Investigation of Non-Metallic Inclusions Constituting Sand Marks by Electron-Diffraction Reflection Method

Abstract

Electron-diffraction reflection methd is applied for the identification of nonmetallic inclusions in steels.
The local analysis of nonmetallic inclusions is very difficult with the exception of use of an electron probe microanalyser developed recently. Notwithstanding the use of the electron probe microanalyser, only the composition of elements constituting the nonmetallic inclusions can be known. On the other hand by means of a crystalographical determination, the modification of the compound constituting the sand marks, could be identified. Hence an electron diffraction method may be considered preferable for the purpose which presume the origin of the sand marks from the knowledge of nonmetallic inclusions constituting it.
The results obtained are as follows:
1) Corundum (α Al₂O₃) and Hercynite (FeO·Al₂O₃) are identified in the nonmetallic inclusions constituting the complicated or mixed type sand-marks in Cr-Mo steel deoxidized with aluminum
2) Titanium nitride (TiN) is identified from the sand marks in 18-8 stainless steel containing titanium and molybdenum.