Metallurgy

The iron ore is smelted to form pig iron (or crude iron), which has as high as 5% of carbon.

Coke is used in this stage as a reducing agent. Coke is made by heating coal or oil in the absence of air.

To produce cast iron and steel, the carbon contents needs to be reduced.

When oxygen come into contact with the carbon it would form carbon dioxide and remove the carbon.

Puddling furnace was used to let the molten iron to interact with the oxygen slowly.

Bessemer process is blowing oxygen directly into the molten iron.

• Open Hearth Process, Siemens-Martin Process, Martin-Siemens Process

Repetition of regenerative preheating of fuel and air for combustion.

• Steel is iron with interstitial carbon. Carbon pressurizes the lattice and make the steel harder, but more brittle.
• Rapid cooling of metal.

If the steel is cooled slowly, the more carbon atoms can escape, creating very low carbon region called Ferrite, and high carbon region Cementite, which collectively called Perlite.

If the steel is cooled rapidly, the lattice structure transforms from cubic to tetragonal, becoming Martensite.

• Lathe and mill is developed.
• Numerical Control (NC, 1955), and Computer Numerical Control (CNC) became widespread providing high reproducibility and great precision.
• Black Oxide surface treatment, Titanium nitride/Titanium Aluminum nitride coating and Cast Alloy tooling is used for the drill bits.
• Tungsten carbide and cobalt binder make a superior tools. Titanium carbide and Tantalum carbide became also used. Leads to cemented carbide tooling.
• Carbides, ceramics, or diamonds are also used for abrasive machining

• https://en.wikipedia.org/wiki/Smelting
• https://en.wikipedia.org/wiki/Pig_iron
• https://en.wikipedia.org/wiki/Coke_(fuel)
• https://en.wikipedia.org/wiki/Bessemer_process
• https://en.wikipedia.org/wiki/Open-hearth_furnace
• How Japanese Masters Turn Sand Into Swords - YouTube
• The Science Of Cutting - YouTube