二次热等静压对TC4合金组织的影响

Effect of re-HIPing on microstructure of HIPed TC4 alloy

研究了二次热等静压(HIP)工艺对不同起始组织HIP态TC4合金显微组织的影响。结果表明,二次HIP主要通过扩散进行组织的致密化,致密化过程中形成等轴块状α相填充孔洞,同时原始致密组织中片状α相层片间距增大。与首次HIP相比,二次HIP的致密化过程相对较慢,孔隙尺寸较大体积分数高的初始组织,经二次HIP后会形成不均匀组织,为了获得细小均匀的致密组织,应尽量在首次HIP时完成致密化。

Effect of re-hot-isostatic-pressing （re-HIPing） on microstructure of as-HIPed TC4 alloy was studied. The results show that the as-HIPed TC4 alloy is densified via the diffusion in the process of re-HIPing. Accompanied with the coarsening of plate-like α phase in the original microstructure, the micro-porosity of the alloy is filled by block equiaxed α phase. The densificatiun of TC4 alloy during re-HIPing is much more slowly than that in the first HIPing. It is found that the heterogeneous microstructure in the re-HIPed alloy forms for the alloy with large volume fraction of large micro-porosity original microstructure, theretore the densification of the alloy must be finished during the first HIP in order to gain dense homogeneous fine microstructure.