Heat treatment changes what a steel is like without changing what it is made of. The carbon content stays the same, but the grain structure changes, and the grain structure decides the properties.
This topic is new to the external exam in 2026, so there are no past questions to learn from. Everything here is built from the syllabus dot point and from the way QCAA marks the neighbouring steels questions. Tick off each skill once you can do it without help.
0
past questions that test heat treatment, 2020–2025
5
groups of processes the dot point names
2
cognitive verbs: identify and explain
Skills in this topic
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Part 1
What the exam asks about heat treatment
Across the six external exams from 2020 to 2025, not one question asks about annealing, normalising, quenching, the martensitic reaction, tempering, or hot and cold working.
The only appearance of the vocabulary is 2024 multiple choice Question 2, which asks which material suits “highly tempered punches and axles”. It tests carbon-steel selection, and the published answer is D, ultra-high carbon steel.
Practise
Exam question: the one appearance of “tempered”
2024 Question 2
Section 1 · Multiple choice · [1 mark]
Which material is most suitable for highly tempered punches and axles?
The wording comes straight from the 2019 syllabus, which listed ultra-high carbon steel (1.25% to 2.00% carbon) for “highly tempered non-industrial-purpose knives, punches and axles”. The marking guide keys D.
(C) is the trap. The same syllabus listed punches under high carbon steel too, and 41.89% of the cohort chose C against 42.55% for D. (B) matches axles but not punches, and (A) is far too soft for either.
The word tempered is scenery here. The question tests carbon-steel selection. The 2025 syllabus has no ultra-high band (high-carbon steel now runs from 0.60% to 2.0%), so this item cannot be set in this form in 2026.
Answer
(D) ultra-high carbon steel
New content for 2026
Normalising, quenching and martensite appear nowhere in the 2019 syllabus. Tempering appears only as the phrase “highly tempered … punches and axles” in an application list, which is where 2024 Question 2 came from.
The one related dot point that did exist, on the effects of processing on grain structure, sat in Unit 1. The external exam has never assessed Unit 1.
So the practice questions at the end of this guide are my best guesses at what will be asked. They follow the syllabus dot point and the marking-guide grammar of the neighbouring materials questions.
What the syllabus says
This is the Unit 4 Topic 3 dot point, word for word:
Identify and explain the effects of materials processing and manufacturing techniques on ferrous metal grain structure in the context of
•hot and cold working, including rolling and forging
•full annealing and process annealing
•normalising
•hardening, e.g. water quenched, oil quenched, air cooled and furnace cooled, and the martensitic reaction and the rate of cooling for eutectoid steel (0.83% carbon)
•tempering, i.e. tempered martensite structure.
The syllabus sets the two hardening examples out as separate sub-points.
Two cognitive verbs are named. Identify means recognise and name something specific, so a short answer will do. Explain means make something clear by revealing a cause, reason or relationship. Here that means naming the change in grain structure and the property that follows from it.
The phrase “in the context of” makes the five sub-points the examinable list. Casting, welding and extrusion were in the old Unit 1 dot point and are not in this one. In the 2025 syllabus they sit in Unit 2, which the external exam does not assess.
What the formula book gives you
The formula book gives you nothing for this topic. There are no cooling diagrams, transformation temperatures or process descriptions, so the topic is all recall.
Learn two numbers exactly. The first is 0.83% carbon, the eutectoid composition named in the dot point. The second is about 723 °C, the eutectoid temperature from the iron–carbon diagram.
Part 2
Working the metal: what happens to the grains
Hot working shapes the metal by rolling or forging above its recrystallisation temperature. New grains keep forming as it is shaped, so it stays soft and workable.
Cold working shapes the metal below that temperature. The grains are stretched and distorted, which makes the metal harder and stronger but less ductile. Keep cold working and the metal eventually becomes too hard to work any further. This is called work hardening.
Cold working distorts the grains. Annealing grows new ones in their place.
Full annealing heats the steel into the austenite range and then cools it very slowly, usually in the furnace. New grains form and the structure becomes coarse pearlite, which is soft, ductile and easy to machine or form.
Process annealing is a lower-temperature version, used to restore ductility to cold-worked steel between forming operations. It stays below the lower critical temperature, so no austenite forms. The distorted ferrite recrystallises, but the steel is never austenitised.
Normalising heats the steel the same way as full annealing but cools it in still air. The faster cooling gives finer pearlite and a finer, more uniform grain, so the steel ends up stronger and tougher than annealed steel, but not as soft.
