Effects of Zn Content on Hot Tearing Susceptibility of Mg–Zn–Gd–Y–Zr Alloys

2022 ◽  
Author(s):  
Ziqi Wei ◽  
Shimeng Liu ◽  
Zheng Liu ◽  
Le Zhou ◽  
Yan Li ◽  
...  
Keyword(s):  
Hot Tearing ◽  
Zn Content ◽  
Hot Tearing Susceptibility ◽  
Zr Alloys

scholarly journals Effects of Zn content on Hot Tearing Susceptibility of Mg–7Gd–5Y–0.5Zr Alloy

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 414
Author(s):  
Ziqi Wei ◽  
Shimeng Liu ◽  
Zheng Liu ◽  
Feng Wang ◽  
Pingli Mao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Parent Phase ◽  
Hot Tearing ◽  
Shrinkage Stress ◽  
Second Phase ◽  
Residual Liquid ◽  
Long Period ◽  
Zn Content ◽  
Feeding Effect ◽  
Hot Tearing Susceptibility

Mg–7Gd–5Y–0.5Zr alloy has excellent mechanical properties but poor hot tearing resistance. The latter makes it difficult to cast billets, which limits the size of subsequently processed parts. Therefore, the hot tearing susceptibility of Mg–7Gd–5Y–xZn–0.5Zr (x = 0, 3, 5, 7 wt%) alloys was studied. It was found that Zn can significantly reduce hot tearing susceptibility of Mg–7Gd–5Y–0.5Zr alloy, which almost linearly decreased with Zn content. When Zn content was 3 wt%, 5 wt% and 7 wt%, hot tearing susceptibility will be reduced by 27%, 83% and 100%, respectively. It was further revealed that the solid solubility of Gd and Y in α-Mg decreased with the increase of Zn content, and the nucleation temperature decreased accordingly, which resulted in the increase of nucleation rate and the refinement of final grains. On the macro level, it showed that the dendrite coherency temperature decreased, the solidification shrinkage stress of α-Mg slowed down, and the residual liquid channel became shorter and hot tearing susceptibility decreased. It was also found that with the increase of Zn content, the content of Zn, Gd and Y enriched on the grain boundary increased, the content of residual liquid phase between dendrites increased after α-Mg crystallization, and the solidified precipitated second phase also changed from Mg5RE phase to long-period stacking ordered phase + W-phase (a little), long-period stacking ordered phase + W-phase (much) and finally to W-phase only. The feeding effect of sufficient intergranular residual liquid on the shrinkage of α-Mg dendrite and the bridging effect of the precipitated phase at the grain boundary (especially long-period stacking ordered phase which is coherent with the parent phase) also led to the decrease of hot tearing susceptibility.

Effects of Y and Zn/Y on hot tearing susceptibility of Mg–Zn–Y–Zr alloys

2019 ◽  
Vol 35 (15) ◽  
pp. 1872-1882 ◽  
Author(s):  
Ziqi Wei ◽  
Zheng Liu ◽  
Xiaofang Sheng ◽  
Yue Wang ◽  
Zhenglai Zhang ◽  
...  
Keyword(s):  
Hot Tearing ◽  
Hot Tearing Susceptibility ◽  
Zr Alloys

Effects of Y on hot tearing susceptibility of Mg–Zn–Y–Zr alloys

2014 ◽  
Vol 24 (4) ◽  
pp. 907-914 ◽  
Author(s):  
Zheng LIU ◽  
Si-bo ZHANG ◽  
Ping-li MAO ◽  
Feng WANG
Keyword(s):  
Hot Tearing ◽  
Hot Tearing Susceptibility ◽  
Zr Alloys

