Effects of Manganese on the Microstructures, Mechanical Properties and Deformation Characteristics of Cu-29Zn Alloy

Abstract

Deformation characteristics of brass alloy are still under discussion, particularly concerning the critical level of when the change of deformation mechanism occurs. Previous research showed that the addition of Mn on brass alloys resulted in grain refinement and mechanical properties alteration. However, the effects of Mn on the deformation characteristic of brass alloys have not been investigated. In this research, Cu-Zn-xMn alloys were manufactured by gravity casting process using pure Cu and Zn ingots, as well as Mn chips as the feeding materials. Mn addition was varied to 1.26, 3.48, and 5.83wt.%. As-cast samples were homogenized at 800 °C for 2 h in a muffle furnace. The samples were then cold-rolled with the level of deformation of 20, 40, and 70 %. Samples characterization includes chemical composition analysis, microstructure observation, tensile and hardness testing. The results showed that addition of Mn for 5.83 wt.% and above created β’ phase, which is richer in Mn compare to that in the matrix. This phase segregated in the grain and along the grain boundary with irregular forms. Significant increase in hardness, yield and tensile strengths was observed with addition of Mn. The maximum elongation was achieved by addition of 3.48 wt.% Mn, while further addition tended to decrease it. At 20% deformation, slip dominated and its density reduced with addition of Mn. When the deformation level increased to 40%, twinning replaced slip as the predominant mechanism. Twinning density is slightly increase with the presence of Mn. Further deformation at 70% produced shear bands and flattened the β’ phase. Greater Mn content led to formation of more shear band.

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

“…Nevertheless, an addition of up to 3 wt.% Mn had a positive effect instead. This was attributed to the increased β-phase presence at higher Mn contents [77].…”

“…The progressive addition of Mn increased the volume fraction of the β-phase in the microstructure as Mn acts as a β-phase stabiliser. Furthermore, the increased Mn content had a minimal effect on twin formation during deformation, while dislocation motion through slip was inhibited due to the pronounced solid solution strengthening effect of Mn [77]. Quan Li et al showed that the microstructure of the hot extruded Sb-Mg lead-free brass was composed of α, β phases and (Sb, Mg)-containing intermetallic compounds [78].…”

Influence of Manganese on the Recrystallization Characteristics and Texture Development of Cu-29Zn Alloys

“…At the same annealing temperature, the higher Mn content results in the higher hardness. The presence of Mn drives the substitutional solid solution which creates the atomic lattice strain and inhibits the dislocation movement and results in the higher hardness [6].…”

“…In metals with the second phase, recrystallization behavior are quite complicated due to its can act as a potential site for nucleation (PSN), and pinning agent for moving boundaries [5]. During annealing, the recrystallization process will continue until all deformed areas have been replaced by the stress-free new grain [6].…”

Effect of cold rolling and annealing temperature to the characteristics of α + β' phases in Cu-29.5Zn-2.5Al alloy produced by gravity casting

“…low pressure valves, heat exchanger pipes, and condensers which involve extensive deformation during their manufacture. Previous studies were conducted to improve the formability of cartridge brass through alloying using Mn [1], Bi [2], and Al [3], with the optimum combination of strength and ductility properties found in duplex brass with 1.9 wt. % Al [3].…”