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The Symbols And Machinability Of Leaded Brass Alloys

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Leaded brass rods are widely used in many applications such as decoration and architecture for electrical and structural systems. Many parts, for example, screws, nuts, bolts, and fittings, are produced by automatic turning operations [10]. Some alloying elements sometimes added to impart special characteristics to brass. Lead, which is insoluble in copper alloys, used to improve machinability of leaded brass. However, Pb and Bi or other elements that are used to improve the machinability often deteriorate the low and high temperature ductility of brass [11]. The content of Pb element is varies between 2.5 and 3.5 %, which make the machining processes at high speed and good surface [12]. The solubility of lead in copper alloys is very low therefore,…show more content…
These alloys exhibit a wide range of useful properties which are basically dependent on the zinc content [15]. Among metal alloys used in casting the most important group consists of copper al¬loys. Depending on the additions, these alloys can be divided into bronzes and brasses. In many cases brasses have properties resem¬bling those of bronzes and are their cheaper, but equivalent substitutes. To all intents and purposes, copper alloys as-cast have soft and plastic matrix, which consists of solid solution crystallites. At their boundaries there are hardening phase elements in peritectic form or free intermetallic phases. By using the chosen alloying elements in optimal quanti¬ties it is possible to obtain the brasses with high machining, technological and utility properties…show more content…
The machinability of copper and copper alloys is improved by lead, sulfur, tellurium, and zinc while it deteriorates when tin and iron are added. Lead in brass alloys with concentrations around 2 wt%, improves machinability by acting as a microscopic chip breaker, and tool lubricant, while they increase the brittleness of the alloy [17]. Lead additions are used to improve machinability. The lead is insoluble in the solid brass and segregates as small globules that help the swarf to break up in to small pieces and may also help to lubricate the cutting tool action. The addition of lead is however, affect cold ductility which may control both the way in which material is produced and the extent to which it can be post-formed after machining
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