Ductile Iron
Purpose：Observe
the microstructure of ductile iron. The morphology, size, and distribution of
graphite are critical to the mechanical properties of cast iron, making their
assessment essential for quality control during production. Samples undergo
cutting (TableCut200), mounting (FLEXPRESS fully automatic modular hot mounting
machine), grinding/polishing (Alpha610), and etching with 4% nitric acid
alcohol solution to observe the microstructure (MN80 metallographic
microscope).
Basic
Guide：
Cutting：1.Use
an A30 resin-bonded alumina cutting wheel for ductile iron. Refer to the Trojan
Cutting Guide for specific
models.
2.Select
pulse mode for cutting, with a recommended maximum cutting speed ≤0.25 mm/s.
Mounting：Use
high-edge-retention hot or cold mounting resin.
Grinding：1.Begin
with P400 silicon carbide sandpaper/lapping films until the sample surface is flat and cutting damage is
fully removed.
2.Continue
grinding with a POS disc+9 µm diamond polishing suspension.
3.Clean
the sample, sample holder, and hands after each grinding step.
Polishing：1.Clean
the polishing cloth, sample holder, and hands before polishing. Repeat cleaning
after each step.
2.Do
not mix polishing disks with different
abrasive particle sizes.
3.Rinse
the sample surface with alcohol and dry with a blower to remove residue and
prevent corrosion.
4.After
each polishing step, inspect under a metallographic microscope to ensure:
Scratch size matches the abrasive grit. Scratch direction is random.
5.Clean
polishing cloths with running water and a soft brush after use, then air-dry.
6.Dedicate
polishing cloths used for ductile iron exclusively to such samples.
