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Effect Of Cold Rolling On Microstructural Properties Of Spray Deposited Al-%18Pb And Al-%22Pb Alloys
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 18 (2019) 2767–2771
www.materialstoday.com/proceedings
ICMPC-2019
Effect Of Cold Rolling On Microstructural Properties Of Spray Deposited Al-%18Pb And Al-%22Pb Alloys B.V.R. Reddya, Ishwar Mazumdarb, S.R. Maityc, K.M. Pandeyd a,b,c,d
Department of Mechanical Engineering, National Institute of Technology, Silchar, Assam, India-788010
Abstract Al-%18 Pb and Al-%20Pb alloys were obtained by spray deposition method to obtain the Gaussian shape and fine grain microstructure. In the present study Al-20%Pb and Al-22%Pb were obtained in the form of disc shape spray castings and their s, microstructural properties were studied before and after cold rolling and compared. It was observed that the shape of spray uniform at 300 inclination angles and required shape was obtained at 00 inclination angles of rotor. It has been observed microstructure of Pb particles distributed equally in Al matrix than cast alloys after rolling. © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
Keywords: Composition; Spray deposition; shape; rolling; Microstructure;
1.
Introduction
Aluminium and its alloys extensively adapted to make the industry as more profitable [1] like automotive, aerospace, crank soft bearings manufacturing organizations etc. due to their extraordinary properties like low weight to high strength [2], corrosive resistance, low wear rate, more fatigue strength and high thermally conductive. To amend the anti-frictional [3] it is required to added to soft phases like Pb, Mg, Sn and graphite to Aluminium. Pb [4] possesses excellent properties like lubrication, frictional, soft and cheaper than the Sn [5] etc. fabrication of Al-Pb alloys had been difficult due to the vast difference between in specific gravity and tolerant immiscibility gap [6]. As a result, during solidification process of Al-Pb. alloy impurities were settle down below the crucible. hence melting and casting by conventional [7] manufacturing process was difficult. Due to the above situation researchers have developed lot of processing techniques like vortex casting, rheocasting, powder metallurgy, bottom discharge and rapid solidification process [8]. among these methods rapid solidification processor spray deposition possesses rapid cooling and turbulence in liquid flow during the deposition of atomized droplets over the substrate due to that reason Pb phase [9] is uniformly distributed along grain boundaries of Al matrix. Rashmi et al. [10] have studied the cold rolling behaviour of the Al-Pb alloys, it was observed for 40% rolling some cracks were observed over the surface and further cracks were disappeared at 80% rolled surface. by varying the various processing parameters spray deposit of Al-Si alloys were produced and microstructural, mechanical and wear properties were studied [11]. S. Mohan et al. [12] It has also been observed that coefficient * Corresponding author. E-mail address: [email protected]
2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
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B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
of friction decreases with increase in lead content in Al-Pb alloys until about 20wt.% but, beyond this composition, it increases sharply. because entire sliding surface covered by Pb thin film. More Pb composition leads wear failure of the alloy. In the present work initially spray deposits of Al-%18Pb and Al-% 22Pb were produced and then rolled central portion of deposit for various thickness reductions. Microstructural, Mechanical and Wear behaviour of the deposits was studied and compared. 2. Experimental 2.1 set up The spray deposition chamber else where[13] mainly consists of (i) Spray deposition unit (ii) Atomizer connected to compressor (iii) Assembly of Atomizer, graphite crucible , induction furnace and connecting rod The compressor was connected to the atomizer and delivered Argon gas at a pressure about 10 bar . the delivery tube connected to the bottom of the graphite crucible . The spray deposition unit consists of copper substrate ,placed over the inclined rotational system and centered to the spray axis . the rotational motion was given to the substrate through gears by a motor. The speed was controlled by the transformed by varying the voltage .the rotational sytem was rotated in the horizantal direction 2.2. Procedure 2.2.1 Spray forming In the process of sprayforming , firstly about 1 kg of Al-Pb alloy is heated in the crucible . A stopper rod is present which prevents the melts to flow prior to its atomization . argon was supplied to melt flowing through the delivery tube .Atomization resulted in the formation of wide range micro size droplets , which were deposited over a copper substrate and after deposition preform is taken out of the substrate . The deposition was carried out for the different alloys compositions i.e Al-20%Pb and Al-22%Pb at a certain temperature and argon gas was released at a pressure about 10 bar as shown in below Table 1 and Table 2. Table 1: Chemical composition of Al-Pb alloys (Wt. %) Pb Al 18 Bal. 22 Bal.
