Hot deformation temperature HDT

The hot deformation temperature is a heat resistance index that characterizes the rigidity (modulus) of a material at high temperatures. The HDT test is a simple mechanical model supported by 3 points and subjected to vertical loads, similar to a bending test. Bending modulus is the determination of the failure load at a constant strain rate state. In contrast, the hot deformation temperature is the temperature at which a constant load (according to ISO72 standard, 0.45MPa for low load and 1.80MPa for high load) is applied, and the temperature is slowly increased (120 ℃/hr) to reach the set deformation amount (as shown in the figure below).