| H68 brass is widely used in the area of instrumentation, valves, sanitary ware and so on, due to its superior processability, mechanical properties, good combination of strength and thermoplasticity. With the development of the national economy, the demand of H68 alloy greatly increases and as well as the quality and performance of its product.Grain refinement is an effective way to obtain copper alloys with excellent comprehensive properties. This paper has investigated the effect of the chemical addition such as La, Fe and Sn and physical field such as rotating, pulsed magnetic field and Intermediate frequency magnetic field on the microstructure and properties of H68 brass.The results show that with the La content increases, the grain size of H68 brass decreases and the hardness increases. When the La content exceeds 0.06 wt.%, the grain size increases and the hardness decreases instead. With the Fe content increases, the grain size of H68 brass decreases and the hardness increases. When the content of Fe exceeds 1.0 wt.%, the reduction of refinement reduces and increment of hardness decreases. With the addition of Sn increases, the grain size becomes smaller and the hardness increases.. The effect of rotating magnetic field on the solidification structures of H68 brass alloy behaved as with the voltage of the rotating magnetic field increases, the grain size decreases and hardness increases. The effect of pulsed magnetic field on the solidification structures of H68 brass alloy behaved as with the voltage and frequency of the pulsed magnetic field increases, the grain size decreases, but the refining effect is not obvious in this study. Applying intermediate frequency magnetic field in the solidification process can refine cast microstructure of H68 tin brass and reduces the casting defects such as shrinkage cavity, porosity. And it can improve the microstructure and mechanical properties of H68 tin brass band after rolling, especially significantly increase the elongation. |
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