Table 2: Experimental conditions Type of Pressure(KPa) Melt Gas used Temperature (0C) Argon
1000
1100
Type of substrate used
Substrate inclination (0)
Substrate Distance(mm)
Copper
0
42
Rotational Speed of Substrate (rpm) 30
2.2.2.Cold rolling Al-18%Pb and Al-%22Pb spray deposits with thickness 25mm were obtained through the spray forming method. Now the deposit was segregated into three strips like Top, central and Peripheral regions. In the present work, particularly worked on the Peripheral regions for various percentage of thickness reductions in sample like 15,30, 45, 60,75 and 90 by using 2-high cold rolled milling. The direction of the rolls is reverse and work piece fed into both sides. 2.2.2 Microstructure After preparation of spray formed deposits, different parts of these were cut down and taken as a samples .and then standard metallographic technique of polishing followed ,with the help of emery paper of 1/0,2/0,3/0 and 4/0 specifications , the polishing was done ,followed by a wheel cloth polishing using an emulsion of Al2O3 powder particles suspended in a water .There after ,these samples were finelly polished by a kerosene oil and brasso .These samples were etched with kellers reagent (1% HF by Volume , 1.5% Hcl by Volume , 2.5 HNO3 by volume and remaining percent of Pure water ) .The resulting microstructure of samples were examined under Leitz Optical Microscope of JEOLJXA890A .
B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
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3.Results and discussions 3.1. Shape of the spray deposit: The shape of the spray deposit was bell type and its depends upon mainly two factors Inclination angle and distance between bottom of the delivery tube and the copper substrate as the inclination angle varied from 00, 150,300and 450, the distance between the delivery tube and substrate is fixed i.e. 43mm and rotational speed of the substrate fixed about 30 rpm. Initially nitrogen gas strikes the liquid molten metal with high pressure i.e. 10 bars and distributed the semi-solid droplets over the substrate. in case of 00 inclination, the substrate is idle and it is exactly perpendicular towards delivery tube. Due to zero-degree inclination the sprayed semi solid droplets were occupied maximum at the centre of the substrate according to the Gaussian distribution and was observed shape of deposit is non-uniform as shown in the figure 1. In case of 150 inclination of the substrate, spray droplets were occupied maximum in peripheral regions and shape was non-uniform.
Figure 1: Shape of the spray deposit as shown in a square box in case of 300 inclination of the substrate, the maximum spray droplets were occupied uniformly through regions of the substrate as shown in the figure. and Finally, in case of 450 inclination, the maximum spray droplets were observed in peripheral regions and the shape is not uniform. As the inclination increased the thickness of the substrate was decreased. Here thickness of substrate was 4, 3.5,2.8.1.5 cm respectively. 3.2. Microstructural features The microstructural views for the spray deposited Al-18%Pb and Al—22%Pb alloys were represented in the figure 2 (a-b), figure 3(a-d) and figure 4(a-d) respectively . it has been observed from figure .2 , in both spray deposits the Pb is homogeneously distributed along the grain boundaries and the surface porosity can observed which is in the form of pores (black holes ) in both the cases . it has been observed from figure 3 & 4 pb was distributed equally in all percentage thickness reductions . The pores are disappeared at 80% thickness reduction sample . As the Pb percentage increased to 18 to 22% the grains are more finer .
