行波磁场耦合顺序凝固改善ZL205A大型薄壁件缺陷及性能

利用行波磁场耦合顺序凝固连续地处理大型薄壁ZL205A合金铸件,消除收缩缺陷,提高力学性能.实验结合模拟,针对行波磁场参数优化对补缩行为、显微组织和性能的影响进行系统的研究.结果表明,本研究条件下,当励磁电流为20 A、频率为200 Hz时,磁场力达到最大值;磁场力随着到磁场发生器距离越近而越大,更有利于对薄壁铸件进行...

Eliminating shrinkage defects and improving mechanical performance of large thin-walled ZL205A alloy castings by coupling travelling magnetic fields with sequential solidification

ZL205A alloys with large thin-walled shape were continuously processed by coupling travelling magnetic fields (TMF) with sequential solidification, to eliminate the shrinkage defects and optimize the mechanical performance. Through experiments and simulations, the parameter optimization of TMF and the influence on feeding behavior, microstructure and properties were systematically studied. The results indicate that the magnetic force maximizes at the excitation current of 20 A and frequency of 200 Hz under the experimental conditions of this study, and increases from center to side-walls, which is more convenient to process thin-walled castings. TMF can break secondary dendritic arm and dendrites overlaps, widen feeding channels, prolong the feeding time, optimize the feeding paths, eliminate shrinkage defects and improve properties. Specifically, for as-cast state, TMF with excitation current of 20 A increases ultimate tensile strength, elongation and micro-hardness from 186 MPa, 7.3% and 82.1 kg/mm² to 221 MPa, 11.7% and 100.5 kg/mm², decreases porosity from 1.71% to 0.22%, and alters brittle fracture to ductile fracture.