Erosion damage of laser alloyed stainless steel in mercury

The effect of laser surface alloying of type 316 stainless steel on the erosion resistance in mercury has been investigated. The alloying was produced by melting predeposited Al-Si powder and a portion of underlying substrate with a pulsed Nd:YAG laser beam. The microhardness of the modified layer was found to be 2.5 times higher than that of untreated steel. The erosion test of laser alloyed surface and steel in mercury was carried out by using the electromagnetic impact testing machine. The laser alloyed surface was found to be less damaged after 105 cycles of impacts compared to untreated stainless steel. However, after 106 cycles the erosion resistance of the modified layer is much lower than that of untreated steel. Liquid metal embrittlement in contact with mercury and residual stresses were considered as factors impairing the erosion resistance of the laser alloyed surface.