Figure 2: Micro structural Views before rolling (a) Al-%18Pb (b) Al-%22Pb
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B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
Figure 3: Micro structural Views of Al-%18Pb after rolling (a)20% (b) 40% (c) 60% (d) 80%
Figure 4: Micro structural Views of Al-%22Pb after rolling (a)20% (b) 40% (c) 60% (d) 80% 4. Conclusions 1.The Gaussian curve (Spray cone) obtained with 30 mm in thick ness, 200 mm in diameter at a Pressure 10 bar, distance between delivery nozzle and copper substrate 420mm and inclination angle of the rotor is about 00 2. The pores are eliminated for higher percentage thickness reductions in both spray deposits i.e. 80% 3. The grains are more finer in case of more Pb composition than the other . And the Pb is distributed homogeneously in the along the Al grain boundaries in both deposits i.e. Al-18%Pb and Al-22%Pb alloys .
B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
L.L. Liu, Q.L. Pan, X.D. Wang, S.W. Xiong, Journal of Alloys and Compounds 735 (2018) 261-276 Wang R, Lu W and Hogan L M, J. Cryst. Growth, 207 (1990)43. M. Anil, V.C. Srivastava, M.K. Ghosh, and S.N. Ojha, Wear, 268 (2010), 1250–1256 Ch V S H S R Sastry, G Ranga Janardhana, Indian Journal Engineering and Materials Sciences ,17(2010) 56-60 J. An, Y.B. Liu, Y. Lu, Q.Y. Zhang, and C. Dong, Wear, 256(2004), 374–385 Sharma Ashok, T V Rajan, Wear, 197(1996) 105-114 Mohan Sunil, Agarwala Vijaya, Ray Subrata, wear 140(1990) 83-92 Ojha S.N, Tripathi A.K, Singh S.N, Int Powder metal 25(2) (1993) 65 R. Mittal, A. Tomar, D. Singh, Adv. Mat. Lett., 3(1) (2012), 55–63 Mittal, R. and Singh, D., Transactions of the Indian Institute of Metals, 67(4) (2014).,551-557. A. Leatham, JOM 51 (4) (1999) 116–121 S. Mohan, V. Agarwala and S. Ray, Wear, 157 (1992) 9-17 Singh D, and Dangwal S, J Mater Sci 41 (2006) 3853.
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ScienceDirect Materials Today: Proceedings 18 (2019) 2767–2771
www.materialstoday.com/proceedings
ICMPC-2019
Effect Of Cold Rolling On Microstructural Properties Of Spray Deposited Al-%18Pb And Al-%22Pb Alloys B.V.R. Reddya, Ishwar Mazumdarb, S.R. Maityc, K.M. Pandeyd a,b,c,d
Department of Mechanical Engineering, National Institute of Technology, Silchar, Assam, India-788010
Abstract Al-%18 Pb and Al-%20Pb alloys were obtained by spray deposition method to obtain the Gaussian shape and fine grain microstructure. In the present study Al-20%Pb and Al-22%Pb were obtained in the form of disc shape spray castings and their s, microstructural properties were studied before and after cold rolling and compared. It was observed that the shape of spray uniform at 300 inclination angles and required shape was obtained at 00 inclination angles of rotor. It has been observed microstructure of Pb particles distributed equally in Al matrix than cast alloys after rolling. © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
Keywords: Composition; Spray deposition; shape; rolling; Microstructure;
1.
