Going deep into Steelmaking – Blog 5

Till now we have seen how steel is manufactured from iron and the process and steps involved in it, now let us the steps involved in detail.

Steelmaking involves different processes based on the end product which is needed for the intended use. Each process produces steel with varying properties and characteristics which is used for different purposes.

Hot rolled steel: It is rolled out of a casting to specific thickness at a very high temperature of 1700 F . It is cheap easy to make and its very big in size.

Cold rolled steel: It is a produced from hot rolled steel having a greater tolerance. It is harder to work with when compared to hot rolled steel process.

Cold hammering: It is a process of hammering a bar or a block steel placed in a die or mould.

Quenching: Creating thin sheets of steel which is hot and rapidly cooling it in water, air or oil, the steel produced by this process is strong and brittle.

Tempering: It is a slow process where the steel is heated at very high temperature and then cooling it in air under high pressure. This is done to change the characteristics of steel and making stronger, harder and ductile.

Galvanisation: It is a process of coating the steel with a layer of metal in order to prevent oxidation which in-turn leads to rusting. There are 2 methods in galvanisation of steel. Hot dipped process involves dipping steel in molten hot zinc which produces a matte look to the surface. Where as in cold dipped process is an electric process of application of metal on its surface giving a shiny and less durable surface coating than hot dipped.

 

There are a few other important factors which are to be seen for the end product of steel in order to make use of it to the fullest which are appearance, weathering and fire resistance. In order to prevent steel from all these factors certain treatments/finishes are done which are as follows:

Polish: electrochemical coating applied which reduces the roughness of the surface.

Electrolytic colouring: A superficial film coated which is as thin as 0.02 micro meter.

Burnishing: Dipping steel in sodium dichromate.

Acid etching: It is a process where the steel surface is scratched and dipped in acid which produces the contrasting patterns on its surface.

Painting: Desired paints are applied as a coating for visibility and aesthetical purposes.

Enamelling: steel is coated by ceramic powder and then baked in high temperature in oven.

Physical vapour deposition: Layer of atoms coated in vacuum chamber.  

Metallic coating: coated with metals like copper or tin etc.

One main factor which affects the usage of steel is the weather in which it is used. Check out my next blog to know more on this.

-Theerthana ✌