Process
Grain structure, then properties
Hot working
Rolling or forging above the recrystallisation temperature. Grains deform and immediately recrystallise into new grains as the metal is shaped. The metal stays soft and workable, so large reductions are possible.
Cold working
Working below the recrystallisation temperature. Grains stretch and distort in the direction of working, with no recrystallisation. The metal becomes harder and stronger but less ductile, and eventually too hard to work further (work hardening).
Process annealing
Stays below the lower critical temperature, so no austenite forms. The distorted ferrite recrystallises, which restores enough ductility to continue forming.
Full annealing
Heated into the austenite range, then cooled very slowly in the furnace to coarse pearlite. The steel is soft, ductile and easy to machine, with the lowest strength.
Normalising
Heated into the austenite range, then cooled in still air to fine pearlite. The steel is stronger and tougher than annealed steel, with a more uniform grain.
Full annealing and normalising differ only in how they cool
Both heat the steel into the austenite range. Full annealing then cools it in the furnace, over hours. Normalising takes it out and lets it cool in still air, over minutes.
Slower cooling gives coarser pearlite and a softer steel. That one difference separates the two processes, and it is the thing you are most likely to be asked to explain.
Part 3
Hardening, martensite and tempering
Hardening heats the steel into the austenite range and then quenches it, which means cooling it very fast. Water quenching is the most severe and oil quenching is gentler. Air cooling and furnace cooling are slower again. The faster the cooling, the harder and more brittle the steel.
All four cooling routes start the same way, by heating the steel into the austenite field. For eutectoid 0.83% C steel that means just above 723 °C. Lower-carbon steels must be heated higher, above the upper critical line. Only the cooling differs, and the cooling decides the structure.
Schematic cooling curves for a eutectoid (0.83% C) steel, all starting at 900 °C. The time axis is logarithmic and only indicative: a quench takes seconds, air cooling takes minutes and furnace cooling takes hours.
Cooling
Result
Water quench (fastest)
Fully martensitic, maximum hardness, very brittle, risk of cracking
Oil quench (fast)
Mostly martensite (thicker plain-carbon sections may also form some fine pearlite), with less distortion and cracking risk than water
Air cool (moderate)
Fine pearlite, strong and tough. This is normalising.
Furnace cool (slowest)
Coarse pearlite, soft and ductile. This is full annealing.
Why fast cooling produces martensite
When austenite cools slowly, the carbon atoms have time to move out of the iron lattice and gather into cementite. The cementite pairs with ferrite to build pearlite.
Quench the steel and there is no time for that movement. The carbon stays trapped where it is and forces the iron lattice out of shape. That strained, carbon-trapped structure is martensite. It is very hard because the distorted lattice resists deformation, and very brittle for the same reason.
The dot point names eutectoid steel (0.83% carbon) because that is the composition where the change is simplest to describe. All of the austenite becomes pearlite on slow cooling, or all of it becomes martensite on fast cooling.
Quench, then temper
Quenched martensite is too brittle to use. A chisel that was quenched and left alone would shatter on the first hammer blow.
Tempering reheats the quenched steel to a moderate temperature and holds it there. Some carbon comes out of the strained lattice, which relieves the internal stress. The steel loses a little hardness and gains a great deal of toughness. The structure is called tempered martensite.
Tempering gives away hardness to gain toughness, and the tempering temperature sets how much. Nearly every hardened tool is tempered afterwards. This is the explain question I would expect first in this topic, so be able to write it in three sentences.
Part 4
Writing a heat treatment answer
Every dot point in the neighbouring materials questions rewards the same chain: the process, then the grain structure, then the property. I expect heat treatment questions to be marked the same way.
The answer chain
1Name the process and what it does thermally. “Normalising heats the steel into the austenite range and cools it in still air.”
2Say what happens to the structure. “The faster cooling produces finer pearlite and a finer, more uniform grain.”
3Name the property that follows. “This gives higher strength and toughness than annealing.”
4Link it to the use, if the question names one. “…which suits components that must carry load without fracturing.”
On the evidence of 2024 Question 14 and 2022 Question 15, steps 2 and 3 are where the marks sit. Naming the process on its own earns little.
How the marks are likely to be allocated
No QCAA marking guide has ever marked a heat treatment question, so there is nothing to quote. The table below is modelled on the dot points QCAA uses for the steels questions, which have kept the same grammar across all six years.
