Question

What should be added to pure iron to make stainless steel?
A.Nickel and cobalt
B.Cadmium and chromium
C.Nickel and cadmium
D.Chromium and nickel

Answer 1

Hint: Stainless steel is a collection of iron-based amalgams which contains at least $11\% $ chromium that is a synthesis that keeps the iron away from rusting the same as giving safe properties. . Chromium produces a thin layer of oxide on the surface of the steel which is known as a 'passive layer'. This layer prevents any further corrosion of the surface.

Complete step by step solution:
If we see stainless steel it is not made from pure iron but some elements or molecules added to iron to save it from various factors which affect pure iron. Those elements are:
Chromium and nickel are added to a pure iron to make it a stainless steel as explained below why it should be added:
Chromium ($Cr$): Chromium is added to steel to expand its protection from getting oxidation. This opposition increases as more chromium is added into it. Treated Steels have at least $10.5\% $ Chromium (nearly $11\% $ or $12\% $). This gives a keen check level of normal consumption obstruction when compared with preparation with a lower level of Chromium. This consumption opposition is due to the arrangement of a self-fixing uninvolved layer of Chromium Oxide which is on the outside of the tempered steel.
Nickel ($Ni$) : Nickel includes a lot of large sums, over about 8%, to high Chromium tempered steels to frame or make the most significant class of erosion and warmth opposing preparations. These are known as the Austenitic treated steels, encapsulated by \[18 - 8\left( {304/1.4301} \right)\], where the inclination of Nickel to frame Austenite is valid or supported for an extraordinary durability ( or sway quality) and provide high quality at both high and low temperatures. Nickel in addition incredibly improves the protection from oxidation and consumption.
So if we see the above explanations we can get that adding these materials Chromium and Nickel to iron to make it stainless steel is providing protection to it such as corrosion.


So the correct option is D.

Note: Protection from erosion and recoloring, low support, and natural radiance make hardened steel an ideal material for some applications where both the quality of steel and consumption opposition are required. Besides, treated steel can be folded into sheets, plates, bars, wire, and tubing.