| 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} | 
| 18 | DF | .~.~.~ Processes of adding magnesium {7} | 
| 20 |  | .~.~.~.~ Flowing molten iron alloy onto solid magnesium containing agent, or adding solid magnesium containing agent to molten stream of iron alloy |