NACE MR0175/ISO 15156-3 Table A.39 for Cobalt-Based Alloys: Q&A Format

Limitations for UNS R30003 Springs

One of the limitations for UNS R30003 as springs is that the alloy must be cold worked, age-hardened, and have a maximum hardness of 60 HRC. However, measuring hardness using HRC can be challenging due to the geometry of the springs, which could lead to inaccuracies. Is this interpretation correct?

Answer: Yes, your interpretation is correct.

Complying with the 60 HRC Limit

When compliance with the 60 HRC limit is difficult to prove using suitable hardness measurements like Vickers or Knoop, what can be done?

Answer: Developing hardness conversions based on test data is not prohibited.

Permissibility of UNS R30003 in Cold-Worked State

Is UNS R30003 permissible in the cold-worked state without age hardening? Are there any corrosion issues with non-age-hardened cobalt base alloys?

Answer: While there was recently a successful ballot to permit UNS R30003 use in both cold-worked and cold-worked + aging conditions, Table A.39 does not include the cold-worked condition without subsequent age hardening, requiring another successful ballot to NACE MR0175/ISO 15156 for inclusion.

Expert Services for NACE MR0175 Requirements

If you have any further questions or need help with NACE MR0175 requirements for cobalt-based alloys, our team of experts is here to assist you.