En15B boron carbon steel

Introduction

we manufacture forging ingots, billets, and blooms in carbon steel specifically for En15B, as listed under carbon manganese steel in the ksl steel grades family. En15B is a medium carbon boron-alloyed steel developed to provide enhanced hardenability compared to standard En15 and En15A. The addition of a small, controlled amount of boron allows En15B to achieve higher and more uniform hardness after heat treatment, making it suitable for heat-treated engineering and automotive components. En15B offers good strength, toughness, and machinability in the annealed or normalized condition, and exhibits good dimensional stability after heat treatment. It is widely used where improved through-hardening is required without adding higher alloy content.

Chemical composition

Element	Content (%)	Function / effect
Carbon (c)	0.30 – 0.40	Provides strength and hardness
Manganese (mn)	0.60 – 0.90	Improves toughness and hardenability
Silicon (si)	0.10 – 0.35	Increases strength and elasticity
Boron (b)	0.0005 – 0.003	Significantly improves hardenability
Phosphorus (p)	Max 0.035	Impurity; controlled for toughness
Sulphur (s)	Max 0.035	Impurity; controlled for machinability
Iron (fe)	Balance	Base metal

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

• Tensile strength: 650 – 850 MPa
• Yield strength: 400 – 550 MPa
• Hardness: 200 – 260 hb (annealed / normalized)
• Impact toughness: good
• Fatigue resistance: good

Heat treatment

• Annealing: improves machinability and relieves internal stresses
• Normalizing: prepares steel for uniform heat treatment response
• Quenching: enables enhanced through-hardening due to boron addition
• Tempering: improves toughness while maintaining required hardness

Heat treatment parameters can be optimized based on required mechanical properties.

Key features and benefits

• Enhanced hardenability compared to En15 / En15A
• Good strength and toughness balance
• Cost-effective alternative to higher alloy steels
• Good machinability in annealed condition
• Dimensional stability after heat treatment
• Suitable for forging and machining operations

Typical applications

• Heat-treated shafts and axles
• Automotive components
• Forged engineering parts
• Pins, bolts, and heavy-duty fasteners
• General mechanical components requiring through hardening

Equivalent steel grades

En15B is commonly referenced as:

• No direct SAE / aisi equivalent (due to boron addition)
• Din / en boron-alloyed carbon steel (approximate)
• Is boron carbon steel (application-based equivalence)

Why choose En15B for your application?

En15B offers superior hardenability and more uniform Mechanical properties compared to standard carbon steels, without the cost of high-alloy grades. Its boron addition makes it ideal for components that require deep and consistent hardness after heat treatment, while maintaining good toughness and machinability.

Comparison table for similar grades

Grade	Carbon (%)	Key applications	Heat treatment	Comments
En15B	0.30–0.40	Heat-treated parts	Q&t	Boron for hardenability
En15A	0.30–0.40	Machined parts	Normalizing	Consistent quality
En15	0.30–0.40	General engineering	Normalizing	Standard version
27Mn2	0.24–0.30	Forgings, shafts	Normalizing	Higher mn content

Summary

En15B is a boron-alloyed medium carbon steel listed in the ksl steel grades family, providing enhanced hardenability, good strength, and cost-effective performance. It is well-suited for heat-treated engineering and automotive applications where through hardening is required.