Comparison of the effect of EB and LB surface treatment on structural characteristics of IN 713LC superalloy

Damage and oxidation resistance are properties characterizing Ni-based superalloys. However, besides the alloy composition, the mentioned properties depend on structural features such as grain and precipitates size. Surface structure refinement via laser beam (LB) and electron beam (EB) was performed on IN 713LC superalloy. The influence of both the treatments on material microstructure, chemical composition, microhardness, and oxidation resistance was examined. Both the treatments resulted in a refined structure of the remelted zone. A homogeneous 30-43 mu m thick remelted zone was created by EB, while a non-homogeneous (semi-circular track) remelted zone (22-86 mu m) was created by LB. EB treatment resulted in higher surface roughness; however, a smaller amount of cracks on the treated sample surface was observed compared to the LB treatment. An increase of surface microhardness by 38 % compared to the as-received material was reached regardless of the used treatment method. The impact of the treatment on oxidation resistance was studied after exposure to 800 degrees C for 24, 48, 72, and 96 hours in the ambient air. The created oxide layer consisted of internal Al2O3 and external Cr2O3 + NiCr2O4 layer. The oxide layer thickness differs in time; however, comparable oxide layer thickness was measured on all samples after 96 hours of oxidation.