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

To be able to work reliably, you need to know the properties of your materials. An important procedure for this is the hardness test: The hardness is determined quickly and easily with a hardness t ester. A conversion table for hardness values and tensile strength according to DIN EN ISO 18265 allows at least a rough estimate of the tensile strength Rm based on the hardness value for various 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, apart from the tensile strength, no statements can be made about the 0.2% proof stress - for this, a costly and destructive tensile test in the materials testing laboratory is necessary. This is no longer up to date for modern product control and quality assurance.

The new imprinting method according to DIN SPEC 4864 from Imprintec 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 imprint process avoids the disadvantages of converting hardness to tensile strength and contact us directly:

Frequently asked initial questions about the indentation method compared to the conversion from hardness to tensile strength

In principle, all metallic materials can be tested that deform plastically and produce an impact in the edge area of the test indentation when a test probe penetrates. Under the topic Materials you will find an overview of all materials verified so far.

The Imprintec indentation method determines the comparative characteristic valuesRIp0.2 and the tensile strength RIm for the tensile test.

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

Measured and simulated throw-up profile for a hardness impression

A look at the conversion table for hardness values and tensile strength: The previous conversion from hardness to tensile strength in detail

The conversion of hardness into tensile strength is known from DIN EN ISO 18265, for which results from empirical work were used to convert hardness into tensile strength. The basis was statistically proven 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 time-consuming, cost-intensive and destructive testing with a tensile testing machine. However, there are limits to the conversion. 

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

According to the standard, the conversion of Rockwell hardness (HRC), Brinell hardness (HB) and Vickers hardness (HV) into tensile strength applies to:

  • unalloyed steel and low-alloyed 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.

Characteristic value restriction: No determination of the
0.2% proof stress Rp0.2 possible

The 0.2% proof stress Rp0.2 cannot be determined with the help of 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 imprinting method Imprintec combines proven testing technology with the latest findings of modern materials testing! 

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

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

Such a relationship was established through new findings from materials science and material simulation: The Imprintec indentation process uses the material throw-up of the hardness indentation as the basis for determining the tensile strength Rm as well as the yield strength Rp0.2.

Definition of material upset: Increase in specimen surface area that forms outside the contact zone of the indenter and specimen due to the application of force by the indenter as a result of material displacement.

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

Determined results from the imprinting method according to DIN SPEC 4864

Conclusion: The Imprintec imprinting process provides more advantages than the conversion table for hardness values and tensile strength.

Testing the 0.2% proof stress Rp0.2

In addition to the tensile strength Rm, the
0.2% proof stress Rp0.2 is also determined.

Cross-material testing

In addition to unalloyed and low-alloyed steels, materials such as aluminium, nickel and high-alloyed 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 as well as the tensile strength Rm for many metals across all materials. This redefines production-related testing processes and laboratory use for the determination of mechanical properties.

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
  • the process-related quality assurance is improved
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