Ex/MET/T/415/25/2009

BACHELOR OF METALLURGICAL ENG. FINAL EXAMINATION, 2009

(4th Year, 1st Semester)

HEAT TREATMENT TECHNOLOGY

Time : Three hours Full Marks : 100

Answer any five questions.

All questions carry equal marks.

1. Discuss the following : 4×5=20

a) Different type of resistors used in electrical heat

treatment furnace.

b) Exo gas and endo gas atmosphere.

c) Salt bath f/c.

d) Batch f/c and continuous f/c.

2. Discuss about the major defects (any four) : 4×5=20

a) Soft spots.

b) Oxidation and decarburisation.

c) Overheating and burning.

d) Quench Crack.

e) Distortion and warping.

[ TURN OVER ]

( 2 ) ( 3 )

3. a) Define Hardenability.

b) Discuss the factors which are responsible for influencing

hardenability.

c) Compare the advantage and disadvantage of Grossman

Critical diameter test with Jominy End Quench test.

4+12+4

4. Give typical composition, heat treatment cycle and

properties evolved in the following grades of steel :

(any two) 2×10

(a) Maraging steel, (b) High speed steel (c) Martensitic

stainless steel.

5. Write short notes on the following thermomechanical

treatment :

(a) Ausforming (b) Isoforming (c) Cryoforming

(d) HTMT and LTMT. 4×5

6. Discuss the heat treatment schedule of the following :

(any two) 2×10

a) Heat Treatment of wrought AL - Alloys.

b) Heat Treatment of Ti Alloys.

c) Heat Treatment of Mg Alloys.

7. a) A small gear made of 0.15% C is to be carburised to a

depth of 1 mm and heat treated. Give the complete heat

treatment schedule. How can you control the surface

carbon content in the carburised portion ? 6+4

b) Nitriding can be performed at a lower temperature than

carburising — why ?

What is white layer in nitriding ?

How is it avoided ? 3+2+1

c) A steel shaft (50 mm dia) is to be surface hardened and

tempered to get a surface hardness of RC 45. Suggest

suitable steel and heat treatment method. 2+2

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