Engineering Materials - Study Mode

[#76] In a hardening process, the hypo-eutectoid steel is
Correct Answer

(B) Heated from 30°C to 50°C above the upper critical temperature and then cooled suddenly in a suitable cooling medium

Explanation

Solution: In a hardening process, the hypo-eutectoid steel is Heated from 30°C to 50°C above the upper critical temperature and then cooled suddenly in a suitable cooling medium

[#77] The temperature required for full annealing in hypereutectoid steel is
Correct Answer

(C) 30° C to 50° C above lower critical temperature

Explanation

Solution: Full annealing is the process of slowly raising the temperature about 50 ºC (122 ºF) above the Austenitic temperature line A3 or line ACM in the case of Hypoeutectoid steels (steels with < 0.77% Carbon) and 50 ºC (122 ºF) into the Austenite-Cementite region in the case of Hypereutectoid steels (steels with > 0.77% Carbon).

[#78] Duralumin contains
Correct Answer

(A) 3.5 to 4.5% copper, 0.4 to 0.7% magnesium, 0.4 to 0.7% manganese and rest aluminium

Explanation

Solution: In addition to aluminium, the main materials in duralumin are copper, manganese and magnesium. For instance, Duraluminium 2024 consists of 91-95% aluminium, 3.8-4.9% copper, 0.3-0.9% manganese, 1.2-1.8% magnesium, <0.5% iron, <0.5% silicon, <.0.25% zinc, <0.15% titanium, <0.10% chromium and no more than 0.15% of other elements together.

[#79] Admiralty gun metal contains
Correct Answer

(B) 88% copper, 10% tin and rest zinc

Explanation

Solution: Admiralty gun metal contains 88% copper, 10% tin and rest zinc

[#80] In grey cast iron, carbon is present in the form of
Correct Answer

(C) Flakes

Explanation

Solution: In grey cast iron, carbon is present in the form of Flakes