Free-cutting steel, also known as machinable steel, is an alloy steel designed to enhance machinability by adding elements such as sulfur, phosphorus, and lead. This type of steel is primarily used in the production of precision mechanical parts requiring high levels of automation and accuracy.
Sulfur:ย Sulfur forms manganese sulfide (MnS) inclusions, aiding in chip formation and breaking, which reduces the contact area between the tool and the workpiece.
Lead:ย Lead exists in the steel as fine particles that melt during cutting, acting as a lubricant to reduce friction and tool wear.
Calcium:ย Calcium helps form a thin oxide film that reduces friction and prevents tool wear during cutting.
Phosphorus:ย Phosphorus dissolves in ferrite, increasing hardness and strength, making chips easier to break.
Sulfur Free-Cutting Steel:ย Improves machinability through manganese sulfide formation, though excessive sulfur can negatively impact mechanical properties.
Lead Free-Cutting Steel:ย Lead provides lubrication during cutting without affecting the steel’s mechanical properties at room temperature.
Calcium Free-Cutting Steel:ย Calcium forms low melting point oxides that act as lubricants during high-speed machining.
Selenium, Tellurium, Bismuth Free-Cutting Steel:ย These elements significantly enhance machinability but may slightly reduce the steel’s ductility and toughness.
Machinability:ย Free-cutting steel offers excellent machinability, reducing tool wear and significantly improving production efficiency and tool life.
Electroplating Performance:ย The steel exhibits good electroplating properties, making it a cost-effective alternative to copper products.
Surface Finish:ย The workpieces made from free-cutting steel have a high surface finish.
Environmental Compliance:ย This steel complies with EU SGS environmental certification standards, making it suitable for export in various mechanical equipment.
Free-cutting steel is widely used in the manufacturing of gears, shafts, bolts, and standard components across various industries, including automatic lathes, electronics, home appliances, and office equipment. Specific products include watch components, eyeglass frames, electronic terminal pins, and carburetors.
Bright Round Bars:ย Diameter ranges from 3.0mm to 25mm, with lengths typically between 3.0mm and 25mm.
Hot-Rolled Round Steel:ย Diameter ranges from 12mm to 50mm, 100mm to 200mm, ะค100mm to 300mm, and 290mm to 500mm.
Hexagon Steel:ย External diameter ranges from 3.0mm to 10.0mm.
Square Bars:ย Edge lengths range from 3.0mm to 20.0mm, with typical lengths between 3.0mm and 20.0mm.
Free Cutting Steel | ||||||||
NO. | Grade | Chemical Composition (Mass Fraction) /% | ||||||
C | Si | Mn | S | P | Pb | Ca | ||
1 | Y 12 | 0.08~0.16 | 0.15~0.35 | 0.70~1.00 | 0.10~0.20 | 0.08~0.15 | ||
2 | Y 12Pb | 0.08~-0.16 | โค0.15 | 0.70~1.10 | 0.15~0.25 | 0.05~0.10 | 0.15~0.35 | |
3 | Y 15 | 0.10~0.18 | โค0.15 | 0.80~1.20 | 0.23~0.33 | 0.05~0.10 | ||
4 | Y 15Pb | 0.10~0.18 | โค0.15 | 0.80~1.20 | 0.23~0.33 | 0.05~0.10 | 0.15~0.35 | |
5 | Y 20 | 0.17~0.25 | 0.15~0.35 | 0.70~1.00 | 0.08~0.15 | โค0.06 | ||
6 | Y 30 | 0.27~0.35 | 0.15~0.35 | 0.70~1.00 | 0.08~0.15 | โค0.06 | ||
7 | Y 35 | 0.32~0.40 | 0.15~0.35 | 0.70~1.00 | 0.08~0.15 | โค0.06 | ||
8 | Y 40Mn | 0.37~0.45 | 0.15~0.35 | 1.20~1.55 | 0.20~0.30 | โค0.05 | ||
9 | Y 45Ca | 0.42~0.50 | 0.20~0.40 | 0.60~0.90 | 0.04~0.08 | โค0.04 | 0.002~0.006 |
Free Cuttingย Steel | ||||
NO. | GB | ASTM/AISI | DIN | JIS |
1 | Y12/Y12Pb | 12L14 | 9SMnPb28 | SUM24L |
2 | Y15/T15Pb | 12L14 | 9SMnPb36 | SUM23 |
3 | Y20 | 1213/1215 | 10S20 | SUM32 |
4 | Y30 | 1132/1144 | 11SMn30 | SUM43 |
5 | Y35 | 1137 | 11SMn37 | SUM43 |
6 | Y40Mn | 1141 | 11SMnPb37 | SUM42 |
7 | Y45Ca | SUM41 | ||
In the Chinese national standards, the grade of free-cutting steel is denoted by a symbol “Y” followed by a number indicating the carbon content, and a symbol for the machinability-enhancing element. For example, “Y30” represents a free-cutting steel with an average carbon content of 0.3%. |