free-machining steel

metallurgy

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Last updated

June 26, 2026

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Free-machining steels are a specific type of steel designed for enhanced machinability, making them ideal for manufacturing components like bolts, screws, and nuts. These steels contain additives such as sulfur (up to 0.35%) and lead, and sometimes tellurium or selenium.1

These elements create numerous inclusions within the steel. While inclusions are typically undesirable, in free-machining steels, they serve a crucial purpose. They break down the long, continuous metal shavings that usually form during machining into smaller chips. This results in cleaner workpieces, extends the lifespan of cutting tools, and allows for faster machining speeds.1

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steel
Free-machining steels
This group, developed for good machinability and fabricated into bolts, screws, and nuts, contains up to 0.35 percent sulfur and 0.35 percent lead; also, it sometimes has small additions of tellurium or selenium. These elements form many inclusions, which are normally avoided but…
Read More
This group, developed for good machinability and fabricated into bolts, screws, and nuts, contains up to 0.35 percent sulfur and 0.35 percent lead; also, it sometimes has small additions of tellurium or selenium. These elements form many inclusions, which are normally avoided but…
Read More