Casting Processes

Front matter

Edited by T. R. Vijayaram Edited by T. R. Vijayaram Various types of casting processes have been developed to manufacture good-quality castings. Different casting processes produce different casting properties and microstructures in castings. This book examines various types of casting processes as well as their properties and applications. Over six chapters in four sections, this volume discusses semi-solid casting and squeeze casting processes, the flowability of sand mixtures and liquid metal flow in mold cavities, gravity die casting, and cast iron technology.

Published in London, UK © 2022 IntechOpen © Shelly Still / iStock ISBN 978-1-80355-495-2

Edited by T . R. Vijayaram Published in London, United Kingdom http:/ /dx.doi.org/10.5772/intechopen.97894 Edited by T. R. Vijayaram Contributors Narducci Junior Carlos Jr., Yuichi Tsukaguchi, Kodai Fujita, Hideki Murakami, Roderick I.L. Guthrie, Mukkollu Sambasiva Rao, Amitesh Kumar, Vincent Haanappel, Jerzy Zych, Marcin Myszka, Janusz Postuła, A. Babafemi Abiodun Ogunkola, Adeolu Adesoji Adediran, Olanrewaju Seun Adesina, Francis Odikpo Odikpo Edoziuno, Christian Okechukwu, M. Saravana Kumar © The Editor(s) and the Author(s) 2022 The rights of the editor(s) and the author(s) have been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights to the book as a whole are reserved by INTECHOPEN LIMITED. The book as a whole (compilation) cannot be reproduced, distributed or used for commercial or non-commercial purposes without INTECHOPEN LIMITED’s written permission. Enquiries concerning the use of the book should be directed to INTECHOPEN LIMITED rights and permissions department (permissions@intechopen.com).

Contents

II Section 4 Cast Iron Technology 105 Chapter 6 107 ‘Vari-Morph’ (VM) Cast Iron with Several Forms of Graphite: Technology, Properties, Application by Jerzy Zych, Marcin Myszka and Janusz Postuła X

Preface Metal casting is a basic manufacturing process in which molten metal at a particular temperature is poured into a mold cavity of a particular shape and allowed to solidify completely. The solidified part is often called the casting, which is taken out by breaking the mold. Casting has the best design flexibility when compared to other manufacturing techniques such as rolling, forging, welding, stamping, and extrusion. The metal casting process also offers advantages in the form of enabling the production and formation of attractive and aesthetic designs, as there is no restriction to the assembly of shapes. Castings or cast components are used in several industries like agriculture, defense, automotive, culinary, mining, construction, health care, and paper. Metals like aluminum, magnesium, copper alloys, tin, lead alloys, iron, and steel are cast in metallic and sand molds. The quality of cast metals and alloys is determined by casting properties like fluidity, shrinkage, porosity, surface finish, and resistance to crack formation.

Different types of casting processes have been developed to manufacture defect-free castings. Foundry technologists have consistently researched several casting techniques to further improve existing processes. Green sand molding mixtures have been tested to optimize the required sand properties to obtain castings of good quality. The molten metal flow is governed by the sand properties. Graphite morphology in cast iron is governed by the solidification rate and inoculation efficiency. Different casting processes produce different casting properties and microstructures in castings. This book discusses various metal casting processes used in the foundry industries. It discusses gravity die casting, semisolid slope casting technology, opportunities and recent trends of the squeeze casting process, novel modeling for molten metal flow in the mold cavity, green sand molding process, and technology of producing cast iron.

Section 1 Semi Solid Casting

Chapter 1 Slope Casting Process: A Review Mukkollu Sambasiva Rao and Amitesh Kumar Abstract Semi solid processing is a near net shape casting process and one of the promising techniques to obtain dendritic free structure of metals. Semi solid casting gives numerous advantages than solid processing and liquid processing. Semi solid casting process gives, Laminar flow filling of die without turbulence, Lower metal temperature, Less shrinkage, Less porosity, Higher mechanical properties. Semi solid casting process is industrially successful, producing a variety of products with good quality. Slope Casting process is a simple technique to produce semi solid feed-stoke with globular microstructure and dendrite free structure castings. Slope casting process depends on different process parameters like slope length, slope angle, pouring temperature etc. The present study mainly focuses on review of various explorations made by researchers with different process parameters of the Slope casting process and explain the mechanisms that lead to microstructural changes which leads to good mechanical properties.

