40MN15S12 Free Cutting Steel
We are 40MN15S12 Free Cutting Steel Manufacturers, Suppliers, and Exporters in Mumbai, India. STEEL MART is an ISO 9001:2015 certified company established in 1986, with decades of experience in supplying high-quality free-cutting steel products to various industries. We specialize in manufacturing and supplying 40MN15S12 Free Cutting Steels (IS 40Mn15S12 / 40Mn15S12 / BS 970 212M40 / EN8M / DIN 40SMn28 / W.Nr 1.0726 / AISI 1141) that meet national and international quality standards for high-tensile turned shafts, heavy drive axles, high-stress gears, studs, bolts, and precision CNC components. 40MN15S12 Free Cutting Steel is a resulphurized medium-carbon high-manganese engineering steel specified under Indian Standards (IS 4432 / IS 1570) and European standards for applications requiring high tensile strength, high core toughness, and excellent chip breaking performance. Formulated with 0.35–0.45% Carbon, 1.30–1.65% Manganese, and controlled Sulphur (0.08–0.15%), 40MN15S12 forms well-dispersed Manganese Sulphide (MnS) inclusions that act as internal chip breakers. This chemical balance reduces tool edge friction, lowers cutting forces, and permits significantly higher CNC lathe turning speeds compared to standard plain carbon 40C8 / EN8 steels. In cold drawn (+C) or quenched & tempered (+QT) supply condition, 40MN15S12 provides high bar straightness, tight h9/h10 tolerances, and high yield strength (380–520 MPa). It also responds exceptionally well to induction hardening (50–55 HRC). Because of its outstanding strength-to-machinability ratio, 40MN15S12 Steel is widely specified across automotive drive axles, hydraulic cylinder rods, high-tensile studs, machine tool spindles, and agricultural machinery spares.
Our 40MN15S12 Free Cutting Steels are 100% Prime – Tested & Guaranteed, ensuring precise chemical composition, dimensional accuracy, and consistent machinability. Each product is supplied with proper Mill Test Certificates (MTC) confirming compliance with IS / BS / DIN standards with EN 10204 3.1 certification. STEEL MART follows strict quality control procedures and ensures timely delivery.
What is 40MN15S12 Free Cutting Steel?
40MN15S12 Free Cutting Steel (IS 40Mn15S12 / 40Mn15S12 / BS 970 212M40 / EN8M / DIN 40SMn28 / W.Nr 1.0726 / AISI 1141) is a resulphurized medium-carbon high-manganese free-machining steel specified under Indian Standards (IS 4432 / IS 1570) and European specifications. Formulated with 0.35–0.45% Carbon, 1.30–1.65% Manganese, and 0.08–0.15% Sulphur, 40MN15S12 combines 0.40% carbon strength with excellent chip breaking capabilities. The Manganese Sulphide (MnS) inclusions break turnings cleanly during high-rpm turning, drilling, and thread milling, extending tool insert life and lowering machine power consumption. In cold drawn (+C) or quenched & tempered (+QT) supply condition, 40MN15S12 delivers tight dimensional tolerances, high bar straightness, and yield strength (380–520 MPa). It can also be heat treated (quenched & tempered or induction hardened to 50–55 HRC) to achieve enhanced core toughness and wear resistance. It is widely specified for automotive drive axles, hydraulic cylinder rods, high-tensile studs, machine tool spindles, gear shafts, and high-volume turned parts.
80% Machinability
Resulphurized structure enables fast CNC turning & extended tool insert life.
550–750 MPa Tensile
Superior mechanical strength compared to plain carbon free-cutting steels.
0.08–0.15% Sulphur
Controlled sulphur and manganese form MnS inclusions for clean chip fragmentation.
50–55 HRC Hardness
Responds to localized induction hardening for high wear resistance on journals & pins.
Cold Drawn (+C)
Provides bright surface finish, high bar straightness, & tight h9/h10 tolerances.
High Stress Fasteners
Ideal choice for automotive drive axles, hydraulic rods, high-tensile studs, & gears.
Why Choose STEEL MART for 40MN15S12 Free Cutting Steel
STEEL MART is the preferred choice for purchasing 40MN15S12 Free Cutting Steel due to its strong reputation for quality and reliability. With over 40 years of experience in the steel industry, the company ensures that every product meets strict industry standards. The company follows strict quality inspection procedures to ensure that every 40MN15S12 Steel product meets international standards.
Each product is carefully tested to ensure durability, strength, and performance. Customers trust STEEL MART for consistent quality, competitive pricing, and timely delivery. The company maintains a large inventory to meet urgent and bulk requirements efficiently. In addition to 40MN15S12 Free Cutting Steels, STEEL MART also supplies a wide range of resulphurized, alloy steel, and carbon steel products for various industrial applications.
Chemical Composition of 40MN15S12 Free Cutting Steel
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.35 – 0.45 % |
| Manganese (Mn) | 1.30 – 1.65 % |
| Sulphur (S) | 0.08 – 0.15 % |
| Silicon (Si) | 0.10 – 0.35 % |
| Phosphorus (P) | 0.050 % Max |
Medium Carbon (0.35-0.45%) and Manganese (1.30-1.65%) combine with Sulphur (0.08-0.15%) for high strength and free machining.
