scholarly journals The Effect of pre-aging treatments on Tensile Properties and Hardness for Aluminum Alloys

Author(s):  
Mahmoud AlAssaad ◽  
Mohamad Yehea Al nefawy

Abstract— In this research the effect of artificial aging on tensile strength and hardness for Al-Mg-Si (6061 Aluminum alloy) was study, samples from 6061 alloy were submitted to one step artificial aging for different temperatures, while others samples were submitted to two steps artificial aging (where there is a first stage as pre-aging) in descending and ascending modes. The results showed that the highest tensile strength values were reached 214.7 [N/mm2] and hardness were reached 220 [HB] for 6061 Aluminum alloy when the samples were treated by one-step ageing in 190 [°C] for 3 [hour]. While tensile strength and hardness values of samples treated by two-step ageing were slightly higher than these values when the samples was aged at one stage. Where the maximum values of tensile strength was 215 [N/mm2] and for hardness was 227 [HB] when the 6061 alloy treated with two-step ageing the first one in 175 [°C] for 2 [hour] and the second one in 205 [°C] for 1 [hour].

Author(s):  
Mohamad Yahya Nefawy ◽  
Mahmoud Al Asad

In this research, we studied the effect of change in artificial aging time and temperature on tensile strength and Microstructure for 7075 aluminum alloy, Where samples of aluminum alloy 7075 were treated with artificial aging at different temperatures are 120 ° C, 160 ° C and 200 ° C for 0.5, 1.5, 3, 18, 48 hours. When the 7075 aluminum alloy was artificially aged in of 120 ° C and 160 ° C, the values of ultimate tensile strength (UTS) of the alloy were higher than when it was aged in 200 ° C. By increasing of artificial aging time, the UTS of 7075 aluminum alloy increased, when the aging temperature was 120 ° C or 160 ° C, while the UTS decreased when the aging temperature was 200 ° C. This is due to changes in the microstructure, grain size, and precipitating phases such as MgZn2.


Author(s):  
Mohamad Yehea Al nefawy ◽  
Fouad El dahiye

Retrogression and Re-Aging (RRA) Heat Treatment improves the tensile of aluminum alloys. In this research, to study the effect of Retrogression temperature and Retrogression time on the hardness, tensile strength and microstructure of 7075 aluminum alloy, have been applied. Retrogression treatments at different temperatures 180°C, 240°C and 370°C for 30 min and 90 min. When the retrogression temperature was 180°C for 30 min, the alloy has reached its highest hardness and tensile strength; they were respectively 165 HB and 586 MPa. RRA treatment of aluminum alloy 7075 led to precipitate a smoother, more homogeneous, and denser phase compared to the T6 treatment.


Author(s):  
Mohamad Yehea Al nefawy ◽  
Fouad El dahiye ◽  
Mahmoud Al Assaad

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. The effect of adding Nickel and heat treatments on the microstructure, formed phases and tensile properties of the 7075 aluminum alloy were studied in this paper. Different percentages of nickel [0.1, 0.5, 1] wt% was added to 7075 Aluminum alloy, and various heat treatments (artificial aging T6 and Retrogression and re-aging RRA) was applied on the 7075 alloys that containing nickel. The results obtained by applying of RRA treatment were better than the results of T6 treatment, the tensile properties increased and the microstructure became softer by adding nickel to the studied alloys. The maximum tensile strength of 7075 aluminum alloy was (UTS = 437 Mpa) when RRA heat treatment was applied and 0.5% nickel was added.


2020 ◽  
Vol 8 (4) ◽  
pp. 37-47
Author(s):  
Mohamad Yahya Nefawy ◽  
Mahmoud Al Asad

In this research, we studied the effect of change in artificial aging time and temperature on tensile strength and Microstructure for 7075 aluminum alloy, Where samples of aluminum alloy 7075 were treated with artificial aging at different temperatures are 120 ° C, 160 ° C and 200 ° C for 0.5, 1.5, 3, 18, 48 hours. When the 7075 aluminum alloy was artificially aged in of 120 ° C and 160 ° C, the values of ultimate tensile strength (UTS) of the alloy were higher than when it was aged in 200 ° C. By increasing of artificial aging time, the UTS of 7075 aluminum alloy increased, when the aging temperature was 120 ° C or 160 ° C, while the UTS decreased when the aging temperature was 200 ° C. This is due to changes in the microstructure, grain size, and precipitating phases such as MgZn2.


