【摘要】 金属熔体电磁约束成形的稳定性始终是困扰该技术进一步发展和阻碍其大规模推广应用的难题,尤其是大比重合金的稳定成形更加困难。为此,作者对电磁约束成形过程中熔体的温度和熔体受力随电流的变化过程以及上、下液 固界面处于不同位置时熔体表面的受力状况进行了理论分析,并对制备圆形1Cr18Ni9Ti不锈钢试件和大宽厚比矩形截面不锈钢试件的电磁约束成形方法的稳定性进行了实验研究。结果表明:电磁约束稳定成形时,熔体的上液 固界面应位于合适位置,下液 固界面必须高于临界位置;熔体的静压力对电流变化非常敏感,且随熔体密度的增加而增大;另外,电磁约束成形实验还表明,熔体静压力对电流也非常敏感,这与理论分析结果一致;而且在变截面电磁成形中,当成形试件与棒料的截面比大于1时,随截面比及抽拉速率的增加,熔体的成形稳定性变差,所以变截面电磁约束成形时截面比和速率都不宜太大。更多还原

【Abstract】 Electromagnetic confinement and shaping (EMCS) for molten metals is an advanced technology developed recently, in which the metal is melted by induction heating and the liquid metal is confined and shaped into desired form by the electromagnetic force at the same time. The stability of EMCS for stainless steel (1Cr18Ni9Ti) was analyzed. The results show that in EMCS process the upper liquid/solid interface should be in appropriate position and the lower liquid-solid interface must be above the critical position. It is found that the static pressure of molten metal is extremely sensitive to current variation and increases with increasing density of molten metal. So the static pressure of molten metal is one key factor affecting EMCS stability. In unequal cross section EMCS, when the ratio of shaping sample section area to feeding sample section area is larger than unity, the shaping stability becomes worse with the increase of the ratio and speed of shaped sample. So for unequal cross section EMCS, the ratio and the speed of shaped sample must not be larger. The results described above were proved by experiments. Several stainless steel samples with different cross section were obtained by EMCS.更多还原