Charpy Impact Testing

The following is an SOP on Charpy Impact Testing as well as Charpy Impact Testing involving testing with samples at temperature extremes. The Charpy Impact Test is located in the Minerals and Materials Building room U208.

Loss Prevention

• Equipment Users must wear proper PPE (Personal Protective Equipment), which includes wearing safety glasses at all times during the operation of the machine and while in room U208.
• The charpy Impact Test has a large swinging pendulum which if not used correctly and cautiously could cause injury.
• Sample fragments may develop into small projectile hazards during fracture. If samples are heated prior to use, sand MUST be spread on the floor to avoid heated samples making contact with the tile. If not, the tile used in the flooring can crack and send fragments into the air which can cause potential injury. Proper fire-resistant clothing must be worn in case of heated fragment contact with a person's body.
• Liquid Nitrogen is commonly used for some samples that are Charpy tested so make sure to wear proper gloves and tongs and dispose of the liquid nitrogen correctly.
• Make sure the area around the Charpy Impact Tester is clear before releasing the pendulum.

Procedure

1. Do a test run with no sample to make sure the Charpy Test is working correctly
2. *Lift pendulum up to starting position and make sure it is locked in place.
   • Set the dial on the front to 264 ft-lbs (all the way to the left).
   • Once the area around the Charpy Test is clear hit the release lever, if you can once the pendulum swings back up catch it and place it back in the starting position (carefully).
   • Do this at least once more to make sure the dial is reading zero (or very close to zero).
3. Lift the pendulum to the starting position and make sure it is locked in place. If you are with someone, have someone hold the pendulum up to make sure it doesn't release while anyone is in the area loading the sample.
4. Load the sample. If the sample has a notch it needs to be facing to the left away from the striker. If you are chilling the sample in liquid nitrogen, the sample needs to be loaded in under 5 seconds.
5. Once the test area is clear release the pendulum and record results.
6. If the sample is being heated or cooled adjacent to the charpy machine, the sample must be placed and broken in the charpy within 5 seconds of extraction from the source of temperature change or results may be invalidated.
7. Broken samples MUST NOT be retrieved unless the pendulum is locked into place to avoid injury or death.

Facts about this specific Charpy Impact Test

• 60# Hammer
• 4.4 ft drop
• 16.8 ft/s striking velocity
• 264 lb load
• Liquid Nitrogen Boiling Temperature is -321 degrees Fahrenheit.
• Heated samples can exceed 400 degrees C.