The major difficulty during welding of aluminium is due to its

An aluminium alloy (density $$2600$$ $$kg/{m^3}$$ ) casting is to be produced. A cylindrical hole of $$100$$ $$mm$$ diameter and $$100$$ $$mm$$ length is made in the casting using sand core (density $$1600$$ $$kg/{m^3}$$ ). The net buoyancy force (in Newton) acting on the core is _____________________

A metal rod of initial length $${L_0}$$ is subjected to a drawing process. The length of the rod at any instant is given by the expression, $$L\left( t \right) = {L_0}\left( {1 + {t^2}} \right),$$ where $$t$$ is the time in minutes. The true strain rate (in $${\min ^{ - 1}}$$) at the end of one minute is _____________

In solid-state welding, the contamination layers between the surfaces to be welded are removed by