A billet 75 mm long and 25 mm in diameter is to be extruded in a direct extrusion operation with extrusion ratio r x = 4.0. The extrudate has a round cross section. The die angle (half angle) = 90. The work metal has a strength coefficient = 415 MPa, and strain-hardening exponent = 0.18. Use the Johnson formula with a = 0.8 and b = 1.5 to estimate extrusion strain. Determine the pressure applied to the end of the billet as the ram moves forward.