A comparative study of creep crack growth behaviour amongst the dissimilar P91-IN182-SS316LN and similar P91 weld joints

ABSTRACT

Towards ensuring the structural integrity of the high-temperature components, it is essential to evaluate the creep crack growth (CCG) behaviour, especially for the weaker creep regions of the components. In this study, the CCG behaviour was investigated in the modified 9Cr-1Mo (P91) and Inconel (IN182) buttered layer interface regions of dissimilar metal weld (DMW) joints of P91 and type 316LN SS at 798 K and 898 K. For a quantitative assessment, the CCG rates were compared with the heat-affected zone (HAZ) of similar metal P91 welds (P91HAZ). The CCG rate was characterised using the creep fracture C* parameter as per ASTM E1457–17. The CCG rate in the P91/IN182 interface region was found to be higher than the P91HAZ, viz. 3.5 times and 4 times at 798 K and 898 K, respectively. This could be attributed to the propensity for creep cavitation in the interface region of the DMW joint.

KEYWORDS:

• Creep crack growth
• dissimilar weld joint
• creep fracture parameter
• interface cracking
• modified 9Cr-1Mo steel

Acknowledgments

This research work is sponsored by the Department of Atomic Energy, Government of India. Technical assistance provided by Mr. Syed Meer Kaleem, IGCAR Kalpakkam, is acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Department of Atomic Energy, Government of India.