Tantalum is a unique, hard metal, but it is generally not harder than steel. With a hardness of around 6.5 on the Mohs scale, tantalum is less hard than many steels, particularly those that are hardened or alloyed for durability. However, tantalum is highly valued for its excellent corrosion resistance, high melting point, and ability to withstand extreme chemical environments, making it useful in electronics, medical devices, and aerospace applications. While steel is harder and commonly used in applications requiring high mechanical strength, tantalum’s properties make it ideal for specialized uses where strength is secondary to corrosion resistance and stability.

Tantalum is added to steel primarily to enhance its strength, durability, and corrosion resistance, especially at high temperatures. When alloyed with steel, tantalum forms stable carbides that increase the steel's resistance to wear and thermal degradation, making it ideal for applications in extreme environments. This combination is often used in aerospace, military, and nuclear industries, where materials must withstand high stress, heat, and corrosive conditions. Tantalum also improves the material's ability to maintain its mechanical properties over time, even under harsh conditions, extending the lifespan of critical components.