1. See how the ductile iron valve and the cast steel valve distinguish the gray surface of the machined surface: it is gray, the gloss is very dark, and the surface looks rough. Ductile iron: gray, brighter than gray iron, rough surface like gray iron.
2. The boring test gray iron: the boring resistance is small, the squeaking sound is “squeaky†when boring, the glue is very sticky, the dust is grayish black, there are a few silver and white spots, and the particle size is different, to small particles. Fine-based, with fingers, it is easy to blacken your fingers. Ductile iron: The resistance is slightly larger than that of gray iron when boring, and there is also a more obvious "唰唰" sound, which is rarely sticky, and the ends are grayish black, with fine spots and different particle sizes, but with large particles. Lord, using your fingers to grind the ends, you can blacken your fingers, but it is lighter than gray iron.
3. Listen to the sound of gray iron: the sound is low and the duration is extremely short. Ductile Iron: The sound is crisp, with a residual sound and a short duration.
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