The coating microstructure of hot-dip aluminum (HDA) of deformed low-carbon steel containing RE was analyzed by metallography microscopy, TEM and XRD, and the forming mechanism was also discussed. The results show tha...The coating microstructure of hot-dip aluminum (HDA) of deformed low-carbon steel containing RE was analyzed by metallography microscopy, TEM and XRD, and the forming mechanism was also discussed. The results show that, the Fe_2Al_5 phase, on whose subcrystal boundaries, Al particles with the size of 7～30 μm existing on parallel linear are, grows a strong orientation. And the spread activation energy of Al is 155.22 kJ·mol -1. In addition, the effects of deformation on coating microstructure of hot-dip aluminum and the function of RE were preliminarily analyzed.展开更多
The welding characteristics of 5052 aluminum alloy and Q235 low-carbon steel sheet were systematically studied by the refilled friction stir spot welding.The effects of rotation speed and pressure speed on weld formin...The welding characteristics of 5052 aluminum alloy and Q235 low-carbon steel sheet were systematically studied by the refilled friction stir spot welding.The effects of rotation speed and pressure speed on weld forming,tensile strength,and welded joint structure were analyzed in different welding modes.The results indicated two different connection modes:the chimeric mode and the non-chimeric mode.The corresponding depression depth are 2 and 2.4 mm,respectively.In the non-chimeric connection mode,the steel/aluminum metallurgical interface is a smooth transition,the hook structure is obvious,and the welding mechanism mainly depends on the mutual diffusion between atoms.However,in the chimeric mode,a hook structure will be formed at the metallurgical interface of steel and aluminum.The connection mechanism is determined by mechanical interlocking and mutual diffusion.The maximum strength value is 7.48 kN in non-chimeric mode.At this time,the spindle speed is 1300 r/min and the pressure speed is 1 mm/s.There were two types of fractures:the button fracture mode and the peel fracture mode.展开更多
Aluminum killed low-carbon steel sheets were cold rolled at different reduction ratios and annealed using different temperatures and holding time.The Vickers hardness was examined.The results show that when cold rolli...Aluminum killed low-carbon steel sheets were cold rolled at different reduction ratios and annealed using different temperatures and holding time.The Vickers hardness was examined.The results show that when cold rolling reduction ratios increase from 40% to 81%,recrystallization temperatures decrease from 602℃ to 572℃ during 4hisochronal annealing,as well recrystallization holding time decreases from 117 min to 5min during isothermal annealing at 610℃.All recrystallization temperatures and holding time can be calculated using the annealing experiment results.Microstructure was examined through electron backscattered diffraction（EBSD）.The results show that as rolling direction preferentially grows,equiaxed grains grow into cake-type during recrystallization.Cake-type grains are more beneficial to obtaining ideal〈111〉//ND（normal direcrtion）orientation texture.{111}orientation grains nucleate and grow up preferentially.Deformation grains of{111}〈110〉orientations grow into new recrystallization grains of{111}〈123〉and{111}〈112〉during recrystallization.Texture formation can be explained by directional nucleation.展开更多
文摘The coating microstructure of hot-dip aluminum (HDA) of deformed low-carbon steel containing RE was analyzed by metallography microscopy, TEM and XRD, and the forming mechanism was also discussed. The results show that, the Fe_2Al_5 phase, on whose subcrystal boundaries, Al particles with the size of 7～30 μm existing on parallel linear are, grows a strong orientation. And the spread activation energy of Al is 155.22 kJ·mol -1. In addition, the effects of deformation on coating microstructure of hot-dip aluminum and the function of RE were preliminarily analyzed.
基金National Natural Science Foundation of China(No.52275306)Beijing Municipal Natural Science Foundation(No.3232021)for their support.
文摘The welding characteristics of 5052 aluminum alloy and Q235 low-carbon steel sheet were systematically studied by the refilled friction stir spot welding.The effects of rotation speed and pressure speed on weld forming,tensile strength,and welded joint structure were analyzed in different welding modes.The results indicated two different connection modes:the chimeric mode and the non-chimeric mode.The corresponding depression depth are 2 and 2.4 mm,respectively.In the non-chimeric connection mode,the steel/aluminum metallurgical interface is a smooth transition,the hook structure is obvious,and the welding mechanism mainly depends on the mutual diffusion between atoms.However,in the chimeric mode,a hook structure will be formed at the metallurgical interface of steel and aluminum.The connection mechanism is determined by mechanical interlocking and mutual diffusion.The maximum strength value is 7.48 kN in non-chimeric mode.At this time,the spindle speed is 1300 r/min and the pressure speed is 1 mm/s.There were two types of fractures:the button fracture mode and the peel fracture mode.
基金funded by National Natural Science Foundation of China(51275216)Initial Funding for Advanced Talents of Jiangsu University(14JDG129)
文摘Aluminum killed low-carbon steel sheets were cold rolled at different reduction ratios and annealed using different temperatures and holding time.The Vickers hardness was examined.The results show that when cold rolling reduction ratios increase from 40% to 81%,recrystallization temperatures decrease from 602℃ to 572℃ during 4hisochronal annealing,as well recrystallization holding time decreases from 117 min to 5min during isothermal annealing at 610℃.All recrystallization temperatures and holding time can be calculated using the annealing experiment results.Microstructure was examined through electron backscattered diffraction（EBSD）.The results show that as rolling direction preferentially grows,equiaxed grains grow into cake-type during recrystallization.Cake-type grains are more beneficial to obtaining ideal〈111〉//ND（normal direcrtion）orientation texture.{111}orientation grains nucleate and grow up preferentially.Deformation grains of{111}〈110〉orientations grow into new recrystallization grains of{111}〈123〉and{111}〈112〉during recrystallization.Texture formation can be explained by directional nucleation.
