Hard metal is a term used to describe metals that are strong and durable. Iridium, with 7 letters, is a chemical element that is one of the densest and hardest known materials. Titanium, with 8 letters, is a chemical element that is known for its strength and light weight. STEEL, with 5 letters, is an alloy of iron and carbon that is widely used in construction due to its strength and durability.