Research On The Microstructure And Properties Of ZL205A Thin-walled Cast Under Traveling Magnetic Field

In this paper, continuous casting was simulated and the basic parameters was established in order to obtain thin-walled cylindrical castings of aluminum-copper alloy, the influence of different parameters on microstructure、properties and macro-defects of ZL205A alloy was researched under traveling magnetic field on vertical pouring system.By using two different casting molds to conduct the experiment. The results showed that the former extended the effect time of magnetic field, casting defects can be removed when the induced current reached10A.The microstructure of ZL205A under cast and T6heat treatment states was observed, and tested room-temperature tensile, respectively. The variation of various performance indicators(σb、σ0.2and δ) have been got.Under traveling magnetic field, the grains were refined obviously. The grain size decreased continuously with increasing the induced current, when the induced current reached20A, the grain size is about1/3of the non-magnetic alloy grain, but when the induced current reached25A, the micro-shrinkage increased. According to the Hall-Petch formula, yield strength σb showed a linear relationship with the reciprocal of the square root of grain diameter d-1/2, then the variation of the cast ZL205A alloy mechanical properties with the induced current(A) was researched, the properties of ZL205A firstly increases and then decreases with the increases of the induced current. When the induced current was20A, σb(max) is221MPa, when it is15A, σ0.2(max) is105MPa,δ(max) is13.8%, increased by11%、17%and18%respectively, compared with non-magnetic alloy, the fracture showed the characteristic of the intergranular fracture. Horizontal contrast found that the central position of the thin-walled cast showed the best properties.Based on the above-mentioned ZL205A thin-walled cylindrical casts, selected the central positon to conduct the same T6heat treatment process, due to the different grain size, lead to the different displacement of the atomic diffusion and the different energy barrier needed to be overcome, ultimately caused the differences of the microstructure. After T6heat treatment,0and T phase existed in the grain boundaries have disappeared, replaced by a homogeneous matrix and dispersed in the matrix’s precipitated phase. The grain size grow up slightly compared to cast state, after T6heat treatment, the mechanical properties were firstly increasing and then decreasing. When the induced current reached20A, σb(max)、σ0.2(max) and δ(max) are503MPA、485MPAand14%respectively. The fracture showed the characteristic of the ductile fracture.