Keywords: semi-solid process, thixo casting, Rheo casting, slope casting, aluminum alloys, non dendritic structure, slope length, slope angle, slope plate temperature, slope vibration 1. Introduction Semi-solid processing as the name suggests is the processing of non-dendritic material between its liquidus and solidus temperatures. In recent years, much work has been conducted in exploring this field with respect to understanding the mechanisms involved. The inherent properties of semi-solid materials at the semi-solid processing temperature such as lower heat content, relatively higher viscosity comparable to liquids and low flow stresses, enables the semi-solid process to show distinct advantages over fully liquid and/or fully solid-state processes. Some of the important benefits of this technique are low mold erosion, low energy consumption, improved die filling, less gas entrapment, lower solidification shrinkage, reduced macro-segregation and fine microstructure. Therefore, this process is rapidly gaining commercial importance [1–3]; A non-dendritic microstructure can be obtained by stirring, either mechanically or electro-magnetically; grain refining; low superheat melt processing; solid state mechanical treatment and reheating [4–7]; The manufacturing industries widely focused on the semi solid routes to produce components with superior mechanical and metallurgical properties. Slope casting process is one of the simplest techniques to produce semi solid slurry [8]. Slope cating process is pouring of molten metal through a slope channel into a mold.

This slope channel help as a site for nucleation and fragmentation of dendrites due to shearing force between different layers of flowing stream [9]. Slope casting process depends on different process parameters like slope length, slope angle, pouring temperature etc. [10–14]. In recent years Aluminum alloys are using mostly in the automotive industries. Among the Aluminum alloys, the Al-Si alloys have good casting characteristics like high fluidity and good cast-ability which makes them advantageous for both small and complicated castings. Every year lakhs of Aluminum alloy components are produced through semi solid processing route. The present study mainly focuses on review of various explorations made by researchers with different process parameters of the Slope casting process and explain the mechanisms that lead to microstructural changes which leads to good mechanical properties. 2. Semi-solid casting The processing of alloy between liquidus and solidus (mushy zone) range is known as the semi solid process, it was first discovered in 1970s, by spancer at Massachusetts Institute of Technology (MIT); found that at semi solid range of alloy behaves thixotropically (Decreases in viscosity if it is sheared but it will thicken again if it is allowed to stand)and by applying continuous stirring on the semi solid state produced no dendritic and spheroidal microstructure [15–19]. The semi solid casting route gives enormous advantages like dendritic free structure leads to globular structure as seen in Figure 1, less defects such as porosity, shrinkage, gas entrapment and macro-segregation. Better advantages than conventional casting that superior quality, low forming temperature, superior mechanical properties with microstructural refinement. The semi-solid process results in a non-dendritic microstructure due to forming at a temperature between solidus and liquidus temperature as shown in phase diagram, Figure 2. In semi solid process, temperature has a pivotal role on the resultant microstructure like orientation of grain, morphology of grain during solidification of alloys [22–24]. Semi-solid processing is used for all the shape forming processes which take advantage of the semi-solid range of the alloys for processing. Rheology and Thixotropy, two basic phenomena play a major role, In semi-solid processing. The apparent viscosity of a material in the liquid state varies with change in shear rate In Rheology. This gives the liquid like slurry to be processed even at sufficiently high solid fraction [25]. Thixotropy, is the ability of a material to Decreases Figure 1.

Using semi solid process technique dendritic structure changes to globular [20].

