Influence of bismuth and lead on the formation of the structure of experimental alloys with a Cu-30% Zn-based composition during crystallization, deformation, and thermal treatment

Nabila

Sari

2022

MSF

Cartridge case ammunition is made from brass alloy by deep drawing process with high degree of deformation. For this reason, the material with a good formability, strength, and hardness is required. The improvement of mechanical propeties of the brass alloy can be conducted by severe process such as addition of alloying element and also termomechanical process. The purpose of this study is to determine the effect thermomechanical processing by cold rolling process with 70% thickness reduction followed by annealing process with variation temperature of 400°C, 500°C and 600°C for 30 minutes to the microstructure and mechanical properties of Cu-28Zn-4Mn alloy. The samples of Cu-28Zn-4Mn alloy were produced by gravity die casting process by using the ingot of Cu, Zn as well as the Mn powder as the feeding materials. The investigation results show that thermomechanical prosess change the microstructures of Cu-28Zn-4Mn alloy. The cold rolling process with 70% thickness reduction will convert the equiaxial grain into an elongated structure (shear band). Furthermore, the heat treatment by annealing process will return the microstructure from elongated to equiaxial grain. Thermomechanical process also tends to change mechanical properties. The 70 % cold rolling process increases the hardness of the Cu-28Zn-4Mn alloy. The hardness of as homogenized and 70% cold rolled samples are 62.34 VHN and 103.96 VHN, respectively. Further, the annealing process tend to decrease the tensile strength and hardness of Cu-28Zn-4Mn alloy. Tensile strength of Cu-28Zn-4Mn after annealing process with variation of 400°C, 500°C, and 600°C are 355.13 MPa, 299.16 MPa, and 294.79 MPa, respectively. On the other hand, the hardness of Cu-28Zn-4Mn with the same treatment are 91.84 VHN, 71.76 VHN and 67.46 VHN, respectively. In contast, the annealing process tend to increase the elongation value. The samples elongation after the annealing process with variation of 400°C, 500°C, and 600°C are 25%, 28%, and 30%, respectively.

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Thermomechanical Treatment on the Microstructure and Mechanical Properties of Cu-28Zn-4Mn Alloys

Nabila

Sari

2022

MSF

“…Similar grain refinement was found by adding 0.1 wt. % Bi to Cu-30Zn, however no significant effect was found on the mechanical properties [4][5][6]. Titarev [7] observed that the addition of 0.5 wt.…”

Section: Introductionmentioning

confidence: 99%

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

Pratiwi

Sofyan³

2018

MSF

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.

“…Bi was developed to substitute alloying constituent Pb in cartridge brass due to their similar properties and a more environmental-friendly nature [2]. Investigation by Emelina [3] on Cu-30Zn-1Bi found that Bi was not completely soluble in brass furthermore tended to segregate at grain boundaries area. A corresponding finding was observed in a research by Basori [4] on microstructures of Cu-29Zn alloys with addition of 0.269, 0.409, and 0.797 Bi.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cold Rolling and Annealing Temperature on the Characteristics of Cu-28Zn-1.1Bi Alloy Produced by Gravity Casting

Tambunan

Angela

et al. 2018

MSF

The microstructures, mechanical properties, deformation mechanism, and recrystallization behavior of Cu-Zn-Bi alloys for cartridge case application have been investigated in this research. Cu-28Zn-1.1Bi wt. % alloys were produced by gravity casting and subjected to a homogenization – cold rolling – annealing sequences with variations on reduction level and annealing temperature. Samples characterizations were done through optical emission spectroscopy, optical microscopy, SEM-EDS imaging, and X-ray mapping modes, while hardness measurements were performed using micro Vickers method. The presence of Bi was found to increase cartridge brass hardness through a dispersoid strengthening mechanism in which dislocation movements are rendered by Bi particles. Higher deformation levels resulted in higher microhardness of the alloy. Recrystallization took place at grain boundaries and areas surrounding Bi dispersoid at 400 °C, while further heating resulted in grain growth phenomenon. Bismuth addition accelerated the recrystallization process in cartridge brass by a particles stimulated nucleation (PSN) mechanism.