Study On Infiuencing Factors Of Laser Cladding Repair Of K418 Superalloy Blades

With the rapid development of laser cladding surface technology,through the unremitting efforts of researchers,laser cladding technology has been successfully transition from the experimental stage to the actual industrial production,it has been widely used in automotive,aerospace,petrochemical and other fields.As the ship's maritime operating environment is complex,the number of equipment is large,the traditional maintenance methods can not fully meet the ship's long-range navigation equipment in the field of maintenance or remanufacturing.The on-site repair and remanufacturing capabilities of the ship's parts are very important for the future development of the Navy.The unique advantage of laser cladding has brought new hope for achieving the repair and remanufacturing of ship parts on-site.The use of laser cladding repair technology to repair damaged parts,only need to carry the right amount of metal alloy powder on the ship.It is an effective way to solve the current China's ship parts and equipment repair on-site.Therefore,it is very important to study the feasibility of laser cladding in the vibration environment of ships.First of all,the K418 superalloy turbine blades were repaired by using semiconductor lasers.The effects of different laser power and scanning speed on the cracking of cladding layer were studied by using K418 and Inconel718 alloy powders.And then studied the influence of ship vibration environment on the morphology,microstructure and properties of laser cladding coating.Vibration frequency range of 0~50Hz,amplitude range of 0~1.2mm.The microstructure and crack morphology of the cladding were observed by using stereomicroscope.The microstructure and composition of the cladding were analyzed by metallographic microscope,scanning electron microscope and X-ray diffractometer.The corrosion resistance of two kinds of alloy powder cladding coatings and cladding coatings under different vibration conditions was studied by the electrochemical workstation.The hardness distribution of each sample was studied by microhardness tester.The morphology of molten pool during laser cladding in vibration environment was studied by using the CCD camera.The experimental results show that the K418 superalloy turbine blade is difficult to be repaired by laser cladding with K418 alloy powder,and the crack tendency is very large.Under certain process parameters,the cladding layer has serious crack and can notget the good quality of metallurgy.However,it is better to repair it with Inconel718 alloy powder.When the laser power is 600 W and the scanning speed is 10mm/s,it is possible to obtain a cladding coating without cracks.The results show that the average hardness of Inconel718 cladding coating is about 580 HV,and the hardness of K418 cladding coating is about 500 HV.The results of corrosion experiments show that the Inconel718 cladding coating has better corrosion resistance than K418 cladding coating.The results of laser cladding in vibration environment show that when the vibration frequency is 50 Hz and the amplitude is 1.2mm,the multi-lap cladding layer is obviously deformed.Microstructural analysis shows that the vibration has a significant effect on the crystal structure in the binding site of the cladding and the substrate.The hardness of the cladding layer in the vibration environment shows that the hardness reaches the highest value when the vibration frequency is 10 Hz,which is about 140 Hv higher than that of the non-vibrating sample,but the hardness decreases with the increase of the frequency.The electrochemical corrosion results show that the vibration can improve the corrosion resistance of the laser cladding coating to a certain extent.