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 in viscosity if it is sheared but it will thicken again if it is allowed to stand [26]; A material with a non-dendritic structure is the best suitable material for semi-solid processing. it is believed that, in the semi-solid state, the non-dendritic equiaxed grains easily slide/glide on each other on the application of a shear force [27]. Thixotropy behavior can be define as when the material state is partially solid with 40–50% solid fraction and is sheared applied by external force, then its viscosity will decrease due to the break/detachment of the coalescence material, and it will flow like a liquid, for a certain time if it is allowed to stand, equiaxed coalescence will increase the viscosity of the material, by that it being able to support its own weight in the same way as if it was solid [28]. 2.1 The mechanism of non-dendritic structure To describe mechanism for non-dendritic structure in semi solid process many theories have been proposed. These mechanisms include dendrite arm fragmentation, dendrite arm root re-melting, and growth control mechanism. Hv Atikson et al. [20], V ogel et al. [29]; proposed that under shearing forces dendrite arms bends due to its plasticity, which introduce large misorientations inside the dendrite arms and dislocations introduced; rearrangements of dislocations occur to form grain boundaries at the melting temperature. The energy of the grain boundaries becomes more than twice the liquid/solid interfacial energy when the misorientations between grain boundaries are more than 20°, then separation of the dendritic arms observes due to wetting of the grain boundaries by liquid metal. Schematically illustrated in Figure 3. Hellawell et al. [30]; proposed grain multiplication theory, Thermal convention and shearing force have a direct effect at the roots of secondary dendrite arms, melting off rather than breaking off secondary arms observed, and grain multiplication, schematically illustrated in Figure 4. Evolution of structure during solidification with shear force depends on the cooling rate and shear rate, with increase in shear and cooling rate gives non dendritic/globular structure that that the particle shape and size vary irreversibly with shear and colling rate. Illustrate in Figure 5. Figure 2.

Phase diagram of Al-Si alloy [21].

2.2 Classification of semi solid process The semi solid casting process mainly classified into the thixo casting and rheo casting and these processes are farther divided into many process techniques show in below (Figure 6).

Figure 4.

Schematic diagram of dendrite multiplication theory [22]. Figure 3.

Schematic illustration of the steps of the mechanism of dendrite fragmentation: (a) undeformed dendrite; (b) after bending; (c) formation of high-angle boundary; and (d) fragmentation through wetting of grain boundary by liquid metal [22].

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 2.2.1 Thixo casting Thixo casting mainly consists of three separate stages the production of a pre-cast billet having the special equiaxed microstructure, the re heating of these billets to the semi-solid temperature and the casting of the components 3. Illustrated in Figure 7. Figure 6.

Classification of semi solid processes [31].

Figure 5.

Evolution of structure during solidification with shear force: (a) initial dendritic fragment; (b) dendritic growth; (c) rosette; (d) ripened rosette; and (e) spheroid [20].

1. feedstock preparation; 2. Reheating of the billet; and 3. The casting process. 2.2.2 Rheo-casting Rheo-casting is single step process to produce semi solid alloy start with liquid alloy, introduced directly into a mold without any intermediate solidification step. The semisolid slurry produced by means of different process like slope casting, new rheo casting etc. and directly introduced into a die. While thixo-forming is a route consists of reheating and forming process (Figure 8).

Figure 8.

Rheo casting process [2].

Figure 7.

Thixo casting and thixo forging [2].

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 3. Slope casting process Slope casting process is a rheo casting process used for the produce semi solid slurry, it consists with simple equipment and operation technique, the process carried out by pouring molten metal through channel with certain angle into a die where subsequent solidification takes place [32]. The solidification of molten alloy along a slope channel involves heat transfer, fluid flow , adhesion behavior. When the molten metal flowing through the slope channel with an angle and length [33–37], heat transfer takes between the slope channel wall and melt in contact, where generation of nuclei takes places, due to the effect of gravitation force and flow of stream the nuclei produced on slope wall are detached from the slope plate and subsequently flow through the melt stream, solid fraction of metal(semi solid slurry) observed at end of slope channel [38–42]. shear stress acting on the slurry layers and melt flow inertia restricted dendritic growth usually observed in conventional casting alloys. Illustrated in Figure 9. Slope casting process is a simple technique, but it can be prone to gas pick up and oxide formation which will impact negatively on mechanical properties [44, 45]. 3.1 Mechanisms involved in slope casting process Two mechanisms have been suggested to explain the formation of non-dendritic microstructure during flow along slope casting process. According to Haga and Kapranos et al. [46, 47], dendritic fragmentation mechanism plays an important role in slope casting process during microstructural evolution. The fragmentation of weak dendritic arms observed when the partially solidified melt collides under gravitational forces on the inclined/slope channel. Motegi et al. [48] proposed, crystal separation theory, where granular crystals nucleate and grow on the slope wall and are washed away from the wall by fluid motion illustrated in Figure 10. The shear force is main factor for dendritic arm fragmentation but its effect is related to the velocity boundary layer [21] as shown in Figure 11. 3.2 Parameters effect the slope casting process The process parameters in the slope casting of semisolid slurry preparation are [21, 31, 43–49]: • Pouring temperature, Figure 9.

