ASTM D6200 Determination of Cooling Characteristics of Quench Oils
ASTM D6200 Standard Test Method for Determination of Cooling Characteristics of Quench Oils by Cooling Curve Analysis
7. Apparatus
7.1 Furnace - Use a horizontal or vertical electrical resistance tube-type furnace capable of maintaining a constant minimum temperature of 850°C (1562°F) over a heated length of not less than 120 mm (4.72 in.) and a probe positioned in the center of the heating chamber. The furnace shall be capable of maintaining the probe's temperature within +/-2.5°C (4.5°F) over the specimen length. The furnace, that is, the radiant tube heating media, shall be used with ambient atmosphere.

7.2 Measurement System - The temperature-time measurement system shall be a computer based data acquisition system capable of providing a permanent record of the cooling characteristics of each oil sample tested, producing a record of variation in the test probe assembly of temperature with respect to time, and cooling rate with respect to temperature.

7.3 Probe - The probe shall be cylindrical, having a diameter of 12.5 +/- 0.01 mm (0.492 +/- 0.0004 in.) and a length of 60 +/- 0.25 mm (2.362 +/- 0.01 in.) with a 1.45 to 1.65 mm (0.057 to 0.065 in.) sheathed Type K thermocouple in its geometric center. The probe shall be made of a nickel alloy 600 (UNS N06600) purchased to SAE Specification AMS 5665 which has a nominal composition of 76.0 % Ni, 15.5 % Cr, 8.0 % Fe, .08 % C, and .25 % max Cu. The probe shall be attached to a support tube with a minimum length of 200 mm (7.874 in.). The thermocouple sheathing and the support tube shall be the same material as the probe (see Note 2). See Fig. 2 for recommended manufacturing details.

NOTE 2 - Care must be taken that the probe specimen is not damaged as surface irregularities will influence the results of the test.

7.4 Transfer Mechanism - One of the following shall be used to transfer the heated probe from the furnace to the test fluid.
7.4.1 Automated Transfer Mechanism - The transfer from the furnace to the oil shall be completed within 3.0 s. Immerse the probe in the center of the heat treating oil container to a minimum depth where there is at least 12.5 mm (1/2 in.) of fluid above and below the probe when quenched. A mechanical stop shall be used for reproducibility of probe placement.

7.4.2 Manual Transfer - If manual transfer is used, the sample container shall be equipped with a fixture to ensure correct placement in the center of the heat treating oil container and to a minimum depth where there is at least 12.5 mm (1/2 in.) of fluid above and below the probe. A timer shall be used to ensure a maximum transfer time of 3.0 s.

7.5 Sample Container - A container, preferably damage-resistant, shall be selected to provide at least 12.5 mm (1/2 in.) of fluid above and below the probe when quenched. It is recommended that at least 700 mL of oil be used. The resulting cooling curve will be dependent on the temperature rise during the quench and on the total fluid volume. Therefore, the cooling curve analysis shall be performed with the same volume of fluid.

7.6 Oil Temperature Measurement - Any temperature detection device may be used that is capable of measuring oil temperature to within +/-1°C (1.8°F) during drying.

7.7 Timer - Graduated in seconds and minutes, and may be part of a computer clock.

8. Reagents and Materials
8.1 Reference Quenching Fluid - Use a reference quenching fluid for initial, and regular probe calibration to determine if the probe will give results consistent to those obtained during initial break-in. If the maximum cooling rate is greater than 3 %, the probe shall be reconditioned (see 9.3). Use a fluid with sufficient historical cooling curve data as a secondary standard. Cooling curve results shall be traceable to a primary standard fluid such as that cited in the Wolfson Engineering Group Specification7 or JIS Standards K 2242 and K 6753. The reference fluids shall be stored in a sealed container when not in use and shall be replaced after 200 quenches or two years, whichever is sooner.

8.2 Cleaning Solvent - A hydrocarbon solvent that will evaporate at room temperature, leaving no residue (Warning - see Note 3).

NOTE 3 - Warning: Flammable. Harmful if inhaled.

8.3 Polishing Paper, 600 grit Emery.

8.4 Cloth, lintless and absorbent.