420 / | HD | ALLOYS OR METALLIC COMPOSITIONS |
8 | DF | FERROUS (I.E., IRON BASE) {24} |
9 | DF | .~ 1.7 percent or more carbon containing {2} |
13 | DF | .~.~ 2.7 percent or more carbon equivalent containing (i.e., cast iron) {7} |
29 | DF | .~.~.~ Processes {4} |
32 | .~.~.~.~ Adding vanadium, titanium, niobium, or zirconium |