Does low-carbon steel undergo any major changes to its microstructure when given a stress-relief treatment at 625° Celsius?

Low-carbon steel typically requires higher temperatures for significant microstructural changes to occur during stress-relief treatment. When subjected to stress-relief treatment, the goal is to alleviate internal stresses that have developed during processes like welding, machining, or shaping. This is often accomplished through heating the steel to a temperature range that allows for the relaxation of these stresses without significantly altering the microstructure.

For low-carbon steel, temperatures that are generally effective for stress relief are typically in the range of 600 to 700°C. However, if the temperature is too low, such as at 625°C, the treatment may not be sufficient to cause substantial effects. While heating to this temperature may help reduce some residual stress, it is not high enough to induce important changes in the microstructure, such as recrystallization or phase transformation. Significant changes generally require temperatures above 650°C, making it crucial for achieving more notable alterations in the grain structure and properties of the steel.

This understanding of stress-relief treatment highlights the importance of temperature in achieving desired outcomes in materials processing, particularly for low-carbon steels where microstructural stability is a key consideration.