Predicted dot point
What would earn it
identifies the process and the temperature range it uses
Naming the process and its temperature
identifies the effect of the process on the grain structure
The change in grain structure
explains how the grain structure change produces the resulting property
The property, with the link to the structure
explains why this makes the material suitable for the stated application
The link to the application
This is a prediction
Every criteria statement in this guide is derived. None is quoted. The wording follows the 2022, 2023 and 2024 materials marking guides (“identifies that…”, “explains appropriately using wording that indicates…”, closing with “or other suitable response consistent with a reasonable understanding”). No QCAA guide has marked a heat treatment question yet.
Treat the marks here as a reasonable expectation of the shape of the marking. There is no published standard yet.
Count the marks in the question
Count the numbers the question names. Add one for a decision if a decision is asked for. Where the question names no number, assume one mark per distinct thing you can name or draw. For a sketch, check how the marks split. Most guides give 1 mark for the whole annotated sketch, 2022 Q11 gave 1 per labelled feature, and only 2020 Q13 split a drawing mark from an annotation mark.
If your count matches the mark value, you have the plan. If it does not, read the question again before you write.
Then write one sentence per number, in the order the question gave them. A marker working down a dot-point list should be able to tick each one without hunting. The 2025 subject report recommends underlining key points and noting the cognitions and the number of marks.
Which material suits highly tempered punches and axles. It tests carbon-steel selection. Published answer D, ultra-high carbon steel, a category the 2025 syllabus no longer uses.
That is the complete list. It has one item in six years, and it is not mainly about this topic.
How to revise a topic with no past questions
It still needs revising. It is new subject matter with a full dot point, and QCAA writes questions to the dot points.
Its form is also easy to predict, because the syllabus names exactly five groups of processes and two verbs. Learn every process in the five groups. For each one, be able to explain the change in grain structure and the property that follows. That covers everything the dot point allows.
Self-checks to run inside the question
Checkpoint
How to run it
Which process is this?
There are five: hot and cold working, full and process annealing, normalising, hardening and tempering.
Did I describe the grain structure?
The marks are for the grain structure. Naming the process is only the start.
Faster or slower cooling?
Faster means harder and more brittle. Slower means softer and more ductile.
Full annealing or normalising?
Same heating, different cooling, furnace against still air.
Did I say why tempering follows quenching?
Because quenched martensite is too brittle to use.
Hot or cold working?
Above the recrystallisation temperature, or below it.
Is the verb identify or explain?
Identify wants a name. Explain wants a cause.
What changes for 2026: this whole topic
Heat treatment is new to the external exam. The QCAA Engineering 2025 general senior syllabus revision report (July 2024) lists heat treatments as introduced in Unit 4. Comparing the two syllabuses shows the Unit 4 dot point now names hot and cold working, annealing, normalising, quenching media, the martensitic reaction and tempering. Processing techniques also appear in Unit 2, which the exam does not assess.
That has two consequences. First, there are no past questions to practise, so the practice below is written from the dot points. Second, my prediction is that the dot point itself is the best guide to what a 2026 question will look like.
Game plan
Your game plan for heat treatment
1Identify the process the question names, or the one the scenario needs.
2Say what it does thermally: the temperature it reaches and how it cools.
3Say what happens to the grain structure: distorted, recrystallised, coarse or fine pearlite, martensite or tempered martensite.
4Name the property that follows, and link it to the use if the question gives one.
5If two treatments are compared, make every sentence comparative and finish with a decision.
Four questions I have written from the dot point. No past example exists for any of them, so the mark values follow the shape of comparable materials questions.
Which heat treatment process cools steel in still air after heating it into the austenite range?
Normalising heats the steel into the austenite range and cools it in still air, which gives fine pearlite and a fine, uniform grain.
(A) Full annealing uses the same heating but cools in the furnace. (C) Tempering reheats quenched steel to a moderate temperature and never goes into the austenite range. (D) Water quenching uses the same heating but the fastest possible cooling.
Three of the options are cooling routes (furnace, still air and water) and one is a reheat. If you learned the cooling sequence, only normalising cools in still air. If you learned the names as separate words, you will be guessing between A and B.
Answer
(B) normalising
Question 2 of 4
Skill 1: hot and cold working · Simple familiar · [4 marks]
Explain how cold working changes the grain structure of a low carbon steel, and describe two effects this has on its mechanical properties.
Explain the grain change by giving its cause. Describe each property effect.