Line illustration of slope casting process [43].

• Slope angle, • Slope length, • Slope plate temperature, • Vibration of slope, • Mold vibration etc.

Figure 11.

Schematic diagram of the shear stress variation and velocity distribution inside the boundary layer during the flow of melt in cooling slope casting process [38].

Figure 10.

Crystal separation theory (a). The generation of nuclei at slope plate wall (b). Segregation of granular crystal (c) flow through the melt [30].

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 3.2.1 Effect of pouring temperature It is the most influencing parameter in slope casting process, T hogo et al. [36] investigated the effect of melt temperature and mold material found that pouring temperature have the great effect on the microstructure and it accounts nearly 35% of the total effect. Y Birol et al. [37] investigated the effect of pouring temperature and slope length, reported that the melt superheat required longer cooling lengths for higher pouring temperatures. Pouring with lower temperature causes forma - tion of solid shell (formation of a thin layer of metal due to the primary nuclei that stick to the slope channel that reduces the effectiveness of the slope channel in generating nuclei) and pouring with the super-heated temperature may not get sufficient time to cool to range to produce solid nuclei on the slope plate, the main reason is that each parameter corelate each. Similar observation reported by Wen Liu et al. [39], if pouring temperature is too high a small number of primary α-aluminum phase will precipitate and some coarse primary α -aluminum phase. If the pouring temperature is too low the melt will cool rapidly and solidify. P . das et al., the temperature of the cooling plate has no prominent effect on microstruc - ture, nevertheless a slurry with approximately 10% fraction solid can easily be obtained at the end of the plate. 3.2.2 Effect of slope length Most of studies, slope length ranges from 200 to 800 mm, H. bidhiman et al. [41]. reported that increase in slope length that means melt flow time through channel increases it may cause the temperature drop and formation of the oxidation and solid shell as we above discussed it causes decrease in rate of heat transfer which leads to the decrease of the nucleation rate of primary solid phase, too short length does not give the proper nuclei formation and the time for the dendritic fragmenta - tion.

Slope length and slope angle are interrelated. If slope angle high need slope length should be more otherwise melt does not get sufficient time for shearing. The slope length effect on final microstructure accounts nearly 30% from studies. P . das et al. [40]. 3.2.3 Effect of the slope angle Most studies the angle ranges from 15 to 60°, the small angle is unable to give the melt to flow and shear effect on the slope plate will be less and the higher angle may cause the high velocity which does not give time to melt formation semi solid slurry and dendritic fragmentation. Farshid Taghavi and Ghassemi [42] reported the angle of slope channel had remarkable effects on the size and morphology of α-Al phase. By increasing the angle of the slope channel, the effect of shear stress and the rate of heat transfer increase. As a result, more solid particles are detached from the layer of slope channel. On the other part, duration time of shear stress and heat transfer between the melt and surface of inclined plate decrease by increase in the angle. As we above discussed in 3.2.2. the slope length and slope angle corelated to each other. 3.2.4 Effect of the slope vibration V ery few studies on effect of vibration slope on microstructural changes. Slope vibration frequency ranges from 10 to 60 Hz. Studies by Shaya Safari et al. [44],

