Materials Science Forum Vol. 969

Abstract: Dissimilar joining of high strength tensile steels are joined using laser beam welding. The selection of the welding conditions for joining of dissimilar materials is highly required to satisfy the quality of the joints. In the present investigation, optimization technique were used to determine the optimal welding conditions. Initially welding conditions were optimized for weld geometry and formation of different zones in the weldment. The metallurgical and mechanical properties of the welds are greatly influenced by the geometry of the welds. The surface response methodology design is carried out for the experimental design by the development of regression equations. Analysis of variance (ANOVA) was used to check the validity of the model. The output of the welding conditions were compared with the predicted values to identify the accuracy of the model. The obtained results from response surface methodology were compared with the experimental results and validated.

Abstract: Titanium is a hard metal with good mechanical properties, corrosion resistant and biocompatibility which makes it have a wide range of applications (biomedical and aerospace). Severe plastic deformation (SPD) is employed to produce Ultrafine Grained (UFG) structures. UFG structures have better mechanical properties due to their compaction. Equal Channel Angular Pressing (ECAP) is adapted to produce a UFG structure in Titanium. In this process, titanium sponge powder is filled in the aluminium shell by intermediate tapping to fill the volume of the shell. The shell is then closed with an Al cap and ECAP is done with continuous back pressure at 300°C. The test specimen has undergone four passes in route B_C at different back pressure (50, 100 and 150 MPa) where titanium is consolidated without any crack. Titanium showed decreased grain size and porosity with increasing backpressure. In particular, it is seen that the sample ECAPed by 100 MPa backpressure showed a relative density of about 98% with a hardness of 37 HRC. It is seen that ECAP is more economical and the product obtained by the ECAP process has better properties.

Abstract: In this study, Friction Welding of Tube to tube-Plate using an External Tool (FWTPET) is carried out by joining SA213 tube and SA387 tube plate alloying materials using an external tungsten tool by close fit methods in absence of backing plate without hole on the circumference of the tube for superior mechanical and metallurgical properties. The optimization techniques such as Taguchi L₉ and Analysis of Variance (ANOVA) is used to endorse the capital joint strength. The output parameter (TS) and input factors (tool rotational speed, tube projections, depth of cut) are designated for the study. The heat that produces from tool pin, dissipates to the tube and the tube plate during FWTPET process. The grain size measurement, x-ray diffraction (XRD) phase analysis, radiography test is carried out after FWTPET process. In this research work, FWTPET process is carried without hole on the circumference of the tube, further FWTPET process is also compared by without employing supporting arrangement. Excellent joint strength of 762.2 MPa is achieved with the absence of supporting specimen which without hole on the circumference of tube for the tool rotational speed of 1300rpm. Keywords: Friction welding, FWTPET, Analysis of Variance (ANOVA), Optimization techniques, Tensile strength

Abstract: The composite plays an important role in the new generation of engineering material with better tribological and mechanical properties. In this paper, the hybrid composites of A7050/Al₂O₃/ZrO₂ with different wt. % of reinforcement materials (0.5, 1, 1.5wt. % ZrO₂, and 1wt. % Al₂O₃ constant for all composites) were fabricated by stir casting method. From the results, it was observed that the good texture in microstructure without defect with an addition of constant 1wt% Al₂O₃ and varying 0.5, 1and 1.5 wt% ZrO₂. The Hardness of hybrid composites is increased by 27% with addition of 1wt % of Al₂O₃ and 1.5 wt% ZrO₂ compare to base alloy. Charpy impact strength decreased with the addition of Al₂O₃ and ZrO₂ ceramic particle in all the composites. From the dry wear studies, the composite with 1wt% Al₂O₃ and 1wt% ZrO₂ was observed with minimum wear loss and low coefficient of friction.

Abstract: This paper presents investigations on the manufacturing of three-dimensional functional metallic parts through melting and deposition of stainless steel 430L wire material by a metal inert gas welding technique. Experiments were performed on wire arc additive manufacturing following face centered composite design of experiments considering voltage, current, electrode wire material feed rate and welding speed as inputs for modeling single bead geometry in terms of bead width, height, and cross-sectional area. Response surface models were built using the collected experimental data. Performance of the models in predicting the responses was found satisfactory. Models of single bead geometry were employed to calculate void and post-processing in fabricating three-dimensional parts following raster scanning deposition of multiple layers considering the different degree of overlapping and build directions. The theoretically estimated values of void and post-processing were verified through fabrications of two three-dimensional shapes. It was shown that the void and post-processing could be controlled by suitable selection of process parameters, the degree of overlapping between two beads and build direction.

