Study On Process And Microstructure Properties Of Aluminum Bronze Laser Cladding Layer On Q345 Steel

The rapid development of industry leads to that structural parts which are mainly made of carbon steel?stainless steel and alloy steel are used in more and more complicated areas.It requires that materials have good surface properties like wear and corrosion resistance property.Because of good comprehensive mechanical properties and wear resistance properties,aluminum bronze is more and more likely to be used as cladding materials to improve the surface properties of construction materials.But this kind of cladding layer is more likely made of aluminum bronze powder by means of electric arc spraying and plasma spraying and it has problems such as low bond strength and large porosity.In order to improve this situation and explore more measures to make cladding layer,this project tries to make coating on the surface of Q345 steel with aluminum bronze wire and aluminum bronze piece by laser cladding and studies the influence of laser power?scan speed and current on the macroscopic morphology and micro-structure of aluminum bronze wire cladding layer and the influence of laser power and scan speed on the micro-structure and micro-hardness distribution law of aluminum bronze piece cladding layer with orthogonal experiment method and single factor experiment method.We analyze micro-structure and properties of this two kinds of aluminum bronze coating by optical microscope?SEM?EDS?XRD and automatic micro-hardness tester and study the impact of different process parameters such as load?rotation rate?temperature and overlap rate on the friction and wear properties of this two kinds of aluminum bronze cladding layer.The chief research results are as follows:This two kinds of aluminum bronze cladding layer have no pores and flaws inside and are metallurgical bonded with Q345 steel.In terms of morphology of aluminum bronze wire coating,laser power has the most significant effects on the penetration depth and dilution rate of caldding layer and scan speed has the most significant impact on the weld width and weld height of coating.When the overlap rate is low,aluminum bronze wire cladding layer is mainly composed of many gray ? phase?black ? phase showed as arborization or point and few white ?2 phase.When the overlap rate is large,aluminum bronze wire coating mainly consists of many gray ? phase and white ?2 phase which show lamellar distribution and few point ? phase.With the raise of overlap rate,the hardness of aluminum bronze wire coating firstly fall and then rise,fluctuation range of hardness gradually declines,size ofmicro-structure and distribution of element inside of cladding layer gradually become uniform.When the overlap rate is 60%,average hardness of aluminum bronze wire cladding layer is 225 HV.Different from aluminum bronze wire coating,aluminum bronze piece cladding layer mainly consists of ?' phase and ? phase when laser power density is low and is mainly composed of ?2 phase and ? phase when laser power density is relatively high.With the increase of laser power density,hardness of aluminum bronze piece cladding layer gradual declines and scan speed has the most significant effects on the hardness of coating and heat-affected zone.The average hardness of aluminum bronze piece coating reaches386 HV which is apparently higher than the hardness of aluminum bronze wire cladding layer and fluctuation range of hardness is relatively large.Friction and wear test were carried out on the two kinds of aluminum bronze coating.we found average friction coefficient of two kinds of aluminum bronze coatings gradually declines while grinding crack width ? wear loss and line roughness of grinding crack gradually raise with the increase of load.Rotation speed has less impact on the average friction coefficient of aluminum bronze cladding layer but grinding crack width?wear loss and line roughness of grinding crack will improve with the increase of rotation speed.The higher the rotation speed is,the more likely oxidized the surface of grinding crack will be,the more terrible adhesive wear and oxidation wear will be.With the increase of temperature,average friction coefficient?wear loss and line roughness of grinding crack of aluminum bronze wire coating firstly rise and then fall,grinding crack width gradually increases while grinding crack width and average friction coefficient of aluminum bronze piece coating gradually increases,wear loss and line roughness of grinding crack firstly fall and then rise.Moreover,the oxidation extent of grinding crack of two kinds of aluminum bronze cladding layer gradually increases,adhesive wear and oxidation wear become more terrible while abrasive wear gradually becomes less.