Influence of Nd on Hot Tearing Susceptibility and Mechanism of Mg-Zn-Y-Zr Alloys

2020 ◽  
Vol 29 (10) ◽  
pp. 6714-6726
Author(s):  
Xingxing Li ◽  
Shimeng Liu ◽  
Zheng Liu ◽  
Yue Wang ◽  
Ziqi Wei ◽  
...  
Keyword(s):  
Hot Tearing ◽  
Hot Tearing Susceptibility ◽  
Zr Alloys

scholarly journals Residual Stresses in the Hot Sprues of as-cast Mg-Zn Alloys Investigated by STRESS-SPEC Neutron Diffractometer

2013 ◽  
Vol 768-769 ◽  
pp. 428-432
Author(s):  
Wei Min Gan ◽  
Yuan Ding Huang ◽  
Zhi Wang ◽  
Norbert Hort ◽  
Michael Hofmann
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Hot Tearing ◽  
Neutron Diffractometer ◽  
Zn Content ◽  
Residual Strains ◽  
Zn Alloys ◽  
Hot Tearing Susceptibility

Residual strains near the sprues of ingots with different contents of Zn (6 wt. % and 9 wt. %) were measured using neutron diffraction. The results showed that the increase of Zn content decreases the residual stress in the hot sprue region. These results are good in agreement with that obtained by the measurement of hot tearing susceptibility.

Hot Tearing Evaluation and Contraction Behaviors of Four AA7xxx Alloys

2015 ◽  
Vol 817 ◽  
pp. 21-26 ◽  
Author(s):  
Qing Ling Bai ◽  
Jun Cheng Liu ◽  
Yue Li ◽  
Hong Xiang Li ◽  
Qiang Du ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Hot Tearing ◽  
Thermal Contraction ◽  
Solidification Range ◽  
Complex Interactions ◽  
Zn Content ◽  
Constrained Rod Casting ◽  
Hot Tearing Susceptibility

The hot tearing susceptibilities (HTS) of some AA7×××alloys, AA7050, AA7055, AA7085 and AA7022 were evaluated with constrained rod casting (CRC). Thermal contraction behaviors during solidification were measured as well in a T-shaped setup. The results showed that alloys with HTS from high to low were AA7055, AA7085, AA7050 and AA7022. Zn content in 7××× aluminum alloys seemed to play a major role with respect to the HTS index. Remarkable differences could be seen on thermal contraction behaviors within solidification range for each alloy. The rate and amount of thermal contraction for AA7055 was most prominent, followed by AA7085 and AA7050, while contraction curve of AA7022 was very flat together with least amount of thermal contraction. There was a well consistency between the amount of thermal contraction and HTS. Despite complex interactions of many variables in the formation of hot tear, thermal contraction behaviors within solidification range could give a quick evaluation of hot tearing susceptibility.

scholarly journals Effect of Returnable Material in Batch on Hot Tearing Tendency of AlSi9Cu3 Alloy

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1583
Author(s):  
Justyna Kasińska ◽  
Marek Matejka ◽  
Dana Bolibruchová ◽  
Michal Kuriš ◽  
Lukáš Širanec
Keyword(s):  
Raw Materials ◽  
Qualitative Evaluation ◽  
Hot Tearing ◽  
Material Content ◽  
Negative Effect ◽  
Increased Sensitivity ◽  
Materials Used ◽  
Shape Complexity ◽  
Tear Propagation ◽  
Hot Tearing Susceptibility

The main reason for the use of returnable material, or recycled alloys, is a cost reduction while maintaining the final properties of the casting. The casting resulting quality is directly related to the correct ratio of commercial grade alloy and alloy made by remelting the returnable material in the batch. The casting quality is also affected by the purity of the secondary raw materials used, the shape complexity and the use of the casting itself. The presented article focuses on the effect of increasing the returnable material content in the batch on the hot tearing susceptibility of AlSi9Cu3 alloy. Hot tears are a complex phenomenon that combines metallurgical and thermo-mechanical interactions of the cast metal. Hot tearing susceptibility was evaluated on the basis of quantitative (HTS — hot tearing susceptibility index) and qualitative evaluation. The negative effect of returnable material in the batch was already manifested at a 20% content in the batch. The critical proportion of the returnable alloy in the batch can be stated as 50%. The alloy with a 50% returnable material content manifested insufficient results of the HTS index and qualitative evaluation, which means increased sensitivity to tearing. The negative effect of returnable material and the increased sensitivity were also confirmed in the evaluation of the fracture surface and hot tear profile. The microstructure of alloys with 50% and higher proportion of returnable material was characterized by a higher amount of iron phases (mainly Al5FeSi), whose sharp ends acted as critical regions of hot tearing and subsequent hot tear propagation, which had a major impact on the increase in hot tearing susceptibility.

