Research On Basic Process Of Laser Cladding Ni60 Coating

With the publishment of China Manufacturing 2025,"Fully Implement of Green Manufacturing" has become the foothold to realize circular economy and green economy.Remanufacturing is one important part in green manufacturing.Remanufacturing uses components of used products as semifinished materials,and utilizes advanced surface engineering technology as repairing methods to createa wear resistant,corrosion resistant and anti-fatigue coating on the damaged surface of used components,which recovers their usabilities.Among those specific techonologies used in remanufacturing,laser cladding is well-known for its advantages such as good metallurgical bonding,broad applications,small thermal deformation and so on.This thesis uses 45#steel as substrate material,Ni60(+WC)powder as cladding materials,and conducts single&multiple track(s)laser cladding research.The obtained research results are outlined as follows:(1)Conduct several single&multiple track(s)experiments with powder spreading method and design templets to verify the possibility of laser cladding Ni60 coating with hand-spreading method.To improve the repairing efficiency of single layer cladding,this thesis carries out two batches of single track cladding experiments with gas-carrying method stage by stage,optimizing the parameters,making cladding height higher than 0.6mm together with dilution ratio less than 40%.(2)Carry out two batches of multiple-track cladding experiments with gas-carrying method stage by stage.For evaluating the forming quality of cladding cross section,this thesis puts forward two methods,which are named Classification of Metallographic phase after expertise and Definition&Calculation of Evenness.The former has 4 main evaluation indexes,which mean crack,hole,cladding height,cladding depth.Each of them is given a weight.The 4 main evaluation indexes are divided into 7 detailed evaluation indexes for expertise and qualitatively classification.The latter gives out definition&calculation of evenness from altitude direction and horizontal direction.(3)For discovering the influence of WC with different mesh number to Ni60 coating,this thesis conducts 9 experiments with WC amount 30%,WC mesh number 400,200 and coarsness.Test and analyze blending condition of mixed powder,microhardness,wear resistence of coating according to the cladding results.(4)This thesis changes the energy density,lowers the hardening effect to the heat-affected zone by means of adjusting scanning speed and laser power.The hardness of Ni60 layer(700-800HV)is 2-3 times higher than that of substrate.The hardness of cladding layer with Ni60+400 mesh number WC reaches about 1000HV,which is above 3 times higher than substrate’s hardness.The wear test shows that only changing the process parameters will cause a large alteration scale of weight loss ratio in Ni60 group(0.54%-0.734%).But adding WC with 400,200 mesh numbers helps more about the wear resistant(one makes the extreme 0.489%of weight loss ratio).This paper ensured a rough range of laser power and proper range of scanning speed according to the possibility of pre-experiments with spreading powder method.Then this paper separately conducted two batches of experiments for single&multiple tracks laser cladding to optimize the process parameters as well as to evaluate the forming quality of cladding cross section.At last,this paper carried out multiple-track cladding of Ni60+WC powder,and finished the wear test and analysis.