scholarly journals Influence of Preheating Temperature on Changes in Properties in the HAZ during Multipass MIG Welding of Alloy AW 6061 and Possibilities of Their Restoration

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1902
Author(s):  
Iva Novakova ◽  
Jaromir Moravec ◽  
Jan Novak ◽  
Pavel Solfronk

Fusion welding of heat-treatable aluminum alloys is generally accompanied by a significant decrease in mechanical properties in the HAZ caused by the dissolution of the hardening phase. The intensity of this decrease in mechanical properties can be reduced by limiting the heat input value. However, this approach is in direct conflict with the principles for welding aluminum and its alloys. Due to the very high thermal conductivity of aluminum alloys, it is necessary to use preheating for thicknesses larger than 5 mm to eliminate non-penetration and cold joints. This paper aims to show the influence of multiple temperature cycles, performed at different preheating temperatures, on changes in the microstructure and mechanical properties. At the same time, the extent to which the original properties of the material can be restored by natural and artificial aging at 160, 175 and 190 °C is also investigated.

2019 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
Mahmoud Alasad ◽  
Mohamad Yahya Nefawy

The aluminum alloys of the 7xxx series consist of Al with Zn mainly, Mg and Cu. 7xxx aluminum alloys has high mechanical properties making it distinct from other aluminum alloys. In this paper, we examine the effect of adding Nickel and heat treatments on the microstructure and hardness of the 7075 aluminum alloy. Were we added different percentages of nickel [0.1, 0.5, 1] wt% to 7075 Aluminum alloy, and applied various heat treatments (artificial aging T6 and Retrogression and re-aging RRA) on the 7075 alloys that Containing nickel. By applying RRA treatment, we obtained better results than the results obtained by applying T6 treatment, and we obtained the high values of hardness and a smoother microstructure for the studied alloys by the addition of (0.5 wt%) nickel to alloy 7075.


2022 ◽  
Author(s):  
Dong Wang ◽  
Dingyao Liu ◽  
JianHua Xu ◽  
JiaJun Fu ◽  
Kai Wu

It is still a formidable challenge to develop ideal thermal dissipation materials with simultaneous high thermal conductivity, excellent mechanical softness and toughness, and spontaneous self-healing. Herein, we report the introduction...


RSC Advances ◽  
2014 ◽  
Vol 4 (83) ◽  
pp. 44282-44290 ◽  
Author(s):  
Jun Hou ◽  
Guohua Li ◽  
Na Yang ◽  
Lili Qin ◽  
Maryam E. Grami ◽  
...  

The fabricated surface modified boron nitride epoxy composites exhibit high thermal conductivity, superior thermal stability and good mechanical properties while retaining good electrical insulation properties.


RSC Advances ◽  
2018 ◽  
Vol 8 (40) ◽  
pp. 22846-22852 ◽  
Author(s):  
Seokgyu Ryu ◽  
Taeseob Oh ◽  
Jooheon Kim

Boron nitride (BN) particles surface-treated with different amounts of aniline trimer (AT) were used to prepare thermally conductive polymer composites with epoxy-terminated dimethylsiloxane (ETDS).


Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2770 ◽  
Author(s):  
Dongxu Wu ◽  
Congliang Huang ◽  
Yukai Wang ◽  
Yi An ◽  
Chuwen Guo

In this work, SiC and Cu particles were utilized to enhance the thermal and mechanical properties of Al matrix composites. The ball-milling and cold-compact methods were applied to prepare Al matrix composites, and the uniform distribution of SiC and Cu particles in the composite confirms the validity of our preparation method. After characterizing the thermal conductivity and the compressibility of the prepared composites, results show that small particles have a higher potential to improve compressibility than large particles, which is attributed to the size effect of elastic modulus. The addition of SiC to the Al matrix will improve the compressibility behavior of Al matrix composites, and the compressibility can be enhanced by 100% when SiC content is increased from 0 to 30%. However, the addition of SiC particles has a negative effect on thermal conductivity because of the low thermal conductivity of SiC particles. The addition of Cu particles to Al-SiC MMCs could further slightly improve the compressibility behavior of Al-SiC/Cu MMCs, while the thermal conductivity could be enhanced by about 100% when the Cu content was increased from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure and/or sintering temperature. This work is expected to supply some information for preparing Al matrix composites with low density but high thermal conductivity and high compressibility.


Nanoscale ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 3759-3768 ◽  
Author(s):  
Bohayra Mortazavi ◽  
Meysam Makaremi ◽  
Masoud Shahrokhi ◽  
Mostafa Raeisi ◽  
Chandra Veer Singh ◽  
...  

Mechanical properties, thermal conductivity, electronic and optical responses of borophene hydride, a newly synthesized 2D material are explored using the first-principles simulations.


ACS Omega ◽  
2017 ◽  
Vol 2 (7) ◽  
pp. 3931-3944 ◽  
Author(s):  
Bowen Zhu ◽  
Jing Liu ◽  
Tianyu Wang ◽  
Meng Han ◽  
Shah Valloppilly ◽  
...  

2013 ◽  
Vol 813 ◽  
pp. 175-178 ◽  
Author(s):  
Cheol Woo Kim ◽  
Jae Ik Cho ◽  
Se Weon Choi ◽  
Young Chan Kim

Recently, demand of aluminum alloys for manufacturing in components with high thermal conductivity application increases. However, the most aluminum die casting alloys exhibit very lower thermal properties, about only a half of pure aluminum. In die casting alloys, alloying elements are essential to obtain sufficient fluidity and mechanical strength, therefore, in this study, the effect of alloying elements, Si, Cu, Mg, Fe and Mn, on thermal conductivity, die casting characteristics and mechanical properties were analyzed and the appropriate amount of each alloying element were investigated. The results showed that Mn had the most deleterious effect in thermal conductivity and Si and Fe contents were important to improve fluidity and strength. The alloy with 1.5~2.0wt.%Si and 0.6wt.%Fe showed very good combination of high thermal conductivity and sufficient casting characteristics.


1995 ◽  
Vol 10 (2) ◽  
pp. 247-250 ◽  
Author(s):  
Jyh-Ming Ting ◽  
Max L. Lake

The first use of continuous vapor grown carbon fiber (VGCF) as reinforcement in aluminum metal matrix composite (Al MMC) is reported. Al MMC represents a new material for thermal management in high-power, high-density electronic devices. Due to the ultrahigh thermal conductivity of VGCF, 1950 W/m-K at room temperature, VGCF-reinforced Al MMC exhibits excellent thermal conductivity that cannot be achieved by using any other carbon fiber as reinforcement. An unprecedented high thermal conductivity of 642 W/m-K for Al MMC was obtained by using 36.5% of VGCF.


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