Abstract

In this paper, surface roughness, microstructure, mechanical properties, and very high cycle fatigue behavior of Ti6Al4V fabricated by selective electron beam melting were studied. Results show that the mechanical properties in xoz direction (yield strength: 891 ± 14 MPa, ultimate tensile strength: 987 ± 8 MPa, elongation: 15.7 ± 1.9%) are better than that in xoy direction (yield strength: 869 ± 11 MPa, ultimate tensile strength: 955 ± 7 MPa, elongation: 9.8 ± 2.3%) due to the presence of continuous columnar prior-β grain boundary (α layer) and the strong 〈0001〉 texture along the building direction. The very high cycle fatigue (10⁵–10⁹ cycles) experiments show that when the fatigue life exceeds 10⁷ cycles, the sample will still undergo fatigue fracture. The S–N curve is a bilinear relation, which is caused by the crack initiation position converted from the surface to the interior.

Graphic Abstract

摘要

本文研究了选择性电子束熔化制备的Ti6Al4V的表面粗糙度，显微组织，力学性能和极高的循环疲劳行为。结果表明，xoz方向的力学性能（屈服强度：891±14 MPa，极限抗拉强度：987±8 MPa，伸长率：15.7±1.9％）比xoy方向的力学性能（屈服强度：869±11 MPa）好，极限抗拉强度：955±7 MPa，延伸率：9.8±2.3％），这是由于存在连续的柱状先验β晶界（α层）和沿构造方向的强烈的<0001>织构。极高的循环疲劳（10 ⁵ –10 ⁹循环）实验表明，当疲劳寿命超过10 ^7时循环，样品仍将经历疲劳断裂。SN曲线是双线性关系，这是由裂纹起始位置从表面转换为内部引起的。

图形摘要