Microstructure And Properties Control Of A517Q Alloy Steel By Wire And Laser Additive Manufacturing

Wire and laser additive manufacturing(WLAM)technology has been widely used in aer ospace,ships,and medical devices due to its advantages of flexible manufacturing,high effici ency,and low cost.However,during the forming process,there are phenomena such as coarse microstructure,pores,incomplete melting of raw materials,and spheroidization in the formed parts,which result in significant fluctuations in microhardness at different positions of the de position layer,large anisotropy,and residual stress in its performance.These limitations are n ot conducive to the engineering application of the formed parts.This article uses A517 Q alloy steel wire as raw material and uses laser fusion additive manufacturing technology to prepare single layer and single layer multilayer deposition layers.The influence of laser process param eters on the microstructure and properties of single layer deposition layers is systematically st udied.Based on this,the effects of tempering heat treatment,ultrasonic vibration,and ultrason ic+tempering treatment on the microstructure and properties of single layer multi-layer deposi tion layers are explored,And characterize and analyze the microstructure and properties of the sedimentary layer before and after treatment.The relevant research results are as follows:The geometric characteristics and microstructure of the deposited layer are directly relate d to the laser process parameters: as the laser power increases,the melting width of the deposi ted layer gradually increases,the melting height gradually decreases,the aspect ratio first incr eases and then decreases,and the microhardness first decreases and then increases;As the wir e feeding speed increases,the melting width and melting height of the deposited layer also inc rease,but the aspect ratio,microhardness,and dilution rate all decrease;As the deposition rate increases,the melting width and melting height of the deposition layer decrease,and the micr ohardness increases;A comprehensive comparison was made on the macroscopic morpholog y,microstructure,and mechanical properties of deposition layers prepared with different laser process parameters.On the basis of the above work,the preparation process of a single channe l multi-layer deposition layer was optimized: laser power 3400 W,wire feeding speed 20mm/s,and deposition speed 4mm/s.The microstructure of the ultrasonic vibration treated single channel multilayer deposit is composed of polygonal ferrite,granular bainite and martensite;The grain size of the single ch annel multi-layer deposition layer treated by ultrasonic vibration is significantly refined,and t he phenomenon of alloy element enrichment is weakened.The microhardness increased from284HV0.2 without ultrasonic vibration treatment to 447HV0.2,an increase of 36.4%;In additi on,the yield strength of the deposited layer treated with ultrasonic vibration increased by 22.7% from 522.7MPa to 675.3MPa,and the tensile strength increased by 26% from 647.7MPa i n the untreated state to 873.7MPa.Under the effect of different tempering temperature and holding time,the microstructure of single pass multilayer deposit mainly consists of tempered martensite,tempered sorbite and polygonal ferrite;The microhardness of the deposited layer decreased from 280HV0.2 to 240HV0.2,a decrease of 14.2%.After tempering,the overall fluctuation of the microhardness of t he deposited layer was small,achieving uniformity in the performance of the deposited layer.The yield strength and tensile strength were slightly reduced compared to the deposited state.The microstructure of a single layer multi-layer deposition layer treated with ultrasonic a nd tempering composite is mainly composed of tempered sorbite and polygonal ferrite.The gr ain size is significantly refined compared to the deposited and ultrasonic states,and defects su ch as pores and inclusions are also significantly eliminated.The microhardness of the composi te single channel multi-layer deposition layer decreased by 45% from 480HV0.2 to 260HV0.2compared to the ultrasonic state,and the overall microhardness of the deposition layer change d slightly in this state,with a yield strength increase of 21.1% from 522.7MPa to 662.7MPa.T he tensile strength increased from 647.7MPa to 758.7MPa,an increase of 14.6%.