Measure maximum force, original cross-section and curve progression—or compare strength locally within a real component zone.
Testing service · Strength properties
Determine tensile strength
Tensile strength Rm is the highest engineering stress reached in a tensile test. Testawell structures the appropriate route: a global reference value from a tensile specimen, a material-specific hardness conversion or a local comparative tensile-strength value from i3D® indentation.
Tensile strength Rm is the maximum engineering tensile stress achieved by a specimen. It supports material comparison, design, quality assurance, batch assessment and material development. A high Rm value does not by itself prove high ductility or suitability for every component function.
Yield strength or proof stress is reached earlier and identifies the transition into permanent plastic deformation. Rm instead describes the maximum of the engineering stress-strain curve.
How is tensile strength calculated?
The maximum force Fm measured during the test is divided by the original unloaded cross-sectional area S0:
Rm = Fm / S0
Term
Meaning
Typical unit
Rm
maximum engineering tensile stress
MPa or N/mm²
Fm
maximum force measured during the tensile test
N
S0
original cross-sectional area
mm²
Because 1 N/mm² equals 1 MPa, both units are equivalent. S0 must be determined before loading; the later reduction in area does not change the reference area used for engineering tensile strength.
Rm is located at the maximum of the engineering stress-strain curve. Yield and proof stress occur earlier.
How is tensile strength determined in a tensile test?
For metallic materials at room temperature, ISO 6892-1 is commonly relevant. The applicable standard still depends on material, specimen geometry, temperature and project requirements. A defined specimen is aligned and gripped so that force and extension can be recorded continuously.
Define the specimen: document condition, orientation, geometry and S0.
Set up the test: align the specimen and select grips and extensometry.
Load under control: record force or strain at the specified rate up to fracture.
Evaluate the curve: determine Fm, divide by S0 and report Rm with the associated properties.
Depending on the material and instrumentation, the same test can provide ReH, ReL, Rp0.2, elongation after fracture A and reduction in area Z.
Tensile strength, yield strength and fracture stress
Property
Meaning
Position in the test
ReH / ReL
upper and lower yield strength where a distinct yield phenomenon occurs
onset or range of permanent deformation
Rp0.2
proof stress at 0.2% specified permanent strain
substitute property without distinct yielding
Rm
highest engineering tensile stress based on S0
maximum of the engineering curve
Fracture stress
stress at fracture based on a defined reference area
end of the test; not automatically identical to Rm
Local strength properties
Assess comparative tensile strength using i3D® indentation
If a representative tensile specimen cannot be removed or a small component zone must be assessed directly, indentation testing can provide a local comparative tensile-strength value. A controlled indentation is measured in three dimensions and matched with inverse finite-element analysis.
The result is identified as the indentation-based comparison value RIm. It is useful for welds, heat-affected zones, strength gradients, additive materials and measurement grids. Transferability to tensile-test Rm must be assessed for the material, condition and task.
Which route is suitable for determining tensile strength?
Route
Result
Typical use
Key limitation
Tensile test
Rm and further global tensile properties
standard evidence, reference data and batch comparison
requires a suitable defined specimen
Hardness conversion
empirical estimate of tensile strength
quick orientation for a suitable material group
material assignment and scatter must be considered
i3D indentation
local RIm and plastic-flow information
real component zones, gradients, welds and grids
task-specific applicability and validation required
Which information is needed for test planning?
material designation, condition, heat treatment and manufacturing route
component or specimen geometry and available material volume
relevant orientation and zone such as base material, weld, HAZ or gradient
required property: Rm, RIm, Rp0.2, elongation or flow curve
applicable standard, specification and required evidence
number of specimens or test points and reporting requirements
Frequently asked questions about tensile strength
What does tensile strength Rm mean?
Tensile strength Rm is the highest engineering tensile stress reached during a tensile test. It is the maximum of the engineering stress-strain curve and is distinct from yield strength, proof stress and fracture stress.
How is tensile strength calculated?
Tensile strength is calculated from the maximum measured force Fm divided by the original cross-sectional area S0: Rm = Fm / S0. The result is normally stated in MPa or N/mm².
How is Rm determined in a tensile test?
A defined specimen is loaded axially while force and extension are recorded. Engineering stress is calculated from force and original cross-section; the maximum stress is Rm. ISO 6892-1 is commonly used for metallic materials at room temperature.
What is the difference between tensile strength and yield strength?
Yield strength or proof stress marks the onset of permanent plastic deformation. Tensile strength is reached later at the maximum engineering stress.
Can tensile strength be estimated from hardness?
ISO 18265 contains conversion relationships for selected material groups. Such values are material- and condition-dependent estimates and are not a universal replacement for a required tensile test.
Can tensile strength be assessed locally without a tensile specimen?
The i3D indentation workflow can derive a local indentation-based comparative tensile-strength value from a controlled indent, its 3D topography and inverse finite-element analysis. Applicability must be assessed for the material and task.
Plan tensile-strength testing for your material
Send the material, condition, geometry, relevant test zone, required property and applicable standard.
