Influence of Ultrasound Treatment on Cavitation Erosion Resistance of AlSi7 Alloy

2018

Metals

Self Cite

In the present review, the main findings on the rheological characterization of semi-solid metals (SSM) are presented. Experimental results are a fundamental basis for the development of comprehensive and accurate mathematics used to design the process effectively. For this reason, the main experimental procedures for the rheological characterization of SSM are given, together with the models most widely used to fit experimental data. Subsequently, the material behavior under steady state condition is summarized. Also, non-viscous properties and transient conditions are discussed since they are especially relevant for the industrial semi-solid processing.

Section: Introductionmentioning

confidence: 99%

Rheological Characterization of Semi-Solid Metals: A Review

Modigell

2018

Metals

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“…At this regard, some authors report the hardness as an indicator of the erosion resistance. Nevertheless, these models reached limited success in prediction erosion damage, as well as the attempt to correlate cavitation resistance and hardness [14][15]. Damage due to cavitation can occur also on various aluminum automotive components, as such as cylinders and pistons, combustion chambers, etc.…”

Section: Introductionmentioning

confidence: 99%

“…Concerning the family of wrought alloys, various alloys belonging to the Al-Cu, Al-Mg, Al-Si-Mg or Al-Zn-Mg families were tested in different conditions [14,17] taking also into account the influence of real erosion environments, as for instance the presence of aggressive fluids or slurries [8,18]. For casting alloys, in general, it was found that Al alloys resistance is strongly affected by several microstructural properties, as such as grain size, number of interfaces between different phases, presence and morphology of secondary phases [14][15][19][20]. This is not surprising since various studies report the influence of eutectic [21][22] and intermetallic phase [23][24][25], as well as the role of grain size [26][27], on other mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of cavitation erosion resistance of Al-Si casting alloys: effect of eutectic and intermetallic phases

Frattura Ed Integrità Strutturale

Montesano

et al. 2017

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In the present paper, the influence of eutectic and intermetallic phases on cavitation resistance of Al-Si alloys was studied. In fact, Al-Si alloys are commonly used for the production of components, such as cylinders, pistons, pumps, valves and combustion chambers, which in service may incur in cavitation phenomenon. Samples of AlSi3, AlSi9 and AlSi9CuFe were characterized from the microstructural point of view. Hardness measurements were also performed. Subsequently, cavitation tests were carried out according to ASTM G32 standard and the erosion mechanism was examined by scanning electron microscope. It was found the both eutectic and intermetallic phases enhance cavitation resistance, expressed in terms of mass loss. Particularly, intermetallic particles with complex morphologies provide a positive contribution, exceeding that of other microstructural features, as grain size. The effect of T6 heat treatment was also evaluated. It was confirmed that the precipitation of fine strengthening particles in the Al matrix successfully hinders the movement of dislocations, resulting in a longer incubation stage and a lower mass loss for heat-treated samples in comparison with as-cast ones. Finally, the relationship between cavitation resistance and material hardness was investigated.Citation: Tocci, M., Pola, A., Montesano, L., La Vecchia, G. M., Evaluation of cavitation erosion resistance of Al-Si casting alloys: effect of eutectic and intermetallic phases, Frattura ed Integrità Strutturale, 43 (2018) 218-230.

“…Other damaging mechanisms of SSM components have been investigated over the years, such as cavitation resistance [110,111]. It was reported that the globular microstructure, as obtained by ultrasound treatment methods (UTS), increases the cavitation erosion resistance of the alloy because of the higher chemical and microstructural homogeneity, the morphology of the primary particles, and the refined structure of the eutectic due to the treatment itself.…”

Section: Wear Resistancementioning

confidence: 99%

“…Surface topographies of the damaged areas of conventionally as-cast (a) before and (b) after T6, semi-solid in (c) as-cast and (d) after T6[111].…”

mentioning

confidence: 99%

Microstructure and Properties of Semi-Solid Aluminum Alloys: A Literature Review

Kapranos

2018

Metals

Self Cite

Semi-solid processing of aluminum alloys is a well-known manufacturing technique able to combine high production rates with parts quality, resulting in high performance and reasonable component costs. The advantages offered by semi-solid processing are due to the shear thinning behavior of the thixotropic slurries during the mold filling. This is related to the microstructure of these slurries consisting of solid, nondendritic, near-globular primary particles surrounded by a liquid matrix. This paper presents a review on the formation of this nondendritic microstructure, reports on the different proposed mechanisms that might be responsible, and illustrates the relationship between microstructure and properties, in particular, tensility, fatigue, wear, and corrosion resistance.fraction. Unfortunately, all these tend to increase the production costs [8], even though recent investigations have shown that SSM processing is only slightly more expensive than conventional die-casting and cheaper than some other competing foundry processes [9].Since its development in the early 1970s at MIT [10], much research has been performed worldwide, aimed mainly at developing new and alternative routes of feedstock production for different alloys suitable for SSM processing. At present, there are a number of different techniques used to produce semi-solid castings, differentiated by the percentage of liquid/solid fraction they employ and the way they produce the alloy in the semi-solid state. SSM methods can be divided in two main categories according to their processing route, known as rheocasting and thixocasting [11]. In rheocasting, the semi-solid slurry is prepared in situ from the liquid state down to a certain percentage of solid fraction (usually between 10 and 30% [12]), and then directly transferred into the shot sleeve for being injected into the die. In thixocasting, a billet, characterized by an almost globular or rosette-like microstructure developed through some specific route, is reheated in the mushy zone (semi-solid region) to an appropriately chosen solid fraction (usually between 50% and 60% [13]), placed in a modified shot sleeve and finally injected into the die [14]. Another classification methodology distinguishes the SSM methods according to the initial step used for obtaining the semi-solid feedstock, i.e., from the liquid state, by controlled solidification or from the solid state, via heavy plastic deformation and recrystallization [11].Some of the most common routes for feedstock material preparation are: mechanical stirring, such as the SSR [15,16] or GISS [17] processes, electromagnetic stirring (EMS or MHD) [18,19], ultrasonic stirring (UTS) [20,21], New Rheocasting (NRC or UBE) [22,23], cooling slope [24], twin screw [25], Rheometal [26], liquid mixing method [27], SEED [28], thermomechanical [29], and SIMA [14,30].A number of interesting reviews about the different technologies available for obtaining nondendritic slurries can be found in the literature [11,13,14,[31][32][33]. Nevertheless, indep...