Question 2
Which material is most suitable for highly tempered punches and axles?
Not quite. Mild carbon steel, 0.15% to 0.30% under the 2019 syllabus, is far too soft for a punch. It also barely hardens when quenched, so there would be little for tempering to work on. In 2024, 3.6% of Queensland students chose (A).
Not quite. Axles are on the medium carbon list, but punches are not, and the option has to suit both. The 2019 syllabus put this exact pair under ultra-high carbon steel. In 2024, 11.5% of Queensland students chose (B).
Not quite, and this is the trap that caught almost as many students as the key. Punches were on the 2019 high carbon list too, but “highly tempered … punches and axles” was the 2019 description of ultra-high carbon steel, 1.25% to 2.0%. The marking guide keys (D). In 2024, 41.9% of Queensland students chose (C).
That is it. The wording comes straight from the 2019 syllabus list for ultra-high carbon steel. Step through the hints below to see why. In 2024, 42.6% of Queensland students chose (D).
This paper was set under the 2019 syllabus, which had five plain-carbon bands. The 2019 bands are on the axis.
Its application list for ultra-high carbon steel was “highly tempered non-industrial-purpose knives, punches and axles”. The stem lifts that phrase almost word for word, so the key is (D).
(C) is the trap. The 2019 syllabus listed punches under high carbon steel as well, so a student who recalled punches alone had two candidates.
The words that settle it are “highly tempered” and “axles”. Only the ultra-high list had both. (B) fits axles but not punches, and (A) fits neither.
Tempering is new examinable content for 2026, so learn what the word means. Use the heat treatment buttons on the left.
Quenching from the austenite range traps the carbon and forms martensite, which is very hard and very brittle. Tempering reheats it below 723 °C. Some carbon leaves the strained lattice, giving tempered martensite, which gives up a little hardness for a lot of toughness.
More carbon makes harder martensite, which is why a punch is made from a high carbon steel and then tempered.
For 2026 the ultra-high band is gone. High carbon steel now runs from 0.60% to 2.0% and has punches on its list. Axles are on the medium carbon list.
So this item cannot be set in this form in 2026. What transfers is the habit of matching the stem’s wording to the syllabus list, and the meaning of tempering.
“Highly tempered … punches and axles” is the 2019 syllabus description of ultra-high carbon steel, 1.25% to 2.0% carbon. The QCAA marking guide keys (D).
The most common wrong answer was (C), chosen by 41.9% against 42.6% for the key. Punches were on the 2019 high carbon list too. The QCAA marking guide keys (D), so go with it over any unofficial answer key. For 2026 there is no ultra-high band, and heat treatment, including tempering, is examinable in its own right.
Only mark this done when you could do it without help. Reading the solution does not count.
Question wording and any figures are from the 2024 QCAA Engineering external assessment, © State of Queensland (QCAA) 2024, licensed under CC BY 4.0, and have been adapted, except where a third-party source is named. Tangent Tuition is not affiliated with the QCAA.
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