| To prevent environment being polluted during the process of process of material machining and forming processing, material researchers brought forward the idea of introducing magnetic filed in the material machining process. As work has been done to go deep into such researches, various kinds of EMCS (Electromagnetic Confining and Shaping) technologies such as EML(Electromagnetic Levitation) , Cold Crucible Induction Melting Process, EMC(Electromagnetic Casting) and MSMP(Magnetic Suspension Melting Process) has been gradually exploited and put into appliance. However, there are still little reports upon the research concerning the electromagnetic field's influence on solidified structure and performance during the course of metal solidification process by now. Choosing nickel based super-alloy K403 test sample, the thesis carried out experiments of super-alloy directional solidification and investigated over structure & characteristics differences of solidified samples under electromagnetic field of different intensities; the thesis finally unveiled the influence law of electromagnetic field effect on super-alloy structure and performance. The main research contents and results are presented as following.The influence of electromagnetic field on super-alloy directional solidification process is researched; results of the influence are listed below. Electromagnetic force changes the growth direction of columnar crystals which incline to the flow direction; electromagnetic stirring force would refine crystal grains of columnar crystals, at the same time crystal grains distribute uniformly and thin in the whole casting. With theincrease of electromagnetic field intensity, the primary interdendritic spacing λ1 decreases; second dendrite arm diminish; growth of second dendrite crystals has been overwhelmingly restrained; carbide morphology has transformed block shape into sheet and Chinese character style.The effect of electromagnetic field on gamma phase coefficient of solutedistribution at solid-liquid interface ki? is researched. The result shows thatelectromagnetic field effect approximates ki? to 1 not mention how much the balanced coefficient of solute distribution k0,i is, bigger or smaller than 1. The influence of electromagnetic field on γ' phase precipitation is also studied. Research resultsshow that with the increase of electromagnetic field intensity, the amount of γ' phase and mean size of γ' phase particles increase,γ' phase arearatio increase and mean size of γ' phase particle increase.
|
PDF Full Text Request