ASTM D3520 for Quenching Time of Heat-Treating Fluids
ASTM D3520 Standard Test Method for Quenching Time of Heat-Treating Fluids (Magnetic Quenchometer Method)
8. Procedure for Making a Single Test
8.1 Using forceps, place the cleaned test ball on the clean ceramic base plate in the heated furnace, with the ball positioned to contact the exposed wires of the thermocouple.
8.2 Maintain the test ball in the furnace for a minimum of 900 s (15 min) at temperature as measured from the time the thermocouple indicates a temperature of 885 more or less 5°C (1625 more or less 9°F).
8.3 Charge 200 mL of the test or reference fluid at 21 to 27°C (70 to 81°F) into a clean stainless steel beaker supplied with the tester.
NOTE 13 - A fresh charge of fluid should be used for each test.
NOTE 14 - The presence of moisture will affect quench time values. Bright and clear-appearing fluids may still contain moisture. The degree of moisture in test fluids may be ascertained by Test Method D1744 or appropriate accepted standard methods. If desired, moisture level may be reduced by laboratory techniques suitable for that particular test fluid.
8.4 Set the dial of the electric timer on the test instrument to read 0.
8.5 Set the switch of the timer to TEST position.
8.6 Using forceps, quickly transfer the heated test ball 885 more or less 5°C (1625 more or less 9°F) from the furnace to the tester, dropping the ball through the photo cell ring into the basket which suspends the ball in the fluid with the total elapsed time for transferring the ball to the tester being less than 5 s. As the test ball passes through the photo cell, the electric timer is energized. When the ball temperature is below 354°C (670°F), Curie Point, the ball becomes magnetic and is attracted toward a magnet enclosed in the instrument activating a switch and stopping the timer.
8.7 After the electric timer stops, read and record the quench time.
8.8 Record the designation number of the test ball being used.
NOTE 15 - Do not disfigure the balls, as small marks change their characteristics. Instead, individually numbered envelopes or containers should be used for storage. Identification of position in the furnace should be used to identify the balls.
8.9 Set switch of the tester to OFF position.
8.10 Swing the photocell ring to the side and remove the ball by lifting the basket from the yoke.
8.11 Remove the beaker containing the fluid. Discard this used fluid.
8.12 Using fresh test fluid, repeat 8.1-8.11 while using the same ball.
8.13 Repeat 8.1-8.11 using fresh primary reference fluid.
NOTE 16 - An evaluation shall consist of two tests using the same stabilized ball followed by a check test with the reference fluid using the same test ball. The evaluation is valid if the check test with the reference fluid agrees within 1.0 s of the previous reading for that ball in the reference fluid.
9. Procedure for Stabilizing New or Unknown Ball
9.1 As indicated, follow 8.1-8.11. Repeat at least three times with the same ball using the primary reference fluid, discarding the fluid after each run and until consecutive tests yield times within 1.0 s maximum deviation. The ball is then considered to be stabilized.
NOTE 17 - Since operation of this test depends upon reliable and repetitive performance of the test balls, it is advisable to maintain an individual chronological record of results obtained from each ball. Rate of degradation and possible contamination of the ball can then be observed. Different test balls frequently give slightly different quench times with the same fluid. It is important, therefore, that comparative tests on a test fluid and a reference fluid be run using the same ball. The round-robin test balls were originally stabilized by General Motors Corp. prior to the initiation of the round robin.