Introduction
Aluminium and its alloys extensively adapted to make the industry as more profitable [1] like automotive, aerospace, crank soft bearings manufacturing organizations etc. due to their extraordinary properties like low weight to high strength [2], corrosive resistance, low wear rate, more fatigue strength and high thermally conductive. To amend the anti-frictional [3] it is required to added to soft phases like Pb, Mg, Sn and graphite to Aluminium. Pb [4] possesses excellent properties like lubrication, frictional, soft and cheaper than the Sn [5] etc. fabrication of Al-Pb alloys had been difficult due to the vast difference between in specific gravity and tolerant immiscibility gap [6]. As a result, during solidification process of Al-Pb. alloy impurities were settle down below the crucible. hence melting and casting by conventional [7] manufacturing process was difficult. Due to the above situation researchers have developed lot of processing techniques like vortex casting, rheocasting, powder metallurgy, bottom discharge and rapid solidification process [8]. among these methods rapid solidification processor spray deposition possesses rapid cooling and turbulence in liquid flow during the deposition of atomized droplets over the substrate due to that reason Pb phase [9] is uniformly distributed along grain boundaries of Al matrix. Rashmi et al. [10] have studied the cold rolling behaviour of the Al-Pb alloys, it was observed for 40% rolling some cracks were observed over the surface and further cracks were disappeared at 80% rolled surface. by varying the various processing parameters spray deposit of Al-Si alloys were produced and microstructural, mechanical and wear properties were studied [11]. S. Mohan et al. [12] It has also been observed that coefficient * Corresponding author. E-mail address: [email protected]
2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
2768
B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
of friction decreases with increase in lead content in Al-Pb alloys until about 20wt.% but, beyond this composition, it increases sharply. because entire sliding surface covered by Pb thin film. More Pb composition leads wear failure of the alloy. In the present work initially spray deposits of Al-%18Pb and Al-% 22Pb were produced and then rolled central portion of deposit for various thickness reductions. Microstructural, Mechanical and Wear behaviour of the deposits was studied and compared. 2. Experimental 2.1 set up The spray deposition chamber else where[13] mainly consists of (i) Spray deposition unit (ii) Atomizer connected to compressor (iii) Assembly of Atomizer, graphite crucible , induction furnace and connecting rod The compressor was connected to the atomizer and delivered Argon gas at a pressure about 10 bar . the delivery tube connected to the bottom of the graphite crucible . The spray deposition unit consists of copper substrate ,placed over the inclined rotational system and centered to the spray axis . the rotational motion was given to the substrate through gears by a motor. The speed was controlled by the transformed by varying the voltage .the rotational sytem was rotated in the horizantal direction 2.2. Procedure 2.2.1 Spray forming In the process of sprayforming , firstly about 1 kg of Al-Pb alloy is heated in the crucible . A stopper rod is present which prevents the melts to flow prior to its atomization . argon was supplied to melt flowing through the delivery tube .Atomization resulted in the formation of wide range micro size droplets , which were deposited over a copper substrate and after deposition preform is taken out of the substrate . The deposition was carried out for the different alloys compositions i.e Al-20%Pb and Al-22%Pb at a certain temperature and argon gas was released at a pressure about 10 bar as shown in below Table 1 and Table 2. Table 1: Chemical composition of Al-Pb alloys (Wt. %) Pb Al 18 Bal. 22 Bal.
Table 2: Experimental conditions Type of Pressure(KPa) Melt Gas used Temperature (0C) Argon
1000
1100
Type of substrate used
Substrate inclination (0)
Substrate Distance(mm)
Copper
0
42
Rotational Speed of Substrate (rpm) 30
2.2.2.Cold rolling Al-18%Pb and Al-%22Pb spray deposits with thickness 25mm were obtained through the spray forming method. Now the deposit was segregated into three strips like Top, central and Peripheral regions. In the present work, particularly worked on the Peripheral regions for various percentage of thickness reductions in sample like 15,30, 45, 60,75 and 90 by using 2-high cold rolled milling. The direction of the rolls is reverse and work piece fed into both sides. 2.2.2 Microstructure After preparation of spray formed deposits, different parts of these were cut down and taken as a samples .and then standard metallographic technique of polishing followed ,with the help of emery paper of 1/0,2/0,3/0 and 4/0 specifications , the polishing was done ,followed by a wheel cloth polishing using an emulsion of Al2O3 powder particles suspended in a water .There after ,these samples were finelly polished by a kerosene oil and brasso .These samples were etched with kellers reagent (1% HF by Volume , 1.5% Hcl by Volume , 2.5 HNO3 by volume and remaining percent of Pure water ) .The resulting microstructure of samples were examined under Leitz Optical Microscope of JEOLJXA890A .
