Compare the maximum heat shaping temperatures for quenched and tempered steel and all other steels. Which is higher?

Compare the maximum heat shaping temperatures for quenched and tempered steel and all other steels. Which is higher?

• A. All other steels (650 C) is higher than quenched and tempered (590 C).
• B. Quenched and tempered (590 C) is higher.
• C. They are equal.
• D. All other steels are lower but not by much.

Answer: (D)

The key idea is how tempering affects a steel’s resistance to heat during shaping. Quenched and tempered steel has been through a hardening process that gives high strength and hardness, but it also lowers the steel’s tolerance to heating. Heating quenched and tempered steel above the tempering range can cause loss of hardness or unwanted microstructural changes, so the maximum heat shaping temperature is kept relatively modest. In contrast, steels that have not undergone quenching and tempering (the “all other steels”) can be heated to higher temperatures without risking the same tempering effects. This means their allowable maximum shaping temperature is higher. Thus, all other steels have a higher maximum heat shaping temperature than quenched and tempered steel (typically around 650 C vs about 590 C).

The key idea is how tempering affects a steel’s resistance to heat during shaping. Quenched and tempered steel has been through a hardening process that gives high strength and hardness, but it also lowers the steel’s tolerance to heating. Heating quenched and tempered steel above the tempering range can cause loss of hardness or unwanted microstructural changes, so the maximum heat shaping temperature is kept relatively modest.

In contrast, steels that have not undergone quenching and tempering (the “all other steels”) can be heated to higher temperatures without risking the same tempering effects. This means their allowable maximum shaping temperature is higher.

Thus, all other steels have a higher maximum heat shaping temperature than quenched and tempered steel (typically around 650 C vs about 590 C).