Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5455898 | Materials Science and Engineering: A | 2017 | 18 Pages |
Abstract
Laser solid forming (LSF) is a newly developed additive manufacturing which offers a less material waste and reduction in lead-time for fabricating aerospace titanium alloys components. In this paper, two types of block with different build dimension (section geometries) were fabricated by LSF with same processing parameters. The corresponding microstructure, texture, and tensile properties were investigated systematically. The results show that the samples exhibits similar columnar β grains morphology and ã100ã fiber texture, but very different α variant characterizations (morphology and texture) due to the different thermal history they experienced respectively. The fine basket-weave microstructure with weak texture can be obtained under the fast cooling conditions, while the colony microstructure shows a strong transformation texture as a result of variant selection in the relative slow cooling rate. The α characterizations depend strongly on the competition growth mechanism between the αWGB (grin boundary Widmanstatten structure) and αI (intragranular α nuclei) during cooling process. The presence of αGB (grain boundary α layers) enhances the nucleation of certain variants in βâα phase transformation. Tensile results reveal that fine basket-weave microstructure has relative high strength and ductility with dimple fracture mode. The colony microstructure shows a feature of dominant brittle fracture appearance and results in low tensile ductility.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Zhuang Zhao, Jing Chen, Xufei Lu, Hua Tan, Xin Lin, Weidong Huang,