Pulse electromagnetic force microstructural control at continuous billet casting 7xxx Al-alloys

9th International Symposium on Electromagnetic Processing of Materials

材料科学;物理学

Slazhniev, M.A.^1 ; Kim, K.H.^1 ; Sim, H.S.^1 ; Kim, S.W.^1 ; Kim, W.J.^1

Dong San Tech. Co. Itd., 169 Hamansandanro, Hamangun, Gyeongnam, Korea, Republic of^1

关键词: Billet casting;    Electromagnetic stirring;    Grain size;    High strength aluminum alloys;    Pulse magnetic field;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/424/1/012020/pdf
DOI  :  10.1088/1757-899X/424/1/012020

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

In this study, the original equipment and methods for the macro/microstructure managed formation in the crystallizers of continuous casting processes by the applying of the amplitude modulated (AM) pulsing magnetic fields (PMF) it the electromagnetic stirrer (EMS) has been developed and tested. Method has provide the complex electrodynamic, hydrodynamic and acoustic pulse-force processing of unsolidified casting product portion for providing equalizing of solidification front in the billet mushy zone. Resulted non-dendritic type of microstructure has been provide by the means applying: Pulse magnetic field with periodically changing in time amplitude (AM-PMF); Pulse amplitude-modulated rotating melt stirring (AM-PRMF); Pulse amplitude-modulated 3D-helicoidally rotating melt stirring. Study efficiency applying of unidirectional axial pulse magnetic field (AM-PMF) with pulse frequency in range 5∼15Hz, carried frequency in range 22∼55Hz, at intensity of MF 0.05∼0.1T, for semi-continuous 7xxx alloys (analogue 7075 alloy) 7 'billet casting on micro- and macrostructure billet formation has been show reaching the stabile effect for non-dendrite state microstructure formation in all billet cross-section. As well-achieved uniform and homogeneity microstructure state with average grain size not more 100μm, and for middle and central billet part in range 60∼80μm, in 3∼5 times lowest instead grain sizes 200∼650μm at DC casting without EMS, or instead 150μm grain sizes as for conventional rotating EMS. As well, fully solved problems of axial and structural segregation, hot-crack ability or micro-cracks on grains edges and micro-porosity occurring.