Engineering Materials - Study Mode

[#321] Steel containing ferrite and pearlite is
Correct Answer

(B) Soft

Explanation

Solution: Steel containing ferrite and pearlite is soft. Ferrite is a form of pure iron with a body-centered cubic crystal structure and occurs in low-carbon steel. Pearlite is a finely laminated mixture of ferrite and cementite present in cast iron and steel, formed by the cooling of austenite.

[#322] Ductile cast iron
Correct Answer

(D) Is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material

Explanation

Solution: Ductile cast iron Is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions.

[#323] Which of the following steel making process is being adopted at Rourkela (in India) Steel Plant?
Correct Answer

(D) LD process

Explanation

Solution: LD process is a steel making process is being adopted at Rourkela (in India) Steel Plant

[#324] Quenching is not necessary when hardening is done by
Correct Answer

(C) Nitriding

Explanation

Solution: Nitriding has a different hardening mechanism than the one caused by quenching a steel with an elevated level of carbon. Instead, the hardening is caused by the fine scale precipitation of alloying element nitrides which does not require quenching.

[#325] The alloy, mainly used for corrosion resistance in stainless steels is
Correct Answer

(D) Chromium

Explanation

Solution: Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium. Chromium produces a thin layer of oxide on the surface of the steel known as the 'passive layer'. This prevents any further corrosion of the surface. Increasing the amount of Chromium gives an increased resistance to corrosion.