LAB MANUAL (EXP 6: HARDNESS TEST)
Use this as your report structure (and check the rubric)
1.0 Objectives
- Identify hardness as resistance to localized plastic deformation (indentation).
- Perform Vickers hardness testing using the correct load, dwell time, and measurement method.
- Record indentation diagonals, compute HV, and compare hardness across specimens.
- Discuss factors affecting hardness results (surface preparation, load, dwell, operator reading, material microstructure).
2.0 Apparatus & Safety
Minimum apparatus (adjust to your lab):
- Vickers hardness tester with diamond pyramid indenter (136°).
- Standard test blocks (verification), microscope/optical system for diagonal reading.
- Specimens (at least 2 materials), polishing papers/cloth, ethanol/cleaning tissue.
- PPE: safety glasses; gloves when handling solvents.
Safety checkpoints:
- Keep fingers away from indenter/anvil during loading.
- Clean specimen (no grit) before placing to avoid scratching optics/anvil.
- Use the microscope carefully; do not force focusing knobs.
3.0 Theory (Vickers)
Hardness is commonly defined as resistance to localized plastic deformation. Indentation methods infer hardness by pressing a known indenter geometry into the surface under a known load for a controlled dwell time.
In the Vickers test, a diamond pyramid indenter is used. After unloading, the two diagonals of the square indentation are measured and averaged to estimate the indentation area.
F = applied load (kgf), d = average diagonal (mm), HV in kgf/mm²
Common Hardness Number Equations (Reference)
Note: Use the equation required by your tester/method. This experiment focuses on Vickers hardness (HV).
Reference Figures (Softcopy Manual)
4.0 Procedure (Recommended)
Students will be provided specimen samples: Steel, Copper, and Aluminum.
To perform the test, position the specimen on the stage and move it under the microscope. Focus until the surface is clear.
Using the X–Y coordinate micrometer screws mounted on the stage, shift the sample and select the area to be tested (avoid edges, scratches, and prior indents).
Select a test load of 0.1 kg, 0.5 kg, and 1.0 kg (100 g, 500 g, and 1000 g), then press Run to perform the indentation. Record the load and dwell time used.
Measure the diagonal(s) of the impression using the length adjustment. The impression seen through the screen is a square with diagonals running between the corners (as shown in Figure 3).
Figure 3: Impression made by Vickers indenter (measure both diagonals)
5.0 Results — Fill In Your Data
How to fill this table:
• Enter d₁ and d₂ (mm) — measured diagonals from the machine optic display.
• Enter HV (Machine) — the hardness value displayed directly by the machine after each test.
• d avg, HV (Calc) and % Error are computed automatically.
% Error = |HVCalc − HVMachine| / HVMachine × 100%
Dwell time is the duration (in seconds) that the Vickers diamond indenter is held under the applied load against the specimen surface before it is lifted. During this period, the material deforms plastically to form the pyramid-shaped indentation. A longer dwell time can allow creep deformation — particularly in soft metals like copper and aluminium — causing the indentation to grow slightly larger and the measured HV to appear lower than the instantaneous value. The international standard ISO 6507 specifies a dwell time of 10–15 seconds for most Vickers tests. Record the dwell time you used so your results can be compared fairly across materials and loads.
| Load F | F (kgf) | F (g) | d1 (mm) | d2 (mm) | d avg (mm) | HV Calc (kgf/mm²) | HV Machine (kgf/mm²) | % Error |
|---|---|---|---|---|---|---|---|---|
| 0.1 kgf | 0.1 | 100 | — | — | — | |||
| 0.5 kgf | 0.5 | 500 | — | — | — | |||
| 1.0 kgf | 1.0 | 1000 | — | — | — | |||
| Mean HV (Copper) | — | — | — | |||||
| Load F | F (kgf) | F (g) | d1 (mm) | d2 (mm) | d avg (mm) | HV Calc (kgf/mm²) | HV Machine (kgf/mm²) | % Error |
|---|---|---|---|---|---|---|---|---|
| 0.1 kgf | 0.1 | 100 | — | — | — | |||
| 0.5 kgf | 0.5 | 500 | — | — | — | |||
| 1.0 kgf | 1.0 | 1000 | — | — | — | |||
| Mean HV (Aluminum) | — | — | — | |||||
| Load F | F (kgf) | F (g) | d1 (mm) | d2 (mm) | d avg (mm) | HV Calc (kgf/mm²) | HV Machine (kgf/mm²) | % Error |
|---|---|---|---|---|---|---|---|---|
| 0.1 kgf | 0.1 | 100 | — | — | — | |||
| 0.5 kgf | 0.5 | 500 | — | — | — | |||
| 1.0 kgf | 1.0 | 1000 | — | — | — | |||
| Mean HV (Steel) | — | — | — | |||||
Auto-generated summary. % Error = |HVCalc − HVMachine| ÷ HVMachine × 100%
| Material | Load | HV Calc | HV Machine | % Error | Status |
|---|---|---|---|---|---|
| Enter data in the tables above — error summary will appear here. | |||||
Enter d₁ and d₂ values above — a full worked example will appear here automatically.
