Study On The Processes Of Multichannel Laser Surface Quenching Of Ductile Cast Iron QT600-3

Ductile cast iron has excellent performance including high strength, good plasticity andtoughness, easy production and low cost than steel, which is widely used in industrialapplications. In order to improve the wear resistance of the ductile cast iron, it is necessary toinvestigate the surface treatment of ductile cast iron. In this thesis, the specimens of ductilecast iron QT600-3were hardened by laser surface multichannel quenching treatment. And theresults were analyzed which could draw some useful conclusions.Based on finite element software ANSYS，a3D numerical temperature fields model forthe laser transformation hardening was created. The numerical simulation of the lasertransformation hardening of ductile cast iron QT600-3were investigated. The widths anddepths of the hardened layer and heat affected zone were predicted based on the analysis ofthe temperature field. The simulate results were compared with the experimental results of thehardened layer. It was found that the results of numerical simulations and experiments were ingood agreement under the same process parameters of laser surface quenching. The numericalsimulation results could be regarded as a basis for choosing laser technological parameters.Laser surface quenching of ductile cast iron QT600-3was investigated experimentallyby using a semiconductor laser unit. The hardness of the hardened surface reached from49to60HRC. The widths and depth of hardened layer were valuable when the test parameters wereas power1600W, laser beam14mm, scan velocity180mm/min.Laser surface multichannel quenching of ductile cast iron QT600-3was investigatedexperimentally by using a semiconductor laser unit. The microhardness and themicrostructure of the hardened layer of ductile cast iron QT600-3under different scanningspace were mainly analyzed. The experimental results showed that great amounts of acicularmartensites were well distributed in the hardened zone. The tempering effect of the secondlaser scanning to previous hardened zone was obvious when scanning space was1mm.Themicrostructure of first hardened zone was tempered martensite. And when scanning spaceincreased to8mm, the tempering effect was not obvious. The microhardness of the specimensincreased at first and then decreased with the increasing of the scanning space. The averagemicrohardness of the specimens reached the highest when the scanning space was8mm. Atthe same time, the influence of hardness of follow-up scanning to previous scanning wasgetting smaller as the scanning space larger.