scholarly journals Novel grain refinement of AZ91E magnesium alloy and the effect on hot tearing during solidfication

2021 ◽  
Author(s):  
Abdallah Elsayed
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Hot Tearing ◽  
Grain Refining ◽  
Grain Refiner ◽  
Structural Applications ◽  
Hot Tearing Susceptibility

For the A1-5Ti-1B grain refiner, the addition of 0.1 wt.% provided a 68 % reduction in grain size as compared to the unrefined AZ91E alloy at a holding time of five minutes. Grain growth restriction by TiB₂ particles was the source of grain refinement. With the addition of A1-5Ti-1B, only a small reduction in hot tearing susceptibility ws observed because large TiA1₃ particles bonded poorly with the eutectic and blocked feeding channels.The addition of 1.0 wt.% A1-1Ti-3B provided a grain size reduction of 63% as compared to the unrefined AZ91E alloy at a holding time of five minutes. The grain refinement with A1-1Ti-3B addition was attributed to a combination of TiB₂ grain growth restriction and A1B₂ nucleating sites. A significant reduction in hot tearing susceptibility was observed with A1-1Ti-3B addition as a result of a higher cooling rate and shorter local soldification time as compared to the AZ91E alloy. The reduction in hot tearing susceptibility was attributed to the good interface between eutectic and TiB₂ particles. Both grain refiners demonstrated a good resistance to fading during the holding times investigated. In addition, the AZ91E + A1-5Ti-1B and AZ91E + A1-1Ti-3B castings showed much fewer dislocation networks as compared to the untreated AZ91E casting.The development of efficient A1-Ti-B refiners can also improve castability of magnesium alloys. In addition, the fade resistant A1-Ti-B grain refiners can reduce operating costs and maintain productivity on the foundry floor. Thus, magnesium alloy with A1-Ti-B treatment have the potential for more demanding structural applications in the automobile and aerospace industries. Vehicle weight in the aerospace and automotive industries directly impacts carbon emissions and fuel efficiency. An increase in the use of lightweight materials for structural applications will result in lighter vehicles. Low density materials, such as magnesium (1.74 g/cm³) are a potential alternative to aluminium (2.70 g/cm³), to reduce component weight in structural applications.However, current magnesium alloys still do not have adequate mechanical properties and castability to meet the performance specifications of the automotive and aerospace industries. Grain refinement can significantly improve mechanical properties and reduce hot tearing during permanent mould casting. Recently, Al-Ti-B based grain refiners have shown potential in grain refining magnesium-aluminum alloys such as AZ91E. This study investigates the grain refining efficiency and fading of A1-5Ti-1B and A1-1Ti-3B in AZ91E magnesium alloy and their subsequent effect on hot tearing.The grain refiners were added at 0.1, 0.2, 0.5 and 1.0 wt.% levels. For the grain refinement and fading experiments, the castings were prepared using graphite moulds with holding times of 5, 10 and 20 minutes. For the hot tearing experiments, castings were produced representing the optimal addition level of each grain refiner. The castings were prepared using a permanent mould with pouring and mould temperatures of 720 and 180 ºC, respectively. The castings were characterized using SEM, TEM, optical microscopy and thermal analysis.

Sign in / Sign up

Export Citation Format

Share Document