class 403 HT material is intended for use in the manufacture of machined blades. Class 403 AN material is intended for use in the manufacture of forged blades. The material shall be ordered in the shortest lengths that will cut without excessive waste. This material is intended for use at service temperatures not over 900°F.

Class 410 material is intended for use in the manufacture of such items as shrouding, packing pieces, wedges, spacer blocks, and locking pieces. This material is intended for use at temperature not over 909°F.

Class 405 material is intended for use in the manufacture of such items as shrouding, diaphragm and partitions, when material of low hardenability is required for welding. This material is intended for use at temperatures not over 950°F.

Class 422 material is intended for use in the manufacture of such items as blades, locking pins, diaghragm and nozzle blocks or rings and shrouding. This material is intended for use at temperatures over 900°F to 1000°F maximum.