Differences between HIC and SSCC experiments
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HIC: Hydrogen cracking resistance test SSCC: Sulfide stress corrosion resistance test
HIC has mainly three acceptance criteria: percentage of crack length: CLR, percentage of crack thickness: CTR, and percentage of crack sensitivity: CSR. No loading force is required, and the testing time is 96 hours. SSC focuses on detecting whether there is fracture or cracking; a loading force is necessary, and there are four methods for applying this force, with the most commonly used being tension testing and four-point bending test, while the testing time is 720 hours
HIC hydrogen resistance: crack inspection after 96 hours; NACE 0284, GB/T 8650: sulfur resistance: crack inspection after 720 hours. There are several different testing methods depending on the size of the material, among which the most common ones are Method A tensile testing and four-point bending test
In the HIC test for hydrogen-induced cracking at 96H, H2S gas generates hydrogen atoms in water, and these hydrogen atoms can pass through the metal grain boundaries; if the metal contains many impurities, cracks will form. The SSC test is a stress corrosion test, and it is determined based on the yield limit of metal materials; in most countries this value is 80% or 85%, while in Japan it is somewhat higher, around 100%. Mostly, the four-point bend test or constant load test is used; for the four-point bend test, ASTM G39 or ISO7959 applies. The national standard 4157 has already included the four-point bend in the E method. The most sensitive and fragile part of a metal is its heart point.