A response that would earn all four marks:
“Cold working shapes the steel below its recrystallisation temperature, so the grains are stretched and distorted in the direction of working and no new grains form to replace them. The distorted grain structure resists further deformation, so the steel becomes harder and stronger. It also becomes less ductile, so it will crack if working continues without an intermediate anneal.”
Predicted criteria: the response
Marks
identifies that cold working occurs below the recrystallisation temperature
1
explains that the grains become elongated and distorted, with no recrystallisation
1
describes that the steel becomes harder or stronger
1
describes that the steel becomes less ductile
1
Work hardening is accepted as the named effect. The shape copies 2024 Question 14 (4 marks), which explains a structure and then gives two property consequences.
Answer
Grains stretched and distorted, no recrystallisation. Harder and stronger, less ductile.
A manufacturer produces high carbon steel chisels. The blades are heated into the austenite range, quenched in oil, and then tempered.
Explain the effect of each of these two treatments on the grain structure of the steel and on the properties of the finished chisel.
A response that would earn all five marks:
“Quenching in oil cools the steel from the austenite range too quickly for the carbon to diffuse out of the lattice, so pearlite cannot form. The carbon is trapped, producing a distorted structure called martensite.”
“Martensite is extremely hard and wear resistant, which lets the chisel hold a sharp cutting edge. It is also very brittle and would fracture under hammer blows.”
“Tempering reheats the quenched blade to a moderate temperature, letting some carbon leave the strained lattice and relieving the internal stress. The structure becomes tempered martensite.”
“The chisel loses a little hardness but gains considerable toughness, so it holds its edge and also survives repeated impact.”
Predicted criteria: the response
Marks
explains that quenching cools the steel too fast for carbon to diffuse, so martensite forms rather than pearlite
1
identifies that martensite is very hard and very brittle
1
links the hardness to the chisel holding a cutting edge
1
explains that tempering reheats the steel, relieving lattice strain to form tempered martensite
1
explains that tempering trades a little hardness for a large gain in toughness, so the chisel withstands hammer blows
1
The shape copies 2020 Question 17 (5 marks), which asks how a structure gives properties in the context of an application.
Answer
Quench: martensite, very hard but brittle. Temper: tempered martensite, a little less hard but much tougher.
A component is machined from a bar of medium carbon steel that has been extensively cold worked, and must finish with good toughness and a uniform fine grain.
Compare full annealing and normalising as the final heat treatment for this component, and determine which is more appropriate. Justify your choice with reference to grain structure and mechanical properties.
This follows the shape of 2022 Question 15, a comparison of two options with a justified decision at the end. On the evidence of that marking guide, every statement must be comparative, and the decision mark depends on naming the property the scenario asks for.
A response that would earn all six marks:
“Both processes heat the steel into the austenite range and recrystallise the distorted cold-worked grains into new equiaxed grains. Full annealing then cools the steel in the furnace, far more slowly than normalising cools it in still air.”
“The slower cooling of annealing produces coarser pearlite and a coarser grain than normalising. Annealed steel is therefore softer and more ductile than normalised steel, but has lower strength. Normalised steel has a finer, more uniform grain than annealed steel, which gives it higher strength and better toughness.”
“Normalising is more appropriate for this component, because it needs good toughness and a uniform fine grain, and only normalising produces the finer grain structure that delivers them.”
Predicted criteria: the response
Marks
identifies that both processes recrystallise the cold-worked grain structure
1
contrasts the cooling rates: furnace cooling against air cooling
1
contrasts the resulting grain structure: coarser pearlite from annealing than from normalising
1
contrasts a mechanical property: annealed steel is softer or more ductile than normalised steel
1
contrasts a second mechanical property: normalised steel has higher strength or better toughness than annealed steel
1
determines that normalising is more appropriate, with a reason referencing the fine grain and toughness
1
Describing annealing in one paragraph and normalising in another, both accurately, would lose the four contrast marks. Choosing normalising because “it is faster and cheaper” is true and worth nothing, because the stem asked for toughness and a fine grain.
Answer
Normalising, because air cooling gives a finer, more uniform grain and better toughness than annealing.
Sources: Engineering 2025 v1.4 general senior syllabus, Unit 4 Topic 3. Engineering 2019 v1.1 general senior syllabus (for the comparison that establishes this as new content). QCAA Engineering 2025 general senior syllabus revision report (July 2024). QCAA Engineering 2024 multiple choice question book, marking guide and subject report (Question 2). QCAA Engineering external assessment marking guides 2020 to 2025 (for dot-point grammar only, as no heat treatment question exists in the past papers). QCAA Engineering 2025 subject report.
