The hardness of S32750 can vary from product form to product form, and from batch to batch.
For solid bars of S32750 supplied to the common specifications of ASTM A182, ASTM A276 and ASTM A479, the maximum hardness allowable is 310 HB (Brinell Harness).
For wrought and cast super duplex stainless steels such as S32750, the hardness shall not exceed 32 HRC (Rockwell Hardness C) as specified in NACE MR0103-2015. The NACE standard is widely referenced for the specification of metals used across the Oil and Gas industry.
The title of this “NACE” specification is “Petroleum, petrochemical and natural gas industries – Metallic materials resistant to sulphide stress cracking in corrosive petroleum refining environments”. As such it aims to better specify metals that will be used in the presence of H2S, where hydrogen charging and sulphide stress cracking (SSC) can result. High strength can reduce susceptibility to cracking, but high hardness levels is known to greatly increase the likelihood of failure. Therefore, controlling the hardness of the metals used is an important control measure. As hardness testing is non-destructive and requires less sample preparation than many other measurements, it is easy to undertake both during production as a quality control measure, and by user in field inspection.
Langley Alloys stocks S32750 solid bars in sizes from 5/8” to 20” (15.87-508mm) diameter, plate up to 3” (76.2mm) thick, plus pipes in scheduled sizes, fittings and flanges.
For more information about our range of alloys, please contact Langley Alloys today.