FAQ's

For CRAs, what is the maximum hardness of the weld consumable and the weldments?

QUESTION:
The statement I’m referring to is in NACE MR0175, Part 3, Sect A.2.3 Welding of austenitic stainless steels of this material group and the statement reads “the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable.” It would be greatly appreciated if you could provide some clarification as to what the standard is referring to by the “maximum hardness limit of the respective alloy” and where I can find these values.

Answer
The maximum consumable hardness applies to the corresponding base metal (UNS number composition). This has been defined as the maximum hardness that is listed in NACE MR0175/ISO 15156 for that UNS number or meets one of defined alloy classes that is in the NACE MR0175/ISO 15156. The question that you ask does not have a defined answer if the consumable used does not correspond to an existing UNS or does not fit one of defined alloy classes that is in the NACE MR0175/ISO 15156 standard. For a better understanding of weld cracking resistance requirements and especially for this latter case, you are directed to ISO 15156-3, Clause 6.2.2 where the cracking resistance of weldments are addressed.

Reference MP Inquiry 2017-10

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