The Practice Of Laser Surface Treatment Of Steel Roller In The Steel Bars And Wires Factory Of Xinsteel Group

Roll tends to get rapid wear on the surface due to the high temperature and highspeed shock of billet at work. The roll cannot be used when wear reaches a certaindegree, which would be used for waste treatment. Therefore, it is become an urgentdemand for steel works how to adopt new roll surface treatment technology thatprovided with high efficiency, low cost and extended service life. In recent years, lasersurface treatment technology has been well used in roll surface treatment。This paperstudy of laser cladding technology applied in the surface of the bar roll base on roll ofbar and coil plant in Xinsteel.High speed steel and ductile cast iron which have same material with roll waschose for experiment sample, then these samples were precoating by Ni45powder andcarry out laser surface alloying processing with high power CO₂laser. Effect of laserpower, scanning speed,feeding rate, the size of light spot and overlap coefficient onsurface quality and internal Microstructure of laser cladding were investigated base onhigh speed steel. Effect of different process condition on hardness of cladding layer wasstudied base on ductile cast iron, then contrastive analysis experiment of wear testbetween substrate of ductile cast iron and the cladding layer were carry out. Claddingpractice experiments were carried out on bloom roll of bar and wire roll base onoptimizing results of above experiments to study the practice effect of cladding processapplication in surface treatment of bar roll.The experimental results are as follow.（1）Optimization of process parameters are as follows: laser power is3400w 3800w, scanning speed is5⁷mm/s, spot diameter is4.0mm, overlapping coefficientis35%⁴5%,which were obtains from high speed steel cladding process with highpower CO₂laser. The cladding layer is uniform, compact and good adhesive withsubstrate of steel, which are no crack and blowhole defects in alloying layer.（2） Optimization of process parameters are as follows: laser power is3800w,scanning speed is5mm/s, spot diameter is4.0mm, overlapping coefficient is40%,which were obtains from ductile cast iron cladding experiment. The thickness ofcladding layer is1.38mm and average hardness is713HV.（3） Abrasive resistance of cladding is1.6times high than base metal of ductile castiron after laser cladding process of ductile cast iron.（4） After cladding practice of bloom roll of rod wire roll and the roll, the averagesurface hardness of roll was increased from38.0to47.2and average steel productionwas increased from9888t to20040t which increased by102.6%than before rollcladding.