GATE 2023 MT – Question 65
A 200 mm thick slab is rolled using 500 mm diameter rolls under cold rolling and hot rolling conditions, separately. The coefficient of friction is 0.04 in cold rolling and 0.4 in hot rolling. The ratio of maximum possible thickness reduction in cold rolling to that in hot rolling is ____________ (round off to 2 decimal places).
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Show answer and explanation
Correct answer: 0.01 to 0.01
Explanation
The standard rolling-bite limit is $\Delta h_{max}=\mu^2R$. Both cases use the same roll radius, so the cold/hot reduction ratio is $(0.04/0.4)^2=\boxed{0.01}$.