 Select the correct statements from the following list.
a), c) and d) correct - incorrect, nitriding tends to produce a smaller case hardened depth than
carburising for similar process times. Carburising produces hardened surface
layers by the formation of martensite and therefore does not require carbide
forming elements to be present whereas nitriding relies on the formation of
nitrides hence strong nitride formers are required. Try again. |
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b) and c) correct - incorrect, carburising occurs at high temperatures (>850°C) and on quenching
distortion of the component can result, low temperature surface hardening
treatments such as nitriding produce less distortion. Carburising produces
hardened surface layers by the formation of martensite and therefore does not
require carbide forming elements to be present . Try again. |
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c) and e) correct - incorrect, whilst e) is correct c) is not as carburising produces hardened
surface layers by the formation of martensite and therefore does not require
carbide forming elements to be present . Try again. |
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d) correct - incorrect, whilst d) is correct it is not the only correct statement in the
list. Try again. |
d) and e) correct - Correct. |
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Try again. |
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Click on your answer to check and make a note of the answer on your notepad.
To answer the next question you will need to review how surface
hardness can be controlled. Click here
for further information |
NOTEPAD
Three most important properties for an engineering steel for a gear in an
automotive gear box: Surface Hardness, Wear Resistance and Fatigue Resistance
Technique used to determine the hardenability of a steel: Jominy End Quench
Correct statement (s) regarding the measure of
hardness and hardenability of a steel:
Increasing the Mn content increases the hardenability of the steel but
not the maximum hardness achieved.
+ Controlled additions of alloying elements such as Cr, Ni, B and Mo
can be used to increase the hardenability of a steel such that
martensite can be obtained on air cooling of a 10mm bar.
Correct statement (s) regarding surface hardness
techniques:
Nitriding grades of steel must contain strong nitride forming elements
such as Cr, Al and / or V.
+ Induction hardening is a versatile technique allowing a range of
compositions to be hardened to a range of case depths with little
distortion produced.
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