Generally cylindrical parts produced by powder metallurgy should not have non uniform cross section and a length to diameter ratio exceeding . . . . . . . . . . . . . . .

In $$DC$$ welding, the straight polarity (electrode negative) results in

For resistance spot welding of $$1.5$$ $$mm$$ thick steel sheets, the current required is of the order

In an explosive welding process, the ..................... (maximum/minimum) velocity of impact is fixed by the velocity of sound in the ............. (flyer / target) plate material.