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Leaving Cert Engineering: Case & surface hardening

How often Case & surface hardening comes up on the Engineering papers, every year it was asked, and questions to try.

HL Asked on 8 of the last 9 Higher Level papers, most recently in 2025. most years

OL Asked on 2 of the last 9 Ordinary Level papers, most recently in 2018.

June 2028 is the first exam on the new Engineering course. These come from the 2016–2025 papers, so read them as a guide.

Case & surface hardening, Higher Level(7 marks)

Quick ones on Case & surface hardening.

(a)Pack carburising is used to case harden which steel?
  1. High-carbon tool steel
  2. Low-carbon (mild) steel
  3. Stainless steel 18/8
(b)Why is a carburised part given a refining treatment before the case is hardened?
  1. To remove the leftover carburising compound from the surface
  2. To add more carbon to the case before hardening
  3. The long soak at high temperature coarsened the grain
(c)Gas used in nitriding to harden the surface of alloy steel?
  1. Ammonia
  2. Acetylene
  3. Argon
Show the answers

(a) Low-carbon (mild) steel

(b) The long soak at high temperature coarsened the grain

(c) Ammonia

Your turn: Higher Level questions on Case & surface hardening.

Higher Level

Asked on 8 of the last 9 Higher Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q4
2024Not asked
2023Q4
2022Q4
2021Q4
2019Q3
2018Q3
2017Q3
2016Q3

Links open the State Examinations Commission’s paper for that year.

More Case & surface hardening questions

Case & surface hardening, 3 marks

How are areas that must stay soft protected during carburising?

  1. Galvanising them in molten zinc
  2. Painting them with a film of oil
  3. Copper plating or a clay coating
Show the answer

Copper plating or a clay coating

Copper plating or a fireclay paste stops carbon reaching those areas, e.g. threads that will be machined later. Zinc would melt and oil burns off.

Case & surface hardening, 3 marks

About how much carbon does the case of a carburised part contain?

  1. About 0.1%
  2. About 0.8–0.9%
  3. About 4%
Show the answer

About 0.8–0.9%

Carburising raises the surface of a 0.1–0.2% C steel to about eutectoid carbon, so it can be quenched to hard martensite. 4% would be cast iron.

Ordinary Level

Asked on 2 of the last 9 Ordinary Level papers, most recently in 2018.

Every paper, year by year

YearWhere it came up
2025Not asked
2024Not asked
2023Not asked
2022Not asked
2021Not asked
2019Not asked
2018Q3
2017Q3
2016Not asked

Links open the State Examinations Commission’s paper for that year.

More Case & surface hardening questions

Case & surface hardening, 2 marks

What does case hardening give a mild steel part?

  1. A soft skin with a hard core
  2. The same hardness all the way through
  3. A hard outer skin with a tough core
Show the answer

A hard outer skin with a tough core

Carbon is added to the surface so only the skin can be hardened. The low-carbon core stays tough, so the part resists both wear and shock, e.g. gear teeth.

Case & surface hardening, 2 marks

Pack carburising is used to case harden which metal?

  1. Brass
  2. Mild steel
  3. Aluminium
Show the answer

Mild steel

Mild steel has too little carbon to harden. Packed in a carbon-rich compound and heated, its surface soaks up carbon, then it can be quenched to give a hard skin.

Case & surface hardening, 2 marks

What does pack carburising add to the surface of the steel?

  1. Carbon
  2. Chromium
  3. Zinc
Show the answer

Carbon

Parts are packed in a box of carbon-rich compound and heated for hours. Carbon soaks into the skin, which is then quenched to give a hard case. Adding zinc is galvanising.

Other Engineering topics

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