The impact toughness of high pressure seamless pipe

The impact toughness of high-pressure seamless pipes represents the material's resistance to external impact loads, typically measured by the impact energy (Ak) in Joules (J).

The impact test for high-pressure seamless pipes, known as the "impact test," varies by test temperature and can be conducted at room temperature, low temperature, or high temperature. Depending on the shape of the sample notch, the test is categorized into two types: "V"-shaped notch and "U"-shaped notch impact tests.

During the test, a sample of the high-pressure seamless pipe with specific dimensions (10×10×55 mm) and a notch (either "V" or "U") 2 mm deep in the center is subjected to an impact load on a specified testing machine until it breaks at the notch.

The impact absorption work Akv(u) refers to the amount of energy absorbed by the metal sample during fracture under impact load, with the unit being Joules (J).

The standard impact test temperature for high-pressure seamless pipes at normal conditions is 20±5°C. The temperature range for low-temperature impact tests is below 15°C to as low as -192°C, while for high-temperature tests, it ranges from 35°C to 1000°C.

For low-temperature impact tests, non-toxic, safe, and non-corrosive cooling mediums are typically used. These include substances that remain in liquid or gas form at the test temperature, such as absolute ethanol, solid carbon dioxide (dry ice), or atomized liquid nitrogen.