Effect Of Thermal Fatigue On The Wear Resistance Of Graphite Vermicular Cast Iron With Bionic Units Processed By Laser Cladding WC

According to previous studies, laser remelting can improve the wear resistance ofgraphite cast iron brake disc used in train in a certain extent. But with the development ofhigh speed trains, the better thermal fatigue resistance and abrasion resistance are required.Therefore, laser cladding developed on the basis of the laser remelting. Deeper claddinglayer units can be obtained through laser cladding which need grooving and preset metalpowder. Laser cladding overcome the weakness of laser remelting in depth of fusion. Lasercladding improve the wear resistance of graphite cast iron surface significantly. Thus，thispaper uses the laser cladding method to study the surface wear resistance of graphite castiron. Previous studies just focus on the wear resistance of graphite cast iron with lasercladding bionic units, rather than the wear resistance after thermal fatigue. Wear andthermal fatigue act on the brake discs at the same time in the process of its service. However,wear and thermal fatigue is the two main failure forms of brake discs. So on the basic ofprevious researches, the thermal fatigue process was added in front of wear to reveal theeffect mechanism of thermal fatigue acting on wear resistance, which can more close toactual situation of the brake disc in service. In addition, WC has the characteristics of highhardness and high strength, so we select Fe+WC and Cu+WC as alloy powder for lasercladding. The addition of Fe powder Cu and powder could eliminate the brittle faults of theWC, retain high hardness of WC, so that units achieve the combination of hardness,strength and toughness.For the laser cladding Fe+WC biomimetic specimens, the results indicate that thermalfatigue has a negative effect on the wear resistance. After the same thermal fatigue cyclestimes, the wear resistance of laser cladding WC samples is superior to that of laser remeltingones and their wear resistance enhances with the increase of WC content. For the lasercladding Cu+WC biomimetic specimens, the results indicate: when thermal fatigue cycle times is less, the wear resistance of laser cladding WC samples is superior to that of laserremelting ones. And with the increase of WC content the wear resistance become s better.When thermal fatigue cycle times is more, the wear resistance of laser cladding samples areworse than laser remelting ones. And with the increase of WC content the wear resistancebecomes worse. As a whole，along with the increase of thermal fatigue times, the wearresistance declines.