Wen Liu et al. [39] conclude that There was no solid shell formation on the surface of slope channel by using slope vibration. The combine effect of vibration and slope channel causes increase in the amount of nucleation and nuclei due to uniform cooling rate. The mechanism in vibration slope channel is proposed that vibrat - ing force and gravity result in Bending stress introduced in between the growing dendritic and liquid. Because of the viscous resistance of liquid, with respect to the dendritic particles and liquid phase there is a difference of the transport veloc - ity, which causes crash among the grains and the scrub of the liquid on dendritic particles. The weak dendrite arms breakoff and form fine grains. Vibration helps the heat transfer mechanism in possible direction. The stirring caused by vibration gives rise to local temperature fluctuation of liquid phase around the primary α -al phase and Re melting of dendritic arms at the necks occurs. Which favorable to form short and homogenous small primary dendrites, equiaxed and rosette non dendritic grains. 3.2.5 Heat treatment by reheating Researchers extended work on Slope casting process by subsequent heat treatment of casts after slope casting for better mechanical properties through spheroidization of grains and removal of defects like internal stress and porosity. Yucel Birol et al. [37] worked on the cooling slope casting and thixo forming of hypereutectic A390 alloy. Reported that The thixoformed part after slope casting process was metallurgically sound, free from porosity and revealed a uniform dispersion of fine Si particles in a homogeneous matrix.

Increase mechanical properties observed. Nursen Saklakoglu et al. [33]: investigated on the microstructural evolution of ETIAL 160 aluminum feed stock produced by the cooling slope casting process experiments done with pouring temperatures of 605 and 615°C respectively subsequent isotheral heating at 565°C at 5 and 10 mins respectively, slope casting process results the primary α-aluminum dendrites has changed into α -aluminum rosette. Subsequent heat treatment helps to modify the rosette to globular structure. P das et al. [40]; too long a heating time will cause structural coarsening, while too short a heating time will lead to incomplete spheroidization of solid particles. Thus, there is a need to get optimum reheating parameters of the semi-solid alloys processed via slope casting. 3.3 Composites by slope casting Composite materials produced using slope casting technique were reported by researchers. P . Das, [40] has studied about the semi solid microstructure of Mg2 Si/Al composite by cooling slope casting process, reported that, the morphology of primary Mg2Si obtained non-dendritic and size of α Al was changed to 10 from 200 μm, Toshio Haga et al. [36]. Reported that slope casting has a significant influence on the shape and grain morphology of the Metal matrix composites (MMCs). The properties of the MMCs produced by slope casting were found to be higher than those of the MMCs produced by using conventional stirring.

Distinguished the literature into table according to the optimum process parameters used in Slope Casting Process of Semi-Solid Alloys and Composites shown in Table 1 and post parameters in Table 2.

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 Author & year Alloy Process parameters Length of slope in (mm) Slope angle in (degrees) Pouring temperature in (centi grade) Slope material, coating material and cooling medium Slope vibration in (Hz) Mold vibration in (Hz) Mold material S. R. Mukkollu et al. (2020) [43] Al-4%cu-2%mg alloy 500 30 X Mild steel X 20(ultrasonic) steel Kerem Altug Guler et al. (2019) [35] AA7075 650 30 & 60 660 Copper plate X X Steel N. K. Kund (2019) [21] A356 — — — — — — Steel Sahaya Safari et al. (2018)[44] AlMg2Si 400 45 880 Copper plate, boron nitride and water 40 X Cast-iron Adnan Mehmood, et al., (2016) [50] A356 800 15, 30, 45, 60 &75 800 Stainless steel and oil × × Stainless steel S. Deepak Kumar, et al. (2015) [51] A356& A356–5TiB2 × 60 650 Mild steel and water inside x x Mild steel S. DeepakKumar et al. (2015) [52] Al-7Si alloy 400 15, 30, 45 and 60 630, 640 and 650 water X X Mild steel Amir. A.

