Advanced Metallography

Carbon
Decision Tree.

Determine graphite formation during solidification. Distinguish flakes from nodules and TEMPER carbon under high-resolution optic logic.

Solidification SIM Export findings

OBJECTIVES & FIELD VIEW

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Mission parameters

  • • Analyze Microstructures of 4 distinct cast iron specimens.
  • • Differentiate flake graphite (Gray CI) vs spheroidal (Ductile).
  • • Observe White Cast Iron's carbide-heavy matrix.
  • • Correlate cooling rates with graphite precipitation.

Specimen Reference

Gray Iron: Slow cooling. Flakes act as stress raisers. High dampening.

Ductile Iron: Mg inoculation makes nodules. Better toughness.

White Iron: Fast cooling. No graphite. Rich in Cementite (Fe3C).

PROCEDURE, SAFETY & TWO LABS

Use this as your lab manual section (write-up ready). Two labs are included: microstructure observation and hardness–microstructure correlation.

Lab 1 — Experiment 5

Observation of Microstructure (Cast Iron)

Metallography

Objective

  • Observe microstructures of cast iron under optical microscope.
  • Identify the classification of cast iron according to the characteristic microstructures obtained.
  • Relate graphite morphology and matrix phases to processing history and expected properties.

Apparatus / Materials

  • Three to four unidentified cast iron samples (as provided by the laboratory)
  • Metallographic grinding/polishing machine, SiC papers (e.g., P240→P1200), polishing cloth, alumina/diamond slurry
  • Etchant (commonly Nital 2–5% for ferrous alloys, as instructed by the lab)
  • Optical microscope (reflected light), camera (if available)
  • Cleaning supplies: ethanol/isopropyl alcohol, tissue, air blower

Summary & Background (Hardcopy Expanded)

Cast irons are a class of ferrous alloys with typical carbon contents around 3.0–4.5 wt% and small amounts of silicon. Cast iron and wrought iron/steel are different terms: cast irons melt and cast readily because they become fully liquid at approximately 1150–1300°C (depending on composition).

Cementite (Fe3C) is a metastable compound and under certain conditions it can decompose to form ferrite and graphite:

Fe3C → 3Fe(α) + C (graphite)

For most cast irons, carbon exists as graphite. Therefore, microstructure and mechanical behavior depend strongly on composition (especially C and Si), cooling rate, and heat treatment. The common types of cast iron include gray, nodular (ductile), white, and malleable cast iron.

Cast Iron Classification (What to Look For)

Gray Cast Iron

Graphite in flakes within ferrite/pearlite matrix. Flakes act as stress raisers; typically good damping and machinability.

Nodular (Ductile) Cast Iron

Small additions (e.g., Mg/Ce) modify graphite to spheroidal nodules. Matrix (ferrite/pearlite) depends on heat treatment; generally improved toughness.

White Cast Iron

Low Si and/or rapid cooling promotes carbon as cementite rather than graphite. Typically very hard and brittle; appears bright carbide-rich regions.

Malleable Cast Iron

Produced by heat-treating white iron (commonly 800–900°C for prolonged time in neutral atmosphere) to decompose cementite and form graphite clusters/rosettes in ferrite/pearlite matrix.

Procedure (Recommended)

  1. Students will be provided with three to four cast iron samples (often unidentified). Label each specimen.
  2. Grind sequentially using SiC papers (rotate 90° between steps). Rinse and clean between papers.
  3. Polish using cloth + slurry until scratches are minimal; clean thoroughly.
  4. Etch briefly with the instructed etchant (time depends on alloy and polish quality). Rinse immediately and dry.
  5. Observe under microscope: start low magnification, then increase (e.g., 50× → 100× → 200×).
  6. For each specimen, identify: graphite shape (flake/nodule/none), matrix (ferrite/pearlite/cementite), and notable features.
  7. Observe and sketch the microstructure of each sample. Identify and label all microstructures drawn (graphite, matrix, carbides).
  8. Summarize findings: connect morphology to properties (ductility, hardness, damping, brittleness).

Report Checklist

  • Microstructure table: specimen → graphite form → matrix → expected properties
  • At least 1 labeled image/sketch per specimen
  • Short discussion: cooling rate/inoculation vs observed phases

Results & Discussion (Hardcopy Guidance)

Attach results and discuss all relevant information related to this experiment. Discussion should connect cast iron microstructures to processing and properties, and should be supported by labeled figures/diagrams (micrographs, sketches, phase descriptions). Compare specimens and justify your classification clearly.

Conclusion

Conclude your findings: state the identified cast iron type(s) for each sample, the key microstructural evidence (graphite form + matrix), and one or two property implications.

References

List all references used (textbook, lecture notes, journal/website). Use a consistent citation style as required by your course.

Lab 2 — Supplementary

Hardness–Microstructure Correlation (Cast Iron)

Mechanical Test

Objective

Measure hardness for cast iron specimens and relate hardness trends to microstructure (e.g., cementite-rich white iron → higher hardness; ferritic ductile iron → lower hardness).

Apparatus

  • Hardness tester (Brinell / Rockwell, as available)
  • Flat, clean specimen surface (polished face from Lab 1 is acceptable)
  • Calipers / microscope scale for indentation measurement (if Brinell)

Procedure (Recommended)

  1. Verify machine settings (indenter, load, dwell time) per lab instruction.
  2. Place specimen securely; ensure the test surface is flat and clean.
  3. Perform at least 3 indents per specimen (spaced adequately to avoid interaction).
  4. Record hardness values and compute average and scatter.
  5. Discuss why different cast irons show different hardness (graphite morphology + matrix + carbides).

