20 MNCR

20MnCr5 Alloy Steel Product Overview

20MnCr5, also known as DIN 1.7147 or AISI 5120, is a low-alloy, case-hardening steel under the EN 10084 standard. It is renowned for its high core tensile strength (1000–1300 N/mm²), excellent wear resistance after carburising, and good toughness in the core, making it ideal for components requiring a hard surface and a ductile core. Typically supplied in the annealed condition (max 248 HB), it achieves a surface hardness of 60–66 HRC after carburising, quenching, and tempering. The steel’s chromium and manganese content ensures good hardenability, machinability, and fatigue strength, though weldability is limited.

Applications

20MnCr5 is widely used in engineering applications requiring high surface wear resistance and core toughness:

Automotive:

• Gears, pinions, and camshafts for transmissions.
• Piston bolts, spindles, and drive shafts.
• High-load wheels and axles.

Machinery:

• Valve bodies, pumps, and fittings for rotating machinery.
• Transmission shafts, rollers, and sleeves in machine tools and tractors.
• Components for steel rolling equipment, boring machines, and railway vehicles.

Other Uses:

• Mining machinery parts, such as steel balls and shaft sleeves.
• Internal combustion engine components and high-strength bolts.
• General engineering parts requiring medium load and low impact resistance.

Chemical Composition

The chemical composition of 20MnCr5 ensures its hardenability, toughness, and wear resistance:

Element	C	Si	Mn	P	S	Cr
Content	0.17–0.22	≤0.40	1.10–1.40	≤0.035	≤0.035	1.00–1.30

• Chromium (Cr): Enhances hardenability, surface hardness, and wear resistance.
• Manganese (Mn): Improves strength, toughness, and hardenability.
• Carbon (C): Low content ensures core ductility, with surface hardness achieved via carburising.
• Phosphorus (P) and Sulfur (S): Kept low to minimise brittleness and improve machinability.

Supply Size

20MnCr5 is available in various forms and sizes to meet industrial requirements:

• Round Bars:
  Diameter 16 mm to 700 mm.
• Flat Bars:
  Minimum: 10 mm thickness x 80 mm width.
  Maximum: 500 mm thickness x 2000 mm width.