Parametric optimization of friction stir processing on micro-hardness of Al/B4C composite

Friction stir processing was used to prepare aluminium metal matrix composite reinforced with B4C particles. The micro-hardness of the composite was improved by selecting the process parameters. Friction stir processing parameters, namely tool rotational speed, tool tilt angle and different pin profiles, were explored by using Taguchi’s L9 orthogonal array and analysis of variance. Optical microscopy and scanning electron microscopy were employed for microstructural analysis. X-ray diffraction was used to evaluate the residual stress. Experimental results illustrated that increased rotational speed, reduced tilt angle and square pin profile of the tool gave more uniform dispersal of B4C content with maximum micro-hardness. Small amounts of compressive residual stress developed at the stirred and thermo-mechanically affected zones confirmed the adequate improvement in micro-hardness. Micro-hardness of fabricated Al 6063/B4C composite surfaces was enhanced by 30% as compared to Al 6063 alloy.

Effect of double-sided friction stir welding on the mechanical and microstructural characteristics of AA5754 aluminium alloy

AA5754Al alloy is widely used in industry. However, as in the case of all Al alloys, the 5xxx series Al alloys cannot be easily joined through fusion welding techniques. To address this problem, in this study, the effect of double-sided friction stir welding at various tool rotational speeds (450, 710, and 900 rpm), feeding rates (40, 50, and 80 mm × min-1), and tool tilt angles (0°, 1°, 2°) on the welding parameters and mechanical and microstructural characteristics of AA5754 Al alloy was determined. Tensile strength tests and microhardness tests were performed to examine the mechanical properties of the welded specimens. The microstructures of the welded zone were examined by obtaining optical microscopy and scanning electron microscopy images. The tensile test results indicated that the specimens exhibited the highest welding performance of 95.17 % at a tool rotational speed, feed rate, and tool tilt angle of 450 rpm, 50 mm × min-1 and 1°, respectively.

Research on the Mechanisms of Internal Gear Honing by use of Cone-shape Honing Wheel with Tool Tilt Angle

Ring gear is an important transmission component, but restricted by its ring-shape structure, the tooth surfaces are pretty hard to be finished after heat treatment. Honing is the most commonly used finishing technique for external gear, but for ring gear, it is inconvenient. In this paper, a new type of cone-shape honing wheel is proposed and the honing mechanism is studied for improving the honing performance of ring gear. First of all, the mathematical model of the honing technology by use of cone-shape honing wheel is built, and the merits of the new honing method are discussed. Then, the contact conditions between the honing wheel and the work gear are analyzed, and it is found that the tool tilt angle of the honing wheel has good influences on the honing mark distribution of the work gear. Finally, the honing simulations for ring gear by use of cone-shape honing wheel are carried out, by which the feasibility of the new honing technique are verified.

Investigation and optimization of friction stir welding process parameters of stir cast AA6082/ZrO2/B4C composites

In the present investigation, aluminium-based alloy (AA6082) is stir-casted with 3 % ZrO2 and 5 % B4C reinforcement particulates to fabricate Aluminium Metal Matrix Hybrid Composites (AMMHCs) which are further friction-stir welded at different welding conditions to develop a welded joint with optimum ultimate tensile strength (UTS) and microhardness. This newly developed AMMHC will find its specific application as bulkhead partitions in the hull of a ship due to its excellent properties, such as lower weight, higher specific strength, superior resistance to wear, and lower thermal expansion coefficient than that of AA6061 and AA5083 composites. The friction-welded butt joints performance of AA6082/3%ZrO2/5%B4C is generally determined by varying the FSW process parameters such as tool rotational speed (TRS), welding speed (WS), axial load (AL), tool tilt angle (TTA), tool pin profile (TPP), shoulder diameter (SD), etc. In the present work, the empirical relationships are established between parameters highly influencing FSW process (TRS, WS, and AL) and their responses (UTS and weld nugget microhardness (WNH)). The desirability approach is employed for predicting the optimal UTS and WNH. The corresponding values of input process parameters are TRS of 1030.95 rpm, WS of 38.5 mm/min, and AL of 5.88 kN. The calculated UTS and WNH for the present investigation are 239.98 MPa and 94.2 HV, respectively, and these values are consistent with the results of validation experiments.

Optimisation of Planning Parameters for Machining Blade Electrode Micro-Fillet with Scallop Height Modelling

Aero-engine blades are manufactured by electroforming process with electrodes. The blade electrode is usually machined with five-axis micromilling to get required profile roughness. Tool path planning parameters, such as cutting step and tool tilt angle, have a significant effect on the profile roughness of the micro-fillet of blade electrode. In this paper, the scallop height model of blade electrode micro-fillet processed by ball-end milling cutter was proposed. Effects of cutting step and tool tilt angle the machined micro-fillet profile roughness were predicted with the proposed scallop height model. The cutting step and tool tilt angle were then optimised to ensure the contour precision of the micro-fillet shape requirement. Finally, the tool path planning was generated and the machining strategy was validated through milling experiments. It was also found that the profile roughness was deteriorated due to size effect when the cutting step decreased to a certain value.

Optimization of Maximum Tool Travel Speed for Friction Stir Welded AA-2014-T6 without Compromising the Mechanical Properties

In this study optimization of maximum travel speed that can be achieved for Friction Stir Welding of Aluminum Alloy 2014-T6 without compromising the mechanical properties was carried out. Joints were made at different travel speeds of 200, 300, 400, 500 and 600 mm/min with constant tool rotational speed of 800 rpm and tool tilt angle of 2.The samples were characterized by stereo microscopy, optical microscopy, scanning electron microscopy, Vickers microhardness testing and tensile testing. Microstructural features of as-welded samples revealed refined equiaxed grains in nugget zone and grain growth in the heat effected zone. Tensile test results showed that the tensile strength was maximum at travel speed of 500 mm/min but then decreased after further increasing the travel speed. Hardness in the nugget zones of all welds was lower than that of base material. Fractographic analysis exhibited significant variations in fracture surfaces of tensile samples. A relationship between the welding parameters and resultant heat inputs was also discussed.

Effect of deforming tool parameters on roughness of hardened surfaces during orbital ironing

The effect of the deforming tool parameters on the roughness of hardened surfaces during orbital burnishing is considered. As result of experimental studies, it is revealed that after orbital burnishing, new surface is formed with significantly lower height of microscopes compared to the original microprofile, which has positive effect on improving of the shape accuracy and quality of hardened parts. It is found that the most significant effect on the roughness parameters during orbital burnishing is exerted by the orbital rotation radius, less significant — by the radius and working tool tilt angle. Increase in the working tool tilt angle the orbital rotation radius and decrease in the working tool radius leads to increase in roughness of surface.