Equivalent Grades of 40MN15S12 Free Cutting Steel
| Standard | Equivalent Grade |
|---|---|
| IS | IS 40Mn15S12 / 40Mn15S12 |
| BS 970 | 212M40 / EN8M |
| DIN / EN | 40SMn28 / 1.0726 |
| AISI / SAE | AISI 1141 / SAE 1141 |
| ISO | 40SMn28 |
These international equivalents ensure global engineering specification compatibility.
Mechanical Properties of 40MN15S12 Free Cutting Steel (Cold Drawn / +QT)
The mechanical properties of 40MN15S12 Free Cutting Steels make them ideal for automotive drive axles, hydraulic cylinder rods, high-tensile studs, and machine spindles. In cold drawn (+C) or +QT condition, 40MN15S12 delivers high tensile strength and uniform hardness.
Manufacturing & Processing of 40MN15S12 Free Cutting Steel
40MN15S12 Free Cutting Steel bars undergo controlled hot rolling, descaling, precision cold drawing (+C), and optional heat treatment to achieve optimal mechanical properties.
Hot Rolling (1050°C - 1150°C)
Hot worked with controlled manganese and sulphur addition to ensure uniform MnS inclusion distribution.
Shot Blasting & Descaling
Surface descaling to remove oxide scale prior to cold drawing operations.
Precision Cold Drawing (+C)
Drawn through carbide dies to elevate yield strength and establish h9 / h10 bar tolerances.
Induction / Quench & Temper (+QT)
Quenched & tempered or induction hardened to achieve surface case hardness up to 50–55 HRC.
40MN15S12 Industry Applications
40MN15S12 Free Cutting Steels are widely used across Automotive Drive Axles, High-Tensile Studs, Hydraulic Cylinder Rods, Machine Spindles, and Gears.
Automotive Drive Axles & Shafts
Heavy-duty drive shafts, axle shafts, steering knuckles, & transmission spindles.
High-Tensile Studs & Bolts
High-strength turned studs, cylinder head bolts, wheel studs, & tie rods.
Hydraulic Cylinder Rods & Pins
Hydraulic piston rods, linkage pins, clevis pins, & high-pressure fitting adaptors.
High-Stress Gears & Pinions
High-rpm drive pinions, spur gears, chain sprockets, & splined shafts.
Machine Tool Spindles
Lathe spindles, milling arbor shafts, indexing pins, & precision guide rods.
Agricultural & Mining Machinery
Tractor PTO shafts, excavator pins, harvester shafts, & heavy implement spares.
Availability and Customization
At STEEL MART, we supply 40MN15S12 Free Cutting Steels in a wide range of sizes and specifications.
| Profiles Available | Round Bars, Hexagon Bars, Square Bars, & Flat Bars |
| Diameter / Size | Round: 5 mm to 250 mm | Hex: 6 mm to 75 mm AF | Square: 6 mm to 100 mm |
| Condition | Supplied in Cold Drawn (+C), Normalized, or Quenched & Tempered (+QT) condition |
| Length | Standard lengths from 3 meters to 6 meters |
| Tolerances | h9, h10, or h11 precision drawn tolerance per ISO / DIN 175 |
| Customization | Band-saw cut-to-length and chamfered bar ends available upon request |
| Certification | Supplied with 100% Prime Mill Test Certificate (EN 10204 3.1) |
Our strict quality control ensures consistent chemical composition and machining performance.
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40MN15S12 Free Cutting Steel (IS 40Mn15S12 / 40Mn15S12 / BS 970 212M40 / EN8M / DIN 40SMn28 / W.Nr 1.0726 / AISI 1141) is a premier Indian IS standard resulphurized medium carbon engineering steel widely specified across automotive drive axles, hydraulic cylinder rods, high-tensile studs, machine tool spindles, and high-stress gears. Combining 0.40% carbon strength and 1.30–1.65% manganese for high tensile strength (550–750 MPa), 80% machinability rating, excellent chip breaking capabilities, and induction hardening response (50–55 HRC), it provides superior performance for CNC turned components demanding mechanical strength. Supplied by STEEL MART with strict quality inspection and full EN 10204 3.1 Mill Test Certification, 40MN15S12 Steel is an outstanding high-strength resulphurized grade.
Frequently Asked Questions
Common answers regarding 40MN15S12 Free Cutting Steel specifications and parameters.
40MN15S12 contains 0.35–0.45% Carbon, 1.30–1.65% Manganese, 0.08–0.15% Sulphur, 0.10–0.35% Silicon, and max 0.050% Phosphorus.
40MN15S12 contains higher manganese (1.30–1.65%) and resulphurized sulphur (0.08–0.15% S) compared to plain 40C8 / EN8, providing significantly improved machinability and chip breaking while maintaining high tensile strength (550–750 MPa).
40MN15S12 (IS 40Mn15S12) is equivalent to British BS 970 212M40 (EN 8M), European DIN 40SMn28 (W.Nr 1.0726), and American AISI 1141 / SAE 1141, offering matching resulphurized medium carbon chemistry and mechanical performance.
Automotive drive axles, hydraulic cylinder piston rods, high-tensile turned studs, machine tool spindles, gear blanks, and agricultural machinery components.
STEEL MART supplies 40MN15S12 in round bars, hexagon bars, square bars, and flat bars in Cold Drawn (+C), Normalized, or Quenched & Tempered (+QT) condition with mill test certificates.