Steel: an iron alloy noted for strength and hardness, used in construction, tools, and machine parts.
このナイフの刃は鋼鉄でできている。
The blade of this knife is made of steel.
鋼鉄のように堅い意志を持っている。
He has a will as firm as steel.
戦後、国内の鋼鉄産業は復興の重要な柱となった。
After the war, the domestic steel industry became an important pillar of reconstruction.