Machinable Leaded and Eco-Friendly Brass Alloys for High Performance Manufacturing Processes: A Critical Review

Paul Stavroulakis,Anagnostis I Toulfatzis,Alkiviadis S Paipetis,George A Pantazopoulos

doi:10.3390/met12020246

Paul Stavroulakis, Anagnostis I Toulfatzis + Show 2 more

Open Access

https://doi.org/10.3390/met12020246

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Journal: Metals	Publication Date: Jan 27, 2022
Citations: 9	License type: CC BY 4.0

Affiliation: University of Sheffield, University of Ioannina

Abstract

The recent environmental/health and safety regulations placed restrictions of use of hazardous substances on critical manufacturing sectors and consumers’ products. Brass alloys specifically face a challenging issue concerning the elimination of lead (Pb) which has been a critical element affecting both the machinability and overall quality and efficiency of their manufacturing process. The adaptation of novel materials and processing routes in the green economy constitutes a crucial decision for competitive business and industry growth as a worldwide perspective with substantial industrial and social impact. This paper aims to review the emergent innovative and sustainable material solutions in the manufacturing industry, in line with environmental regulations, by highlighting smart alloy design practices and promoting new and innovative approaches for material selection and manufacturing process optimisation. In this review we analyse the processing, structure and machinability aspects of leaded brasses and underline the major guidelines and research methodologies required to overcome this technical challenge and further improve the mechanical properties and machinability of lead-free brass alloys. Various alloying and processing strategies were reviewed together with the most important failure types, as they were extracted from the existing industrial and technological experience, covering more than 20 years of research in this field.

Highlights

Cu–Zn alloys are widely used industrial materials because of their superior properties such as high corrosion resistance, low friction coefficient, non-magnetism, good plastic deformability and machinability [1,2,3,4]
Brasses are used in a wide range of applications ranging from plumbing fittings to architectural hardware and decorations
The machinability of said alloys has been heavily dependent on the incorporation of Pb, which has traditionally been the key to their success

Summary

Introduction

Cu–Zn alloys (brasses) are widely used industrial materials because of their superior properties such as high corrosion resistance, low friction coefficient, non-magnetism, good plastic deformability (forgeability) and machinability [1,2,3,4]. Owing to its low solidification temperature, lead acts as a filler for micropores that form during casting These lead particles improve the machinability of brasses through their dual functionality as a lubricant and a stress concentration point, promoting the formation of small discontinuous chips and minimising tool wear [8]. The gradual intake of particulate lead would elevate the blood lead levels, eventually leading to poisoning with devastating effects to human health. These include slower cognitive development in children, hypertension and even renal failure [10,11,12,13,14,15,16]. The development of lead-free brasses became a focal research point to ensure compliance with the regulatory standards and improve quality of life [17,18]

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