Investigation of the surface integrity of Q345 steel after Nd:YAG laser cleaning of oxidized mining parts

Abstract

As a common mechanical material for mining machinery, Q345 is prone to oxidation due to the moist working environment. At present, laser cleaning is often used to remove rust oxides from the substrate. The pollutant of mining machinery is comprised of a heavy oxide layer and organic ingredients, which are difficult to remove and require high energy per pulse. However, excessive energy is capable of easily destroying surface integrity, such as increasing surface roughness (Ra), generating ablative pits, oxidizing, decreasing microhardness (HV), and decreasing corrosion resistance. Therefore, this paper focused on investigating the surface integrity of mining parts under different laser powers, repetition rates and overlapping rates of the laser spots. The results showed that the surface integrity of the samples gradually improved as the energy per pulse and overlapping rates increased. However, excessive energy caused a negative effect on surface integrity. Based on the comprehensive analysis, optimal parameters were obtained when the power was 280W, the repetition rate was 10 kHz (pulse duration 84 ns), and the overlapping rate of the laser spot was 70%. This work can provide theoretical guidance for the laser cleaning of mining machinery.