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Lüders bands in Hot Dip Galvanising

February 27, 2014

Q. PREPAINTED GALVANISED COIL SHOWS LÜDERS BAND AFTER COLOR COATING AT 232 PMT. IF TEMPER ROLLING IS INCREASED FROM 2 TO 4%, THEN NO LÜDERS BAND IS OBSERVED. BUT THEN WHAT IS SAFE PERIOD OF FORMING BY USER?

JAYA BOREGOWADA
CONTINUOUS GALVANISING - MUMBAI MAHARASHTRA India

March 5, 2014

A. Dear Jaya,
You can carry out the accelerated aging test for this purpose.
1. Mark the rolling direction on the sample.
2. Heat sample to 150 °C for 1 hour.
3. Test the sample for luders band.
If there is no evidence of luders bands, then the material will be safe for 3 months.

Best regards
Voo

Kwee Voo
- Karachi, Pakistan

March 8, 2014

Q. Thickness of sample will be 0.35 to 0.50; for that 150 °C is ok to check. All the prepainted GI specimens show luders band during test. But if GI samples given heavy deformation, then no band observed. Please suggest. We select low carbon steel with 0.045 C, 0.20 Mn.

Jaya boregowada [returning]
- thane mumbai India

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