Page 40 - MSAM-1-1

Materials Science in Additive Manufacturing

ORIGINAL RESEARCH ARTICLE
Processing and characterization of crack-free

7075 aluminum alloys with elemental Zr
modification by laser powder bed fusion

1
2
2
Wenhui Yu , Zhen Xiao 1,3,4 *, Xuhui Zhang , Yetao Sun , Peng Xue , Shuai Tan ,
1,2
1
1
1
Yongling Wu , Hongyu Zheng *
1 School of Mechanical Engineering, Shandong University of Technology, 255000, Zibo, Shandong,
P.R. China
2 Shengli Oilfield highland Petroleum Equipment Co., Ltd, 257091, Dongying, Shandong, P.R. China
3 School of Transportation and Vehicle Engineering, Shandong University of Technology, 255000, Zibo,
Shandong, P.R. China
4 PrinxChengshan (Shandong) Tire Co., Ltd, 264300, Weihai, Shandong, P.R. China

Abstract

High-performance engineering alloys, such as 7000 series aluminum alloys,
suffer poor printability in laser powder bed fusion (LPBF) additive manufacturing.
An enormous challenge lies in the suppression of solidification cracks caused by
solidification shrinkage and thermal stresses. Porosity formation, as one of the
main concerns for LPBF application, should also be avoided at the same time.
*Corresponding authors: In this study, aluminum alloy (AA) 7075 with and without Zr modification was
Zhen Xiao
(xiaozhen@sdut.edu.cn); additively manufactured by LPBF. Processing parameters of laser power and
Hongyu Zheng scanning speed, resulting in various volumetric energy density (VED), were
(zhenghongyu@sdut.edu.cn) experimentally determined to produce crack-free components with tailored
Citation: Yu W, Xiao Z, Zhang X, microstructure. Optical microscopy was used to reveal how the crack density and
et al., 2022, Processing and porosity vary with VED. Scanning electron microscopy and transmission electron
characterization of crack-free
7075 aluminum alloys with microscopy uncovered the detailed microstructure in the molten pool and the
elemental Zr modification by laser evolution of the elemental Zr addition. The results indicate that 1 w.t.% addition
powder bed fusion. Mater Sci Add of elemental Zr in AA7075 led to lower crack density compared with 0.3 w.t.%
Manuf. 1(1): 4.
https://doi.org/10.18063/msam.v1i1.4 addition. In 1 w.t.% Zr-modified AA7075, crack-free components were obtained
under high VED. Fine equiaxed grains, instead of large columnar grains, were
Received: February 27, 2022
formed at the bottom of the molten pool boundary due to the existence of Al Zr
3
Accepted: March 5, 2022 compound, which favored the nucleation of aluminum grains and elimination
Published Online: March 25, 2022 of cracks. The phenomenon of silicon segregation near cracks remained in Zr
Copyright: © 2022 Author(s). This modified alloys, although its effects on cracking were suppressed. Spherical
is an Open Access article pores in the Zr-modified AA7075 increased due to the deterioration of fluidity
distributed under the terms of the by unmelted particles, which distracted the Marangoni flow as well. Sufficient
Creative Commons Attribution
License, permitting distribution, and laser energy input can increase the viscosity and ease the pores escaping. By
reproduction in any medium, optimizing parameters, crack-free AA7075 parts with low porosity can be
provided the original work is
properly cited. manufactured through LPBF with Zr addition.
Publisher’s Note: Whioce
Publishing remains neutral with Keywords: Laser powder bed fusion; 7075 aluminum alloys; Zr modification; Crack
regard to jurisdictional claims in
published maps and institutional elimination; Porosity
affiliations.

Volume 1 Issue 1 (2022) 1 https://doi.org/10.18063/msam.v1i1.4