Fatigue strength of a material increases by

Which of the following is universally employed as the low expansion metal in the bimetallic thermometer, which is an iron-nickel alloy containing 36% nickel and has very low co-efficient of expansion (l/20th of ordinary metals)?

A. Invar

B. Constantan

C. Chromel

D. Alumel

In drop forging process, the forging is done by dropping the __________ at high velocity.

A. Hammer

B. Workpiece

C. Die with hammer

D. Weight on hammer

Most of the common metals have __________ crystal structure.

A. Cubic

B. Hexagonal

C. Orthorhombic

D. None of these

Chrome vanadium steels usually contain 0.8 to 1.1% Cr, 0.25 to 0.35% C and < 0.25% V. It is

A. Used for making axle & shafts of aeroplanes, automobiles and locomotives

B. Having poor fatigue resistance

C. Having poor toughness

D. Not helpful in producing cleaner steel due to oxidising action of vanadium