Flattening cracking cause and its mechanism analysis of the continuous annealed DP1000 steel
LIU Hua-sai1,2��WU Nai3��LI Zhen3��HAN Yun1,2
��1. Shougang Group Co.�� Ltd. Research Institute of Technology�� Beijing 100043�� China 2. Beijing Key Laboratory of Green Recyclable Process for Iron and Steel Production Technology�� Beijing 100043�� China 3. Beijing Shougang Co.�� Ltd.�� Beijing 101304�� China��
Abstract��Taking C-Si-Mn DP1000 steel and Ti added microalloyed C-Si-Mn-Cr-Mo DP1000 steel as the study subject�� according to the different rejection rate of the two materials used for manufacturing seat frame after a flattening procedure�� the cause and mechanism of cracking for the two DP1000 steels are analyzed. For Ti added microalloyed C-Si-Mn-Cr-Mo DP1000 steel�� the martensite in the microstructure is fine and diffuse. While�� the microstructure of C-Si-Mn DP1000 steel contains bulk martensite and band structure�� and the volume fraction of martensite is around 45%. Furthermore�� compared with Ti added microalloyed C-Si-Mn-Cr-Mo DP1000 steel�� C-Si-Mn DP1000 steel has a higher elongation and lower yield ratio. The hole expansion ration of Ti added microalloyed C-Si-Mn-Cr-Mo DP1000 steel is about 55.6%�� which is about ten times of C-Si-Mn DP1000 steel. Therefore�� the bulk martensite�� band structure�� low hole expansion ratio and bending properties are the main reason for the higher fracture ration of C-Si-Mn DP1000 steel.
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2018, Vol. 36 
