The histori of bulding in iron and steel is hardly more that a hundred years old.The construction of the first railways has given considerable impetus to cast and wrought iron production.The commonest quality of steel for building construction is that known as mild steel.Several qualities of high tensile steel are widely used every wtere.They vary both in their chemical composition and their mechanical properties.The elements used for most steel structures are the hot-rolled sections,prodused in a great variety by the rolling mills.
wt
Объяснение:
waht