Abstract:

Under the current technological conditions, inclusions have become inevitable in steel. To investigate the impact of micron inclusions on the mechanical properties of metals, vacuum arc melting was used to control the mass fractions (contents) of micron Al₂O₃ powder at 0%, 0.2%, 0.6%, 1%, and 2%, thereby preparing samples with different contents of micron inclusions. Statistical analysis of inclusion sizes via computed tomography imaging and scanning electron microscopy (SEM) revealed that most inclusions had a size of <5 μm. Moreover, the quantity of inclusions proportionally increased with increasing Al₂O₃ content. Mechanical properties were tested using the indentation method; the test results indicated that the addition of a certain amount of micron inclusions can enhance the mechanical performance of a metal. However, when the Al₂O₃ content exceeded 1%, the tensile strength increase slowed down and the yield strength decreased. SEM observations revealed that at high Al₂O₃ content, inclusions tended to agglomerate into large inclusions or clusters, which caused local stress concentration. This phenomenon in turn negatively affected the strengthening effect of the micron inclusions on the mechanical properties of the investigated metal.

Key words: micron inclusions, inclusion statistics, scanning electron microscopy, indentation method, mechanical properties