Research On The Performance Of Nodular Cast Iron Roller Laser Alloying

In this paper,nodular cast iron and WC-Co alloyed material are selected as thesubstrate and the coating material, and5KW laser device is accepted to conduct thelaser surface alloying test. For the alloying layer in different parameters， itsmorphology、microhardness、wear performance and cold and hot fatigue are tested.Bythe comparison and analysis of the performance of the alloying layer，the best laseralloying parameter is obtained.In the different parameters，surface alloying zone、HAZ and substrate zone will beappeared from the bottom.Small grain and fine organization structure can be seen inalloying layer,and the alloying layer has metallurgical bonding with substrate.The results of Vickers microhardness indicate that alloying layer has the highesthardness and the hardness of the HAZ has a significant reduction，and the hardness ofsubstrate is the lowest.With the increase of scanning speed,the hardness of alloyinglayer is decreasing,however,with the decrease of scanning speed,the hardness ofalloying layer is increasing.The results of wear performance test indicate that500℃wear performanceincreases by37%~72%and the room wear performance increases by56%~128%incompared to substrate.In conclusion,the substrate alloyed can significantly improve itswear performance.In the selected temperature and the same conditions，the experiment of cold andhot fatigue performance indicated that0.5mm tiny cracks will be appeared in anaverage of66times in laser alloying samples,and0.5mm tiny cracks will also beappeared in an average of64times in substrate sample,so alloying sample andsubstrate have the same fatigue strength.In conclusion，best parameters：laser power of3.5kw，scanning speed of1800mm/min，laser spot diameter of3.5mm，focal distance of440mm，overlap ratioof30％，coating thickness of85~105μm.