scholarly journals Effect of Al Content in Magnesium Alloy on Microstructure and Mechanical Properties of Laser-Welded Mg/Ti Dissimilar Joints

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2743
Author(s):  
Wen Dong ◽  
Rongrong Huang ◽  
Hongyun Zhao ◽  
Xiangtao Gong ◽  
Bo Chen ◽  
...  

Laser penetration welding of magnesium alloys and pure titanium TA2 with unequal thickness was performed. Mg base metal with different Al content (AZ31B, AZ61A, AZ91D) was used to investigate the influence of Al element in microstructure and mechanical properties of Mg/Ti dissimilar joints. The results revealed that the change of Mg base metal did not influence the weld appearance of the joints. Three kinds of joint all presented the best mechanical property when the laser power was 3500 W. With the increase content of Al elements in Mg base metal, a reaction layer was observed which was identified as Ti3Al. The highest enrichment of Al element was obtained and its fraction reached 19.31 at% at the AZ91/TA2 interface. The chemical potential gradient of Al from AZ91 to Ti alloy was higher than that from the other two base metals based on thermodynamic calculation. The maximum fracture load reached 3597 N when AZ61 was employed as the base metal and the fracture position was the Ti base metal. AZ31/TA2 joints failed at the weld seam without necking due to the rapid propagation of cracks at the Mg/Ti interface. The AZ91/TA2 joint failed inside the Mg fusion zone with necking at the middle area of the weld, which resulted from the precipitation of brittle phases such as Mg–Al, Ti–Al phases in the fusion zone of Mg alloys.

2011 ◽  
Vol 418-420 ◽  
pp. 1396-1399
Author(s):  
Feng Wang ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Hong Wei Liu ◽  
Zhi Hui Li ◽  
...  

Abstract. The microstructure and mechanical properties of a metal inert gas welds in a medium strength Al-4Zn-1Mg alloy were characterized by optical microscope (OM), scanning electron microscope (SEM) and tensile tests. It is found that the joint of the alloy contained three distinctive regions, i.e. fusion zone, heat affected zone and base metal region. Extensive microhardness measurements were conducted in the weld regions of the nuggets exhibited a hardness loss in the fusion zone due to the loss of strengthening phases. Microstructural examination of the joints revealed typical eutectic structure was appeared in the heat-affected zone. Tensile properties of the joints were obtained by testing flat transverse tensile specimens, and the results indicated that tensile strength of these welds approached 83.3~84.2% of the base metal.


2022 ◽  
Vol 905 ◽  
pp. 44-50
Author(s):  
Li Wang ◽  
Ya Ya Zheng ◽  
Shi Hu Hu

The effects of welding wire composition on microstructure and mechanical properties of welded joint in Al-Mg-Si alloy were studied by electrochemical test, X-ray diffraction (XRD) analysis and metallographic analysis. The results show that the weld zone is composed of coarse columnar dendrites and fine equated grains. Recrystallized grains are observed in the fusion zone, and the microstructure in the heat affected zone is coarsened by welding heat. The hardness curve of welded joint is like W-shaped, the highest hardness point appears near the fusion zone, and the lowest hardness point is in the heat affected zone. The main second phases of welded joints are: matrix α-Al, Mg2Si, AlMnSi, elemental Si and SiO2. The addition of rare earth in welding wire can refine the grain in weld zone obviously, produce fine grain strengthening effect, and improve the electrochemical performance of weld.


2017 ◽  
Vol 112 ◽  
pp. 04005 ◽  
Author(s):  
Daniela-Monica Iordache ◽  
Cătălin-Marian Ducu ◽  
Eduard-Laurentiu Niţu ◽  
Doina Iacomi ◽  
Adriana-Gabriela Plăiaşu

2020 ◽  
Vol 67 (1) ◽  
pp. 101-105
Author(s):  
Yongxin Zhou ◽  
Qian Li ◽  
Zhiguo Xing ◽  
Renze Zhou ◽  
Zhenhua Huang ◽  
...  

Purpose This paper aims to investigate the effect of aluminum addition on the microstructure and mechanical properties of Mg-8Gd-4Y-1Zn alloy. Design/methodology/approach Mg-8Gd-4Y-1Zn-xAl (x = 0, 0.5, 1.0, 1.5, 2.0 Wt.%) alloys were prepared by the conventional gravity casting technology, and then microstructures, phase composition and mechanical properties were investigated by material characterization method, systematically. Findings Results show that the as-cast microstructure of Mg-8Gd-4Y-1Zn alloy mainly consists of a-Mg matrix as well as Mg12REZn (18 R LPSO structure), and island-like Mg3(RE, Zn) phase is distributed at the grain boundary. The addition of a small amount of Al (0.5 Wt.%) can decrease the content of island-like Mg3(RE, Zn) phase, but significantly increase the content of long-period stacking ordered (LPSO) structure, resulting in the improvement of both tensile strength and elongation of Mg-8Gd-4Y-1Zn alloy. However, the addition of excessive Al will consume Re element and decrease the amount of LPSO structure, leading to the decrease of tensile properties. When the content of Al is 0.5 Wt.%, the tensile strength and elongation are 225 MPa and 9.0% of Mg-8Gd-4Y-1Zn alloy, which are 14% and 29% higher than that of Mg-8Gd-4Y-1Zn alloy, respectively. Originality/value Adding aluminum to Mg-8Gd-4Y-1Zn alloy strengthens its mechanical properties. And the effect of Al content on the alloy strengthening. The formation mechanism of LPSO structure with different aluminum content was revealed.


2019 ◽  
Vol 25 (4) ◽  
pp. 744-751 ◽  
Author(s):  
Xiaomiao Niu ◽  
Hongyao Shen ◽  
Guanhua Xu ◽  
Linchu Zhang ◽  
Jianzhong Fu ◽  
...  

Purpose Mg-Al powder mixture was used to manufacture Mg-Al alloy by laser powder bed fusion (LPBF) process. This study aims to investigate the influence of initial Al content and processing parameters on the formability, microstructure and consequent mechanical properties of the laser powder bed fused (LPBFed) component. Design/methodology/approach In this study, Al powder with different weight ratio ranged from 3 to 9 per cent was mixed with pure Mg powder, and the powder mixture was processed using different LPBF parameters. Microstructure and compressive properties of the LPBFed components were examined. Findings It was found that the presence of Al significantly modified the microstructure and improved the mechanical properties of the LPBFed components. Higher volume of ß-Al12Mg17 precipitates was produced at higher initial Al content and higher laser energy density. For this reason, the a-Mg was significantly refined and the compressive strength was improved. The highest yield compressive strength achieved was 279 MPa when using Mg-9 Wt. % Al mixture. Originality/value This work demonstrates that LPBF of Mg-Al powder mixture was a viable way to additively manufacture Mg-Al alloy. Both Al content and processing parameters can be modified to control the microstructure and mechanical properties of the LPBFed components.


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