AlSi10Mg Samples Research Articles

Performance Consistency of AlSi10Mg Alloy Manufactured by Simulating Multi Laser Beam Selective Laser Melting (SLM): Microstructures and Mechanical Properties.

Multi-laser beam selective laser melting (SLM) technology based on a powder bed has been used to manufacture AlSi10Mg samples. The AlSi10Mg alloy was used as research material to systematically study the performance consistency of both the laser overlap areas and the isolated areas of the multi-laser beam SLM manufactured parts. The microstructures and mechanical properties of all isolated and overlap processing areas were compared under optimized process parameters. It was discovered that there is a raised platform at the junction of the overlap areas and the isolated areas of the multi-laser SLM samples. The roughness is significantly reduced after two scans. However, the surface roughness of the samples is highest after four scans. As the number of laser scans increases, the relative density of the overlap areas of the samples improves, and there is no significant change in hardness. The tensile properties of the tensile samples are poor when the overlap area width is 0, 0.1, or 0.2 mm. When the widths of the overlap areas are equal to or greater than 0.3 mm, there is no significant difference in the tensile strength between the overlap and the isolated areas.

Study of heat treatment parameters for additively manufactured AlSi10Mg in comparison with corresponding cast alloy

A solution, quenching and ageing heat treatment is often performed on additive manufactured AlSi10Mg parts to dissolve the anisotropy due to the layer-by-layer building.This study investigates the influence of temperature and duration of solution and ageing treatment on microstructure, hardness and density of AlSi10Mg alloy produced by direct metal laser sintering.A parallel investigation is carried out on AlSi10Mg samples produced by gravity casting to analyse the different response to the same heat treatment conditions.The highest hardness, combined with an acceptable increase of porosity, is reached after selected heat treatment parameters. It was also found that, compared to the as-produced condition, this treatment leads to a decrease of ultimate tensile strength, without affecting the yield strength of additive manufactured samples, and reduces the difference in properties along the two building directions. The high properties of the as-produced samples are related to the finer microstructure and, as proved by the differential scanning calorimetric measurements, to the self-quenching phenomenon.

Linking microstructure and processing defects to mechanical properties of selectively laser melted AlSi10Mg alloy

Here we analyse the relationship between the monotonic and cyclic behaviour of cylindrical AlSi10Mg (CL31 AL) samples fabricated by Selective Laser Melting (SLM) to the build direction, the presence of manufacturing defects (pores, voids, oxides, etc.) and the beneficial effect of post-processing – T6 and hot isostatic pressing (HIP) – treatments. Correlative Computed Tomography (X-ray tomography, optical microscopy, electron backscatter diffraction, SEM and TEM) is used to characterise the microstructure and the three-dimensional (3D) structure of fatigue samples to shed light on the role of defects on the experimental fatigue behaviour. Pancake-shaped pores are observed in the plane of the deposited layers having a 130% higher volume fraction for the vertical layering deposition (VL) than for horizontal layered (HL) orientations and being larger and flatter.Further, while T6 treatment had relatively little effect on reducing porosity, the HIPping reduced the pore fraction by 44% and 65% for VL and HL samples, respectively. T6 + Hipping decreased the yield stress and the ultimate tensile strength considerably while increasing elongation and reduction of area accordingly. Our results suggest that the fatigue life seems to be dominated by the presence of these crack-like (pancake-like) defects perpendicular to the loading direction such that it is better to build samples transverse to the highest fatigue loads. T6 heat treatment appears to reduce the fatigue strength of the material regardless of the AM deposition scheme due to two main reasons: (i) a reduced tensile strength of the T6-treated alloy and (ii) the inability to reduce (or even increasing) porosity in both layering orientations. The presence of larger and flatter pores/voids (crack-like defects) after T6 were observed. From X-ray tomography, it was observed that T6 + Hipping resulted in improved densification and in smaller and blunter defects which resulted in improved fatigue lives.

Pulsed SLM-manufactured AlSi10Mg alloy: Mechanical properties and microstructural effects of designed laser energy densities

The effects of laser energy densities on microstructures and mechanical properties of AlSi10Mg samples fabricated by pulsed selective laser melting (P-SLM) were studied. Scanning electron microscope, transmission electron microscope, X-ray diffraction, Vickers hardness tester and electronic testing machine were used for analysis and measurement of microstructures, phases and mechanical properties of the samples, respectively. The results show that fine cellular microstructures are composed of α-Al, eutectic Si, and secondary Si. Moreover, the microhardness values of the specimens perpendicular to the building directions fluctuate between HV0.1110∼HV0.1130 while those of the specimens along the building directions decrease with increasing building heights. Finally, comparison of the mechanical properties of P-SLM and casting samples were discussed, the better mechanical properties of P-SLM samples were showed than those of the casting samples, which can be attributed to solid solution strengthening, grain refinement strengthening, dislocations strengthening and second-phase strengthening.

