Heat Deflection Temperature (HDT)
Heat Deflection Temperature (HDT) is a value that indicates a polymer’s resistance to structural changes when subjected to a given load at an elevated temperature. HDT is also known as Heat Distortion Temperature or Deflection Temperature Under Load (DTUL) or Heat Deflection Temperature Under Load (HDTUL).
Heat Deflection Temperature (HDT) Measurement Procedure
Heat Deflection Temperature (HDT) is a value that indicates a polymer’s resistance to structural changes when subjected to a given load at an elevated temperature. HDT is also known as Heat Distortion Temperature or Deflection Temperature Under Load (DTUL) or Heat Deflection Temperature Under Load (HDTUL).
The ASTM D648 (equivalent to ISO 75) test is an international standard that defines the testing procedure to measure the HDT of polymers. In this method, a test bar made of the polymer to be tested is loaded into a type of 3-point bending apparatus filled with oil. The temperature of the oil is increased incrementally with a known constant load applied at the center of the polymer bar. The temperature of the oil is increased till the polymer bar deforms by 0.25mm which denotes the Heat Deflection Temperature (HDT).
Common Uses of Heat Deflection Temperature (HDT)
- Comparing heat tolerance of different materials.
- Product design and manufacturing.
Limitations of Heat Deflection Temperature (HDT)
- Thick samples will have a temperature gradient.
Industrial Applications of Heat Deflection Temperature (HDT)
- Metallurgy
- Automotive
- Aerospace
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