| 摘要 |
<p>PURPOSE: A thick-sheet iron plate is provided to control the area rate of a island shape martensite among the structure of the plate for improving the toughness of a weld heat-affected unit. CONSTITUTION: A thick-sheet iron plate contains 0.03~0.15 mass% of C, 1.0~2.0 mass% of Mn, less than 0.25 mass% of Si, less than 0.03 mass% of P, less than 0.015 mass% of S, less than 0.005~0.05 mass% of Al, 0.010~0.080 mass% of Ti, 0.002~0.10 mass% of Nb, 0.0005~0.010 mass% of Ca, 0.002~0.020 mass% of N, and Fe and an impurity.</p> |
