International Journal of Emerging Technologies and Engineering (IJETE) Volume 4 Issue 7, July 2017, ISSN 2348 – 8050 7 www.ijete.org Near-Net-Shape Superplastic Forming of Intricate Shaped Magnesium Alloy Components Anjaiah Madarapu 1 , AbhijithDutta 2 , M Manzoor Hussain 3 , J Kandasamy 4 1 Department of Mechanical Engineering, GNITC, Ibrahimpatnam, Hyderabad, India 2 DMRL, Sc.G, (Retd), Kanchanbagh, Hyderabad,India 3 Department of Mechanical Engineering, JNTUH, Kukatpally, Hyderabad, India 4 Department of Mechanical Engineering, MVSREC, Nadergul, Hyderabad, India Abstract: Finite Element (FE) simulations are performed to predict the Superplastic Forming behavior of AZ31B magnesium sheet intoregular and complex shape components viz., Square, Multiple V grooves, Combination of square and multiple V grooves. The Pressure-Time simulated from MARC isused to blow form the components. The forming time, height of the component at pole,sheet thicknessand strain rateof the manufactured components are found to be in close agreement with the FE results. Keywords: SPF, Magnesium alloys, FE Simulations, Regular and Intricate parts. INTRODUCTION “Superplasticity is the ability of a polycrystalline material to exhibit in a generally isotropic manner, very high tensile elongation prior to failure”[1].SPF is a sheet metal forming process used to deform such materials under controlled conditions of temperature and strain rate. SPF has become a viable process in manufacturing of aircraft and automotive parts. In superplastic forming process, the uniformity of sheet thickness during and after forming is vital for ensuring the mechanical quality of the formed component. The SPF technique seems to go hand-in-hand with magnesium alloys due to the vast usage as structural parts in automotive sector. Magnesium alloys components produced through SPF posseses improved anti-fatigue, anti-corrosion properties of the structure with light weight and high strength.[1−6]. The superplastically formed part exhibits non-uniform thickness distribution because of stretch forming nature of the process.[7,8] This leads to the increase of weight and reduction of the integral property of the parts, and easily causes cracks and decreases the forming limit of materials.[9] Therefore, the non- uniform thinning limits the practical application of superplastic forming. The direct-reverse superplastic forming process an effective approach to improve the thickness uniformity, consists of two stages: firstly, the sheet was formed into the pre-forming die to pre-thin material in local regions, and then the pre-formed sheet was blow formed into the forming die to obtain the final shape.[10] A simple form of constitutive equation for superplastic material is given by Backofen=Kέ m [3] where σ flow stress, K strength coefficient, έ strain rate, and m strain rate sensitivity index. Three mechanisms namely vacancy creep, creep by grain boundary diffusion, and grain boundary sliding accounts for the high strain-rate sensitivity found in superplastic materials. The strain-rate sensitivity of metals arises from the viscous nature of the deformation process.[11 – 15]Mathematical modeling of the superplastic forming operation at a constant strain rate condition, developed in two simple equations relates required gas pressure to the material parameters. It predicts the thickness variation between the pole and the equator. Simulation results of SPF in conical die by 2D model with axisymmetric elements and 3D model with shell elements in ABACUS are observed to be similar.[8] Titanium alloys superplastic deformation capability is demonstrated by successful forming Ti-Al-Mn alloy into hemispherical components.[9] The influence of friction depends on the type of bulging on the die geometry. This is analyzed by FE technique and validated experimentally on conical bulging and rectangle box bulging.[17] Investigations on a series of axisymmetric models on the influence of component shape and the contact friction on the final thickness distribution reveals a small friction coefficient can improve the uniformity of the thickness. For a rectangular box bulging, as friction decreases, the filling ability of the sheet towards the die corner and the uniformity of the thickness increases.[16-17]The literature available indicates that the research was performed on the development of SPF for various alloys. However, any breakthrough in the processing of sheet materials is more likely to come from the development of new alloys with very high formability at low temperature and various strain rates. The development of superplastic forming technique is to improve formability of existing alloys that will relax the precise requirements. The thickness distribution, effective stress, effective strain, critical damage characteristics of the formed sheet depends on the material properties K and m. The forming time in superplastic forming is a function of die entry radius, die angle, die diameter, height of the die and friction coefficient between the sheet and die. The optimum pressure-time diagram, controls the pressure to maintain the target strain rate and minimizes the thinning and forming time. The hot deformation behavior of AZ series magnesium alloys is due to large manganese intermetallic particles. Cavitation and diffuse necking is the main cause for failure, the mechanism being the difference in distribution of particles.Several authors have reported the change in philosophy, today’s choices and developments in the SPF process, its cost effectiveness, SPF major role in producing airframes, engine structures. Superplastic forming of components with abrupt change in shapes leading to near