Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metal corrosion protection,metal surface treatment > Corrosion control and protection > Metal surface protection technology > Metal complex layer of protection

Analysis of the Interface Bonding Strength and Formability of the Nickel Coating Electrodeposited Steel Sheet

Author ZhangHuan
Tutor ZhouLiQun
School Xiangtan University
Course Mechanical Manufacturing and Automation
Keywords the electrodeposited nickel coating formability interfacial bonding strength cupping test scratch test
CLC TG174.44
Type Master's thesis
Year 2009
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There are several mechanical steps for the deeply drawing with the electrodeposited nickel coating steel to be a battery mantle, so it demands that the blank should have high tensile strength and extensibility in order to non-fracture. At the same time, the reliability and service life of the nickel coating is required more and more, however it is decided by the bonding properties between nickel coating and substrate.This paper has researched on the interface bonding property and formability with electrodeposited nickel coating steel at both ways of theory and numerical simulation. The studied contents are as follows.Firstly, finite element methods were used to simulate the stamping process (Erichsen test) for the electrodeposited nickel coating with plane modeling. The stress and strain fields at the interface were obtained within the nickel coating and steel substrate. The computational results showed that the value and property of the stress at the interface are variational, and the normal stress between -10~10MPa, the shear stress between -20~30MPa, while it was found that the strains of coating and substrate were approximately matchable during the stamping process.Secondly, based on the method of cupping test (Erichsen test),by utilizing the theory of sheet metal forming plastic, analytical process of nickel coating steel forming was elaborated and discussed. In corporation the Mises yield criterion, the drawing mechanical model based on double friction coefficient was established. The geometric relationship of sheet drawing and the stress-strain relationship between the coating and the nickel coating were deduced, and the punch force and the stress condition of flange deformation region and punch fillet region were discussed in the course of sheet forming.Thirdly, the dynamic explicit finite element code was used to simulate the process of the electrodeposited nickel coating forming. The stress and strain fields of nickel coating and steel substrate were obtained, and so the thickness variations of them were obtained. The studies indicated that the thickness reduction of the nickel coated sheet and the substrate were reached to 54% and 52%, while the blank was fractured. And it was discovered from the interface stress in the process of the forming that the shearing stress of the interface was from -4MPa to 6MPa, the normal stress was from -30MPa to 0.2MPa, and the punch fillet region was the maximum of the shearing stress and normal stress.Fourthly, it was forecasted that the IE of the nickel coated sheet was 12.5 which the nickel coating was 0.01(mm) thick and the substrate was 0.25(mm) thick by coupling ductile fracture criteria which was taken by Clift with the finite element code. Compared the results with the FLD which was read by postprocessor of the LS-DYNA, they were consistent.Fifthly, based on the theory of scratch test, the theoretical calculation method of the interfacial adhesion has been developed through the theory of Lee and Shaffer’s slip-line field and the interfacial adhesion of nickel coating whose thickness is from 0.01mm to 0.09mm has been calculated, and the results are from 5.4N/mm to 48.6N/mm, and the courses of scratch test have been stimulated by finite element code. Compared the analytic results with the numerical results, we found that they were almost consistent.Through the resrarch work, the inrerfacial bonding strength and the formability of the electrodeposited nickel coating steel were obtained which had guidance function for the forming of the electrodeposited nickel coating steel.

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