Question

Why is steel tempered after being hardened?

A. To increase its hardness and ductility
B . To increase its strength and decrease internal stresses
C. To relieve its internal stresses and reduce its brittleness

Answer 1

Steel is tempered after being hardened to balance its strength and ductility, by relieving internal stresses and reducing brittleness. This ensures the material's durability and resistance to cracking under stress.

Step-by-step explanation:

Steel is tempered after being hardened to relieve internal stresses and reduce its brittleness. Hardening steel increases its strength but also makes it very brittle and introduces internal stresses. Tempering is a process of heating the hardened steel to a lower temperature, then cooling it, to achieve better balance between hardness and ductility. This process is crucial because although a hardened steel is stronger, a material that is too brittle can be prone to cracking and breaking under stress.

For example, high carbon steel contains up to about 1.5% of carbon, making it very hard but also more brittle. By tempering hardened steel, its strength is maintained while making it less susceptible to failures that can occur due to brittleness and internal stresses which are common in untempered, hardened steel components.

Answer 2

Steel is tempered after being hardened to balance its strength and ductility, by relieving internal stresses and reducing brittleness. This ensures the material's durability and resistance to cracking under stress.

Step-by-step explanation:

Steel is tempered after being hardened to relieve internal stresses and reduce its brittleness. Hardening steel increases its strength but also makes it very brittle and introduces internal stresses. Tempering is a process of heating the hardened steel to a lower temperature, then cooling it, to achieve better balance between hardness and ductility. This process is crucial because although a hardened steel is stronger, a material that is too brittle can be prone to cracking and breaking under stress.

For example, high carbon steel contains up to about 1.5% of carbon, making it very hard but also more brittle. By tempering hardened steel, its strength is maintained while making it less susceptible to failures that can occur due to brittleness and internal stresses which are common in untempered, hardened steel components.