Mechanical and Microstructural Properties of 2618 Al-Alloy Processed by SLM Remelting Strategy

2017 ◽  
Vol 891 ◽  
pp. 343-349 ◽  
Author(s):  
Libor Pantělejev ◽  
Daniel Koutný ◽  
David Paloušek ◽  
Jozef Kaiser

Paper deals with the comparison of mechanical properties and microstructure of aluminium alloy 2618 fabricated by Selective Laser Melting (SLM) and material of the same grade manufactured by standard extrusion process. The SLM specimens were fabricated with different processing strategies (meander and remelting). Presence of cracks was found in both cases of used strategies, but in case of meander strategy, crack are of shorter character and distributed rather within individual welds. In case of remelting strategy, cracks are oriented mostly parallel to building direction and transcend fusion boundaries (FB) across several layers. It was found that defects present in microstructure of SLM material significantly affect its mechanical properties. Ultimate tensile strength (UTS) for extruded material reached 392 MPa, while for SLM material produced with meander strategy UTS was 273 MPa and for remelting strategy it was 24 MPa only.

Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Yun Wang

Metal components produced by additive manufacturing processes usually have inferior properties and performances as compared with the counterparts by the traditional forming and machining processes. To close the gap, the metal matrix can be strengthened by adding reinforcement particles in additive manufacturing processes. This research presents the fabrication of nano-TiC reinforced Inconel 718 composites using selective laser melting (SLM). Tensile and wear performance tests are conducted to evaluate the mechanical properties of the formed composites. It is discovered that the composites exhibit improved mechanical properties in terms of ultimate tensile strength and yield stress. Compared with the pure Inconel 718 specimens by SLM, the ultimate tensile strength and yield stress of the reinforced Inconel 718 increase by 207 MPa and 204 MPa, respectively, with 0.5 wt.% addition of nano-TiC particle. Smaller increases are observed with 0.25 wt.% and 1.0 wt.% nano-TiC additions. On the other hand, the addition of nano-TiC particles decreases the ductility of Inconel 718. To investigate the strengthening mechanism of nano reinforcement particles in SLM, the microstructures with different levels of nano-TiC particles are observed. The results indicate that the microstructure of Inconel 718 is remarkably refined by the TiC particles, and the reinforcement particle significantly impede the growth of columnar grain in the solidification process.


2013 ◽  
Vol 668 ◽  
pp. 823-829 ◽  
Author(s):  
Xiu Qing Zhang ◽  
Ge Chen ◽  
Yang Wang ◽  
Min Yu Han

Homogenized magnesium alloy Mg-6Zn-Si-0.25Ca has been hot-extruded and then aging treated for improving the magnesium alloy plastic deformation ability and promoting applications of magnesium alloys. In the hot extrusion process, the influences of extrusion parameters for microstructures and mechanical properties of Mg-6Zn-Si-0.25Ca magnesium alloy were investigated. The results show that dynamic recrystallization occurred during hot extrusion. Compared with as-cast alloy, the grains are fined remarkably, and the mechanical properties are enhanced obviously. Twin crystals appeared in grains after hot extrusion, with the extrusion temperature rising, twin crystal structures has been reduced. Aging further increased the mechanical properties of the estruded alloy. The ultimate tensile strength of Mg-6Zn-Si-0.25Ca alloy is about 385 MPa and the elongation is about 11% when extruded at 320°C(extrusion ratio is 10) and aged at 190°C for 8h.


2014 ◽  
Vol 794-796 ◽  
pp. 526-531 ◽  
Author(s):  
Douglas Watson ◽  
Shou Xun Ji ◽  
Zhong Yun Fan

Super-ductile diecast aluminium alloys are critical to future lightweighting of automotive body structures. This paper introduces a diecast aluminium alloy that can satisfy the requirements of these applications. After a review of currently available alloys, the requirement of a diecast aluminium alloy for automotive body structural parts is proposed and an Al-Mg-Si system is suggested. The effect of the alloying elements, in the composition, has been investigated on the microstructure and mechanical properties, in particular the yield strength, the ultimate tensile strength and elongation.


2018 ◽  
Vol 877 ◽  
pp. 98-103
Author(s):  
Dhananjayulu Avula ◽  
D.K. Dwivedi

In this study the effect of process parameters on mechanical and microstructural properties of similar AA6082-T6 joints produced by friction stir welding was investigated. Different samples were produced by varying the transverse welding speeds of the tool from 19 to 75 mm/min and a fixed rotational speed of 635 rpm. A more uniform hardness values in the nugget zone were observed at 48 mm/min welding speed. The lowest hardness values were recorded on nugget zone at all the welding speeds. The increase in welding speed increases ultimate tensile strength and reaches maximum and further increase in welding speed results decrease in tensile strength were observed. The welded joint has highest joint efficiency (52.33 %) obtained at the welding speed of 48 mm/min. Similarly with the increase in welding speed decrease in the percentage elongation were recorded.


