Study On Microstructure Evouution And Properties Of Laser Cladding Nickel-Based Alloy On Q345 Surface

With the rapid development of society and modern industry,traditional single-performance metal materials can no longer meet the needs of practical applications,which has led to higher requirements for the comprehensive performance of materials in various fields.Iron and steel materials were an indispensable part of nowadays industrialization process,among which low-alloy steel accounts for about 30%of its use.However,the contradiction between the service environment and unreasonable service life of low-alloy steel was particularly worthy of attention.As present,surface engineering technology can effectively solve this situation.Inconel 625 has excellent high temperature performance and excellent anti-corrosion and anti-aging ability.At the same time,it can serve stably for a long time above 600?,so it is often used as surface modification materials.However,Laves phase often appears in Inconel 625 during molding.The existence of this phase consumes the elements such as Mo and Nb that should play a strengthening role,which will make the mechanical properties of y-Ni deteriorate.Therefore,how to reduce or eliminate Laves phase to improve the comprehensive performance of Inconel 625 has become the focus of attention.In the present paper,Inconel 625-mWC/nTiN was prepared on the surface of Q345 by laser cladding,where m=5,10,15,20wt.%,n=5,10wt.%.The effects of WC and TiN on the precipitated phase and its various properties in Inconel 625 alloy were investigated.The microstructure,change behavior of precipitated phases,the bonding property and the corresponding mechanical properties of Inconel 625-mWC/nTiN after the introduction of different WC and TiN were compared,and the influence of WC and TiN on Inconel 625 under different introduction mechanisms was revealed.The results showed that both WC and TiN can effectively reduce the number of secondary phases in Inconel 625,but the number of precipitates in 20%WC was higher than that in 15%WC.Meanwhile,the dendrite morphology is more sensitive to the content of TiN,and the part of 10%TiN metallography was mainly cellular.In addition,when the TiN content was 5%,the hardness decreased due to the decrease of the secondary phase,and the hardness recovered after further increasing TiN.During the solidification of Inconel 625,L?L+?-Ni?L+?-Ni+MC?L+?-Ni+MC+Laves occurred successively,and there was a good metallurgical bonding with Q345 substrate after the introduction of WC and TiN.At the same time,it was found that the strength of the forming zone decreased after the introduction of WC and TiN except 5%WC.Based on the above studies,the influence mechanism of WC and TiN on the friction behavior and corrosion resistance of Inconel 625 at room temperature was further explored.The results showed that the introduction of WC and TiN has significantly enhanced the wear resistance of Q345 substrate and Inconel 625.Meanwhile,the wear resistance of Q345 substrate and Inconel 625-mWC/nTiN had different degrees of decline under high load,but the load had no effect on the wear order.The Q345 substrate and each cladding layer undergone different degrees of abrasive wear,as well as adhesive wear caused by continuous friction due to the plastic deformation of the wear surface.The electrochemical results showed that the introduction of a proper amount of WC and TiN pairs allowed the release of Mo and Nb etc.In Laves,and the corrosion resistance was improved compared with that of Inconel 625.The corrosion resistance first increased and then decreased with the increase of WC introduction.Among them,the corrosion resistance of 5%TiN was better than that of 10%TiN,and the entire system exhibited a capacitive load during the corrosion process.In addition,stearic acid was used as modifier to modify the surface of Inconel 625,and it was found that the corrosion resistance of Inconel 625 was effectively improved after surface modification,due to the contribution of long hydrophobic hydrocarbon chain in the CH₃(CH₂)₁₆COO^- grafted on the surface.