Question

Among the following surface hardening processes, steel is heated to the lowest temperature in:

• A. carburizing
• B. cyaniding
• C. nitriding
• D. carbonitriding

Hint:

Nitriding is a surface hardening process that occurs at lower temperatures compared to other methods like carburizing and cyaniding.

Answer 1

The Correct Option is C

Among the listed surface hardening processes, nitriding involves the lowest heating temperature for steel. In nitriding, the steel is typically heated to temperatures between 500°C and 550°C. This is lower than carburizing, cyaniding, and carbonitriding, where the temperatures generally range higher, up to 900°C or more.

Step 1: Process Temperatures
Carburizing typically occurs at high temperatures (850°C to 950°C).
Cyaniding also involves heating steel to relatively high temperatures (800°C to 900°C).
Nitriding is conducted at lower temperatures (500°C to 550°C).
Carbonitriding involves heating to temperatures slightly higher than nitriding but still lower than carburizing (750°C to 900°C).

Step 2: Conclusion
Thus, nitriding involves the lowest temperature for steel heating among the listed surface hardening processes.

Therefore, the correct answer is (C) nitriding.