SLAG COMPOUNDS FORMED FROM THE NODULARIZATION TREATMENT UNTIL POURING THE MOLDS TO PRODUCE SPHEROIDAL GRAPHITE CAST IRON PARTS

摘要

The present work is included as part of research undertaken about the effect of raw materials and some processing variables on the origin and the composition of those slag compounds formed during the manufacturing of spheroidal graphite cast iron parts. The composition and phases present in a number of slag samples obtained from Mg-treated melts have been investigated and discussed. Both slag samples which are floating in the melts surface and those adhered to the refractory lining of the pouring device have been analyzed. Finally, two different morphologies of slag inclusions found on cast iron parts have been studied and then compared to the results obtained from the previous slag samples characterization. It has been observed that composition of slag varies along the different steps of the production process as a function of the oxidizing level of the gas which is in contact with the melts and also of the remaining time in the ladle. Regarding crystallinity of slag, it has been found that it strongly depends on its composition and formation rate. All the information obtained from the study of slag formed before pouring process has been then used for estimating the origin of the slag inclusions commonly found in manufactured cast parts.