TABLE OF CONTENTS The distortion of the metal in a steady-state process can be determined from a slip-line field and its hodograph. As an example, consider the 2:1 extrusion through a 90 die illustrated in Figure 9.14(a).
Figure 9.14(b) is the hodograph. The triangle to the right of AO is a dead metal zone. A metal entering the field at A suffers a velocity discontinuity 
parallel to the arc at A. A metal entering the field at C suffers a velocity discontinuity 
parallel to the arc at C. All of the velocity discontinuities along the arc have the same magnitude and are parallel to the arc. There is also a velocity discontinuity 
parallel to GO and of magnitude such that V e is horizontal.
Stream lines can be drawn for particles (Figure 9.14(c)). Consider a particle on line 3, entering the field between C and D. As it enters the field it acquires an absolute velocity midway between V C and V D. Its direction gradually changes as it moves through the field. Its velocity equals V D as it crosses OD, equals V E as it crosses OE, and equals V F as it crosses OF. When it crosses OG its velocity must become horizontal. If this construction is made correctly, it emerges...
