Delta iron exists within which temperature range?

• A. 0 C to 768 C
• B. 768 C to 900 C
• C. 900 C to 1400 C
• D. 1400 C to 1530 C

Answer: (D)

Delta iron, also known as δ-iron, is a specific allotrope of iron that exists within a distinct temperature range. The correct temperature range for delta iron is from 1400 °C to 1530 °C. This allotrope is important in the study of iron and steel metallurgy as it represents the body-centered cubic (BCC) structure that iron adopts at elevated temperatures.

At temperatures below 1400 °C, iron exists in different phases, such as alpha iron (ferrite) and gamma iron (austenite), particularly in the ranges of 0 °C to 768 °C and 768 °C to approximately 900 °C. As the temperature increases and reaches above 1400 °C, delta iron becomes the stable phase until it melts at temperatures around 1530 °C.

Understanding the characteristics and temperature ranges of different iron allotropes is essential for applications in metallurgy and material science, as they influence the physical properties and behavior of iron-based materials under various temperatures.