HIC hydrogen induced cracking test is also called anti hydrogen induced crack test, hydrogen embrittlement test, hydrogen induced cracking (HIC) in English full name: Hydrogen induced cracking, abbreviated as HIC. Compared with metal atoms, the size of hydrogen atoms is very small, and it is easy to spread from the gap between metal atoms to the metal matrix, and have physical and chemical effects with the matrix, thus reducing the mechanical properties of the metal matrix. The source of hydrogen can be divided into two kinds of internal hydrogen and external hydrogen: (1) internal hydrogen refers to the hydrogen existing in the material before use, mainly smelting (the water in the raw material), acid washing (acid), electroplating (cathode hydrogen evolution), welding (before welding), heat treatment (quenching, etc.); (2) External hydrogen or ambient hydrogen refers to the hydrogen absorbed by the material during use. For example, H2 or H2S can decompose H into components or samples when serving in H2 or H2S gas or H2S aqueous solution. Under the action of hydrogen pressure, the adjacent hydrogen bubble cracks at different levels are connected to each other, and the internal cracks of the staircase characteristics are called hydrogen induced cracking, and the cracks can also be extended to the metal surface. The occurrence of HIC does not require additional stress, and is generally related to the irregular microstructure of high density large plane inclusions or alloy elements segregated in steel. Hydrogen-induced cracking (HIC) has been widely used to describe crack types and has been adopted by NACE International Organization. Test scheme and standard NACE TM0284 pipeline steel and pressure vessel resistance to hydrogen cracking evaluation method GB/T 8650 pipeline steel and pressure vessel steel resistance to hydrogen cracking evaluation method sample size: long 100mm, wide 20mm. 1) thickness < 30mm: parallel sampling, the same product is taken 1 groups of samples, the number is 3, 2) 30mm < 88mm > thickness < 88mm: the same product takes 1 groups of samples, the number is 3; the thickness is more than 88mm: the step sampling, the thickness of the 1 sample is < 30mm, the maximum number of samples is taken according to the actual thickness.