Effect of heat treatments on fatigue property of selective laser melting AlSi10Mg

The fatigue property of selective laser melting AlSi10Mg samples with different heat treatments was investigated. The samples were tested in the state of as-built condition, stress relief treatment, solution treatment and solution + artificial aging treatment. It is found that the as-built sample displays the highest fatigue property, and the solution treatment samples exhibit the lowest fatigue property. Heat treatment reduces the fatigue property. The fatigue cracks originate from the surface or subsurface of all the samples, surface or subsurface pores have quite important effect on fatigue property. It is found that the fatigue property is closely related to the yield strength other than ultimate tensile strength or elongation. The change in fatigue property and static mechanical properties is mainly due to the microstructural transformation. Heat treatment changes the size and morphology of Si, which leads to a decrease in fatigue property.

Nondestructive ultrasonic evaluation of additively manufactured AlSi10Mg samples

Pulse-echo ultrasonic method was carried out to investigate possible anisotropy in selective laser melting additively manufactured (AM) AlSi10Mg samples. Three types of ultrasonic analyses were employed: time of flight (TOF) sound velocity measurement, frequency depended attenuation and exponential fitted attenuation. Analysis of the transverse waves TOF sound velocity as a function the oscillation angle relative to the build direction reveals that the AM AlSi10Mg material has anisotropy in both transverse wave velocity and attenuation with respect to the build direction. Such an anisotropy is with symmetry around the build direction. Three transverse wave velocity zones were identified, low-velocity zone, where the transverse oscillation direction perpendicular to the build direction, high-velocity zone where the transverse oscillation direction parallel to the build direction and a transition zone. This behavior held even after heat treatments. The transverse velocity and the frequency depended attenuation seems to be sensitive tools that enable detection of subtle changes in AM products.

Development and Characterisation of Aluminium Matrix Nanocomposites AlSi10Mg/MgAl2O4 by Laser Powder Bed Fusion

Recently, additive manufacturing techniques have been gaining attention for the fabrication of parts from aluminium alloys to composites. In this work, the processing of an AlSi10Mg based composite reinforced with 0.5% in weight of MgAl2O4 nanoparticles through laser powder bed fusion (LPBF) process is presented. After an initial investigation about the effect of process parameters on the densification levels, the LPBF materials were analysed in terms of microstructure, thermo-mechanical and mechanical properties. The presence of MgAl2O4 nanoparticles involves an increment of the volumetric energy density delivered to the materials, in order to fabricate samples with high densification levels similar to the AlSi10Mg samples. However, the application of different building parameters results in modifying the size of the cellular structures influencing the mechanical properties and therefore, limiting the strengthening effect of the reinforcement.

Corrosion Properties of AlSi10Mg Alloy Prepared by Gravity Casting and 3D Printing Technology

Aluminium and its alloys are widely used in the transport industry. In combination with 3D printing technology, lightweight parts can be successfully achieved. 3D-printing of AlSi10Mg alloy is already well-managed. However, corrosion behaviour of such 3D-printed material has not been intensely studied yet. This paper is thus focused on a primary determination of corrosion properties of AlSi10Mg samples prepared by SLM technology and on comparison with conventionally gravity cast samples in thermally untreated and treated state (T6). Audi immersion test has revealed the 3D-printed samples are the most vulnerable to local corrosion attack, while the as-cast samples are the most resistant. In all three material states, selective dissolution occurred as result of microgalvanic processes between silicon particles and aluminium matrix. Eutectics and α-Al solid solution in between the intercellular network were attacked preferentially in the cast and 3D-printed samples, respectively.

Fatigue of AlSi10Mg specimens fabricated by additive manufacturing selective laser melting (AM-SLM)

The fatigue resistance of AM-SLM AlSi10Mg samples built in the Z direction after various heat treatments was investigated. Specimens were tested in the as-built (AB) condition, after stress relief (SR) treatment and after SR and hot isostatic pressing (HIP) at either 250°C or 500°C. The AB machined and polished specimens displayed the highest fatigue limit (Sf = 125MPa, Nf = 107 cycles). SR and HIP cycles decrease the yield strength, hardness and fatigue limit. The SR and HIP treatment at 500°C resulted in the lowest fatigue resistance due to significant microstructural changes. A relation between the yield stress and fatigue resistance was established. Linear elastic fracture mechanics were employed for evaluating fracture surface morphology. Based on the results of fracture surface characterization, values of the critical stress intensity factor (Kcr) for AM-SLM AlSi10Mg specimens after various heat treatments were estimated.

