Additional Requirement for DSS Material from LUFENG.
Charpy V-Notch (ASTM A370）
Not applicable when the maximum obtainable Charpy specimen width less than 2.5mm Absorbed energy shall be 61J average and 48J Single value minimum Test temperature shall be minus 46 deg C. Impact test specimen taken from mid-thickness position.
Ferrite Count (ASTM ES62）
Ferrite content shall be determined by manual point count on a cross section near OD, ID surface & midwall location. Sample shall be electrolytically etched in NaOH or KOH, and in such a manner as to provide optimum contrast for austenite and ferrite phase discrimination. Minimum 30 field and 16 points per field shall be used. Ferrite content shall be between 40% to 60%.
Metallographic Examination
Sample shall be etched using ASTM E407, K3Fe (CN)6 with KOH or NaOH. Sample cross section shall be examined at OD, ID and midwall locations. Examination shall be conducted at a minimum of 400X to 500X magnification. Material shall be free of intermetallic phases and precipitates A microphotograph at a minimum of 400X to 500X shall be supplied.
Corrosion Test
Shall be carried out as per ASTM G4S at 25 deg C for 24 hours with an acceptance criteria of no visual pitting at 20X and weight loss of less than 4 g/m2.
NACE Hardness
Hardness test according to NACE MR-0175 the maximum shall be HRC 28, HB 271, or HV10 310.
Other Requirements
LUFENG representative examination required for heat number traceability, visual examination, dimensional examination and mill test certificate review. All testing required to be per heat number.
NOTE:
Duplex Stainless Steel (DSS)
All DSS Material shall be in accordance with a minimum PREN of 34 according to the formula:
PREN = %Cr + 3.3×(%Mo + 0.5×%W ) + 16×%N