1. CHEMICAL COMPOSITION
„P550“ is a special nonmagnetic, austenitic Mn-Cr-steel with a high nitrogen content.
|max. 0,06||20,50 - 21,60||18,30 - 20,00||min. 0,50||min. 0,60||min. 1,40|
2. MECHANICAL PROPERTIES
Following mechanical properties (tested at room temperature) are achieved by a special cold-working process over the full length of the collar:
|Yield Strength (min.) 0,2%-offset method:||OD up to 9 1/4“||140 ksi||965 N/mm²|
|OD 9 1/2“ and larger||130 ksi||900 N/mm²|
|Tensile Strength (min.):||150 ksi||1035 N/mm²|
|Reduction of area (min.):||50%||50%|
|Impact energy (min.):||60 ft.lb||82 J|
|Endurance Strength / N=10⁵ (min.):||± 80 ksi||± 550 N/mm²|
|Hardness Brinell: (min.):||335-450 HB||335-450 HB|
3. MAGNETIC PROPERTIES
Relative permeability: ≤ 1,005.
4. CORROSION RESISTANCE
• Transgranular SCC: Prevented by special surface treatments (Hammer peening, roller burnishing, shot peening).
• Intergranular SCC: The occurrence of material sensitization is prevented by quenching after warmforging. Each collar is tested according to ASTM A 262, Pract.A and E, last edition.
• Pitting Corrosion: Due to a high chromium- and nitrogen content a high resistance to pitting corrosion is given.
5. NON-DESTRUCTIVE TESTING
• Magnetic inspection: Drill collars are 100% tested by a proprietary probe-testing process using a Förster Magnetomat 1.782. (“Hot Spot“-test). Magnetic permeability of each collar is certified with the printout of probe-testing.
• Ultrasonic inspection: Each collar is ultrasonically inspected over 100% of the volume according to ASTM E 114, last edition as a minimum level.