Author(s):  
Mukesh Kumar ◽  
Muhammad Moazam Baloch ◽  
Muhammad Ishaque Abro ◽  
Sikandar Ali Memon ◽  
Ali Dad Chandio

Aluminum alloys have been attracted by several engineering sectors due to their excellent strengthweight ratio and corrosion resistant properties. These are categorized into 1, 2, 3, 4, 5, 6, 7and 8xxx on the basis of alloying elements. Among these 6xxx series contains aluminum–magnesium–silicon as alloying elements and are widely used in extruded products and automotive body panels. The major advantages of these alloys are good corrosion resistance, medium strength, low cost, age hardening response no yield point phenomenon and Ludering. 6xxx series alloys generally have lower formability than other aluminum alloys which restrict their utilization for wide applications. Keeping in view of the shortcomings in the set of mechanical properties of 6xxx series the efforts were made to improve the tensile strength and toughness properties through age hardening. In present study heat treatment cycles were studied for 6061 aluminum alloy. Three different age hardening temperatures 160, 200 and 240oC were selected. The obtained results showed that 17.26, 7.69, and 10.51% improvement in tensile strength, toughness and hardness respectively was achieved with solution treatment at 380oC followed by an aging 240oC. Microstructural study revealed that substantial improvements in the mechanical properties of 6061 aluminum alloy under heat treatment were achieved due to precipitation of Mg2Si secondary phase.


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.


2013 ◽  
Vol 662 ◽  
pp. 251-257
Author(s):  
Ning Xia ◽  
Zhi Min Zhu ◽  
Hui Chen

6005A aluminum alloys were welded at different relative humidity conditions. The effects of relative humidity on the salt fog corrosion of the welding joints were researched. The results showed that the weight loss of the joints after 14 days corrosion was higher than that corroded after 7days, but the corrosion rate was lower. The corrosion rate first increased then declined with the increase of environmental humidity for the joints corroded for 7days. However, when the environmental humidity was 80%, corrosion rate achieved the maximum, when environment humidity was 70%, corrosion rate was the lowest. After corroded for 14 days, corrosion rate was the maximum when the environmental humidity was 50%, and it was the lowest when the environmental humidity was 90%. The tensile strength declined obviously after corrosion.


Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4157 ◽  
Author(s):  
Isidro Guzmán ◽  
Everardo Granda ◽  
Jorge Acevedo ◽  
Antonia Martínez ◽  
Yuliana Dávila ◽  
...  

Precipitation hardening aluminum alloys are used in many industries due to their excellent mechanical properties, including good weldability. During a welding process, the tensile strength of the joint is critical to appropriately exploit the original properties of the material. The welding processes are still under study, and gas metal arc welding (GMAW) in pulsed metal-transfer configuration is one of the best choices to join these alloys. In this study, the welding of 6061 aluminum alloy by pulsed GMAW was performed under two heat treatment conditions and by using two filler metals, namely: ER 4043 (AlSi5) and ER 4553 (AlMg5Cr). A solubilization heat treatment T4 was used to dissolve the precipitates of β”- phase into the aluminum matrix from the original T6 heat treatment, leading in the formation of β-phase precipitates instead, which contributes to higher mechanical resistance. As a result, the T4 heat treatment improves the quality of the weld joint and increases the tensile strength in comparison to the T6 condition. The filler metal also plays an important role, and our results indicate that the use of ER 4043 produces stronger joints than ER 4553, but only under specific processing conditions, which include a moderate heat net flux. The latter is explained because Mg, Si and Cu are reported as precursors of the production of β”- phase due to heat input from the welding process and the redistribution of both: β” and β precipitates, causes a ductile intergranular fracture near the heat affected zone of the weld joint.


2002 ◽  
Vol 51 (9Appendix) ◽  
pp. 156-161
Author(s):  
Hiizu OCHI ◽  
Takeshi SAWAI ◽  
Yoshiaki YAMAMOTO ◽  
Masayuki KURITA ◽  
Koichi OGAWA ◽  
...  

2014 ◽  
Vol 875-877 ◽  
pp. 1397-1405 ◽  
Author(s):  
G. Dinesh Babu ◽  
M. Nageswara Rao

Cast aluminum alloy 354 is used extensively for production of critical automobile components, owing to its excellent castability and attractive combination of mechanical properties after heat-treatment. With the advent of higher performance engines, there has been a steady demand to further improve the mechanical behavior of the castings made of the alloy, among others, through improvements in processing. The present study explores the possibility of improving tensile properties of the alloy by adopting certain non-conventional aging treatments. The non-conventional treatments include aging cycles similar to T6I4 and T6I6 referred to in the published literature, artificial aging in two steps instead of in single step and artificial aging preceded by various natural aging times. The results show that none of these non-conventional treatments leads to improvement of all tensile properties compared to the standard T61 treatment. Significant hardening takes place in the alloy due to natural aging. Changing the time of natural aging preceding artificial aging was found to have little effect on tensile properties.


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