent of modern metal alloys cast and hot rolled to construction beam sizes, sword makers of antiquity produced steel by the handful. Melting and casting a good alloy the size of a sword was difficult. Hollywood has described a fictional event where a crusader throws down his cast sword that shattered, for a damascene sword, taking home the folded hard and soft steels, changing European sword making forever. In actuality, folding/forging was well known. But this discovery of better metallurgy happened at the beginning of the age of alchemy, and so the legend of Damascus Steel was born. Recent studies have suggested that carbon nanotubes were included in its structure, which might explain some of its legendary qualities, though given the technology available at that time, they were produced by chance rather than by design
Crucible Steel was produced around the 9th and 10th century AD. in Merv.
There is evidence that in Song China in the 11th Century production of Steel using two techniques: a "berganesque" method that produced inferior, inhomogeneous steel and a precursor to the modern Bessemer process that utilized partial de carbonization via repeated forging under a cold blast.
ASTM A710 Grade B the name of a high-performance structural steel A copper-precipitation-hardened, high-performance Grade 70 weathering steel and was developed at developed at Northwestern University with the support of the Federal Highway Administration, the Illinois Department of Transportation, and Northwestern University’s Infrastructure Technology Institute.
The steel is not only stronger then conventional high-performance structural steel it is also cheaper and easier to make and needs less maintenance then conventional high-performance structural steel. The steel was designed to achieve a minimum of 70 ksi yield strength on air cooling from hot rolling without quenching and tempering (Q&T), accelerated cooling or thermomechanically-controlled processing (TMCP).
This allows for elimination of alloying elements needed for hardenability as well as a low carbon content, resulting in a very low carbon equivalent for welding. As a result, its processing cost is less than for Q&T or TMCP steels. For steelmakers, this means that special equipment for Q&T or TMCP is not required.
ASTM A710 Grade B steel possesses high Charpy absorbed impact fracture energies at really low temperatures. By the addition of titanium (up to 0.1%) which combines with interstitial atoms, the absorbed impact fracture energy further increases. This addition lowers the yield stress to 60 Ksi minimum but increases the Charpy Absorbed Impact Fracture Energy to more than 265 ft-lbs at -80oF
Because of its very low carbon equivalent, ASTM A710 Grade B steel typically does not require pre-heat or post-heat amid welding with matching welding consumables. Weatherability of ASTM A710 Grade B steel is more suitable than that of any other commercially available weathering steel. Paint on this steel resists degeneration much better than on other weathering steels.
This steel does not contain intended additions of chromium. This is of interest because of health and environmental hazards due to accumulation of carcinogenic Cr+6 well welding.
The combination of these properties can result in significant cost savings when this steel is used instead of other structural steels.
This form of steel has been around for a couple years now ASTM A710 Grade B steel was used in 2000 to retrofit the I-55/I-64/I-70/US-40 Poplar Street Bridge Complex over the Mississippi River, East St. Louis, Illinois. High strength steel was required for the retrofit because of weight limitations and for the high fracture energy that was required for seismic redundancy.
In 2006 this steel was used for construction of a bridge in Lake Villa, Illinois. For the north Milwaukee Avenue Bridge, 500 tons of steel plates were produced and fabricated into girders. The bridge was not painted, resulting in a significant savings in construction and maintenance costs.
ASTM A710 Grade B steel can be used in applications that require high strength, good fracture toughness at low temperatures, easy welding, good weatherability and corrosion resistance. These potential applications include:
guard rails and sign poles
tall buildings for wind and seismic resistance
power and illumination towers
construction and mining equipment
Also Because of ASTM A710 Grade B50 Tensile strength and ductility in both longitudinal and transveres rolling directions, making modified ASTM AT10 Steel very suitable for light poles, highway structures, tubing and signal structrures just any aplication requiring weather steel plates.
Due to the simple procees involved in manufacturing, ASTM A710 Grade B is produced at a lower cost then other competing high-performace steels. Weathering resistance, corrosion properties are among the best of any construction steel and has great fracture toughness, especially in cryogenic temperatures.
To reinterate ASTM A710 Grade B50 steel is an excellent for infrastructure applications such as bridges, signs, railings, posts, etc. and many other fields.
This site is about steel buildings and steel structures