On the Extraction of Large Inclusions in Steel by Slime Method and Classification According to the Size

Abstract

A study has been carried out to establish the rapid and reliable method of isolation of large inclusions (>50μ) in steels and classification according to the size.
The results are as follows.
1) A large quantity of slime obtained by electrolysis of steel are separated from inclusions about in an hour by ultrasonic sieving method (applied except Al killed steel) or by elutriation method using the improved apparatus.
2) A small quantity of cementite and metallic iron particles are separated magnetically, and nonmagnetic iron rust is also separated similarly after the reduction to metallic iron. The quality of inclusions is not affected by this treatment. Inclusions attached to magnet with magnetic substance must be recovered by the Br₂-CH₃OH method or by picking up them observing through a microscope.
3) Using the sieves, the obtained inclusions are classified reliably according to the size.
4) The shape of silicate inclusions is hardly damaged by the ultrasonic vibration, but chemical treatment changes markedly their composition. On the other hand aluminate inclusions are chemically stable and very brittle.