| Popis: |
The use of a high charge of reduced pellets (91 to 94 percent iron) in the electric furnace enables steels containing a maximum of 0.010 percent sulfur to be obtained without desulfurization. A typical sulfur value is 0.007 percent for a 100 percent pellet charge. At such low sulfur levels, it is shown that good inclusion shape control is obtained by simple additions of calcium silicon to the ladle. Various methods of evaluating transverse ductility in hot-rolled, high-strength, low-alloy (HSLA) steels are compared. A relationship is obtained between the ratio of transverse to longitudinal Charpy shelf energy values and projected inclusion length, which is upheld for a wide range of steel compositions. A minimum Charpy ratio of 0.7 is required for a given severe stretching application. The influence of manganese and sulfur contents on transverse ductility is also considered. |
