The word 钢铁 is formed as a coordinative compound, combining the characters 钢 (gāng, meaning "steel") and 铁 (tiě, meaning "iron"). Both characters represent hard, strong metals, and their combination creates a single, more robust concept that metaphorically extends beyond the sum of its parts. Literally, it refers to the steel industry or steel as a material, but its power lies in its widespread figurative use to describe qualities like unbreakable will, unwavering resolve, or immense strength (e.g., 钢铁意志, "iron will"). Thus, the formation leverages the inherent properties of both elements to forge a term that signifies ultimate solidity and resilience, both materially and abstractly.