B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
2769
3.Results and discussions 3.1. Shape of the spray deposit: The shape of the spray deposit was bell type and its depends upon mainly two factors Inclination angle and distance between bottom of the delivery tube and the copper substrate as the inclination angle varied from 00, 150,300and 450, the distance between the delivery tube and substrate is fixed i.e. 43mm and rotational speed of the substrate fixed about 30 rpm. Initially nitrogen gas strikes the liquid molten metal with high pressure i.e. 10 bars and distributed the semi-solid droplets over the substrate. in case of 00 inclination, the substrate is idle and it is exactly perpendicular towards delivery tube. Due to zero-degree inclination the sprayed semi solid droplets were occupied maximum at the centre of the substrate according to the Gaussian distribution and was observed shape of deposit is non-uniform as shown in the figure 1. In case of 150 inclination of the substrate, spray droplets were occupied maximum in peripheral regions and shape was non-uniform.
Figure 1: Shape of the spray deposit as shown in a square box in case of 300 inclination of the substrate, the maximum spray droplets were occupied uniformly through regions of the substrate as shown in the figure. and Finally, in case of 450 inclination, the maximum spray droplets were observed in peripheral regions and the shape is not uniform. As the inclination increased the thickness of the substrate was decreased. Here thickness of substrate was 4, 3.5,2.8.1.5 cm respectively. 3.2. Microstructural features The microstructural views for the spray deposited Al-18%Pb and Al—22%Pb alloys were represented in the figure 2 (a-b), figure 3(a-d) and figure 4(a-d) respectively . it has been observed from figure .2 , in both spray deposits the Pb is homogeneously distributed along the grain boundaries and the surface porosity can observed which is in the form of pores (black holes ) in both the cases . it has been observed from figure 3 & 4 pb was distributed equally in all percentage thickness reductions . The pores are disappeared at 80% thickness reduction sample . As the Pb percentage increased to 18 to 22% the grains are more finer .
Figure 2: Micro structural Views before rolling (a) Al-%18Pb (b) Al-%22Pb
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Figure 3: Micro structural Views of Al-%18Pb after rolling (a)20% (b) 40% (c) 60% (d) 80%
Figure 4: Micro structural Views of Al-%22Pb after rolling (a)20% (b) 40% (c) 60% (d) 80% 4. Conclusions 1.The Gaussian curve (Spray cone) obtained with 30 mm in thick ness, 200 mm in diameter at a Pressure 10 bar, distance between delivery nozzle and copper substrate 420mm and inclination angle of the rotor is about 00 2. The pores are eliminated for higher percentage thickness reductions in both spray deposits i.e. 80% 3. The grains are more finer in case of more Pb composition than the other . And the Pb is distributed homogeneously in the along the Al grain boundaries in both deposits i.e. Al-18%Pb and Al-22%Pb alloys .
B.V.R. Reddy et al. / Materials Today: Proceedings 18 (2019) 2767–2771
References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
L.L. Liu, Q.L. Pan, X.D. Wang, S.W. Xiong, Journal of Alloys and Compounds 735 (2018) 261-276 Wang R, Lu W and Hogan L M, J. Cryst. Growth, 207 (1990)43. M. Anil, V.C. Srivastava, M.K. Ghosh, and S.N. Ojha, Wear, 268 (2010), 1250–1256 Ch V S H S R Sastry, G Ranga Janardhana, Indian Journal Engineering and Materials Sciences ,17(2010) 56-60 J. An, Y.B. Liu, Y. Lu, Q.Y. Zhang, and C. Dong, Wear, 256(2004), 374–385 Sharma Ashok, T V Rajan, Wear, 197(1996) 105-114 Mohan Sunil, Agarwala Vijaya, Ray Subrata, wear 140(1990) 83-92 Ojha S.N, Tripathi A.K, Singh S.N, Int Powder metal 25(2) (1993) 65 R. Mittal, A. Tomar, D. Singh, Adv. Mat. Lett., 3(1) (2012), 55–63 Mittal, R. and Singh, D., Transactions of the Indian Institute of Metals, 67(4) (2014).,551-557. A. Leatham, JOM 51 (4) (1999) 116–121 S. Mohan, V. Agarwala and S. Ray, Wear, 157 (1992) 9-17 Singh D, and Dangwal S, J Mater Sci 41 (2006) 3853.
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