JNTU B.Tech II Semester Examinations, METAL FORMING
, Aug/Sep 2008
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) State the maximum shear stress criterion and derive it.
(b) Explain why the elastic deformation does not disappear, even after the load
which had caused plastic deformation in polycrystalline materal is relased.
2. (a) Explain why is it neded to perform annealing during cold working process.
(b) Draw a typical recrystalization curve representing
ii) % of recrystallization, and
iii) time of annealing. Explain about the curve. [8+8]
3. Define hot working, warm working and cold working.Discuss the relative features
of hot work and cold work for Al, Pt and Molybdenum considering melting point,
brittleness and oxidation behaviour. 
4. (a) Explain the differeces between
i. drwing and
ii. deep drawing
(b) Expalin why normal anisotrophy is important in determining the deep drwawability of a material . [8+8]
5. (a) Distinguish between press forged and drop forged components.
(b) Discuss the forging process in plane strain condition.
(c) A 13kN power-forging hammer has a total nominal energy of 47 kJ. If the
blow efficiency is 40 percent and the forging load builds up from P/3 at the
beginning of the stoke to P at the end of the stroke, what is the total forging
i. a stroke of 5mm
ii. a stroke of 15mm. [6+4+6]
6. (a) Explain the following:
i. Roll forming
ii. Tandum mill
iii. Angle of nip
iv. No slip angle
v. Redundant work
(b) What is the effect of presence of front and back tensions in rolling load?
7. (a) Calculate the force required in extruding a copper alloy at 7500C, if the billet
diameter is 80 mm and the extrusion ratio is 20.
(b) Explain the term ‘efficiency of a forming process’ in terms of energy consumed.
(c) What is the significance of grain size control for metal forming? [6+5+5]
8. (a) Explain about the residual stresses in rods, wires and tubes drawn.
(b) Discuss the effects of the following on maximum possible reduction in wire
drawing with no back tension.
i. Cone angle
ii. Friction [10+6]