Characterization of Fe-Cr-Ni Alloys Produced by Laser Surface Alloying Using Mixed Powder Feeds
by
T. Chande
A. Ghose
J. Mazumder
Department of Mechanical and Industrial Engineering
Abstract
A new screw-fed, gravity-flow, carrier-gas aided powder delivery system was used to make laser surface alloys using Cr and Ni powders on AISI 1016 steel. A 10 kW CW CO2 laser was used for alloying, at incident power densities up to 2 x 107 W/m2 and traverse speeds up to 0.03 m/s. Ten overlapped passes were used to make alloyed zones 0.05 m long by 0.015 m wide. Alloys with up to 80 weight percent Cr and 58 percent Cr + 26 percent Ni were obtained. Surface roughness and corrosion resistance measurements were made. The microstructure was characterized by transmission and scanning electron microscopy. Smoother surfaces were obtained by increasing traverse speed and beam diameter. Corrosion samples passivated spontaneously in a 3.5 percent NaCl solution in distilled water, but were susceptible to pitting corrosion when uneven surfaces were subjected to corrosion testing. Microstructures were highly refined with a high dislocation density. These results are related to process mechanisms. The reported method of powder delivery is versatile, flexible and reproducible, and can be used to make useful alloys.
Download (1 MB)