When a metal is undergoing heat treatment,...

Question 1 / 270705eccef9cbacbc34ba4d45bcd

Question 1 of 270705eccef9cbacbc34ba4d45bcd

When a metal is undergoing heat treatment, what happens when the metal is heated above its critical temperature?

Question 1 of 27070

When a metal is undergoing heat treatment, what happens when the metal is heated above its critical temperature?

🔍 Key Concepts

• Heat treatment critical temperature in metals • Difference between phase change (solid/liquid/gas) and internal crystal structure changes • What happens to steel when it is heated for hardening or annealing

💭 Think About

• Ask yourself: in normal heat treatment of steel parts (like for hardening), do we normally melt the steel, or keep it solid while changing its properties? • Which of the options describes a change you’d see on a phase diagram of water (ice–water–steam), and which describes something happening inside the solid metal? • Think about why heating to a specific ‘critical’ temperature is important before quenching—what has to change inside the metal first?

✅ Before You Answer

• Identify which choices describe phase changes between solid, liquid, and gas and which choice refers to internal lattice/crystalline changes within a solid. • Remember that in common industrial heat treatments the metal part must remain solid, not melted or vaporized. • Connect the idea of critical temperature with the temperature at which the metal’s internal structure transforms while staying in the same physical state.

Question 1 of 27070

When a metal is undergoing heat treatment, what happens when the metal is heated above its critical temperature?

The metal changes from the solid state to the molten state.

The metal changes from a molten state to a vapor state.

The metal undergoes a change in crystalline structure.

The metal undergoes thermal contraction.

Question 1 / 270705eccef9cbacbc34ba4d45bcd

Question 1 of 270705eccef9cbacbc34ba4d45bcd

When a metal is undergoing heat treatment, what happens when the metal is heated above its critical temperature?

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Question 1 of 27070

When a metal is undergoing heat treatment, what happens when the metal is heated above its critical temperature?