HIC test pipes, valves

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HIC hydrogen embrittlement testing: Hydrogen-induced cracking is the full English name for HIC, abbreviated as HIC. Compared to metal atoms, hydrogen atoms are very small, allowing them to diffuse into the interior of the metal matrix from the gaps between metal atoms. There they undergo physicochemical reactions with the matrix, thereby reducing the mechanical properties of the metal matrix. The sources of hydrogen can be divided into internal hydrogen and external hydrogen: (1) Internal hydrogen refers to the hydrogen that is already present within the material before it is used, mainly arising from processes such as smelting (moisture in raw materials), pickling (acids), electroplating (hydrogen evolution at the cathode), welding (failure to dry the material before welding), and heat treatment (quenching, etc.) ； (2) External hydrogen or ambient hydrogen refers to the hydrogen absorbed by the material during use. When operating in H2 or H2S gas or an aqueous solution of H2S, H2 or H2S can release H into the components or specimens. Under hydrogen pressure, adjacent hydrogen blister cracks at different levels connect with each other, forming internal cracks with a stepped pattern; this phenomenon is known as hydrogen-induced cracking. The cracks can sometimes also extend to the metal surface. The occurrence of HIC also does not require external stress; it is generally associated with high-density, large-planar inclusions in the steel, or with the irregular microstructure resulting from the segregation of alloying elements within the steel. Hydrogen-induced cracking (HIC) is now widely used to describe this type of crack, and it has been adopted by NACE International. Test plan and standards: NACE TM0284 – Method for evaluating resistance to hydrogen-induced cracking in pipeline steels and pressure vessels; GB/T 8650 – Method for evaluating resistance to hydrogen-induced cracking in pipeline steels and pressure vessel steels. Sample requirements: Sample size: length 100 mm, width 20 mm. 1) Thickness < 30mm: Sample in parallel; 1 set of samples per product, with 3 samples in each set ； 2) 30mm ≤ thickness < 88mm: Staged sampling; 1 set of samples is taken for the same product, with a quantity of 3 samples ； 3) Thickness ≥ 88 mm: Sample in a stepped manner; if the thickness of 1 sample is < 30 mm, the maximum number of samples shall be taken based on the actual thickness. At present, the pass rate for HIC tests is very high. Since I do this myself, feel free to leave me a message if you have any questions so we can discuss them together.