Experimental Research on Properties of Naval Brass Castings

Abstract

Naval brasses consisting of the α–β duplex phases are a special kind of Cu-Zn alloys. They are known to have excellent corrosion resistance to sea water and marine conditions. The aim of this study is the investigation of properties and behaviours of naval brass parts formed by different casting processes. A medium leaded naval brass alloy with 60 % Cu, 39 % Zn and 1 % Pb approximate composition was used. Several samples were subjected to mechanical testing by means of tensile and hardness tests. Light optical microscopy with image analyser and scanning electron microscopy were used for microstructure observations. The corrosion test was applied in sea water conditions. Results reveal that besides hot forging also casting is a very suitable technique for naval brass shaping. Casting does not have a negative effect on the most important property corrosion resistance. Furthermore, the obtained mechanical properties are satisfactory.

Identification of Colourants and Varnishes in a 14th Century Decorated Wood-Carved Door of the Dionysiou Monastery in Mount Athos

“…Lead white (2PbCO 3 •Pb(OH) 2 ) was identified through the characteristic peak at 1055 cm −1 in its Raman spectrum due to the v 1 , or the symmetric stretch vibration of CO 3 2− [14]. Small black areas (granules) were revealed in the cross sections of several samples, which consisted of carbon black as observed in the appearance of a characteristic broad band at~1584 cm −1 , assigned to a doubly degenerate deformation vibration of the aromatic ring and a second one at~1318 cm −1 , and attributed to a crystalline size effect [18,19].…”

New Results Regarding the Cavitation Destruction Behavior of Heat-Treated CuZn39Pb3 Brass with Different Parameters

“…Because the stainless steels have high costs, for ship propellers, and more recently for pump rotors and vanes, where the destruction by cavitation erosion, combined with chemical corrosion are very fast and deep, imposed copper-based alloys (brass and bronzes) [5,8,9,13,14,15,16], due to lower costs, even if they have lower mechanical and anti-cavitation characteristics than stainless steels. Moreover, the applicability of copper-based alloys [8,10,11,12] in industry is known due to the technological properties and physical-mechanical characteristics that give them resistance not only to chemical and cavitation corrosion of the operating environment but also to thermal stresses.…”

“…However, due to the rapid destruction by cavitation, most of the researches aim to understand the mechanism of degradation of the structure under the cyclic stresses of micro-jets and shock waves produced by the implosion of cavitation bubbles. Unfortunately, these studies, such as those carried out on CuZn39Pb3 brass by Küçükömeroğlu and Kara [13], respectively Abedini and collaborators [16], and those carried out by Türke and collaborators [15] on naval brass offer only elements about the mode of destruction at the structural level and those who exploit are interested in increasing the surface resistance to cavitation erosion, so that the duration of exploitation to become as large as possible. For this reason, the research performed on CuZn39Pb3 brass, with the results presented in this paper, shows the need to use volumetric heat treatments, such as hardening with tempering, as solutions to increase the service life, by changing the structure and properties of the surface subjected to cavitation.…”