Study On Laser Quenching Process Of High Phosphorus Cast Iron

The cylinder liner is affected by the high temperature and high load working environment in the diesel engine.The cylinder liner is prone to wear-out failure and thus reduces the output power of the diesel engine,directly affecting the ship's work and restricting the development of the shipbuilding industry.Based on the wear-out failure of marine diesel engine cylinder liners,this paper combines the research and application of laser quenching technology,which is popular in the field of surface engineering technology.Through experimental results on the laser quenching of the high-phosphorus cast iron of the cylinder liner raw material,analyzing the feasibility of the laser quenching technology on the cylinder liner.The study of laser quenching technology of high-phosphorus cast iron surface is mainly carried out by combining experimental analysis with numerical simulation of temperature field.A single laser quenching process was carried out on the surface of the specimen by using IPG YLS-6000 fiber laser.According to the metallographic photograph for analyzing the microstructure of the quenched specimen,the microstructure region is divided into quenching phase transformation zone,heat-affected transition zone and matrix.A large part of acicular martensite is observed in the quenching phase transition zone by SEM photograph.Through the appearance inspection and microhardness distribution results of the quenched specimens,the friction and wear properties of the quenched process parameters after optimization were tested.The test results show that under the same conditions of load,rotation speed and duration,the amount of unquenched specimen wear is much larger than that of quenched specimen.Combined with the analysis of wear behavior,the friction and wear properties of the quenched specimens are best under the parameters of laser output power of 1100 W and spot scanning speed of 25mm/s.Based on the optimization of laser single-channel quenching test parameters,Abaqus finite element analysis software was used to simulate the temperature field distribution during laser quenching.The temperature field distribution and the austenite transformation critical temperature are used to calculate the size of the hardened layer.Experiments were carried out to validate the size of the hardened layer.The simulation results are consistent with the experimental results.According to the distribution results of laser single-pass quenching temperature field,the thermal influence range of the previous hard quenching layer during laser quenching is calculated,and the scanning distance of multi-pass quenching is proposed.After the multi-channel laser quenching,the microhardness distribution of the surface was analyzed.Finally,the optimal process parameters of laser quenching of high-phosphorus cast iron were as follows: laser output power 1100 W,spot scanning speed 25mm/s and laser quenching distance 1mm.