Steel is one of the most important alloy in engineering. Steel is used vastly used in engineering from creating machines to buildings its present everywhere but in different forms. So let's take a look on what is steel and what are its types?


what is steel and its types? | Properties and uses | The Mechanical post

Introduction 
Steel is mainly an alloy of iron and carbon in which the maximum percentage of carbon is 1.5%. Various types of steels can be formed by varying the % of carbon. If the amount of carbon in the steel exceeds 1.5% then it is called as Cast Iron. In steel the higher the % of carbon, the more harder is the steel.

Physical properties of steel
  • Steel has a density of 7,850 kg/m3, making it 7.85 times as dense as water. 
  • Its melting point of 1,510 C is higher than that of most metals.
  •  In comparison, the melting point of bronze is 1,040 C, that of copper is 1,083 C, that of cast iron is 1,300 C, and that of nickel is 1,453 C. 
  • Tungsten, however, melts at a searing 3,410 C, which is not surprising since this element is used in light bulb filaments.
  • Steel's coefficient of linear expansion at 20 C, in ┬Ám per meter per degree Celsius, is 11.1, which makes is more resistant to changing size with changes in temperature than, for example, copper (16.7), tin (21.4) and lead (29.1).
Classification of steels:
  1. On the basis of amount of carbon present
  • Low carbon steel or mild steel (carbon 0.01% -.3%)
  • Medium carbon steel (carbon 0.30% - 0.70%)
  • High carbon steel (carbon 0.70 % - 1.5%)
    2. On the basis of alloying elements added
  • Low alloy steels 
  • High alloy steels
    3. On the basis of amount of hardening
  • Non - hardenable steel
  • Shallow hardnenig steel
  • Deep hardening steel


Alloy steels.

Steels which have elements like chromium, nickel, vanadium, titanium, molybdenum etc in a considerable amount then it is said to be an Alloy steel. Buy adding different elements the properties of steel can be changed greatly.
Alloy steels are used for:
  • Improving hardening proprties of steel.
  • To improve elasticity
  • To improve machinability and weldability 
  • To improve corrosion and fatigue resistance
  • To improve its wear resistance
  • To improve its temperature stability.
The most well known example of alloy steel is stainless steel. Let us learn more about it.

Stainless Steel 


(Note: stainless steel is formed by adding at least 10.5% chromium, less than 1.2% carbon and other alloying elements. Stainless steel's corrosion resistance and mechanical properties can be further enhanced by adding other elements, such as nickel, molybdenum, titanium, niobium, manganese, etc.)

Stainless steels are employed in construction when corrosion resistance is a major asset, as with knives that must maintain a sharp edge. Another common reason stainless steels are used is their high-temperature properties. In some projects, high-temperature oxidation resistance is an absolute requirement, while in others, high-temperature strength is a primary need.

what is steel and its types? | Properties and uses | The Mechanical post

Applications of steels
  • Cutlery and kitchenware
  • Engineering tools such as vernier caliper etc.
  • Universal joint in automobiles.
  • Clutches in automobiles.
  • Chemical, processing and oil & gas industries
  • Power generation (for making boiler parts)
  • Food production
  • Architecture, building and construction
  • Medical applications (for making equipments)
  • Automotive etc.