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MATERIALS SCIENCE
ArticleName Examining the microstructure of production defects in brass and copper billets for industrial applications
DOI 10.17580/tsm.2018.11.10
ArticleAuthor Tkachuk G. A., Maltsev V. A., Shimov V. V., Chikova O. A.
ArticleAuthorData

Ural Federal University named after the First President of Russia B. N. Yeltsin, Yekaterinburg, Russia:

G. A. Tkachuk, Senior Lecturer, e-mail: g.shardakova@mail.ru
V. A. Maltsev, Director
V. V. Shimov, Head of Department
O. A. Chikova, Professor

Abstract

This paper describes the results of a metallographic study that looked at the production defects observed in alloyed wrought brasses of L63, L68, LS 59-1А grades and in М2 copper processed by Revda Non-Ferrous Metal Processing Works. Conventional optical microscopy was applied for the microstructural analysis of the test pieces. To understand how production defects evolved, the authors looked at different processing stages – ingot, pressing billet, rolling billet, heat treatment, drawing. Three types of defects were observed: exogenous nonmetallic inclusions, segregation inclusions, discontinuities and cavities. No correlation was found between the microstructural characteristics and production defects. The authors demonstrate how one type of defects (e.g. exogenous nonmetallic inclusions, segregation inclusions, and cavities), if not eliminated at the initial processing stage, would lead to other defects (e.g. cracks) and a final fracture of the billet at one of the final processing stages. It was established that the L68 brass billets that are ready to crack would typically acquire a dual-phase structure (α + β). Apart from the main phases, i. e. α-solid solution of alloying elements in copper and β-phase on the basis of the CuZn electron compound, billets made from the LS 59-1А leaded brass grade contain free lead particles. Lead inclusions, as well as exogenous nonmetallic inclusions, tend to localize at grain boundaries or in the interdendritic regions. Exogenous nonmetallic inclusions are present in the microstructure of the L63, L68, LS 59-1А brass grades and in М2 copper at all stages of processing. It was established that the reliability of machines and structures designed for critical applications can only be ensured through quality control by metallography.

keywords Brass, copper, microstructure, production defects, workpiece, casting, pressing, rolling, quality control
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