What is Free-Machining Steel?

The better the machinability of a steel, the faster you can gain speed on the production line. This is exactly where free-machining steel comes into play!

Free-machining steels are alloyed or non-alloyed steels specifically designed for machining, offering high machinability. The main feature of these steels is that they create short and brittle chips during cutting, minimizing tool wear and increasing production speed. So, how are these steels different from others?
The secret lies in the alloying elements such as sulfur (S) and lead (Pb) in their composition. Sulfur increases the brittleness of the steel, while lead, when added to certain types, reduces friction between the cutting tool and the workpiece, leading to a smoother machining process. This results in lower energy consumption, extended tool life, and reduced production costs.

Thanks to these properties, free-machining steels have become an indispensable material for mass production in many industries such as automotive, machinery, white goods, fasteners, and defense. If you're looking for high precision, low machining cost, and efficiency, free-machining steel is the right choice!

What are the Types of Free-Machining Steels?

If you want speed, precision, and efficiency in mass production, you can’t afford to waste time with ordinary steels! That’s why free-machining steels, with their special alloys, provide high machinability and revolutionize production processes. However, not all free-machining steels are the same. There are different types depending on their intended use. Here are the most common types of free-machining steels:

a) Leaded (Pb) Free-Machining Steels:

Leaded free-machining steels reduce cutting resistance, extend tool life, and allow higher machining speeds. Thanks to the lead (Pb) content, the chips break more easily, surface quality improves, and tool wear is minimized. These steels are preferred, especially for mass production, as they provide time and cost savings.

Examples:
• 11SMnPb30 (1.0718) - 11SMnPb37 (1.0737)
• 36SMnPb14 (1.0765)
• 44SMnPb28 (1.0763)

b) Non-Leaded (Pb-Free) Free-Machining Steels:

Non-leaded free-machining steels have a high sulfur (S) and manganese (Mn) content that facilitates chip formation, while the absence of lead ensures minimal tool wear. This results in increased machining speeds, improved surface quality, and reduced tool wear. These steels are especially advantageous for machining parts that require high precision in mass production.

Example Grades:
• 11SMn30 (1.0715) - 11SMn37 (1.0736)
• 36SMn14 (1.0762)
• 44SMn28 (1.0761)

Mechanical Properties of Free-Machining Steel

a) Mechanical Properties of Cold Drawn Free-Machining Steels

b) Mechanical Properties of Annealed Free-Machining Steels 

Free-Machining Steels Suitable for Heat Treatment and Those Not Suitable for Heat Treatment

Applications and Properties of Free-Machining Steels

Free-machining steels can exhibit better performance through processes such as tempering and carburizing. Due to these properties, free-machining steels are materials frequently preferred in serial production and applications that require precision machining.

Hasçelik’s High Machinability Free-Machining Steels

The machinability of steel materials is one of the most important factors directly affecting the efficiency of modern manufacturing processes. The ability to apply high cutting speeds, shorten processing times, extend tool life, and perform operations with lower cutting forces ensures energy efficiency. This results in lower operational costs and higher product quality. Hasçelik responds perfectly to industry requirements with its free-machining steels, designed to provide the highest quality.
Free-machining steels have a carbon content ranging from 0.07% to 0.60%, a sulfur content between 0.15% and 0.40%, and a phosphorus content between 0.07% and 0.10%. While sulfur and phosphorus are typically minimized in other types of steel, these elements are specifically added in Hasçelik’s free-machining steels. The goal is to enhance the steel’s chip removal capability and improve the quality of the cutting surface. The addition of sulfur and phosphorus also imparts metallic brittleness to the steel, promoting the formation of short, brittle chips. This makes controlling the chips during the machining process easier. Additionally, these components provide lubrication effects, increasing the part’s durability and allowing for cleaner surfaces.

Hasçelik's free-machining steels are typically used in cold-drawn form to achieve precise dimensional tolerances on surfaces that do not require chip removal. These steels are materials preferred in production lines that require serial production and precise machining. Moreover, Hasçelik also offers lead-alloyed free-machining steels, where the addition of lead significantly enhances the lubrication properties without altering the steel’s mechanical characteristics. This further improves the machinability of the steel.
With its free-machining steels, Hasçelik ensures faster, more efficient, and higher-quality results in production. Additionally, processes such as tempering and carburizing can further enhance the steel’s performance. Therefore, Hasçelik free-machining steels provide superior machinability features throughout every stage of industrial production.