5.7 With some materials, a critical width of specimen may be found below which specimens will appear ductile, as evidenced by considerable drawing or necking down in the region behind the notch and by a relatively high-energy absorption, and above which they will appear brittle as evidenced by little or no drawing down or necking and by a relatively low-energy absorption. Since these methods permit a variation in the width of the specimens, and since the width dictates, for many materials, whether a brittle, low-energy break or a ductile, high energy break will occur, it is necessary that the width be stated in the speci?cation covering that material and that the width be reported along with the impact resistance. In view of the preceding, one should not make comparisons between data from specimens having widths that differ by more than a few mils.
5.8 The type of failure for each specimen shall be recorded as one of the four categories listed as follows:
C= Complete Break—A break where the specimen separates into two or more pieces.
H= Hinge Break—An incomplete break, such that one part of the specimen cannot support itself above the horizontal when the other part is held vertically (less than 90° included angle).
P= Partial Break—An incomplete break that does not meet the de?nition for a hinge break but has fractured at least 90 % of the distance between the vertex of the notch and the opposite side.
NB = Non-Break—An incomplete break where the fracture extends less than 90 % of the distance be- tween the vertex of the notch and the opposite side.