Microstructure And Mechanical Properties Analysis Of Aluminum Brass Produced By Hot-working

In this paper, we use scraps copper as materials to melting, refining and removing impurity,finally produced by horizontal continuous casting and subsequent hot-extrusion to complicatedHAl61-4-3-1Al-brass bar. Then, we studied the microstructure and mechanical properties and theinfluence of hot-extrusion to it. Afterwards, we analysis the differences of microstructure andmechanical properties between complicated HAl61-4-3-1aluminum brass and simple copper-alloywhich produced by hot-extrusion and equal-channel angular pressing such as reported in literatures.In the end, we discussed the question of improving the extrusion process.Microstructures of HAl61-4-3-1which produced by HCC (horizontal continuous casting)present projecting β phase, dendritic γ primary phase and granulous strengthening phase whichdiffuse distributed in β phase. Revealing669MPa tensile strength,484MPa yield strength,5.5%ductility and230Vickers hardness. Microstructures produced by hot-extrusion which after HCCbecame more complicated, present α, β phase, γ primary phase, granulous strengthening phase in βphase. The degree of these phases refinement is so large, decreasing from>100μm、50~150μm to10~25μm、2~16μm where texture became from the horizontal continuous casting state to thesubsequent hot extrusion state, which decreasing amplitude exceed75%. Meanwhile, β phase onthe granular phase size had no change, still for1~8μm. Mechanical properties had a great growth,which10Mpa tensile strength and7.5%yield strength, nevertheless, the yield strength and Vickershardness decrease133MPa and38Hv.Tensile fracture microstructures of of HCC and hot-extrusion is researched, HCC’s is roughand hot-extrusion’s is smooth, which all belongs to the combination of ductile fracture and brittlefracture, whereas the proportion of hot-extrusion’s ductile fracture is much larger. Microstructureof tensile fracture of HCC exists a large number of petal-like and dendritic compound hard phases,which is rich Al-Ni compounds, while toughening matrix phase surrounding them. In the course oftensile fracture, primary phase gathers dislocation and generate void, void spreading until samplerupture. In the microstructure of hot-extrusion, dimple is depper and larger, primary phase ofdimple is much closer to matrix and exists a change of element between dimple and matrix.Comparing hot-extrusion HAl61-4-3-1and ECAPed Copper-alloys, we found grain size ofhot-extrusion’s is much larger, shows15~80μm and5~20μm of α phase and primary phase. In themicrostructure of hot-extrusion, several factors maintains favorable strength and plasticity, include equiaxed primary phase, dynamic recrystallization grain size and dynamic recovery, whichrevealing679MPa tensile strength,351MPa yield strength and13.0%ductility. The grain size ofECAPed simple copper and its alloy are0.28~0.05μm, more small than hot-extrusion’s, whichmake effect of grain refinement strengthening better. The strength of Cu-8at.%Al and Cu-16at.%Alis720MPa and862MPa, exceed hot-extrusion of HAl61-4-3-1, whereas ductility is extreme lowwhere due to Serious work hardening as2.0%and2.2%.