Abstract: The aluminium alloys AA2024 and AA6061 are widely used for fabricating light weight structural member with better strength and corrosion resistance. Friction stir welding (FSW) parameters such as rotational speed, tool shoulder profile and traverse speed are used to identify the corrosion resistance and microstructural analysis in different weld region of AA2024-AA6061 dissimilar joints. In this work, Taguchi L9 orthogonal array with three variables and three stages has been used to reduce the number of experiments. Potentiodynamic polarization (PDP) testing results are optimized by ANOVA technique and obtain the corrosion rate as 5.72 mil/yr and resistance polarization as 835.28 ohm.cm². The optimal parameter set is found to be 1000 rpm, flat shoulder and 45 mm/min. The microstructural analysis reveals localized pit dissolution in the nugget zoneThe aluminium alloys AA2024 and AA6061 are widely used for fabricating light weight structural member with better strength and corrosion resistance. Friction stir welding (FSW) parameters such as rotational speed, tool shoulder profile and traverse speed are used to identify the corrosion resistance and microstructural analysis in different weld region of AA2024-AA6061 dissimilar joints. In this work, Taguchi L9 orthogonal array with three variables and three stages has been used to reduce the number of experiments. Potentiodynamic polarization (PDP) testing results are optimized by ANOVA technique and obtain the corrosion rate as 5.72 mil/yr and resistance polarization as 835.28 ohm.cm². The optimal parameter set is found to be 1000 rpm, flat shoulder and 45 mm/min. The microstructural analysis reveals localized pit dissolution in the nugget zone.

Abstract: Electrochemical honing (ECH) is an encouraging technique of gear finishing because of its micro-removal characteristic. In ECH, material removes by combined effect of anodic dissolution and mechanical abrasion. It is a hybrid micro-finishing process. ECH is a productive technique of gear finishing with high accuracy and long tool life. However, the lack of comprehensive research and complex setup design prevents it from being commercialized. This paper discusses the emphatic features of electrochemical honing of gears; its prospective features and capabilities. A comparative study is executed to explore the improvement in process capability and advantages of it. The shortcomings of the process are also discussed. Some guidelines are also mentioned for future research. It helps research community to mature this process further.

Abstract: Plasma Arc Welding (PAW) is one of the important arc welding processes used in electronics, medical, automotive and aerospace industries due its high accuracy and ability of welding any hard materials which is more tolerant to joint misalignment than Laser Beam Welding (LBW) at a lower cost. Thickness of 1.6mm plates were used to obtain full penetration and a strong joint with a very narrow Heat Affected Zone. The present study deals with the effect of mechanical and corrosion resistance properties of butt welded 1.6 mm thick martensitic stainless steel-similar (SS410 and SS410) joints made by plasma arc welding technique. Similar butt Welded joints were analyzed by using mechanical (Bend test, Erichsen cup test, Tensile test) characterization methods. Their corresponding corrosion resistance properties were also investigated by potentiodynamic polarization corrosion testing technique. The tensile strength was found to be 341 MPa for similar SS410 weld. During tensile test the failure occurred on the base metal on both similar joints Keywords: SS304; SS410; PAW; Butt weld; Erichsen Cup Test; Microstructure.

Abstract: This research work presents an incorporated approach to modelling of WEDM of AA6063 (armour applications) using support vector machine technique. The experimental investigation has been carried out with four input variables namely pulse-on-time (P_on), pulse-off-time (P_off), servo-voltage (V_S) and peak-current (I_P). Surface roughness is measured as response parameter. The experimental runs are designed according to 3^k full factorial design (k is number of input variables). It is apparent from this study that values anticipated by developed model are found closer to experimental results. Thus, it ensures appropriateness of model for prediction purpose and smart manufacturing. Machined surfaces are also examined by SEM to critically evaluate the process.

Abstract: Laser beam welding is one of the most favorable welding technique and its importance in industry is demanding due to higher welding speeds and lower dimensions and distortions in the welds. Moreover, its high strength to weld geometries and minimal heat affected zones makes favorable for various industrial applications. In the present study, laser welding of titanium alloy was investigated to observe the effects of parameters on the bead geometry and metallurgical properties. The laser power and welding speeds were varied to identify their impact on the formation of weld geometry. The width and depth of the fusion zone is varied with welding conditions. The finer grains identified in weld zone and the width of heat affected zone was significantly changes with laser welding power. The mechanical properties of the weld joint are controlled by obtaining optimum weld bead geometry and width of the head affected zone in the welds.