The Role of Lug Preheating, Melt Pool Temperature, and Lug Entrance Delay on the Cast-on-Strap Joining Process
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-4094-x Ó The Minerals, Metals & Materials Society and ASM International 2017
SOHRAB PAHLAVAN, SAMAN NIKPOUR, MOSTAFA MIRJALILI, and IMAN TAJI are with the Materials and Metallurgical Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Iran. Contact e-mail: [email protected] ALI ALAGHEBAND and MOHAMMADYOUSEF AZIMI are with the Research and Development Center, Nirougostaran Khorasan Co., Mashhad 91775-1486, Iran. Manuscript submitted November 26, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS A
I.
INTRODUCTION
IT is hardly possible to find a transport vehicle on the street operating using something other than a lead-acid battery. Despite the availability of alternative electrochemical storage systems that may have higher specific energy and efficiency, lead-acid batteries are still the
world’s most important rechargeable power source.[1] This is because the life and cost play a key role in all industrial applications.[2] Knowing this fact, a great deal of effort has been exerted to enhance the performance of lead-acid batteries. For example, Foudia et al.[3] found a remarkable improvement in the discharge capacity of the positive active materials by using some mineral additives. The effect of graphene and nanotubes on the performance of negative active materials is also investigated elsewhere.[4,5] There are also many studies dealing with the corrosion resistance and configuration of the grids and their electrochemical aspects. Pavlov[6] formerly found that Se ameliorates the corrosion resistance of Pb-Sn alloys. In another work, Prengaman[7] concluded that the segregation of calcium, tin, and silver in Pb-Ca-Sn-(Ag) alloys also enhances the corrosion resistance. Controlled casting and the preprogrammed solidification process can also improve the corrosion resistance of Pb-Sb grids by affecting the microstructure.[8] Peixoto et al.[9] expressed in their work that choosing an appropriate cell spacing can lead to a compromise between good mechanical properties and good corrosion resistance. Using a novel electrochemical approach, Benhangi et al.[10] perceived the utile influence of antimony on water loss in positive plates. Nakhaie et al.[11] also stressed the importance of grid configuration on the potential and current distribution by means of numerical modeling. Even with all of these improvements, some batteries still suffer from early failure. Poor lug-strap joints achieved by the cast-on-strap (COS) process, which groups plates of the same polarity, are one of the major defects causing battery failure, as has been emphasized in previous studies.[12–14] Lack of fusion and voids forming during the COS process leads to production of poor lug-strap joints, which have lower strength and higher electrical resistance. Hence, many attempts have been made to improve the strength and quality of the COS joints. Lakshmi[12] reviewed the parameters involved in the COS process and their effects on joint quality. According to his work, the alloying elements in the lead-antimony and lead-
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