Verification of Heat Treatments Effect on the Microstructure of Aluminum Alloy (Al-Zn)

VERIFICATION OF HEAT TREATMENTS EFFECT ON THE MICROSTRUCTURE OF ALUMINUM debauch (Al-Zn) *1 I. A. LATEEF, and 2 M. O. DUROWOJU 1Department of Mechanical engine room, Osun State College of Technology, P. M. B. 1011, Esa Oke, Nigeria. emailprotected com 2Department of Mechanical Engineering, Ladoke Akintola University of Technology, Ogbomoso, Oyo,State, Nigeria *(Address of correspondence) ABSTRACT This workplace foc utilise on the effect of modify treatment on the microstructure of atomic number 13 surface debauch.The establishment of the aluminum alloy use is eighty part (80%) of Aluminum and twenty percent (20%) of Zinc. The method of modelling employed is gritrock casting, while annealing and fill were heat treatment processes its subjected to. The microstructure is taken. It is cerebrate that heat treatment have effect on the microstructure of Aluminum Zinc alloy and responded well to crude crude oil quench. Keywords Aluminum-Zinc Alloy, ignite treatment, Micr ostructure, Tensile test, Hardness test, normalize and urine quenching. INTRODUCTION The extensive application of metals in the field of Engineering has necessitated the need for metal heat treatments in order to meet the apprehension of firm, industries and individual as a result of their wide engineering application. integrity of the major engineering fields where the application of confused metals was used is auto engineering. In order to reduce motor vehicle weight, many self-propelled comp unmatchednts have been redesigned to take advantage of material such as whippersnapper and polymers.To this end aluminum casting alloys ar being widely used for many automotive components (CAD, 2006), the alloys have good casting characteristics, reasonable mechanic properties, and ar heat treatable (Melo, Rizzo and Santos, 2005). Material science and engineering today has highly-developed to a stage where correlations between microstructure, properties and application earth-closet be established for many commonly used alloys.The structure of a material is link to its composition, properties, processing history and performance (Argo and Gruziesk,(1988) and Rooy,(1993)). And therefore, argonaing the microstructure of aluminum alloys provides information linking its composition and processing to its properties and performance interpretation of microstructure requires the understanding of the process by which various structures ar formed. There be many processes by which aluminum alloys batch be formed.The major process that is common and the focus of this study is the rachis casting process (Albert, (1957)). One of the common defects in aluminum castings is porosity (Monroe, (2005) and Tyler, 1981)). It is a clear fact that the quantity and the appearance of the porosity are very crucial to the mechanical properties of the aluminum alloy casting, most curiously the fatigue properties because the pore in micro scale are principal(a) source of initial cracks for the final failure of the aluminum parts.Due to this the aluminum alloys structure need to be improved by metal treatment to have the required properties. Olanrewaju (2000), stated that metal treatments are classified into twain groups namely- Heat treatment and surface treatment. Surface treatment as corroding resistance operations includes phosphating chroming nickeling, anodization and so on, While heat treatment as structural adjuster includes hardening, tempering toughening and so on (Ojediran and Alamu, (2004) and Vincet,(1968)).In this study, the effect of such heat treatment are determined to know the finish of their impact on the aluminum Zinc alloys (Al- Zn). MATERIAL AND EXPERIMENTAL TECHNIQUES Materials used The targeted materials composition, uses and forms are as follows TABLE 1 THE COMPOSITION, USES AND FORMS OF ALUMINUM ALLOYS Composition Uses Forms Al Zn 20% fit vehicle, Military Rod (10mm x one hundred fifty mm) bridge, Motorcycle and Bi cycle frames, Air frames etc Equipments used The pursuance equipments were used for the study Pit furnace, Sand mould, Electrical furnace, and Crucible Pots at FIIRO, Nigeria. And Mosanto Tensometer, Wild metallurgic Microscope, Polishing Machine,and Manual Grinding Machine at Obafemi Awolowo University, Ile-Ife, Nigeria.Others are-Digital Cameral, Patterns, Grit papers, Emery textile/Paper, Silicon carbide solution of different grade and NaOH Solution Methods Casting ferment A Crucible pots is used, 1 kg of commercial purity Aluminum (99. 7 % pure by weight) and 250g of Zinc is used. The alloying broker Zn is hurtle first in the Pot because of its high melting point (1108oc) which is high than that of the base metal aluminium (660oc). So, the Zinc (Zn) in the pot is take low first into the furnace while the aluminium is added after Zn has commenced melting.The press of all(prenominal) of the alloying elements used for separately type can be obtained as follows im part mass of mixture for the renders= frames Mass of Al + Mass of alloying element = 1kg + 0. 250kg = 1. 250kg constituent of Aluminum (Al) in the mixture = mass of Al/Total mass x one hundred =1/1. 250 x 100 = 80% function of alloying element (Zn) = Mass of alloying element/Total mass x 100 =0. 25 / 1. 50 x 100 = 20% The dimension of one sample distribution is as following Height of the sample =150mm (15cm) Diameter of the sample = 12 mm (1. 2 cm) Radius of the sample =60mm (0. 6cm) Shape of the sample= Cylindrical Volume of the sample (V) =? r2h = 3. 142 x (0. 6) 2 x 13 = 16. 