Deformation Analysis And Experimental Study Of Angle Steel In Ultra-Fast Cooling Process

Ultra-Fast Cooling(UFC)technology can improve the mechanical properties of steel,and it has been widely applied in hot rolled steel plate and wire rod.However,because the angle steel will happen warping,distortion deformation in UFC process,the angle steel can't enter the straightening machine and be straighten.UFC technology is still immature.In this paper,we use Q235 angle steel as the research object,We did UFC experiment and thermal simulation experiment,then the UFC process after rolling of the angle steel were accurate simulated by using ANSYS FEM software.The main research contents and results are as follows:(1)The angle steel happened two kinds of macroscopic deformation after Ultra fast cooling,one is the buckling deformation along the length direction,the other one is the bending deformation on the both sides.Combined with mechanical properties testing,we knew that Ferrite + bainite is the most powerful organization,final cooling temperature was controlled between 5 80?700?.(2)The angle steel under super fast cooling after rolling was simulated.It is known that there are serious uneven temperature distribution in the angle steel,temperature of the angle steel R corner is higher than other locations by observing the two-dimensional temperature field;Due to the uneven cooling,the stress field are also serious inequality.(3)As the final cooling temperature decrease,the buckling deformation along the length direction is on the increase,the bending deformation on the both sides remain unchanged;The greater the cooling rate,the smaller the buckling deformation along the length direction and the bigger the bending deformation on the both sides;When the thickness of the angle steel is consistent,the longer the length,the smaller the buckling deformation along the length direction and the greater the bending deformation on the both sides;With the final cooling temperature decrease,the buckling deformation along the length direction is on the decrease,the bending deformation on the both sides remain unchanged.(4)According to the characteristic that the angle steel R corner cold slower than other locations.Applying bigger cooling intensity on the R corner and smaller cooling intensity on other locations can greatly reduce the deformation of angle steel in UFC process,the best heat transfer coefficient optimization scheme is Hr/Hs =1.5.After optimizing heat transfer coefficient,the decrease degree of the buckling deformation along the length direction is 40.1%,and the bending deformation on the both sides is basically disappeared.(5)In the thermal simulation experiments,when the initial cooling temperature is 940?,the final cooling temperature is 600?,Cooling rate is 90?/s,the microscopic structure of experimental steel is F + B,the size of bainite is more small,the distribution is more diffuse.