2018 ◽  
Vol 3 (5) ◽  
pp. 71
Author(s):  
Joseph Temitope Stephen ◽  
Adeyinka Adebayo ◽  
Gbenga Joshua Adeyemi

This paper reports the influence of solidification rate and stress-relief annealing on the mechanical properties of cast 6063 Aluminium alloy (Al6063). Ingots of Al6063 were melted and then cast using sand and metal moulds. Some of the cast samples were heat treated and then cooled in natural air. Tensile test, hardness test, impact test and microstructural analysis were carried out on the samples. The results show substantial changes in the mechanical properties of the specimens. The ultimate tensile strength, yield strength and hardness percentage elongation of cast Al6063 increases with the use of casting method with high thermal conductivity and reduces when annealing is carried out on the specimens. The ultimate tensile strength of 146.7 MPa and 163.5 MPa were recorded for sand mould and metal mould samples, respectively and the values decreases by 10.3% and 7.5% for the respective moulds. In contrast, the values of impact strength and percentage elongation of cast Al6063 rod improved with the increase in thermal conductivity of casting method and annealing operation. The ductile increased by 51.01% and 45.82% for sand mould and metal mould samples, respectively, after they were annealed. Furthermore, microstructural analysis of cast Al6063 rod revealed a fine-grained structure with increase in thermal conductivity of casting method used; however, the annealing process encouraged grain growth as a result of the stress being relieved from the samples.


2006 ◽  
Vol 519-521 ◽  
pp. 853-858 ◽  
Author(s):  
Manuel A. Salazar-Guapuriche ◽  
Y.Y. Zhao ◽  
Adam Pitman ◽  
Andrew Greene

The tensile strength, proof strength, hardness and electrical conductivity of Al alloy 7010 under different temper and ageing conditions were investigated with the aim to correlate strength with hardness and electrical conductivity so that the strength of the alloy can be determined nondestructively. Following the solutionising treatment, continuous age hardening was performed on a series of test coupons, taken from a large plate, to produce a wide range of precipitation hardening conditions, which gave rise to progressive variations of strength, hardness and conductivity. The relationship between strength and hardness was found to be reasonably linear, whereas the relationship between hardness and strength with electrical conductivity was non-linear. The ageing conditions and therefore the mechanical properties of the components can be predicted more accurately by the simultaneous combination of hardness and conductivity values.


2012 ◽  
Vol 629 ◽  
pp. 198-202 ◽  
Author(s):  
Ping Yang ◽  
Kai Huai Yang

Three groups of commercial 1050 Al alloy were subjected to equal channel angular pressing (ECAP) at room temperature using route A, route C and route Bc, respectively. Mechanical properties and fracture modes of as-annealed and ECAPed samples were investigated. The microhardness of 1050 Al fabricated by ECAP increases by a factor of about 1.5 compared to the as-annealed state. The ultimate tensile strength (UTS) increases significantly after ECAP, while the elongation decreases. But they are strongly dependence on the number of ECAP passes and the pressing route. The UTS and elongation of the samples processed by route Bc are best, consequently, the static toughness U of the samples is enhanced. Besides, all specimens subjected to ECAP deformation failed in a ductile manner.


2013 ◽  
Vol 765 ◽  
pp. 486-490 ◽  
Author(s):  
Feng Xia ◽  
Jian Ping Li ◽  
Yong Chun Guo ◽  
Zhong Yang

The microstructures and mechanical properties of an Al-Si-Cu-Mg-Ni aluminium alloy have been investigated after thermal exposure at 350 °C for time intervals up to 1000 h. Experimental results showed that, with increasing the thermal exposure time, room temperature ultimate tensile strength, elevated temperature ultimate tensile strength, and Brinell hardness firstly decreased remarkably (up to 100 h) and then decreased slightly to a certain constant value (100-1000 h). Before thermal exposure, room temperature ultimate tensile strength, elevated temperature ultimate tensile strength, elevated temperature elongation percentage, and Brinell hardness of the alloys are 203.5 MPa, 48.7 MPa, 9.2%, and 82.3, respectively. With increasing the thermal exposure time, eutectic silicon grows up steadily, and the amount of Q phase with a flower shape increases. Transmission electron microscopy analysis showed that the formation of stable θ precipitates was found in the microstructure.


2012 ◽  
Vol 468-471 ◽  
pp. 1831-1835
Author(s):  
Kai Huai Yang ◽  
Na Lin ◽  
Shao Feng Zeng ◽  
Wen Zhe Chen

Three groups of commercial 5052 Al alloy sheets were subjected to groove pressing (GP) at room temperature using parallel GP, 180° cross GP and 90° cross GP, respectively. Mechanical properties and fracture modes of as-annealed and GPed samples were investigated. The microhardness of the samples processed by parallel GP increases by a factor of about 1.6 compared to the as-annealed state, and that of the samples processed by cross GP is higher. The ultimate tensile strength (UTS) increases significantly after GP, while the elongation decreases. But they are strongly dependence on the number of GP passes and the pressing modes. Besides, fracture surface morphology demonstrates that the fracture mode is ductile even after four passes. With increasing the number of GP pass, the amount of small dimples increases, and the dimples become shallow and more uniform.


2006 ◽  
Vol 114 ◽  
pp. 145-150 ◽  
Author(s):  
Pawel Widlicki ◽  
Halina Garbacz ◽  
Małgorzata Lewandowska ◽  
Wacław Pachla ◽  
Mariusz Kulczyk ◽  
...  

Hydrostatic extrusion can be viewed as one of the methods of Severe Plastic Deformation, SPD, for the fabrication of ultra-fine grained alloys which causes a significant increase in the mechanical properties such as tensile strength and hardness. In the present study the microstructure of 6082 aluminium alloy after hydrostatic extrusion was investigated. Hydroextrusion was performed in three steps with accumulated true strains of 1.34, 2.73 and 3.74 respectively. Microstructural observations were carried out using SEM, TEM and light microscopy. Grain and inclusion sizes, shapes and distribution were investigated in the HE processed samples. The study has shown that the hydrostatic extrusion process results in a profound refinement of both the grain size and the inclusions in 6082 aluminium alloy.


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