Investigation of High-strength Lead-free Machinable Cu40Zn Duplex Graphite Brasses by Powder Metallurgy

Abstract

Graphite was proposed as candidate to substitute lead for increasing machinability of Cu40Zn brass in this study. Cr, Fe, Ti and Sn were used as trace alloying elements to improve the mechanical properties and strengthen graphite/brass boundary bonding. The brass powder prepared by water atomisation process were premixed with graphite particles and consolidated by warm compact. The sintered billet was hot extruded to increase density and improve microstructure. The super-saturated solid solution of alloying elements precipitated in form of nano/micro scale particles in the subsequent hot working. Graphite particles with appreciate content can improve machinability effectively without deteriorating the mechanical properties. Graphite content and hot working temperatures are essential parameters which affect machinability and mechanical properties of the graphite brasses.

This paper is part of a Themed Issue on Brass Alloys.

Keywords:

• Brass alloys
• Graphite
• Lead-free
• Powder metallurgy
• Mechanical properties
• Machinability

Acknowledgements

This work was partially supported by the Japan Society for the Promotion of Science via a Grant-in-Aid for Scientific Research (A) (Grant number 25249102). The authors are grateful for the financial support of the National Natural Science Foundation of China (Grant Number 51571160). The authors would like to thank the Pivot Innovation Team of Shaanxi Electric Materials and Infiltration Technique 2012KCT-25 (Grant number 15JS071) for partial financial support.