A strip with cross-sectional area 150 mm × 4.5 mm is

A strip with cross-sectional area 150 mm × 4.5 mm is being rolled with 20% reduction of area using 450 mm diameter rollers. The angle subtended by the deformation zone at the roll centre is (in radians)

Bite angle ; θ = tan^-1		√R∆h
		{ R - (∆h / 2) }

From question, we have 20% reduction in cross sectional area
150 × 4.5 × 0.8 = 150 × h
∆h = 3.6 mm
h = 4.5 – 3.6 = 0.9 mm

Given , R =	450	= 225 mm
	2

θ = tan^-1		√225 × 0.9
		{ 225 - (0.9/ 2) }

θ = 3.62° = 0.06 rad