Cold shut is a defect in casting due to

A casting of size $$400mm \times 200mm \times 140mm$$ solidifies in $$20min.$$ The solidification time for a casting $$400mm \times 200mm \times 35mm$$ under similar conditions is

The cutting tool material normally used for turning steel of very high hardness is

In the manufacture of twist drills, the shank is joined to the body of the drill using