In precision metal machining, material selection is the first step to ensuring component performance, machining efficiency, and long-term reliability. Stainless steel is widely used due to its corrosion resistance, mechanical strength, and versatility, yet the characteristics vary significantly across different grades. Choosing the wrong material can lead to machining difficulties, increased tool wear, or even shortened product lifespan. This article compares common stainless steel grades and shares practical selection principles to help engineers and R&D teams make optimal decisions.