What is Hardenability and Why It Matters in Die Steels?

How Hardenability Impacts Performance, Life & Reliability of Die Steels – A Guide by Goel Steel Enterprises

Author

Goel Steel Enterprises
June 30, 2025

If you're in the business of dies, molds, forging, or machining Hardenability is a word you should know.
At Goel Steel Enterprises, we regularly guide our customers on selecting the right die steel, and one of the most misunderstood yet critical properties is hardenability.

Whether you’re choosing grades like H13, D2, EN24, or EN31, this blog breaks down what hardenability means, why it matters, and how it affects the strength, wear resistance, and lifespan of your tools.

What is Hardenability?

Hardenability is NOT how hard a steel can get.
It is how deep into the steel the hardness can reach when heat-treated.

Imagine you are cooking a thick piece of meat. The outside may be well-done (hard), but the inside could still be rare (soft). That’s low hardenability.

If the heat penetrates all the way through and cooks it evenly, you’ve got high hardenability.

In steel:

  • High hardenability → Full hardness even deep inside

  • Low hardenability → Only the surface becomes hard

Why Does Hardenability Matter in Die Steels?

Die steels are used to make tools that cut, shape, or compress metal. These tools face:

  • Extreme pressure

  • High temperature

  • Repeated impact

If only the surface is hard and the inside is soft, the tool may:

  • Crack or deform

  • Wear out fast

  • Fail in production

That’s where hardenability matters:

✔ Ensures uniform hardness throughout the die
✔ Improves tool life and performance
✔ Reduces risk of cracking or early failure

Real-Life Example: D2 vs. H13 vs. EN24

Steel Grade

Carbon %

Hardenability

Best For

D2

~1.5%

High

Cold work dies, punches

H13

~0.4%

Medium-High

Hot dies, extrusion tools

EN24

~0.45%

Medium

Forging tools, shafts

EN31

~1.0%

High

Roller bearings, wear parts

How Hardenability is Measured – The Jominy Test

Steel bars are heated and one end is quenched with water. The hardness is then measured from the quenched end to the other side.

  • The farther the hardness travels, the better the hardenability.

  • This test helps us determine if the steel can become hard deep inside or only at the surface.

Confused Between Hardness Scales? Use Our Free Converter

Different industries use different hardness testing methods—Brinell, Rockwell, Vickers, etc. To help you compare them easily, we’ve built a simple-to-use online Hardness Conversion Tool:

🔗 Use our Hardness Conversion Tool here:
👉 www.goelsteelenterprises.com/hardness-conversion

Hardness Comparison Chart

Here’s a quick reference of how different hardness values compare across popular scales:

Brinell (HB)

Rockwell HRC

Rockwell HRB

Vickers (HV)

Approx. Tensile Strength (N/mm²)

100

—

75

105

~330

200

—

95

210

~670

300

32

—

310

~940

400

43

—

420

~1220

500

52

—

520

~1450

600

57–60

—

620

~1680

✅ Note: Values are approximate and for reference only. Always confirm with certified testing.

Hardenability vs. Surface Hardening – Don’t Confuse

Term

What it Means

Hardenability

Depth to which steel hardens internally

Surface Hardening

Only outer layer is made hard (e.g., case hardening)

At Goel Steel Enterprises, we provide both hardenable steels and case-hardening steels (like EN36) based on your needs.

“You don’t just want hard steel. You want steel that’s hard all the way through.”

📞 Need Die Steels That Don’t Fail? Call Us.

We supply UT-tested, MTC-certified die steels with high hardenability, ready for heat treatment and production use. Choose from:

  • ✅ H Series – H11, H13

  • ✅ D Series – D2, D3

  • ✅ EN Series – EN19, EN24, EN31, EN36

  • ✅ Forged blocks, Rolled Rounds & Flats

📞 Goel Steel Enterprises
📱 +91-9686477515
🌐 www.goelsteelenterprises.com
🔧 www.goelsteelenterprises.com/hardness-conversion

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