Chapter 12 ndash; Steel Products.ppt

Tool Steel Classification Letters pertain to significant characteristic W,O,A,D,S,T,M,H,P,L,F E.g. A is Air-Hardening medium alloy Numbers pertain to material type 1 thru 7 E.g. 2 is Cold-work * Iron – not usally used as an engineering material because of its low strength. Cast iron extremely hard to machine! The Bessemer process is a method of steel production named for British inventor Sir Henry Bessemer. During the Bessemer process, iron workers inject air into molten steel to remove carbon and impurities. After the Bessemer process was introduced in the 1850s, steel refining and production increased dramatically. Modern steel manufacturing uses a similar technique, but the process has been refined over the years to create high-quality steel with very few impurities. Steel manufacturers use a special furnace, known as a Bessemer converter, to produce steel using this technique. They place iron in the furnace and melt it to produce a molten liquid, then use a high-powered blower to pass air through the liquified iron. As the air passes through, oxygen molecules within the air interact with minerals and carbon molecules in the metal. As the air exits the molten iron, it brings the carbon and other particles with it in the form of gas or slag. The remaining iron can then be poured into molds to form steel objects. Using the Bessemer process, manufacturers were able to produce better quality steel than was previously possible. The resulting steel was stronger and more durable, allowing larger and longer-lasting structures to be built. This process also helped manufacturers produce steel more quickly, and at a lower cost than with previous techniques. For more than a century, the Bessemer process became the most popular method of mass steel production, and much of Bessemers techniques live on in modern industry. * * Solidification Concerns The liquid steel is converted into finished shape called steel castings Or the liquid steel is converted into suitable shap