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An improved mass addition approach based on enthalpy balance is used for the numerical simulation of the temperature distributions and geometries during laser rapid manufacturing (LRM) of a multi-layered thin-wall. The approach involves the estimation of the local track height at every node along the track width on the substrate/previously deposited layer by simultaneous balancing of the excessive enthalpies above solidus temperature about the laser axis and the material interface at the substrate/previously deposited layer for material addition during the laser rapid manufacturing of a multi-layer thin wall. It takes laser power, laser beam size, scan-speed, powder feed rate, powder stream diameter, and time-delay between the deposition of two subsequent tracks as user-defined input, and computes the temperature distributions and the geometries of the deposited layers across the process domain in a dynamic fashion. In the present study, the laser rapid manufacturing of five layered thin walls of SS 304L on a work piece of the same material was simulated for various combinations of processing parameters and compared with experimental results. The percentage errors in simulated and corresponding experimental cumulative track heights along with track width were calculated and compared with those of other existing models and the results of present approach were found to be the least. The result indicates that the height and width of the layer under deposition depends on the geometry and temperature distribution of previously deposited layer and, consequently, governed the final geometry of thin wall. [ABSTRACT FROM PUBLISHER]

This work deals with the influence of laser peening on the fretting wear behavior of Ti-6Al-4V. Laser peening was carried out on Ti-6Al-4V. The laser-peened surface was characterized by transmission electron microscopy. Surface roughness, nanoindentation hardness, residual stress, and tensile properties of the material in both laser-peened and unpeened conditions were determined. Fretting wear tests were conducted at different normal loads using a ball-on-flat contact geometry. Laser peening resulted in the formation of nanocrystallites on the surface and near-surface regions, increased hardness, and compressive residual stress. Laser peening did not affect the tensile properties and surface roughness significantly. There was no considerable difference between the values of the tangential force coefficient of laser-peened and unpeened samples. The fretting scar size, wear volume, and wear rate of laser-peened specimens were lower than those of unpeened samples. This may be attributed to an increase in surface hardness due to strain hardening and grain refinement at the surface and near-surface regions, higher compressive residual stress, and higher resistance to plastic deformation of laser-peened samples. [ABSTRACT FROM AUTHOR]