Why is sainless steel used instead of a pure iron for the ball of the pen?

Stainless steel is used instead of pure iron for the ball of a pen due to its superior corrosion resistance, strength, and durability. Unlike pure iron, which can rust easily when exposed to moisture, stainless steel maintains its integrity and appearance over time. Additionally, stainless steel offers better wear resistance, ensuring a smoother writing experience and a longer lifespan for the pen. These properties make it more suitable for everyday use in writing instruments.