Conversion table for hardness values and tensile strength:
Discover the further development of modern materials testing

To work reliably, you need to know the properties of your materials. An important method for this is hardness testing: With a hardness tester the hardness is determined quickly and easily. A conversion table for hardness values and tensile strength according to DIN EN ISO 18265 allows an at least rough estimate of the tensile strength Rm on the basis of the hardness value for different steel materials.

However: For materials such as aluminium and nickel, a conversion from hardness to tensile strength is not possible, as no conversion tables are available. In addition, no statements can be made about the 0.2% proof stress apart from the tensile strength – this requires a costly and destructive tensile test in the material testing laboratory. This is no longer up-to-date for modern goods control and quality assurance.

The new Imprintec indentation method according to DIN SPEC 4864 solves these limitations of the conversion table for hardness values and tensile strength according to DIN EN ISO 18265: You receive all important key figures in one test procedure!

Learn more about how the Imprintec indentation method avoids the disadvantages of the conversion from hardness to tensile strength and contact us directly:

Frequently asked first questions about the process of converting hardness into tensile strength

In principle, all metallic materials can be tested that deform plastically and create a throw-up at the edge of the test impression when a test probe penetrates. Under the topic Materials you will find an overview of all materials that have been verified so far.

The Imprintec indentation process determines the comparative characteristic values RIp0,2 and the tensile strength RIm to the tensile test.

You have further questions? Take a look at our FAQ or contact our specialists directly!

Measured and simulated throw-up profile from a hardness impression

A look at the re­rating table for h­values and train strength: The previous re­shy of hardness in train­strength in detail

Known is the conversion of hardness to tensile strength by DIN EN ISO 18265, for which results from empirical work for the conversion of hardness to tensile strength were used. The basis were statistically verified hardness tests and tensile tests. The most common methods are the Rockwell, Brinell and Vickers methods. The conversion table for hardness values and tensile strength is of great importance, as it saves the more complex, cost-intensive and destructive testing with a tensile testing machine. However, there are limits to the conversion.

Material limitations in the conversion table according to DIN EN ISO 18265

The conversion of Rockwell (HRC), Brinell (HB) and Vickers hardness (HV) into tensile strength is valid according to the standard:

  • Unalloyed steel and low-alloy steel
  • Cast steel
  • Quenched and tempered steel
  • tool steel 1.1243
  • tool steel 1.2714

When converting to tensile strength, an increased measurement uncertainty must also be taken into account. A large number of materials such as Cr-Ni steel, cast aluminium alloys and wrought alloys, titanium, copper or nickel are not listed in the published conversion tables.

Limitation of characteristic values: No determination of the 0.2% proof stress Rp0.2 possible

The 0.2% proof stress Rp0.2 cannot be determined using the conversion table for hardness values and tensile strength according to DIN EN ISO 18265. However, the 0.2% proof stress plays an important role as a characteristic value in the mechanical characterization of metals.

Leave these limitations behind: With the innovative indentation method Imprintec combines proven testing technology with the latest findings of modern materials testing!

Indentation method according to DIN SPEC 4864 instead of a conversion table for hardness and tensile strength: Optimal use of the functional relationship between hardness indentation and stress-strain behavior.

The DIN EN ISO 18265 standard for the conversion table for hardness values and tensile strength stipulates that there are significant differences between the hardness test and the tensile test in terms of material stress. Furthermore, it is pointed out that the derivation of a functional relationship between hardness and tensile strength is very complex.

Through new findings in materials science and material simulation, such a relationship has been established: The Imprintec indentation method uses the material throw-up of the hardness indentation as a basis for determining the tensile strength Rm as well as the yield strength Rp0.2.

Definition of the material throw-up: Increase of the sample surface, which is formed due to the force of the indenter by material displacement outside the contact zone of indenter and sample.

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The hardness impression in its entire deformed geometry provides new information. The so-called “pile up” or the material throw-up shows the plastic deformation behaviour of the material and behaves – like a fingerprint – characteristically to the material. The Imprintec indentation method uses this information and establishes a functional relationship between indentation and stress-strain behaviour.

Determined results from the indentation method according to DIN SPEC 4864

Conclusion: The Imprintec indentation method offers more advantages than the conversion table for hardness and tensile strength

Testing of the 0.2% proof stress Rp0.2

In addition to the tensile strenght Rm, the
0,2% proof stress Rp0,2 is also determined.

Cross-material testing

In addition to unalloyed and low-alloy steels, materials such as aluminium, nickel and high-alloy steels can also be tested.

Compared to the conversion of hardness into tensile strength by means of a conversion table, the indentation method according to DIN SPEC 4864 provides the 0.2% proof stress Rp0.2 and the tensile strength Rm for many metals. Thus, production-related testing processes and laboratory use for the determination of mechanical properties are redefined.

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Your advantages with the indentation method compared to the conversion table for hardness values and tensile strength:

  • Cost-effective results without time-consuming sample preparation
  • Low-destructive and fast tests, which facilitate the daily work of materials testers
  • Process-oriented quality assurance is improved
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T +49 (0) 234970414 00
F +49 (0) 234970414 09
info@imprintec.de