Safety (Applies to Both Labs)

  • Wear safety glasses at all times; use face shield if instructed for grinding/polishing.
  • Grinding dust and splashes: keep guards in place; do not wear loose sleeves.
  • Etchants are corrosive/flammable: use gloves, work in ventilated area, and rinse immediately after etching.
  • Do not touch freshly etched surfaces; handle specimens by edges.
  • Hardness tester pinch/crush hazard: keep fingers away from anvil/indenter during loading.

Observation Simulators

Score ID marks to populate your student lab record

SIM 1: Solidification Engine Rate: Amb
Mission Target
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Pick a cooling rate to match the target microstructure. Faster answers score higher.
Round
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Streak
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Score
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Best
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Select Cooling Rate:

SOLIDIFY SAMPLE TO VIEW LATTICE
GAME: Microstructure Identifier Precision: 0%
Round
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Time
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Score
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Best
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Identify the microstructure shown. Earn points for correct morphology.

Streak: 0 · Attempts: 0
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Auth Signature Mandatory

Micro-Solidification simulations are restricted to
authenticated student credentials only.

5-QUESTION QUIZ

Answer and submit to get an instant score. Your answers remain on-screen (exported into PDF if you export the page report).

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Q1. Which cast iron typically shows graphite flakes under the microscope?

Q2. Ductile cast iron has improved toughness mainly because graphite appears as:

Q3. White cast iron tends to be hard and brittle mainly due to:

Q4. The best safety practice when using an etchant is to:

Q5. If cooling rate increases during solidification, cast iron is more likely to form:

Score: —

Official scoring criteria

Assessment criteria Excellent (9-10) Good (7-8) Satisfactory (5-6) Poor (3-4) Very Poor (0-2)
1. Appearance & OrganizationCorrect sequence, clean headers, computer typed bound cover, single PDF formatted well.Formatting good, missing one minor front info, tape/ring bound.rough format organization uneven readable language slips stapled no bind.Sloppy format torn inserts poor staple out of order missing titles.Absent.
2. Objective & TheoryAll objectives identified clearly, detailed paragraph describing prior knowledge linked to research.Objectives clear manual paraphrase some attempt at new wording detailed prior info.Objective partially defined manual copy mainly new attempt paragraph limited.missing objective theory manual direct.Absent.
3. Apparatus & ProcedureAll materials listed labeled diagrams machine steps own word protocol, safety report photo.Vital items listed paraphrase manual diagram attached report lack picture safety.Partial equipment diagrams missing confused non-numbered steps confused order manual direct.Missing Equipment unusable confused manual direct.Absent.
4. Results (x2)Organized recorded data Easy trends clearly Figures/Charts numbered Titled labeled. calc walk.correct trends less obvious labeling units correct calculation Walk miss equation formula.Some data missing sloppy figure incompleteness missed units.Error constructs Figures bad numbers reliability missing Titles.Absent.
5. Discussion (x2)Answers all correctly explained outcome outcomes linkage errors discussed strategies.Miss one result minor gap interpreted correct effect discussed.Miss 2 incomplete understanding objective link mentioned shallow.incorrect comparison Understanding lacks missing fulfilling objectives error discuss missing.Absent.
6. ConclusionsEssential data summarized findings achieve objectives VALID VALIDITY experiment improvement suggestion logic.1 element missing.2 element missing.3 excellent logic element missing.None.
7. ReferencesMultiple journal book Mag internet >9. Standard Manual Format. 30% references < 5 years.6 - 8 source source formatted manual format.3 - 5 from 2 media type comply partial.1 - 2 cited ignore format.Absent.
Absent: 0% total score Experiment conducted but no report: 10% maximum marks

Metallography report hub

Recorded microstructure decisions are verified in real-time. Finalize and conclude your metallographic findings. PDF engine generates a university-standard artifact.

Quick Reference (Optional)
Cementite decomposition (conceptual): Fe3C → 3Fe(α) + C(graphite)
Specimen Classification (Fill What You Observed)
Document each sample type and microstructural evidence (graphite form + matrix).
Sample Classification Evidence (Graphite/Matrix)
Sample 1
Sample 2
Sample 3
Sample 4
Table of Results (Auto)
Fill at least graphite morphology, matrix, and magnification. This table is exported into the Submission PDF.
Sample Graphite Morphology Matrix Notable Features Magnification
Sample 1
Sample 2
Sample 3
Sample 4
Lab 2 (Optional) — Hardness Data
SampleHardness Value
Sample 1
Sample 2
Sample 3
Sample 4
Photo Evidence (Microscope / Sketch)

On smartphone, tap to open camera. Add clear photos of micrographs, sketches, or setup. These will be embedded into the submission PDF.

Authenticated Mark
0
Solidification accuracy
Photos Added: 0

LABORATORY SCORECARD HUB

Fill in marks and generate a professional PDF scorecard (preview first, download only if you want).

Total
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/ 100
Criteria Max Mark
Safety & PPE Compliance 20
Specimen Preparation (Grinding/Polishing) 25
Microscope Use & Identification Accuracy 25
Data/Sketch Quality 15
Discussion & Conclusions 15