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Why is the impact toughness test for petroleum cracking pipes?

The impact toughness of petroleum cracking pipe is the ability of materials to resist deformation and fracture under impact load. Mechanical parts are not only subjected to static load or vibration load during service, but also subjected to varying degrees of impact load. Such as the hammer rod of the forging hammer, the punch of the punch, the flat shovel for the fitter, etc. Due to the high loading speed of the impact load and short action time, the impacted petroleum cracking pipe often produces local deformation and fracture due to local loads. In particular, parts made of high-strength and low-plasticity materials tend to break unexpectedly and cause major accidents during service. Therefore, for petroleum cracking pipe parts and tools that are subjected to shock loads, high strength is not enough, and sufficient resistance to shock loads must also be provided.

Practice has proved that the impact test is very sensitive to the defects of the petroleum cracking pipe. Impact test is a traditional conventional mechanical test method. Because the sample is easy to process, the test time is short, and it is easy to distinguish whether the choice of petroleum cracking pipe material and heat treatment process is reasonable, it has been widely adopted by the engineering community.


Impact toughness test process of petroleum cracking pipe

The impact toughness test of petroleum cracking pipe is carried out on a special pendulum impact testing machine. Place the sample on the support of the testing machine, with the notch of the petroleum cracking tube sample facing away from the direction of the pendulum impact. Lift the pendulum with mass G to the height of H, so that the pendulum has potential energy GHG (g is the acceleration of gravity). Then let the pendulum drop, break the sample, and rise to a certain height h in the other direction. At this time, the pendulum has potential energy Ghg. Therefore, the potential energy lost by the pendulum to break the sample is GHg-Ghg, which is the work consumed by the deformation and fracture of the petroleum cracking tube sample, called the impact absorption work (impact energy), which is represented by the symbol AK, and the unit is Joule ( J). According to the different shape of the notch of the petroleum cracking tube sample, the impact absorption energy can be expressed by Aku and AKv respectively. The value of impact absorption energy can be directly indicated by the pointer on the dial of the testing machine. The impact absorption energy is divided by the original cross-sectional area F at the notch of the petroleum cracking tube sample to obtain the impact value (impact toughness), which is represented by the symbol aK (or aKu, aKv).
 

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