Experimental investigation on densification behavior and surface roughness of AlSi10Mg powders produced by selective laser melting

Effects of laser energy density (LED) on densities and surface roughness of AlSi10Mg samples processed by selective laser melting were studied. The densification behaviors of the SLM manufactured AlSi10Mg samples at different LEDs were characterized by a solid densitometer, an industrial X-ray and CT detection system. A field emission scanning electron microscope, an automatic optical measuring system, and a surface profiler were used for measurements of surface roughness. The results show that relatively high density can be obtained with the point distance of 80–105μm and the exposure time of 140–160μs. The LED has an important influence on the surface morphology of the forming part, too high LED may lead to balling effect, while too low LED tends to produce defects, such as porosity and microcrack, and then affect surface roughness and porosities of the parts finally.

Metallurgical investigations of laser remelted additively manufactured AlSi10Mg parts

AbstractSelective laser melting is gaining importance to manufacture reliable and highly complex parts. However, the surfaces of the selective laser melted parts exhibit for many applications an insufficient high roughness, thus require subsequent post processing steps. A relatively new way to reduce the surface roughness is the laser polishing technique. In the present paper, additively manufactured AlSi10Mg samples were polished with different laser intensities and laser modes. The investigations contain the potential of roughness reduction and enhancement of the surface appearances, which can be achieved by laser polishing of the as‐built surfaces. An initial arithmetic mean roughness of 8.43 μm was remarkably reduced up to 98 %. The compositions of the polished surfaces were detected and the surface appearances were examined. Reasons and mechanisms were explained and depicted for the occurred shade formations on the polished surfaces. High laser intensity led to segregation of silicon and magnesium on the surface. A higher laser intensity enabled an increased melt depth within the conture layer of the selective laser melting structure. Through increasing melt depth, a porosity of max. 1.7 % was detected in the remolten area. Hardness investigations of the initial and laser remolten cross section revealed no significant reduction in hardness.

A study on cavitation erosion behavior of AlSi10Mg fabricated by selective laser melting (SLM)

Cavitation erosion causes serious problems for hydraulic machinery. Selective laser melting (SLM), is a type of additive manufacturing that can produce metal parts directly and it has begun to be used in various industrial settings. However, the erosion properties of the SLM processed parts have only rarely been reported. The paper addresses the cavitation erosion behavior of AlSi10Mg samples fabricated by SLM at different laser scanning speeds. A wrought sample was also tested to provide a basis for comparison. Sample hardness and microstructure were investigated. Results showed the cavitation erosion behaviors of SLM samples to differ greatly from that of the wrought sample. The erosion rate of SLM samples was found to peak in the first 30s. This was accompanied by the removal of particles inside pores. After peaking, the erosion rate of the SLM samples decreased significantly. SLM samples showed an extremely low erosion rate entering the steady-state period. Large, deep craters which were common wear marks on the wrought sample, were not present on the SLM samples. Different scanning speeds resulted in different max erosion rates.

The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

The Influence of Post-Heat-Treatments on the Tensile Strength and Surface Hardness of Selective Laser Melted AlSi10Mg

Recent investigations revealed major fluctuations in the material properties of selective laser melted AlSi10Mg, which corresponded with the varying precipitation-hardening state of the microstructure, caused by the differing dwell times at elevated temperatures. It was indicated that a subsequent heat treatment balances the age-hardening and results in a homogenized material strength. In order to further investigate this statement selective laser melted AlSi10Mg samples were subject to multiple post-heat-treatments. Subsequently, the surface hardness and tensile strength was determined and compared with the as-built results. The post-heat-treatment led to an arbitrary occurrence of rupture, indicating a successful homogenization, coupled with a remarkable improvement in ductility, but to the costs of a lowered tensile strength, which was highly dependent on the chosen heat-treatment procedure.

Microstructure and preliminary fatigue analysis on AlSi10Mg samples manufactured by SLM

Nowadays, selective laser melting (SLM) is considered as the most challenging technology for manufacturing complex components in different industrial fields, such as biomedical, aerospace and racing. It is well-known that SLM may yield to microstructures significantly different from those obtained by conventional casting, thus affecting the mechanical properties of the component.In the present paper, microstructural and mechanical tests were carried out on AlSi10Mg samples manufactured by SLM technique in the XY building configuration. Homogeneous composition and typical microstructures were achieved for all the investigated samples. The mechanical properties were assessed through a tensile test and through the Impulse Excitation Technique (IET). The feasibility of ultrasonic Very High Cycle Fatigue (VHCF) tests with Gaussian specimens characterized by large loaded volumes (risk-volumes) was also experimentally verified in the paper. A Gaussian specimen was designed and manufactured. A preliminary ultrasonic test was then carried out on the manufactured specimen and the fracture surface was finally investigated.

