Regular Article

Effect of inclusions on mechanical properties of Nb stabilized austenitic stainless steels (316Nb) with centrifugal and sand casting techniques

¹ Istanbul Naval Shipyard, Istanbul, Turkey
² Department of Mechanical Engineering, Kocaeli University, Kocaeli, Turkey

^* e-mail: e-mail: mehmetturker75@gmail.com

Received: 1 November 2017
Accepted: 21 November 2017

Abstract

In this study, 316Nb stabilized austenitic stainless steel pieces were produced via sand and centrifugal casting method in order to be investigated. Heat treatments were done in two stages, and cooling was made in various quenching mediums. As-cast parts and the parts with only the highest and the lowest tensile strength were investigated. Metallographical analyses were made and the content of non-metallic inclusions was examined. Various types of carbides in microstructures were determined by means of SEM-EDX analysis. The sand casting samples had more non-metallic inclusions than the centrifugal casting ones. After the tensile tests, it was seen that these inclusions had significant effect on the mechanical properties. The tensile strength, the yield strength, the elongation and the hardness values of the centrifugal casting samples were higher than the sand casting ones. Investigating the SEM-EDX analyses, it was determined that the sand cast samples had chromium carbides in small quantities, in addition to niobium carbides. Centrifugal cast parts had niobium carbides.