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采用自行设计的低频低压脉冲电源对工业纯铝进行处理。脉冲电流处理的熔体宏观组织从外向内生长的长条柱状晶被碎断,外围粗大的树枝晶呈现变短变细趋势。随着脉冲电压不断增加,等轴晶面积不断加大,晶粒尺寸不断减小,影响程度呈现衰弱的趋势。当占空比不断增大时,等轴晶面积和晶粒尺寸的影响呈现先增大后减小的趋势,当占空比为60%时,熔体处理效果最佳。最佳件与未施加脉冲试样相比,布氏硬度、抗拉强度、屈服强度、伸长率分别提高10%、13.9%、9.3%、10.4%。试验表明,脉冲电流影响了铝熔体在凝固过程中的过冷度,使得晶粒细化程度出现波动。这种影响是多种参数共同作用的结果,但并不是线性关系。
Use of low-frequency low-voltage pulse power supply designed to deal with industrial pure aluminum. Impulse current treatment of the melt macrostructure from the outside inward growth of long columnar crystals were broken, the periphery of the coarse dendrites showed a trend of shorter and thinner. With the increase of pulse voltage, the area of equiaxed grains is continuously increased, the grain size is continuously reduced, and the influence degree shows a weakening trend. When the duty cycle increases, the influence of equiaxed grain size and grain size first increases and then decreases. When the duty cycle is 60%, the melt treatment effect is the best. The Brinell hardness, tensile strength, yield strength and elongation increased by 10%, 13.9%, 9.3% and 10.4% respectively compared with the non-pulsed samples. The experimental results show that the pulse current affects the undercooling of the aluminum melt during the solidification process, causing the grain refinement to fluctuate. This effect is the result of a combination of multiple parameters, but not linear.