Experimental Study On Improving Properties Of 18Cr2Ni4WA Materials By Laser Cladding

Because of its excellent plasticity,toughness and low temperature impact performance,18Cr2Ni4WA steel is widely used in aviation aircraft and marine carrier-based aircraft,such as engine gears,pistons in flaps and valves.However,18Cr2Ni4WA steel has poor hardness and abrasion due to its low amount of carbon.Although carburizing treatment can increase the hardness and wear resistance of the materials,it does not improve the corrosion resistance significantly which is extremely detrimental to the spares of marine aircraft.This paper uses laser cladding technology to coat SIA-62 alloy on the surface of 18Cr2Ni4WA steel to improve the hardness,wear resistance and corrosion resistance of the surface of the spares and increase their service life.First of all,this article analyzed the mechanisms of defects,such as cracks,porosity and warpage in the cladding process,and proposed measures to control defects.On the basis of avoiding defects,combined with the width and height of the cladding layer,a reasonable process interval is determined.The process parameter range of the cladding experiment was preliminarily determined:the laser power is 1500-2200W,the powder feeding speed is 1-2r/min,and the scanning speed is 4-7mm/s.Within the process interval,16 sets of experimental parameters were selected in order to conduct a single-pass cladding experiment to observe the macroscopic geometry of the single-pass cladding layer.The experimental results showed that the morphology of the cladding layer of 7 samples can effectively meet the actual needs.Furthermore,according to the initial interval,the single factor method was used to carry out cladding experiments on 18Cr2Ni4WA plate parts.And the results of 7 groups of experiments would be measured.By measuring the mechanical properties of 7 groups of samples such as hardness,wear resistance and corrosion resistance,the study found that the microstructure of the cladding layer was dense and accompanied by grain refinement,the yield strength was greatly improved,the hardness was 2-3 times than the base material,and the wear resistance and corrosion resistance were significantly improved.We chose the 5 groups of process parameters with the best performance of the cladding layer for the cladding experiment of the rotating parts.By Testing the mechanical properties of materials after cladding,the study found that the excellent performance of cladding layer was still applicable to rotating parts.It showed that the various process parameters under the initial interval had a great influence on the performance of the cladding layer.Finally,based on the cladding experiments of 1 8Cr2Ni4WA plate parts and rotating parts,we selected the most favorable process parameters for the cladding of aerospace parts:The power is 1500W-2200W,the scanning speed is 6mm/s,the overlap rate is 40%,and the powder feeding speed is 1r/min.By using this parameters to perform cladding experiments on typical aerospace parts and increasing the chemical heat treatment experiment of the base material,the study found the performance of the cladding layer was superior to the chemically treated material,and the performance of the base material was qualitatively improved through the detection of the mechanical properties of the cladding layer and the matrix material after chemical heat treatment.