96 cm3 Density of Aluminum = 2. 69g/cm2 (Olagoke, 1999). Mass of sample used = ? x V = 2. 69 x 16. 96 = 45. 64 g Therefore, 80 % of Aluminum = 36. 51 g for each sample Also, 20% of Alloying element (Zn)= 9. 13 g For each sample (rod form) 36. 51 g Al + 9. 13 g of alloying element (Zn) were used.The samples for heat treatment are standard 1 =as received from Casting process. exemplification 2 = for qu enching in Water. Sample 3 = for Oil quench Sample 4 = for annealing (Furnace nerveless). The method adopted in casting the samples is gritstone delimitation (Sand casting). The casting process is performed at FIIRO Nigeria Limited, Lagos. The pattern is made from wood with the following dimensions Height 15 cm Diameter 1. 2 cm The back used is the traditional-green sand which is a mixture of sand grains and clay particles, clean-cut sand with oil and binders).The mould used is a conventional erect sand mould. The drag is placed upside down on a firm flat surface and the pattern is placed face down and pattern is placed face down and then, dusted with a parting powder. Handfuls of sifted sand are then thrown at the pattern, covering every expound (Sand slinging). The sand is rammed. The drag is turned upside down with a nimble movement. The cope is fitted onto the drag. The cope is rammed with sand and strictly making the top smooth-spoken and firm. And the cope is remove d.The crucible is held about half way down with tongs and withdrawal from he furnace. Dross is raked away from pouring lip with heated up skimmer and the metal poured in one continuous stream until it appears at the head of the riser. When the casting has solidified and cooled, the sand is knocked out and the casting fettled. Heat treatments process Heat treatment is also carried out at FIIRO Nigeria limited, Lagos. The types of heat treatment carried out are Annealing and Quenching. Three each of Al-Zn casting samples were put in the electrical furnace (up to 3300oc).The soaking time for the sample in the furnace is one hour, after which two of the Al-Zn casting samples is removed and quench in both water and oil while the last one of Al-Zn is allowed to cool in the furnace atmosphere (annealing). Microstructure Analysis Process. The microstructure was through with(p) at Obafemi Awolowo University, Ile-Ife, Osun State. The samples were machined and grounded to gauge 240, 320, 400, 600 each using Grinding Machine and Grit paper. Each sample is ab initio polished, using Polishing machine, emery cloth and Silicon Carbide.The final polishing is done with the aid of Polishing machine, Emery cloth and Silicon carbide of different grades while etching took effect using 5% NaOH Solution. Each sample is examined using the optical Microscope to check that etch reveal clearly the Microstructure of the sample. The photograph of the resulting microstructure of the aluminum-Zinc (Al- Zn) alloy samples were taken using Optical microscope with x100 magnification and Digital Cameral. RESULTS AND DISCUSSION Discussion on the Microstructure Results of Al- Zn Alloys. The figure 2 to a lower place shows the microstructure of Al-Zn alloy, As received sample i. without heat treatment. It can be observe that the grains were not homogeneous and pores are legion(predicate) towards the peripheral zone Figure 2 Microstructure of As reliable Al Zn alloy Sample 1. The figure 3 be low shows the microstructure of Al Zn alloy, Oil quenched sample. It can be observed that the grains are more homogeneous and well distributed towards the core. The pores are not numerous compare to Al- Cu alloy, As received sample. Figure 3 Microstructure of Oil Quench Al Zn Alloy Sample 3.. Figure 4 below shows the microstructure of Al- Cu alloy, Furnace cooled sample.It can be observed that the grains were deformed at peripheral more than at the core of the structure and there are more pores than that of As received sample and Oil quenched sample. this indicates that there is no significant improvement in the microstructure arrangement of grains when Al-Cu alloy is oil quenched Figure 4 Microstructure of Furnace Cooled Al Zn Alloy Sample 4. Figure 5 below shows the microstructure of Al- Zn alloy, Water quenched sample. It can be observed that the grains were deformed throughout the structure and there are more pores than that of As received sample and Oil quenched sample.This i ndicates that there is no significant improvement in the microstructure arrangement of grains when Al-Zn alloy is Water quenched. Figure 5 Microstructure of Water Quench Al Zn Alloy Sample 2. . CONCLUSION From the result of the experiments, it can be deduced that (i) The arrangement of the microstructure grains and pores are more even with the Oil quench method than any otherwise heat treatment methods in Al Zn alloy. (ii) There is family between the heat treatments method (Oil quench) and microstructure of Al- Zn alloy. iii) Oil quench aluminum Zinc alloy (Al Zn ) is more appropriate for the production of Armored vehicle, Military bridge, Motorcycle frames and Bicycle frames and Air frames ACKNOWLEDGEMENT The workers of FIIRO Nigeria limited,Lagos and Mr Alo of Metallurgy and Material Department, Obafemi Awolowo University Ile- Ife, Osun State, Nigeria are acknowledge for providing the facilities for this research work. REFERENCES Ojediran, J. O. and Alamu, O. J. (2005) Fundam ental concepts in Materials Science and Engineering Kunle (Nig) Printers Ijebu-Ode, Nigeria.Vol. 1, world-class ed, pp. 46. Vincet, A. (1968) Workshop Theory for G. C. E. 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