Homogenization Treatment And Hot Deformation Behavior Of A New Al-Mn Alloy

In order to meet the correspond ing e levated corrosion resistance performancerequire ments o f a lloys account of thinning, a series of Al-Mn a lloy materia ls withhigh strength and high corrosio n resistance are constantly used at home and abroad. Inthis paper, the new Al-Mn a lloy were ho moge nized under the te mperature at560oC,580oC,600oC,620oC, respective ly, and with ho moge nizatio n time for12h,24h,48h,72h, respectively. And reasonable ho moge nizatio n condition was experimentedthrough hardness tests, conductivity tests and microstructure obser vation. The alloywas compressed on Gleeble-3500system at deformatio n temperature during350-550oC and strain rate during0.01-10s-1. The flow stress behavior of the alloyunder high te mperature compression was experimented. Organization evo lution o f thealloy during hot compressio n deformation was analysed by optica l microscope (OM),scanning e lectron microscopy (SEM), trans miss ion e lectron mic roscopy (TEM) andother methods.(1) The conductivity of the new Al-Mn allo y reduced with the ho mogenizationtemperature increasing and the ho ld ing time extend ing under the conditio n of heatingtemperature at560-620oC and the ho lding time at12-72h. Hardness values reducedwith the homo genization te mperature increasing and the ho lding time extend ing whe nthe temperature was below600oC. W ith the homo genization te mperature increasingand the ho lding time extend ing, the Al(Fe, Mn) phases in the new Al-Mn a lloy ingotgradually d issolved, Al(Fe,Mn)S i phases on the gra in boundaries tended to stick andspherica l, and those in matrix d isso lved and sphered more obvio us ly, a lot ofdispersed phase precip itated in the gra in. In the experimenta l conditio ns, inte gratedhardness, conductivity, microstructure and other properties were experime nted toconfirm that the reasonable homogenization condition is600oC/24h.(2) The flow stress of the new Al-Mn a lloy exhib ited a peak stress at criticalstrain, after which the flow stresses decrease d with varying degreed during hotcompress ion deformation. The Flow stress decrease d with the deformationtemperature increased, and increased with the strain rate increased, whic h could berepresented by the Zener-Hollomon parameter Z in the hyperbolic sine equation withthe hot deformation activation energy o f respective ly212.05kJ/mo l and194.76kJ/mo lof the allo y before and after heat treatment. According to the processing map，thealloy can be well processed at temperature500-550oC and strain rate of0.1s-1. (3) Microstructure of the new Al-Mn allo y specimens d uring hot compressionwas analysed by TEM: With the lnZ value decreased, the dis locatio n dens ity reducedand subgra in size gradually grew, the size of (Al(Fe,Mn)Si) precipitatio n decreasedand then increased during deformation. Al(Fe,Mn)SiV phase in the new Al-Mn alloywith the size about200nm.