| Laser surface-alloying method was applied on steel in order to develop a functional gradient Inconel/Steel material. Inconel 690 sheet was placed on steel substrate, and then a series of high power CO₂: laser beam was irradiated on surface in order to produce homogeneous alloyed layer. Simultaneous compositional gradients of two different kinds of alloying elements (Cr and Ni) were investigated in this material. In order to determine the microstructure, phase and compositional profiles in this material, SEM, XRD and EDS were used. Sequential repetition of laser surface-alloying treatments up to 4 times resulted in about 3 mm layer of fair compositional gradients from 21℃ to 0% for Cr, from 40% to 0% for Ni and from 39% to 99% for Fe in this material. Since compressive stress was formed in heat-affected region due to martensitic transformation while relative tensile stress was developed in alloyed region, cracks were formed at the boundary region between alloyed region and substrate region. |
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