6 Mechanical properties
6.1 Tensile requirements
The tensile properties of standard steel drill collars, as manufactured, shall comply with the requirements of Table 17.
These properties shall be verified by performing a tensile test on one specimen per heat per heat-treatment lot.
Tensile properties shall be determined by tests on cylindrical specimens conforming to the requirements of ISO 6892, 0,2 % offset method.
NOTE For the purposes of this provision, ASTM A 370 is equivalent to ISO 6892.
The tensile specimen may be taken from either end of the bar or tube. The specimen shall be machined so that the central point of the gauge area is located a minimum of 100 mm (4 in) from the end of the bar or tube. The tensile specimen shall be oriented in the longitudinal direction, with the centreline of the specimen located 25,4 mm (1 in) from the outside surface or mid-wall, whichever is closer to the outside surface.
6.2 Hardness requirements
In addition, a hardness test shall be performed on each drill collar as prima facie evidence of conformation. The hardness test shall be made on the OD of the drill collar (Brinell hardness in accordance with ISO 6506-1 is preferred although Rockwell C hardness is an acceptable alternative). The hardness number shall conform to the requirements of Table 17.
NOTE For the purposes of this provision, ASTM A 370 is equivalent to ISO 6506-1.
6.3 Impact strength requirements
Charpy V-notch impact tests shall be conducted on specimens conforming to the requirements of ISO 148 and shall be conducted at a temperature of 21 °C士3°C (70 °F士5 °F). Tests conducted at lower temperatures that meet the requirements stated in 8.2.1.3.4 are acceptable.
NOTE For the purposes of this provision, ASTM A 370 and ASTM E 23 are equivalent to ISO 148.
7 Specimens
One set of 3 specimens per heat per heat-treatment lot shall be tested.
Specimens shall be taken at 25,4 mm (1 in) below the surface or at mid-wall, whichever is closer to the as heat-treated outer surface.
The specimens shall be longitudinally oriented and radially notched.
7.1 Specimen size
Full size (10 mm x 10 mm) shall be used except where there is insufficient material, in which case the next smaller standard subsize specimen obtainable shall be used.
If it is necessary to use subsize test specimens, the acceptance criteria shall be multiplied by the appropriate adjustment factor listed in Table 2. Subsize test specimens of less than 5 mm are not permitted.
7.2 Acceptance criteria
The average impact strength of the three specimens shall be 54 J (40ft-lbs) or greater, with no single value less than 47 J (35ft-lbs).
8 Marking
Standard steel drill collars conforming to this part of ISO 10424 shall be die-stamped on the drill collar OD with the following information:
a) the manufacturer's name or identifying mark;
b) outside diameter;
c) bore;
d) connection designation;
e) “ISO 10424-1”
NOTE The drill collar number consists of two parts separated by a hyphen. The first part is the connection number in the NC style. The second part, consisting of 2 (or 3) digits, indicates the drill collar outside diameter in units and tenths of inches. Drill collars with 209,6 mm, 241,3 mm and 279,4 mm outside diameters are shown with 6 5/8, 7 5/8 and 8 5/8 REG connections, since there are no NC connections in the recommended range of bending-strength ratios.
EXAMPLE 1 A drill collar of diameter 158,6 mm (6 1/4 in) with 71,4 mm (2 13/16 in) bore and NC46 connections, manufactured by A B Company, shall be stamped:
AB Co. (or mark) NC46-62 71,4 ISO 10424-1
EXAMPLE 2 A drill collar of diameter 209,6 mm (8 1/4 in) with 71,4 mm (2 13/16 in) bore and 6 5/8 Reg connections, manufactured by A B Company, shall be stamped:
A B Co. (or mark) 209,6 71,4 6 5/8 REG ISO 10424-1
