Posted on Jun 07, 2008 under History |
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.
more on the history of steel tomorrow
Posted on Jun 01, 2008 under News |
Table of contents for New Types of Steel
- ASTM A710 Grade B
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:
- bridges
- ships
- tank cars
- pipe lines
- oil platforms
- guard rails and sign poles
- tall buildings for wind and seismic resistance
- power and illumination towers
- construction and mining equipment