⚙️ Tensile Test of Steel
In short
Static tensile test of metallic materials at room temperature. Determination of yield strength, tensile strength and elongation. The test is performed according to PN-EN ISO 6892-1:2020; Machine force range: 50–600 kN (typical for steel testing). The procedure comprises 11 steps (about 56 min–1 h 33 min in total); it is used for: Qualification of structural steel into grades (S235, S355, S460), Mill certificates — acceptance certificates 3.1/3.2 per PN-EN 10204, Quality control of reinforcing bars (PN-EN 10080).
At a glance
- Standard: PN-EN ISO 6892-1:2020
- Category: Construction
- Procedure steps: 11
- Total time of stages: 56 min–1 h 33 min
- Test temperature: 10–35°C (room temperature)
- Strain rate (method A2): 0.00007 s⁻¹ (to Re) → 0.00025 s⁻¹ (after Re)
- Extensometer class: Class 1 per ISO 9513 (accuracy ±1 µm)
Overview
The static tensile test is the most important and frequently performed method for testing mechanical properties of metals. It involves uniaxial tension of a specimen with standardized dimensions at constant strain rate until fracture. From the recorded force-elongation curve, key strength parameters are determined: yield strength (Re or Rp0.2), tensile strength (Rm), elongation (A) and reduction of area (Z).
Standard PN-EN ISO 6892-1 specifies test method at room temperature (10–35°C) and defines three rate control procedures: A1 (with feedback loop on strain rate), A2 (with constant crosshead speed) and B (with constant stress rate in elastic range). Method A is recommended as more precise and reproducible.
Tensile test results form the basis for qualifying steel into appropriate grades (e.g., S235, S355 per PN-EN 10025) and assessing material suitability for specific structural applications. Testing is mandatory in mill certificates (certificates 3.1 and 3.2 per PN-EN 10204) and in quality control of reinforcing bars (PN-EN 10080), bolts, sheets and tubes.
Test specimens can be flat (from sheets) or round (from bars), with standardized dimensions depending on the product. Most commonly proportional specimens with gauge length L₀ = 5.65√S₀ (short) or L₀ = 11.3√S₀ (long) are used.
Method principle
A metal specimen of standardized dimensions is gripped in the jaws of a testing machine and subjected to uniaxial tension at controlled strain rate. The machine continuously records force (load cell) and elongation (extensometer), generating a tensile curve σ-ε. From the curve, the following are determined: upper and lower yield strength (ReH, ReL) or 0.2% proof strength Rp0.2 (at 0.2% permanent strain), tensile strength Rm (maximum stress), elongation A (percentage change in gauge length after fracture) and reduction of area Z (percentage change in cross-sectional area at fracture location).
Applications
- Qualification of structural steel into grades (S235, S355, S460)
- Mill certificates — acceptance certificates 3.1/3.2 per PN-EN 10204
- Quality control of reinforcing bars (PN-EN 10080)
- Testing of bolts, nuts and steel fasteners
- Acceptance control of sheets, tubes, sections
- Qualification of welding procedures (specimens from welded joints)
- Research and development of new alloys
- Failure analysis — investigation of fracture and failure causes
Key parameters
| Parameter | Value |
|---|---|
| Test temperature | 10–35°C (room temperature) |
| Strain rate (method A2) | 0.00007 s⁻¹ (to Re) → 0.00025 s⁻¹ (after Re) |
| Extensometer class | Class 1 per ISO 9513 (accuracy ±1 µm) |
| Gauge length L₀ | 5.65√S₀ (short) or 11.3√S₀ (long) |
| Machine force range | 50–600 kN (typical for steel testing) |
| Rm repeatability | ±1% (within same material) |
Standard
- Standard number
- PN-EN ISO 6892-1:2020
- Title (PL)
- Metale — Próba rozciągania — Część 1: Metoda badania w temperaturze pokojowej
- Title (EN)
- Metallic materials — Tensile testing — Part 1: Method of test at room temperature
Step-by-step procedure
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Specimen preparation
Take specimen from product per product standard. Machine to standardized dimensions. Apply gauge length L₀ marks.
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Specimen dimension measurement
Measure width and thickness (flat specimen) or diameter (round) at 3 locations. Calculate cross-sectional area S₀.
