Study On Microstructure And Properties Of 5052 Aluminum Alloy Casting At Low Temperature

The change rule of different cryogenic heat preservation time and cooling off drawing temperature on the mechanical performance and organizational of the18.5mm thick5052aluminum alloy continuous casting slab specimen are analyzed by means of room temperature tensile test, as well as optical metallographic microscope, transmission electron microscope and scanning electron microscope analysis methods, etc. And the change rule of microstructure and mechanical properties of continuous casting slab of different location in the thickness direction are also analyzed.When stretched under-100℃and-150℃, tensile strength, elongation and reduction of area of5052slab whole thickness plate have increased from the room temperature. The tensile strength increases with temperature decrease, while elongation and reduction of area have increased after the first decrease. At the same time, the consistency of the material performance at different locations affects the elongation, reduction of area and tensile strength of the whole plate materials directly. With lower temperature, relevance of5052slab plate tensile strength and elongation to3/10location reduced after rising first, and the correlation of reduction of area to3/10location gradually reduced.With the loss of the stretching temperature, the effect of normal stress on toughening nest morphology is greater than shear stress at the three locations of the slab. Parabolic toughening nests come into irregular toughening nest, and finally become typical circular toughening nests with larger nest depth. Crack propagation begins to rapidly expand from the second phase particles at room temperature, and gradually becomes into grain boundary shape toughening nest slow extension giving priority to grain boundary. Material strength and toughness increase accordingly. Further study found that deformation of5052aluminum alloy slab originated from grain boundaries and phase boundaries with higher energy at room temperature, the dislocation distribution relatively scattered in long range order status. The deformation process dominated by the formation of the stacking fault at low temperatures, forming the long dislocation and transforming from a long range order to short-range order.