Study On The Effect Of Laser Cleaning Pretreatment On The Quality Of HSLA Steel Plating/Welding

HSLA steel is often used to produce various structures that require high strength,such as bridges,ships,vehicles and other large steel structures.Antirust and welding are the core technological requirements of high-end HSLA steel structure products.How to improve the coating and weldability of HSLA steel has become an urgent demand for major engineering applications.As a new surface pretreatment process,laser cleaning is considered to be an ideal solution for pre plating/pre welding because of its high efficiency,good consistency,little damage to the substrate,good rust removal effect and environmental protection.By adjusting the laser power,scanning speed,overlap rate and other process parameters,this paper explores the mechanism of laser cleaning pretreatment process of Q345B steel surface,and explores the influence of laser cleaning pretreatment on the performance of zinc coating and welded joint of HSLA steel surface through analysis and comparison.By adapting the laser cleaning parameters,this paper examines the mechanism of laser cleaning pre-treatment on the steel surface of Q345B and analyzing and comparing the influence of laser cleaning pre-treatment on the performance of the zinc coating and the welded joint on the steel surface of HSLA at the same time.Firstly,the influence of laser cleaning on the surface quality of HSLA steel was analyzed.Too large or too small laser energy density,cleaning speed and spot overlap rate will result in the degradation of cleaning surface quality.A good combination of laser cleaning parameters was obtained:19.5 J/cm~2 laser energy density,2000 mm/s cleaning speed and40%spot overlap rate,which can effectively remove the pollutants before plating/welding of HSLA steel and improve the quality of surface pretreatment.Then,the quality of galvanized layer of laser cleaning pretreatment sample and pickling HSLA steel sample was compared.The roughness and special groove structure of HSLA steel treated by laser cleaning and plating make the growth direction of zinc iron alloy layer increase and the binding force is improved,the thickness,surface quality and anti-pulverization properties of the zinc coating on the surface of the samples are greatly improved.Finally,the effects of laser cleaning on the welding quality of HSLA steel is studied.Appropriate laser cleaning process parameters can remove the rust and grease on the surface of the workpiece,form wavy micro groove texture,and improve the absorption rate of HSLA steel matrix to laser beam energy.Compared with the traditional welding joint pre-treatment,the welding joint after laser cleaning pretreatment has good weld forming quality,and the tensile strength,yield strength and elongation are510MPa,416MPa and 36%respectively,which are very close to the properties of the base metal.Laser cleaning pretreatment can effectively avoid the weld defects and improve the weld forming quality.Based on the systematic study of laser cleaning to optimize the plating/welding quality of HSLA steel,this paper provides rich and reliable experimental data support for making appropriate laser cleaning pretreatment specification to replace the traditional plating/welding pretreatment.