The term STEEL INGREDIENT can be solved by the 4-letter word IRON. IRON is a chemical element and is the main component of steel. It is one of the most abundant elements on Earth and is essential for life. IRON is used in many industries, including construction, manufacturing, and transportation. Steel is an alloy made up of IRON and other elements, such as carbon, manganese, and chromium. Steel is strong, durable, and resistant to corrosion, making it an ideal material for a variety of applications.