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Effect of artificial ageing temperature in T6-heat treatment on the mechanical properties of dissimilar metals weld between AA5083 and AA6063

Setyawan H., Muhayat N., Yuliadi M. Z., Manurung Y. H. P., Triyono T.

Archives of Materials Science and Engineering

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2023

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Vol. 123, nr 2

72--85

EN

Purpose: Aluminium AA5083 is commonly utilised in constructing ship hull shells, which are welded with aluminium AA6063 to act as stiffeners. However, the joints often suffer structural damage, such as longitudinal and transverse cracks in the dissimilar weld area, particularly in the Heat-Affected Zone (HAZ) of AA6063, which includes frames, brackets, and collars. To enhance the mechanical properties of AA6063, T6 heat treatment is commonly employed. The given study investigates the impact of temperature in artificial ageing during the T6 heat treatment on the microstructure and mechanical properties of the dissimilar materials welding between AA5083 and AA6063. Design/methodology/approach: The T6 heat treatment variations involve a solution treatment at 540°C for 6 hours, followed by quenching and artificial ageing at temperatures of 158°C, 200°C, and 230°C for 6 hours, followed by air cooling. The T6 heat treatment variations involve a solution treatment at 540°C for 6 hours, followed by quenching and artificial ageing at temperatures of 158°C, 200°C, and 230°C for 6 hours, followed by air. The weld joints were visually inspected and examined using radiography, then characterised by microstructure investigation and tensile and impact tests. Findings: The study's findings reveal that the T6 heat treatment significantly improves the mechanical properties of AA6063. However, the T6 heat treatment does not notably affect the mechanical properties of AA5083, the fusion line and the weld metal area. Among the artificial ageing temperature variations, the highest mechanical properties are achieved at 200°C, while the lowest mechanical properties are observed at 230°C. Research limitations/implications: Aluminium AA5083 is commonly utilised in constructing ship hull shells, which are welded with aluminium AA6063 to act as stiffeners. However, the joints often suffer structural damage, such as longitudinal and transverse cracks in the dissimilar weld area, particularly in the Heat-Affected Zone (HAZ) of AA6063, which includes frames, brackets, and collars. The paper focused on the influence of artificial ageing temperature in T6 heat treatment on the microstructure and mechanical properties of the dissimilar metals welding between AA5083 and AA6063. Originality/value: The optimum artificial ageing temperature in T6 heat treatment for the dissimilar metals welding between AA5083 and AA6063 was 200°C. The method can be applied in ship structures where AA5083 is typically utilised for constructing the hull shells, while AA6063 is employed as stiffeners.

2

Effect of T6 Heat Treatment on the Scratch Wear Behavior of Extruded Al-12wt.%Si Alloy

Kang Yeon-Ji, Kim Jong-Ho, Hwang Jong-Il, Lee Kee-Ahn

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

617--622

EN

This study investigated the effect of T6 heat treatment on the microstructure and scratch wear behavior of hypoeutectic Al-12wt.%Si alloy manufactured by extrusion. Microstructural observation identified spherical eutectic Si phases before and after the heat treatment of alloys (F, T6). Phase analysis confirmed Al matrix and Si phase as well as Al2Cu and Al3Ni, Mg2Si in both alloys. In particular, Al2Cu was finer and more evenly distributed in T6 alloy. This resulted in Vickers hardness of T6 alloy that was 2.3 times greater compared to F alloy. The scratch wear test was conducted using constant load scratch test (CLST) mode and multi-pass scratch test (MPST) mode. The scratch coefficient and worn out volume obtained by such were used to evaluate wear properties before and after heat treatment. In the case of T6 alloy, its scratch coefficient was lower than F alloy in all load ranges. After 15 repeated tests to measure worn out volume, F alloy and T6 alloy measured 1.2×10-1 mm3 and 7.8×10-2 mm3, respectively. In other words, the wear resistance of T6 alloy were confirmed to be better than those of F alloy. In addition, this study attempted to identify the microstructural factors that contribute to the better scratch wear resistance of T6 alloy and wear mechanism from surface and cross-section observations after the wear tests.

3

The Effect of Nickel on Shaping the Structure of Al-Cu-Mn Alloys

Górny M., Sikora G., Tyrała E.

Journal of Casting & Materials Engineering

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2017

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Vol. 1, no. 1

20--26

EN

This study investigated the effect of nickel on shaping the structure of aluminum alloys of the Al-Cu-Mn type in the “as-cast” condition and after heat treatment according to the T6 procedure. The aluminum alloys of type Al-5%Cu-1%Mn, containing nickel in a range of up to 1.9%, were taken into consideration in this work. Experiments were carried out for thin-walled thickness casting (g = 5 mm) and for reference casting with a wall thickness of g = 35 mm. Metallographic investigations of both the macro- and micro-structure were conducted to estimate the secondary dendrite arm spacing (SDAS), average diameter (dav) of the primary α (Al) grains, and surface fraction of the interdendritic phases (f). Moreover, the degree of dissolution of these interdendritic phases during the solution treatment process was determined. An SEM-EDS analysis was conducted, from which it follows that the addition of nickel at the level of 0.5% changes the un-dissolved particles from a needle-like β-Fe shape to blocky and coagulated. Higher additions of nickel starting from 0.88%) give rise to as many as four phases with higher copper content, the deficit of which results in the smaller strengthening effect of α (Al) dendrites.

4

Experimental Investigation Of Modified Heat Treatment Of AK64-Type Al-Si-Cu Sand Cast Alloy

Cupido L. H., Żak P. L., Mahomed N., Lelito J., Piwowarski G., Krajewski P. K.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2397--2402

EN

An experimental investigation was conducted to observe and analyze the microstructural evolution of phases present in the AK64 Al-Si-Cu alloy subjected to a modified T6 heat treatment (HT). The AK64 alloy1 is the Polish alternative of the A319.0 ASM standard aluminium alloy. The modified T6 HT schedule with a higher temperature and shorter duration was applied in the solutioning process and lower quenching and higher artificial ageing temperature than the prescribed by the ASM standard were used. The cooling curves registered during the liberating of overheating and solidifying processes give important information on nucleation temperatures for the Al dendrite network, Al-Si eutectic reaction and precipitation of Cu-rich phases. Comparison of the as-cast and heat treated microstructures revealed predicted microstructural changes and also partial fragmentation of the Fe-rich phases was observed after the application of the modified HT programme.

PL

Artykuł poświęcony jest obróbce cieplnej stopu AK64, który jest odpowiednikiem stopu ASM: A319.0. W badaniach zastosowano zmodyfikowaną obróbkę cieplną T6 o podwyższonej (w stosunku do procedury T6 HT – ASM) temperaturze wyżarzania i skróconym czasie starzenia naturalnego po przesyceniu w wodzie. Obserwacje struktury stopu po obróbce cieplnej wykazały dużą zgodność ze strukturami przewidzianymi na podstawie przeprowadzonych symulacji numerycznych. Dodatkowo określono wartości temperatury odpowiadającej początkowi zarodkowania fazy α(Al), reakcji eutektycznej Al-Si oraz wydzielania z roztworu fazy bogatej w Cu. Opisano również częściową fragmentację fazy zawierającej Fe, będącą następstwem zastosowanej zmodyfikowanej obróbki cieplnej.