Engineering Materials - Study Mode

[#171] Which of the following impurity in cast iron makes it hard and brittle?
Correct Answer

(B) Sulphur

Explanation

Solution: Sulfur is normally regarded as an impurity and has an adverse effect on impact properties when a steel is high in sulphur and low in manganese. Sulphur improves machinability but lowers transverse ductility and notched impact toughness and has little effects on the longitudinal mechanical properties.

[#172] An engineer's hammer is made of
Correct Answer

(D) High carbon steel

Explanation

Solution: An engineer's hammer is made of High carbon steel

[#173] The alloying element which can replace tungsten in high speed steels is
Correct Answer

(D) Molybdenum

Explanation

Solution: Molybdenum has effects similar to manganese and vanadium, and is often used in combination with one or the other. This element is a strong carbide former and is usually present in alloy steels in amounts less than 1%. It increases hardenability and elevated temperature strength and also improves corrosion resistance as well as increased creep strength. It is added to stainless steels to increase their resistance to corrosion and is also used in high speed tool steels.

[#174] Grey cast iron
Correct Answer

(A) Contains 1.7 to 3.5% carbon in Free State and is obtained by the slow cooling of molten cast iron

Explanation

Solution: Grey cast iron Contains 1.7 to 3.5% carbon in Free State and is obtained by the slow cooling of molten cast iron.

[#175] Which of the following element results in presence of free graphite in C.I.?
Correct Answer

(C) Silicon

Explanation

Solution: Silicon element results in presence of free graphite in C.I.