FAQ's

NACE MR0175 and cold work of 316L and other austenitic stainless steels.

With reference to NACE MR0175 / ISO 15156-3 (2015), I am querying one of the comments under Note b (applicable to UNS S31603) in the notes section of Table A.2 which states; “after the final solution annealing and quenching treatment, hardness and cold work incidental to machining or straightening shall not exceed the limits imposed by the appropriate product specification”.
The product specification ASTM A479 does not state a maximum hardness limit for UNS S31603. Cold drawing is permitted for straightening purposes under Supplementary Requirement S5 (related to SCC resistance) of ASTM A479, which ties in with ‘cold work incidental to straightening’ stated in your NACE MR0175 / I15156-3 (2015) standard. However, due to their being no hardness limit and also no clear limit on the amount of cold work (other than for straightening purposes) in this ASTM A479 product specification, what is your definition of these limits? Do we assume a maximum limit of 22 HRC stated under note ‘a’ in table A.2? Also, can a limit be placed on the material’s maximum yield and tensile strength (that correlates with the amount of permitted cold work) that does not compromise the material’s resistance to SCC?
ANSWER:

Q1: Referring to 15156-3 Table A.2, what is the definition of cold work limits for UNS S31603 with respect to straightening in accordance with ASTM A479 Supplement S5?
A1: The cold work limit is not defined in Table A.2 only that the material shall be free of cold work intended to enhance mechanical properties.
Q2: With the straightening cold work, can we assume that the hardness limit of 22 HRC applies?
A2: Correct, the maximum hardness is 22 HRC.
Q3: Can a limit on the material’s maximum yield and tensile strength be placed on the material that corresponds to the maximum permitted cold work?
A.3: The maximum yield and tensile is not defined. During our discussions on the ballot regarding cold work of UNS S31603 and Table A.2, there was a lot of agreement that the maximum “specified minimum yield strength (SMYS)” needed to correspond to that of the annealed without cold work condition. However, there was not sufficient consensus to define what this maximum SMYS should be.
Reference: ISO 15156 Maintenance Panel Inquiry #2016-04
This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

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