30 research outputs found
Ultrafine grained materials through mechanical processing: An assessment
In this paper severe plastic deformation (SPD) and friction stir processing/ welding are examined. The structural changes due to SPD are reflected in improved mechanical properties. Advantages of SPD are pointed out. Within the SPD technique, a number of approaches are possible, e.g., equi-channel angular pressing/extrusion, high pressure torsion, accumulative roll bonding/fold - roll process, reciprocating extrusion – compression, cyclic close die forging, repetitive corrugation and straightening. Analyses available are elementary and often assume uniform stress and strain distribution. These processes are easily adapted to suit standard metal working equipment fitted with inexpensive devices and tools. However, scaling up the processes to handle large billets and achieve large tonnage production is difficult. In the near future, medium and small-scale industrial production only is likely.
Friction stir process, a solid state technique for joining similar or dissimilar materials of equal or different thickness, has some key metallurgical, environmental and energy benefits. It is already being considered for applications in aerospace and automotive industries. Significant improvements in surface properties and superplastic flow have been established in friction stir processed materials. Velocity of tool movement and power input needed for fast rotation of the tool are the major variables. Since significant temperature rise is there during processing, in a proper analysis, the boundary conditions arising from thermal and mechanical constraints have to be satisfied simultaneously, which is an extremely difficult. A few key issues have to be addressed before large-scale production can be attempted. An integral approach that takes into account the total system of material, design, mechanics and component forming is likely to lead to industrially relevant solutions
Ultrafine grained materials through mechanical processing: an assessment
In this paper severe plastic deformation (SPD) and friction stir processing/ welding are examined. The structural changes due to SPD are reflected in improved mechanical properties. Advantages of SPD are pointed out. Within the SPD technique, a number of approaches are possible, e.g., equi-channel angular pressing/extrusion, high pressure torsion, accumulative roll bonding/fold - roll process, reciprocating extrusion - compression, cyclic close die forging, repetitive corrugation and straightening. Analyses available are elementary and often assume uniform stress and strain distribution. These processes are easily adapted to suit standard metal working equipment fitted with inexpensive devices and tools. However, scaling up the processes to handle large billets and achieve large tonnage production is difficult. In the near future, medium and small-scale industrial production only is likely. Friction stir process, a solid state technique for joining similar or dissimilar materials of equal or different thickness, has some key metallurgical, environmental and energy benefits. It is already being considered for applications in aerospace and automotive industries. Significant improvements in surface properties and superplastic flow have been established in friction stir processed materials. Velocity of tool movement and power input needed for fast rotation of the tool are the major variables. Since significant temperature rise is there during processing, in a proper analysis, the boundary conditions arising from thermal and mechanical constraints have to be satisfied simultaneously, which is an extremely difficult. A few key issues have to be addressed before large-scale production can be attempted. An integral approach that takes into account the total system of material, design, mechanics and component forming is likely to lead to industrially relevant solutions
Effect of stirrer design on microstructure of MWCNT and Al alloy by stir casting process
Influence of process parameters of aluminothermic reduction process on grain refinement of in-situ Al/ TiB2 composites
Comparative evaluation on the performance of nanostructured TiAlN, AlCrN, TiAlN/AlCrN coated and uncoated carbide cutting tool on turning En24 alloy steel
45-59<span style="font-size:11.0pt;mso-bidi-font-size:
10.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="" lang="EN-US">In
the present work, the performances of the nanostructured TiAlN, AlCrN,
TiAlN/AlCrN coated are evaluated by comparing the machining performance with
uncoated carbide cutting tool by conducting the machining studies on En24 alloy
steel. Taguchi’s experimental design is used to design the turning experiments
and fix the turning parameters, such as the cutting speed (<i style="mso-bidi-font-style:
normal">V), feed rate (f) and
depth of cut (d). The signal-to-noise
ratio and anova were used to investigate the effects of the machining
parameters and their contribution to the tool wear and surface roughness. The
results show that the nanostructured TiAlN/AlCrN coated insert has developed
minimum flank wear and shown minimum surface roughness on the machined surface,
compared to the TiAlN, AlCrN coated and uncoated tools. The cutting parameters
in which the TiAlN, TiAlN/AlCrN coated and uncoated inserts have shown lesser
tool flank wear and better surface finish of the work-piece are identified. For
the TiAlN tool, the better machining parameters are, cutting speed = 160 m/min,
feed rate = 0.119 mm/rev, and the depth of cut = 1.0 mm. For TiAlN/AlCrN, the
better machining parameters are, cutting speed = 160 m/min, feed rate = 0.318
mm/rev, and the depth of cut = 0.3 mm, and for the uncoated tool, the cutting
speed = 100 m/min, feed rate = 0.318 mm/rev, and the depth of cut = 1.0 mm is
the best machining condition. But for the AlCrN tool the minimum tool wear was
obtained, when the cutting speed = 40 m/min, feed rate = 0.477 mm/rev, and the
depth of cut = 1.0mm and better surface finish of the work-piece was obtained,
when the cutting speed = 160 m/min, feed rate = 0.119 mm/rev, and the depth of
cut = 1.0 mm.</span