Abdelsalam, et al. (2015) [53] A356/Al2O3 500 60 X low carbon steel, hard chrome and water X X Steel Saffari, et al. (2015) [54] Al-Mg2Si 1000 45 X Copper plate and boron nitride 40 X X S. Deepak Kumar, et al. (2015) [55] A356 and A356-5TiB2 400 60 640 Mild steel & water X X Mild steel

Author & year Alloy Process parameters Length of slope in (mm) Slope angle in (degrees) Pouring temperature in (centi grade) Slope material, coating material and cooling medium Slope vibration in (Hz) Mold vibration in (Hz) Mold material S. Deepakkumar, et al. (2014) [32] A356 alloy 400 60 640 zirconia, and water X X Mild steel Amitesh Kumar, et al. (2014) [56] High chromium cast iron 1000 15 X Mild steel coated with graphite X X Sand Prosenjit Das, et al. (2014) [57] A356 alloy 500 30, 60 and X Stainless steel, boron nitride and oil X X Mild steel Hamed Khosravi, et al. (2013) [58] A356 alloy 100, 300 and 500 30, 45 and 660, 680 and 700 Boron nitride X X Mild steel K. S. Alhawari. (2013) [28] A356 and Al2O3 300 60 650 Steel, boron nitride X X Steel P . Das, et al. (2013) [59] A356 alloy — 60 and 45 — Boron nitride X X Steel R. Ritwik, et al. (2013) [60] AlSi7Mg alloy — 10 — — X X Steel Prosenjit Das et al. (2012) [40] A356 X 60, 45 925 Oil, boron nitride coating X X Mild steel N. Saklakoglu (2011) [34] A380 350 60 615, 630, 650 water cooled, boron nitride X X Steel Zongning Chen (2011) [26] Al-12Si and K2 TiF6 and KBF4 X X 650 Water cooled X X Copper Wen Liu et al. (2011) [39] ZAlSi9Mg 400–900 60 590–620 Copper plate and water 0–50 Hz X X

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 Author & year Alloy Process parameters Length of slope in (mm) Slope angle in (degrees) Pouring temperature in (centi grade) Slope material, coating material and cooling medium Slope vibration in (Hz) Mold vibration in (Hz) Mold material Jun X et al. (2011) [45] A356 alloy 300, 500, 30, 45, 60 650, 670, 690 Mild steel and water cooled X X X H. Budiman et al. (2011) [61] A356 alloy 250 60 610–630. Mild steel, boron nitride X X Steel T . Haga et al. (2010) [62] A356 30, 50, 100, 200 and 300. 15, 30, 45 and 60 620 Mild steel. Coated with BN X X Steel S. Gencalp Saklakoglu (2010) [63] A380 alloy 500 60 630 Mild steel. Coated with BN 5.75 Hz. X Steel W . Wierzchowski et al. (2010) [64] hypoeutectic gray cast iron and high-chromium cast iron 600 0–15 TP = TL + 20 K Copper plate, boron nitride X X X Farshid Taghavi and Ghassemi (2009) [42] A356 alloy 20, 40, 60 20, 30, 40, 50, 60 680 Copper plate X X Steel H. Budiman et al. (2009) [41] Al-Si alloy 250 60 620 Mild steel, boron nitride and water X X Steel Nursen Saklakoglu (2008) [33] ETIAL 160 300 60 605, 615 Steel Plate Coated With BN And water X X Steel Yucel Birol (2008) [17] A390 alloy 500 60 — Steel plate and water cooled X X Steel

Author & year Alloy Process parameters Length of slope in (mm) Slope angle in (degrees) Pouring temperature in (centi grade) Slope material, coating material and cooling medium Slope vibration in (Hz) Mold vibration in (Hz) Mold material Q. D. Qin and Zhao, (2007) [27] Al/mg2Si composite X X X Alumium plate X X Steel E. Cardoso Legoretta et al. (2008) [65] A356 alloy 150, 200 45, 60 +20 K–30 K Mild steel coated with boron nitride and Cold water X X Satinless steel Yucel Birol (2007) [17] A357 alloy 200, 300, 60 620–640 Steel plate coated with the boron nitride and water X X Mild steel Alex Muumbo et al. (2003) [66] Cast iron — 5–15 +20 k Boron nitride coated X X Mild, graphite, sand Tetsuchi Motegi (2002) [48] Al-Si-Mg alloy 80, 160, 200, 240 40, 60, 80 656, 666, 676, 686, Copper plate X X X Toshio Haga (2002) [67] A356 300 60 602, 630, 650 Mild steel coated with BN X X X Toshi Haga (2001) [36] Al-6 Si 300 60 600 Mild steel coated with BN X X Mild steel with out insulator and with insulator Table 1.

