Final answer:
Carburizing must be performed at temperatures above the A₁ temperature, as it is a process that requires the steel to be in the austenite phase, which can absorb more carbon. The statement presented is false.
Step-by-step explanation:
The statement that carburizing must be performed at temperatures below the A₁ temperature is false.
Carburizing is a heat treatment process where carbon is added to the surface of low-carbon steel at high temperatures, generally above the A₁ temperature, also known as the lower critical temperature. This results in a high-carbon surface layer with improved wear resistance and hardness while maintaining a tougher and more ductile interior.
In steel, the A₁ temperature is the temperature at which the steel transforms from ferrite to austenite during heating. In the carburizing process, the steel is typically heated to a temperature of 160°C to 200°C above A₁ so that the austenite phase can absorb more carbon due to its greater solubility for carbon compared to ferrite. Therefore, correct carburizing takes place above the A₁ temperature.