Question

differance between. hard steel and mild steel

Answer 1

The terms carbon steel is used generally for iron alloys where carbon is the principal alloying element. These will often contain a few other elements such as manganese and silicon (used to mitigate embrittlement from impurities) and sulphur and phosphorus which are (normally) unwanted.

Steels typically contain up to about 1.2% carbon. Those containing more than about 0.3% can be hardened by heating and quenching. Mild steel covers alloys which fall below this threshold.

Medium carbon steels contain around 0.3–0.6 % carbon

High carbon steels usually around 0.6 to 1.2% carbon

Cast iron contains between 2.5 and 5% carbon but is not normally considered a steel as such.

Alloys with a carbon content between that of cast iron and high carbon steel generally don’t have useful properties.

Mild steel is generally inexpensive and easy to work with, being relatively easy to cut, form (hot and cold), machine and had excellent weld-ability.

Higher carbon steels tend to have better mechanical properties (esp tensile strength, toughness and hardness) but are more expensive to produce and more difficult to work with and tend to be used mostly when high strength components are required (springs, drive shafts, gears, bearings etc).

There are also classes of steel which contain significant quantities of alloying elements other than carbon (vanadium chromium, nickel etc) which tend to be formulated for specific application eg :

bearings

cutting tools

very high strength/hardness components

corrosion resistance

high temperature application

very high wear resistance

Answer 2

hard steel and mild steel are alloy of oron carbon is principle for it