Regarding the testing of stainless steel ferrite

This post was last edited by Liu Jiajia on 2016-7-28 at 10:23. 1. Significance of testing: Upper limit for FN: controlling low-temperature toughness； FN lower limit: Controls hot cracks (which tend to occur at the arc crater) ； 2. Influencing factors: Cr equivalent, Ni equivalent ； Material condition: castings, forgings; whether there is work hardening; whether heat treatment has been applied. The starting point for welding, the welding method used during normal welding, the ending position of welding, etc ； 3. Measurement methods: Magnetic method (FN tester), metallographic analysis, etc. 4. FN is usually controlled at 4–12%, while TP347 is recommended to be controlled at 5–10%. When FN < 3%, almost no thermal cracks occur. For low-temperature, non-magnetic, and special corrosion conditions, lower requirements can be specified. 5. Relevant information can be found in API 582, GB/T1954, ISO 8249, etc.