Study On Microstructure And Properties Of Al-Mg-Mn Alloy Processed By Equal Channel Angular Pressing

The objectives of this research were to study the development of microstructure and properties in equal channel angular pressed a new Al-Mg-Mn alloy and 5083 alloy. The main point of the paper was to investigate the effect of the different processing parameters of ECAP on the microstructure and properties of the alloy. The relationship between microstructure and mechanical properties has been discussed. At the same time, the thermal stability of the samples after ECAP was also studied.Microstructure analysis shows that the grain size of the alloys after ECAP has obviously decreased from about 100~200μm to 2~4μm. It was known that the processing route had little effect on the structure morphology. The fine sub-grain structure was observed at route B. Except the route A, the SAED patterns of other routes present well defined-rings. After a single pressing, the grain size has decreased to several micron meters. With the increasing of the pressing passes, the low-angle boundaries transformed to high-angle boundaries but the grain size keep stability. During the ECA pressing, the main second-phase was broken to pieces and slide along the shear planes, distributing like parallel bands. It was confirmed that by EDS the main second-phase contains the element of Al,Mn,Fe. Some small round phases have been found in the Al-Mg-Mn alloy.It was concluded that this phase is Al3Zr dispersoids. According to mechanical properties testing, the alloys exhibit good overall qualities after ECAP at 573K. Among the four routes, the route BC appears to be more efficient in terms of room temperature strength and elongation than other routes. The route C is the lowest. The mechanical properties have been improved as a result of increasing the number of pressings. The better UTS,yield strength and elongation have been gotten at the fourth pass, there was no significant difference between 4 and 6 passes. The ECA pressing play a more reasonable effect on the Al-Mg-Mn alloy than 5083 alloy. The microhardness is higher in the center of the samples than in the edge. The relationship between microstructure and properties can be interpreted in terms of grain refinement with a classical Hall-Petch relationship.