Practical dividing line between a ductile and brittle materials is suggested, when the ultimate elongation is about 5%. Generally, larger the knuckle radius, stronger is the corner torus section of a head. The knuckle radius provided should be less than __________ of the head.

• A. Either A or B, whichever is larger
• B. 6% of I.D.
• C. 3 times the thickness
• D. Either A or B, whichever is smaller

Answer: (A)