The impact toughness of ASTM standard seamless tube reflects the resistance of the metal to the external impact load. It is generally expressed by the impact toughness value (ak) and the impact energy (Ak), whose units are J/cm2 and J (joules) respectively.
Impact toughness or impact energy test (referred to as “impact test”) is divided into three types: normal temperature, low temperature and high temperature impact test due to different test temperatures; according to the shape of the sample notch, it can be divided into “V”-shaped notch and “U” There are two types of notch impact tests.
Impact test: use a sample of a certain size and shape (10×10×55mm) (with a “U” or “V”-shaped notch in the middle of the length direction, the notch depth is 2mm) under the impact load on the specified testing machine. Experiment with broken at the notch.
A. Shock absorption work Akv(u) The work absorbed when a metal pattern with a certain size and shape is broken under the action of shock load. The unit is Joule (J) or Kgf.m.
B. The quotient of the impact toughness value akv(u) divided by the cross-sectional area of the bottom of the sample at the notch. The unit is Joule/cm2 (J/cm2) or kilogram force.m/cm2 (Kgf.m/cm2).
The normal temperature impact test temperature is 20±50C; the low temperature impact test temperature range is <15~-1920C; the high temperature impact test temperature range is 35~10000C.
The cooling medium used in the low temperature impact test is generally non-toxic, safe, non-corroding metal and non-solidifying liquid or gas at the test temperature. Such as absolute ethanol (alcohol), solid carbon dioxide (dry ice) or liquid nitrogen atomizing gas (liquid nitrogen).