电子束快速成形Ti-6Al-4V合金的组织与性能（英文）

Microstructure and Mechanical Properties of Ti-6Al-4V by Electron Beam Rapid Manufacturing

电子束快速成形是一种利用金属丝材沉积直接制造金属零件的新型增材制造技术。用电子束快速成形方法制备了Ti-6Al-4V合金,对其显微组织和快速成形态、退火态、热等静压态下的力学性能进行了研究。电子束快速成形Ti-6Al-4V合金的低倍组织典型特征为沿堆积高度方向生长的贯穿多层沉积层的粗大柱状晶以及分布于层间及堆积路径间的明暗相间的带状条纹。各种状态下室温拉伸性能均有明显的方向性,其中X向、Y向强度较高,Z向强度低但塑性较好;消应力退火处理对室温拉伸性能没有明显影响;热等静压处理后材料的抗拉伸强度显著降低,但具有良好的塑性与韧性,同时能够明显降低高周疲劳性能数据的分散性。快速成形态及退火态室温拉伸性能均可满足AMS4999标准的要求,但与锻件标准HB5432相比仍有差距。

Electron beam rapid manufacturing （EBRM） is a novel layer-additive manufacturing process which was developed to di- rectly fabricate metal parts from computer aided design （CAD） data. The present study was conducted to evaluate the microstructure and the mechanical properties of Ti-6Al-4V by EBRM. Results show that typical microstructures exhibit large columnar β grains nucleated at the substrate and grew epitaxially along the height direction of deposits through many deposition layers, and alternately light and dark banded textures at layer-layer and bead-bead interfaces have been also found due to complex thermal history during deposition process. As a result, the tensile properties of the as-deposited and the as-annealed deposits exhibit distinct anisotropy. The strength in X and Y directions are similar and markedly higher than that in Z. No significant impact of annealing treatment has been found on room temperature tensile properties. Hot isostatic pressing （HIP） treatment obviously decreases the dispersion of the high cycle fatigue data and improves both ductility and toughness, while at the expense of the tensile strength. The tensile properties of the as-deposited and as-annealed Ti-6Al-4V by EBRM can meet the mechanical property requirements of AMS4999 standard, but can not fully meet the requirements of HB5432 standard.