Attach a photo of each specimen's indentation surface below, then discuss your results.
Note: Images are stored in memory for this session only. Re-attach after page reload. Max 5 MB per image. Images will be embedded in your exported PDF.
Graph updates automatically as you enter data. Compare Steel vs Copper vs Aluminum.
Using values at 500 g and 1000 g, interpolate HV at 800 g for each material. Formula: HV800 = HV500 + [(800−500)/(1000−500)] × (HV1000 − HV500)
Interpolation working will appear here once you enter data for 0.5 kgf and 1.0 kgf loads.
Use your finger, stylus, or mouse to write/draw your HV calculation working below. This drawing will be embedded in your exported PDF.
Tip: Write the HV formula, substitute your values, and show the final answer. Use this as your handwritten evidence of manual calculation.
6.0 Discussion
What material or treatment differences could explain the trend?
How do load and dwell time influence indentation size and measurement uncertainty?
List at least 3 sources of experimental error and propose mitigation steps.
Relate hardness to strength or wear performance (briefly, with references if used).
Report reminder
Results & Calculations and Discussion are weighted ×2 in the rubric. Ensure all calculations show substitution and unit consistency.
Quick Quiz (5 Questions)
Answer all questions, then grade to check understanding.
Q1
What indenter geometry is used in the Vickers hardness test?
Q2
Which equation is commonly used for Vickers hardness (HV)?
Q3
If the measured diagonals are d1 and d2, how do you find the value of d used in the HV equation?
Q4
In this experiment, students test loads of 0.1 kg, 0.5 kg, and 1.0 kg. What are these loads in grams?
Q5
Your report requires HV vs loading (g) graphs and HV at 800 g. If you only measured at 500 g and 1000 g, the most appropriate method to estimate HV at 800 g is:
AUTHENTICATED LAB SIMULATIONS
Interactive scorecards will sync to legitimate university rosters
Evaluate impression relative toughness:
PROFESSIONAL Performance SCORING BAND
| Item | Score 5 (Excellent 9-10) | Score 4 (Good 7-8) | Score 3 (Satisfactory 5-6) | Score 2 (Poor 3-4) | Score 1 (Very Poor 0-2) |
|---|---|---|---|---|---|
| 1. Appearance | All sections sequence perfectly; layout clean; minor slips only; custom typed cover; single PDF. | Good formatting; occasional issues; one detail missing; bound. | Rough formatting; uneven organisation; 2 details missing; stapled. | Messy; torn inserts; >2 details missing; poorly stapled. | Meets “Poor” or absent. |
| 2. Objectives | Rephrased clearly; links to prior knowledge; integrates external sources. | Phrasing good; partial paraphrasing; prior knowledge present. | Loosely stated; heavy manual reliance; some prior knowledge. | Unclear; minimal prior knowledge; copied verbatim. | Content absent. |
| 3. Apparatus | Complete list + diagrams; numbered steps (own words); safety photo included. | Vital items; paraphrased; safety report (no photo). | Partial list; steps unclear/copied; no diagrams. | Missing equipment; procedure unusable. | Content absent. |
| 4. Results & Calcs (×2) | Accurate data showing trends; figures labelled/captioned; consistent units; full calc walkthroughs. | Trends less obvious; figures labelled; minor calc gaps. | Data missing/disorganised; inconsistent labels; calc errors. | Unreliable data; poor figures; calcs absent. | Content absent. |
| 5. Discussion (×2) | Answers all Qs; explains trends/theory link; analyses errors & mitigation. | Misses 1 Q; minor gaps; notes errors. | Misses 2 Qs; partial understanding; shallow error mention. | Misses multiple Qs; incorrect interpretation. | Content absent. |
| 6. Conclusions | Summarises data; validates objectives; addresses errors & improvements. | Missing one “Excellent” element. | Missing two elements. | Missing three+ elements. | No conclusion. |
| 7. References | >9 sources; >30% recent; correct format. | 6-8 sources; manual formatting. | 3-5 sources; mixed formatting. | 1-2 sources; format ignored. | No references. |
Validated Performance Center
Record your observations. Your simulation score is shown on the right. Export a formatted PDF summary for submission.