Effect of annealing parameters on the microstructure and tribological properties of FeCoCrNiMn laser cladding layers

The FeCoCrNiMn laser cladding layer exhibits low hardness and poor wear resistance, limiting its applications in the tribology field. The effect of annealing temperature (500 degrees C-900 degrees C) and holding time (2-14 h) on the properties of FeCoCrNiMn layers which fabricated on the 45# steel substrate were systematically studied. The results demonstrate that the layers' surface hardness and wear resistance initially increase and decrease with increasing annealing temperature and holding time. The FeCoCrNiMn layers subjected to annealing at 700 degrees C for 8 h exhibit optimal performance. Specifically, the micro-hardness and wear resistance of the 700 degrees C-8h annealed layers (T700-8) increased by 15.8 % and 41.4 %, respectively, compared to the substrate. The friction coefficient of T700-8 is 0.635, which is 0.025 lower than that of the substrate. The primary wear mechanisms of the T700-8 are adhesive wear and oxidative wear. Microstructural analysis indicates that annealing at 700 degrees C for 8 h forms a Ni-Cr-Fe solid solution phase, strengthening the solid solution. Besides, the average grain size of the layers decreases from 178.7 mu m to 115.2 mu m, indicating grain optimization induced by the annealing process. However, excessively long annealing time or excessively high annealing temperatures lead to the dissolvement of the Ni-CrFe solid solution phase, thus decreasing the surface hardness and wear resistance. Therefore, appropriate annealing parameters can refine the crystal grain, and improve the wear resistance of FeCoCrNiMn layers.