Effects of vacuum annealing treatment on microstructures and residual stress of AlSi10Mg parts produced by selective laser melting process

Selective laser melting (SLM)-fabricated AlSi10Mg parts were heat-treated under vacuum to eliminate the residual stress. Microstructure evolutions and tensile properties of the SLM-fabricated parts before and after vacuum annealing treatment were studied. The results show that the crystalline structure of SLM-fabricated AlSi10Mg part was not modified after the vacuum annealing treatment. Additionally, the grain refinement had occurred after the vacuum annealing treatment. Moreover, with increasing of the vacuum annealing time, the second phase increased and transformed to spheroidization and coarsening. The SLM-produced parts after vacuum annealing at 300[Formula: see text]C for 2 h had the maximum ultimate tensile strength (UTS), yield strength (YS) and elongation, while the elastic modulus decreased significantly. In addition, the tensile residual stress was found in the as-fabricated AlSi10Mg samples by the microindentation method.

Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB2 Composites Produced by Direct Metal Laser Sintering (DMLS)

Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.

Effect of heat treatment on AlSi10Mg alloy fabricated by selective laser melting: Microstructure evolution, mechanical properties and fracture mechanism

The present paper systematically investigated the influence of solution and artificial aging heat treatments on the microstructures and mechanical properties of SLM-produced AlSi10Mg alloy parts. Due to the high cooling rate of SLM, an ultrafine eutectic microstructure in the as-built samples is characterized by spherical nano-sized network eutectic Si embedded in the Al matrix, which gives rise to significantly better tensile properties and Vickers micro-hardness. The solubility of Si atom in the Al matrix of as-built SLM samples is calculated to be 8.89at%. With the increase in the solution temperature, the solubility decreases rapidly. The artificial aging causes the further decrease of the solubility of Si atoms in the Al matrix. Upon solution heat treatment, Si atoms are rejected from the supersaturated Al matrix to form small Si particles. With increasing the solution temperature, the size of the Si particles increases, whereas their number decreases. After artificial aging, the Si particles are further coarsened. The variation in size of Si particles has a significant influence on the mechanical properties of the AlSi10Mg samples. The tensile strength decreases from 434.25±10.7MPa for the as-built samples to 168.11±2.4MPa, while the fracture strain remarkably increases from 5.3±0.22% to 23.7±0.84% when the as-built sample is solution-treated at 550°C for 2h. This study indicates that the microstructure and mechanical properties of SLM-processed AlSi10Mg alloy can be tailored by suitable solution and artificial aging heat treatments.

The Influence of Selective Laser Melting Parameters on Density and Mechanical Properties of AlSi10Mg

Selective Laser Melting (SLM) is one of the most effective powder bed technique in the additive Manufacturing (AM) which able to fabricate functional metal parts directly from 3D Computer Aided Design (CAD) file data. In this paper, the influence of SLM parameters, such as laser power, scanning speed and hatching distance on the density of AlSi10Mg samples are investigated using one factor at a time (OFAT). Furthermore, the optimum results are used to fabricate samples for hardness, tensile strength, and impact toughness test. It is revealed that AlSi10Mg parts fabricated by SLM achieving the best density of 99.13% at the value of 350 watts laser power, 1650 mm/s scanning speed and hatching distance 0.13mm, whereby resulted comparable and even better mechanical properties to those of conventionally HDPC A360F and HDPC A360T6 alloys although without any comprehensive post processing methods.

Phase analysis and microstructure characterisation of AlSi10Mg parts produced by Selective Laser Melting

ABSTRACTMicrostructural features of AlSi10Mg samples produced by Selective Laser Melting (SLM) technique were systematically characterised. The results showed that certain amount of Si dissolved in the Al matrix (face centre cubic) to form cellular-dendritic α-Al phase. These cells were approximated to be 500 nm. The lattice constant value was found to decrease, resulting from the solid solution of Si in α-Al. Along the boundary of these cells, Mg element clusters were also detected where X-Ray diffraction and energy dispersive X-ray spectroscopy results indicated that Mg2Si dispersoid hardening phase was formed during the SLM process. In addition, the network features along the boundary of Al phase were identified to be eutectic Al/Si phase according to the transmission electron microscopy (TEM)–EDS result. Very fine grainy features of nanometric scale were observed within this phase with dimensions less than 5 nm.