20mnCr5 alloy steel

Introduction

We manufacture forging ingots, billets, and blooms in alloy steel specifically for 20mnCr5, designed for applications requiring high surface hardness, excellent wear resistance, and a strong, tough core.

20mnCr5 is a low carbon manganese-chromium alloy steel primarily used for case hardening applications. The combination of manganese and chromium improves hardenability and wear resistance after carburizing, while the slightly higher carbon content (compared to 16MnCr5) provides better core strength.

This grade offers good machinability in the annealed condition and excellent response to carburizing and heat treatment processes. Due to its reliable performance and cost effectiveness, 20mnCr5 is widely used in automotive, transmission, and heavy engineering applications.

Chemical composition

Element	Content (%)	Function / effect
Carbon (c)	0.17 – 0.23	Provides higher core strength
Manganese (mn)	1.00 – 1.30	Improves hardenability and toughness
Silicon (si)	Max 0.40	Increases strength
Chromium (cr)	1.00 – 1.30	Improves hardenability and wear resistance
Phosphorus (p)	Max 0.035	Impurity; controlled for toughness
Sulphur (s)	Max 0.035	Impurity; controlled for machinability

Mechanical properties (typical, depending on condition & heat treatment)

• Core tensile strength: 650 – 850 MPa
• Core yield strength: 450 – 650 MPa
• Surface hardness (carburized): 58 – 62 HRC
• Core hardness: 190 – 240 HB
• Impact toughness: Good

Heat treatment

• Annealing: improves machinability before carburizing.
• Carburizing: addition of carbon at high temperature to achieve a hard, wear-resistant surface.
• Quenching: rapid cooling to obtain hard martensitic case.
• Tempering: relieves internal stresses while maintaining surface hardness and core toughness.

The heat treatment process can be tailored to achieve the required case depth and mechanical properties.

Key features and benefits

• Excellent case hardening response
• Hard, wear-resistant surface with strong core
• Better core strength than 16MnCr5
• Good hardenability due to mn–cr combination
• Good machinability in annealed condition
• Cost-effective case hardening steel

Typical applications

• Gears and pinions
• Transmission and differential components
• Shafts and camshafts
• Automotive and tractor parts
• Heavy-duty engineering components subjected to wear

Equivalent steel grades

20mnCr5 has several well-recognized international equivalents:

• En 10084 – 20mnCr5 (european standard)
• Din 1.7147 – german standard
• Aisi 5120 – american standard (approximate)

Why choose 20mnCr5 for your application?

20mnCr5 offers an excellent balance of surface hardness, wear resistance, and core strength at a competitive cost. Its consistent response to carburizing makes it a preferred material for automotive and transmission components subjected to continuous load and friction.

Comparison table for similar grades

Grade	Carbon (%)	Key applications	Heat treatment	Comments
20mnCr5	0.17 – 0.23	Gears, transmission parts	Carburizing + q&t	Higher core strength
16MnCr5	0.14 – 0.19	Gears, pinions	Carburizing	Lower core strength
15Cr3	0.12 – 0.18	Gears	Carburizing	Lower mn
En36	0.12 – 0.18	Heavy-duty gears	Carburizing	Ni-cr steel
Aisi 5120	0.18 – 0.23	Automotive parts	Carburizing	Us equivalent

Summary

20mnCr5 is a low carbon manganese-chromium alloy steel specifically designed for case hardening applications. It provides a hard, wear-resistant surface, strong core properties, and reliable performance for demanding engineering and automotive uses.