Question 4
Low carbon steel wire becomes hard and brittle after it is cold drawn.
Which process restores the ductility of the wire?
Not quite. Hardening raises hardness, the opposite of what you need.
That is it. Step through the hints below to see why.
Not quite. Tempering reheats quenched steel. Your wire has been cold worked, not quenched.
Not quite. Cold rolling is more cold working, which makes your wire harder still.
The cold drawn wire has distorted, stretched grains. Each test shows what the process does to it. Process annealing grows new grains in place of the distorted ones.
Hardening raises hardness. The wire is already hard and brittle, so this is the opposite of what is needed. Not this one.
The wire is heated below the lower critical temperature. The distorted grains recrystallise and ductility returns. This is the one.
Tempering reheats quenched steel. This wire has been cold worked, not quenched. Not this one.
Cold rolling distorts the grains even further. More cold working makes the wire harder still. Not this one.
Process annealing heats the steel below the lower critical temperature, so the distorted grains recrystallise and ductility returns.
Cold drawing distorts the grains (work hardening). Recrystallisation removes that distortion between cold-working stages.
Process annealing heats the steel below the lower critical temperature, so the distorted grains recrystallise and ductility returns.
New for 2026: QCAA has not examined this yet
No past QCAA question tests heat treatment, so compare the structure of the question instead.
Only mark this done when you could do it without help. Reading the solution does not count.
A Tangent Tuition mock exam question. It is not a past QCAA question, and Tangent Tuition is not affiliated with the QCAA.
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