At what temperature range does ordinary steel begin to lose strength and elasticity significantly?

Ordinary steel begins to lose strength and elasticity significantly at elevated temperatures due to the alterations in its microstructure. As temperature increases, the physical properties of steel start to change, which can lead to a significant reduction in its mechanical performance.

The correct temperature range, from 600 to 700°F, is critical because, within this threshold, the tempering effects and the initiation of transformations in the crystalline structure become pronounced. The yield strength and elastic modulus can drop significantly, affecting the steel’s load-bearing capacity.

Operating in this temperature range can lead to issues such as permanent deformation or failure under load, which are crucial considerations in mechanical design, especially for components that must maintain their integrity under heat exposure. Thus, understanding the temperature limits for steel is essential in applications involving high-temperature environments, such as in engines or structures exposed to high heat.

In contrast, the other ranges (900 - 1000°F, 800 - 900°F, and 750 - 850°F) indicate temperatures where the properties of steel are affected further, but the initial significant loss of strength occurs at the lower temperatures specified.