Process parameters.

Slope Casting Process: A Review DOI: http://dx.doi.org/10.5772/intechopen.102742 Author & year T ensile test Hardness Grain size & shape factor Findings S. R. Mukkollu et al. (2020) [43] x ✓ x Refined microstructure can be obtained by if cooling slope integrated with ultrasonic acoustic cavitation.

Kerem Altug Guler et al. (2019) [35] ✓ ✓ ✓ Castings with the slope angle of 60 are superior to 30.

N. K. Kund (2019) [21] ✓ ✓ ✓ Cooling slope leads to globular and nondendritic microstructure.

Sahaya Safari (2018) ✓ ✓ ✓ The hardness, values of the as-cast VCS sample are higher than those of its CS Adnan Mehmood, et al., (2016) [50] ✓ X ✓ Tensile and hardness are highest at the sloping plate at the angle of 600 S. Deepak Kumar et al. (2015) [51] X ✓ ✓ A cooling slope length of 400 mm, a low cooling slope angle of 150 was effective in dendrite fragmentation Amir. A. Abdelsalam, et al. (2015) [53] X X ✓ Stir casting and cooling slope casting (SC/ CSC) exhibited higher Porosity and watercooling using SC/CSC technique effect the average size of the α-Al grains.

S. Deepak Kumar, et al. (2014) [32] — ✓ — Pouring temperature, which accounts for 42.08% of the total effect, followed by cooling length 40.4% and slope angle 17 .44% respectively.

K. S. Alhawari. et al. (2013) [28] — ✓ — The hardness and wear resistance of the MMC s produced by cooling slope casting were found to be higher those of MMCs produced by using conventional stirring.

R. Ritwik, et al. (2013) — — — The spheroidization effect of the alpha aluminum dendrites increases with the increase in the angle of inclination.

Prosenjit Das, et al. (2012) [40] — — ✓ 925 K pouring temperature, 60 slope angle, 500 mm cooling length and wall temperature of 333 K has been identified as the ideal processing condition, which is in good correlation with the numerical findings Prosenjit Das et al. (2012) [40] X X ✓ Spheroids and rosettes of primary Al phase has been obtained through the angle 600 N. Saklakoglu (2011) X X Wear test conducted.

Cooling slope does not given substantial changes in friction characteristics compared to gravity casting, isothermal treatment reduced after cooling slope casting decreased the friction.

Zongning Chen (2011) ✓ ✓ ✓ The grain size of alpha aluminum phase can be globularized using the cooling slope Wen Liu et al. (2011) X X ✓ Vibration effects the nucleation by increase the pressure subsequently temperature and the dendritic arms are sheared due to the vibration.

Jun X et al. (2011) [45] X X X Optimum globular microstructure with uniform distribution of A356 alloy is obtained with slope angle 45, plate length 500 mm and pouring temperature 650

4. Conclusions A considerable review of the literature on slope casting of semisolid Aluminum alloys suggest the following: 1. The slope casting process is a simple and cost-effective way of producing feed stock material (non-dendritic or globular) microstructure. 2. slope casting process mainly depends on the process parameters like slope length, slope angle which mainly controls the shear force on metal flow subsequently the better morphology structure obtained. 3. Reheating and isothermal holding temperature after slope casting observed better mechanical properties from different studies.

Author & year T ensile test Hardness Grain size & shape factor Findings H. Budiman et al. (2011) [41] X X ✓ The cooling slope casting produced smaller equiaxed α-aluminum grains with better shape factor than the conventional stirring.

T . Haga et al. (2010) X X X The cooling distance affects the cooling of the melt and adhesion of solidified metal.

The melt temperature becomes lower as distance becomes longer. The adhesion of the solidified metal occurs when the cooling distance becomes longer than the suitable distance.