| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.12 ( July 1985 ) Special Issue on Hot-and Cold-rolled Steel Sheets ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Effects of Heat Cycle and Carbon Content on the Mechanical Properties of Continuous-annealed Low Carbon Steel Sheets Takashi Obara, Kei Sakata, Minoru Nishida, Toshio Irie |
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Synopsis : Effect of the continuous-annealing heat cycle and carbon content on the mechanical properties of continuous-annealed low carbon steel sheets is discussed. The metallurgical basis of the continuous annealing process for producing deep drawing quality cold rolled steel sheets consists of the following: (1)Lowering carbon content to increase grain sizes,(2)high temperature annealing followed by slow cooling, (3)rapid cooling and (4)holding around 400, all the four factors combined contributing to softening and decreasing solute carbon. Increasing grain sizes by decreasing carbon content is necessary not only for softening but also for enhancing the surpersaturation of solute carbon resulting in the dense cementite precipitation. The solute carbon profile in grain during cooling can be estimated on the assumption that a ferrite grain is of a spherical shape and the carbon diffusion to grain boundaries is the rate controlled process. Rapid-cooling and over-aging processes in fine-grained low-temper tinplates are also discussed. |
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