Match the terms in Group 1 to their descriptions in Group 2.

Group 1	Group 2
P. Hall-Petch effect	1. Solute dislocation interaction
Q. Bauschinger effect	2. Dislocation multiplication
R. Cottreli atmosphere	3. Grain boundary strengthening
	4. Barelling under compression
	5. Mechanical hysterisis during plasticity

In a tensile test of ductile material, necking starts at

A metallic sheet 1 m wide and 10 mm thick is to be rolled under a front tension force of 100 KN. A specimen from the sheet, tested under tension, shows a yield stress of 100 MPa. Assume plain strain condition during rolling and ignore the friction. If yielding is assumed to start at a roll pressure of σ3 MPa, then the stress in the width direction (where strain is zero) is

Match the forming methods in Group 1 with the defects in Group 2.

Group 1	Group 2
P. Extrusion	1. Flash cracking
Q. Closed die forging	2. Fir-tree cracking
R. Rolling	3. Alligatoring
	4. Earing

The maximum axial compression stress during cold upsetting of a cylindrical rod of radius, 'r', occurs at