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Specimen gripping
Grip specimen in testing machine jaws. Ensure axiality (no eccentricity). Attach extensometer.
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Test parameter setup
Select rate control procedure (A1, A2 or B). Set strain rate: 0.00007 s⁻¹ to yield strength, then 0.00025 s⁻¹.
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Preload application
Apply small preload (max 5% of expected Re) to eliminate slack in grips.
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Tension — elastic zone
Start tensioning at constant strain rate. Record force and elongation. Observe plotted σ-ε curve.
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Transition through yield strength
Observe yield plateau (ReH/ReL) or determine Rp0.2 from curve. After yield strength, increase rate to 0.00025 s⁻¹.
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Tension to fracture
Continue until specimen fracture. Record maximum force (→ Rm) and force at fracture.
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Post-fracture elongation measurement
Join both specimen parts. Measure final length Lu. Calculate: A = (Lu - L₀)/L₀ × 100%.
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Reduction of area measurement
Measure cross-sectional dimensions at fracture location. Calculate: Z = (S₀ - Su)/S₀ × 100%.
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Calculations and report
Calculate Re (or Rp0.2), Rm, A, Z. Compare with product standard requirements. Prepare report with tensile diagram.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Universal testing machine (tensile tester) | ZwickRoell Z100/Z250, Instron 5985/8802, MTS Criterion C45 | 150 000–600 000 PLN |
| Contact extensometer | ZwickRoell makroXtens, Instron 2630-series, MTS 634 | 15 000–50 000 PLN |
| Grips and specimen holders | Wedge hydraulic or mechanical, adapted to specimen cross-section | 5 000–25 000 PLN/set |
| Caliper / micrometer | Mitutoyo 293-240, accuracy 0.001 mm — for measuring specimen dimensions | 200–2 000 PLN |
| Testing software | ZwickRoell testXpert III, Instron Bluehill Universal | 10 000–40 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Standardized specimens | — | Proportional flat or round specimens, machined per PN-EN ISO 6892-1 annex B |
| Reference material (CRM) | — | Certified reference material for machine verification (e.g., steel with known Rm) |
| Marking medium | — | Scriber or marker for applying gauge length L₀ marks |
Health and safety (OHS)
- Testing machine — crushing hazard from hydraulic grips, use guards
- Specimen fracture — elastic energy, fragment ejection risk, use protective shield
- Specimen machining — sharp metal edges, protective gloves
- Noise during fracture — use hearing protection for large cross-sections
- Safety glasses mandatory during entire test
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN ISO 6892-1:2020 — “Metallic materials — Tensile testing — Part 1: Method of test at room temperature”.
How does this method work?
A metal specimen of standardized dimensions is gripped in the jaws of a testing machine and subjected to uniaxial tension at controlled strain rate. The machine continuously records force (load cell) and elongation (extensometer), generating a tensile curve σ-ε.
What is the measuring range and accuracy?
Test temperature: 10–35°C (room temperature); Strain rate (method A2): 0.00007 s⁻¹ (to Re) → 0.00025 s⁻¹ (after Re); Extensometer class: Class 1 per ISO 9513 (accuracy ±1 µm); Gauge length L₀: 5.65√S₀ (short) or 11.3√S₀ (long).
How long does the test take?
The times given for the individual stages add up to approximately 56 min–1 h 33 min. The procedure comprises 11 steps.
What equipment is required?
Universal testing machine (tensile tester), Contact extensometer, Grips and specimen holders, Caliper / micrometer, Testing software. Indicative cost of the core instrument (Universal testing machine (tensile tester)): 150 000–600 000 PLN.
Where is this test used?
Qualification of structural steel into grades (S235, S355, S460); Mill certificates — acceptance certificates 3.1/3.2 per PN-EN 10204; Quality control of reinforcing bars (PN-EN 10080); Testing of bolts, nuts and steel fasteners; Acceptance control of sheets, tubes, sections; Qualification of welding procedures (specimens from welded joints); Research and development of new alloys; Failure analysis — investigation of fracture and failure causes.
What safety precautions apply?
Testing machine — crushing hazard from hydraulic grips, use guards; Specimen fracture — elastic energy, fragment ejection risk, use protective shield; Specimen machining — sharp metal edges, protective gloves; Noise during fracture — use hearing protection for large cross-sections; Safety glasses mandatory during entire test.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN ISO 6892-1.