| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.8 ( September 1983 ) ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Development of Non-Aging Cold Rolled Steel Sheets with Deep Drawability by a Continuous Annealing Process Susumu Satoh, Takashi Obara, Minoru Nishida, Nobuo Matsuno, Junsuke Takasaki, Hirotake Satoh |
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Synopsis : In order to develop a non-aging, deep drawable cold rolled steel sheet by a continuous annealing process, metallurgical factors affecting mechanical properties of extra-low carbon aluminum-killed steels were investigated. (1) In low C content less than 0.002 wt%, substantial non-aging property can be obtained without overaging treatment by continuous annealing. Improvement of deep drawability by lowering C content is relatively small because the planar anisotropy is extremely large. (2) For decreasing the planar anisotropy, Nb is the most effective alloying element among Nb, Ti, Cr, V, and W. This mainly results from the fact that the grain size of hot band effectively decreases by adding a small amount of Nb. (3) By using the steel containing 0.002wt% C and 0.005-0.010wt%Nb, non-gaing cold rolled steel sheets with excellent deep drawability and low planar anisotropy were commercially produced without overaging treatment in continuous annealing line. (4) Using only this type of steel and controlling the processes after steelmaking, various grades (DQ, DDQ, and EDDQ) of non-aging cold rolled steel sheets can be manufactured by a continuous annealing process. |
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