Which testing method is commonly used to detect carburization and decarburization?

Hardness testing is a widely accepted method for detecting carburization and decarburization in materials. Carburization is the introduction of carbon into the surface of a material, typically steel, which increases hardness and wear resistance. Conversely, decarburization involves the loss of carbon from the surface, leading to a decrease in hardness.

By performing hardness testing, one can determine the surface hardness of the material and thereby infer changes in carbon content. Increased hardness usually indicates that carburization has occurred, while a decrease in hardness points to decarburization. Techniques such as the Rockwell or Vickers hardness tests can effectively measure these properties.

In contrast, other methods like radiographic testing, liquid penetrant testing, and ultrasonic testing are more suited for detecting different types of flaws or discontinuities, such as cracks or voids, rather than changes in chemical composition or surface hardness due to carburization and decarburization. Therefore, hardness testing is the most relevant technique for assessing the effects of carbon concentration on the material's properties related to these processes.