Surface Quality And Microstructure Performance Analysis Of 22MnB5 Hot Stamping Steel

In recent years,high-strength automotive parts manufactured by hot stamping technology have become more and more widely used on the body.In the future,parts manufactured by hot stamping technology on the body-in-white may account for about 40%.At present,research on hot stamping technology is actively carried out in many countries around the world.The high strength of the steel sheet for automobiles can simultaneously satisfy the safety of automobile collision and the demand for weight reduction of automobiles,but the high strength of the steel sheet reduces the shape freezeability and formability.At the end of the 1990s,hot stamping forming technology was born.It is characterized in that the heating and forming process of steel is completed in the austenitic state,and the martensite transformation process of steel is completed in the hot stamping die.Hot stamping forming technology has promoted the development of high-strength automotive parts manufacturing.The research content of this paper is based on 22MnB5 hot stamping forming steel produced by a certain company.It mainly studies two practical production problems encountered by a certain company in the production of 22MnB5 annealed sheets.Through laboratory simulation and comparative analysis,the problem of serious iron oxide peeling of 22MnB5 continuous annealed sheet and the formation cause,mechanism and solution of the problem of surface color difference of the cover annealed sheet were studied.At the same time,the similarities and differences of coating thickness,silicon-rich phase morphology,tensile mechanical properties and three-point bending properties of two thicknesses of 22MnB5 aluminum-silicon plate were studied.The main research results of this paper are as follows:(1)The cause and mechanism of the serious falling off of oxide scale on the surface of 22MnB5 hot stamping steel annealed sheet produced by an enterprise during hot stamping were studied.The small surface roughness of steel plate is the direct cause of the serious loss of oxide scale.By adjusting the process of roll roughening,increasing the surface roughness of rolls,and then increasing the surface roughness of steel plate,the problem of serious peeling off of oxide scale of continuous strip can be solved.(2)The cause and mechanism of color difference on the surface edge of 22MnB5 annealed steel sheet for hot stamping were studied.The oxidation of the edge of the cover plate is more serious than that of the center part,which is the direct cause of the chromatic aberration at the edge.By adjusting the roll roughening process,the roughness parameters of the edge and the center of the roll surface are uniform,and the roughness of the edge and the center of the cover back plate is uniform.The oxidation of the edge and the center of the cover back plate occurs to the same extent in the air,thus solving the problem of the color difference of the cover back plate surface.(3)The coating thickness,coating morphology,tensile mechanical properties and three-point bending properties of 2MnB5 aluminium-silicon coatings with two thicknesses produced by an enterprise were studied,and the comprehensive evaluation of 2MnB5 aluminium-silicon coatings with two thicknesses was made.