Experimental study on Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the ferrite region

Ji-ping Chen1),Yong-lin Kang1,2),Ying-min Hao1),Guang-ming Liu3),Ai-ming Xiong3) 1) School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China 2) The State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China 3) Steel Research Institute of Shougang,Beijing 100041,China

摘 要：A Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the conventional austenite region and in the ferrite region with lubrication was experimentally studied.Subsequent cold rolling and continuous annealing processes were also conducted.The results show that microstructures of ultra-low carbon bake hardening hot strips at room temperature are basically irregular polygonal ferrites.The yield strength,ultimate tensile strength,n value,and r value of the No.2 specimen hot-rolled in the ferrite region with lubrication are 243 MPa,364 MPa,0.29,and 1.74,respectively,which are similar to those of the No.1 specimen hot-rolled in the conventional austenite region.The elongation rate and bake hardening value of No.2 specimen are 51% and 49.4 MPa,respectively,which are greater than those of No.1 specimen.The No.2 specimen hot-rolled in the ferrite region with lubrication exhibits good mechanical properties and relatively excellent baking hardening performance.Therefore,the hot rolling experiment of Ti+Nb bearing ultra-low carbon bake hardening steel in the ferrite region with lubrication is feasible and can be considered in the future industrial trial production.

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