OBJECTIVES & PROTOCOL
Mission Targets
- • Identify Microstructures: Ferrite, Pearlite, Martensite.
- • Quantify cooling impact on Modulus of Rigidity (G).
- • Compare ductile flat vs brittle helical failures.
Real World Application
Driveshafts must maintain toughness yet withstand wear. Heat treatment provides the hard outer case for gears and shafts.
Master Protocol (Safety)
Extract with long tongs only. Temperature exceeds 850°C.
Protective eyewear mandatory during water quenching release.
Observe etchant behavior only under localized fume hood control.
Heat Treatment Quick Facts
Use these facts to improve your discussion and conclusions.
Mini Challenge
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LABORATORY MANUAL
Complete Reference: Apparatus, Theory, Procedures & Sample Preparation
1.0 Detailed Objectives
- i. To study preparing of metallographic sample for microstructure observation.
- ii. To study various types of heat treatment process: annealing, normalizing, quenching.
- iii. To study the effects of heat treatment on the microstructure of steel.
- iv. To discover the microstructure of ferrite, pearlite, cementite, austenite and martensite under microscopic view.
2.0 Apparatus
i) Five different samples of heat-treated steel (see table)
ii) Hand grinding machine
iii) Polishing machine
iv) Optical microscope
Heat Treatment Samples
| Sample | Treatment |
|---|---|
| 1 (WHT) | Without Heat Treatment |
| 2 (QW) | Water Quenched |
| 3 (QO) | Oil Quenched |
| 4 (N) | Normalizing |
| 5 (A) | Annealed |
3.0 Theory — Heat Treatment Process
The properties of steels can be changed by several techniques such as alloying and heat treatment. Heat treatment modifies microstructures, producing a variety of mechanical properties important in manufacturing — such as improved formability and machinability.
Heat treatment where material is taken to elevated temperature, held, then slowly cooled.
- • Reduce hardness and brittleness
- • Alter microstructure for desirable properties
- • Soften metals for improved machinability
- • Recrystallize cold-worked metals
Heating ~55–88 °C above upper critical temperature then air cooling.
- • Higher strength and hardness
- • Improve machinability
- • Refine grain size & uniform distribution
Heating to austenite range then rapid cooling. Various media: water, oil, air, brine — each gives different results.
| Property | Fast Cooling (Quenching) | Slow Cooling |
|---|---|---|
| Hardness | Hard | Soft |
| Strength | Strong | Weak |
| Ductility | Brittle | Ductile |
| Microstructure | Martensite | Ferrite-Pearlite-Cementite |
| Grain Size | Small | Large |
3.2 Sample Preparation
Objective: generate a flat surface with mirror-like finish for metallographic observation. The surface must be totally flat and smooth before viewing under optical microscope.
Sample molded in plastic after cutting to ease holding during polishing.
Surface ground to remove rough scale, followed by fine grinding until it reflects light.
Rough polishing removes grinding imperfections. Fine polishing removes all scratches.
Clean with alcohol, immerse in etchant, wash with water, then alcohol to prevent watermarks. Ready for microscope.
4.0 Experiment Procedures
Students will be provided with five different samples of heat-treated steel.
Observe and sketch the microstructure of each sample under optical microscope.
Identify and label the microstructures observed in each sample.
Attach results and discuss all relevant information on heat treatment including etching process, characteristics of materials with appropriate figures.
Conclude your findings based on the experimental results and theoretical expectations.
List all references consulted during the course of your research and findings.
Interactive Scorecard Simulations
Quench speed and phase logic impact performance points
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Quiz (5 Questions)
Your quiz score contributes to the leaderboard
Leaderboard
Competitive ranking: total points = Game 1 + Game 2 + Quiz
| Rank | Student | Total | G1 | G2 | Quiz |
|---|
Official self-audit rubric
| Criteria Assessment Item | Excellent (9-10) | Good (7-8) | Satisfactory (5-6) | Poor (3-4) | Very Poor (0-2) |
|---|---|---|---|---|---|
| 1. Appearance & Organization | Perfect sequence, formatted clean, manual neat slips correction, computer cover bound, single PDF. | Format good missing one minor cover information detail. readable. | rough format organization uneven readable multiple mistakes spelling. stapled no bind. | Sloppy formatting out of ordertorn inserts language errors staples poor. | Most poor conditions met or absent report submission. |
| 2. Theory & Information | All objectives rephrased own sentences, detailed paragraph linking torsion theory coursework, external source research integration. | Objectives clear prior knowledge present phrasing manual attempt minor phrasing. | Loose statements objectives identified somewhat reliance text manual original phrasing limit. | theory copy verbatim Objectives unclear or missing minimal relevant offered content. | Theory content absent. |
| 3. Apparatus & Procedure | All materials listed labeled diagrams machine setup steps own words safety photo included. | Vital items included omission maybe 1, paraphrased manual procedure attached report lacking photo. | Partial list omissions key missing difficult follow steps copied unclear unnumbered. | Equipment absent procedure unusable confusing diagrams missing. | Content absent. |
| 4. Results & Calculations (x2) | Accurate data trends easy see organized correctly Tables numbered captioned. calc walkthrough samples formula MS equations. | Correct trends less obvious table labels units equation formulas use few misses. | Some data missing sloppy tables titles units missed no calc walk. | Poor construction figures poor number Titles captions absent incorrect reliable bad data. | Results absent. |
| 5. Discussion (x2) | Answer allAccurately links Outcomes theory trends interpreted correct discussed error reduce ways. | miss one answer minor improvements trends notes errors correctly clearly. | miss 2 partial understanding inconsistencies depth shallow error mention. | Indicator lack understanding Incorrect comparison interpretation Objective theoriy missing error discuss absent. | Absent. |
| 6. Conclusions | Summarizes essential data conclusion achieve Objectives VALID VALIDITY experiment improvements learned logic. | missing 1 excellent element. | missing 2 elements. | missing 3+ elements. | no conclusions. |
| 7. References | >9 multiple source standard manual format written. 30% references < 5 years. | 6 - 8 sources multiple media written format. | 3 - 5 source 2 media format partial compliance. | 1 - 2 cited sources formats manual ignore. | No references. |
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