Abstract
Friction stir welded steel pipelines were tested in high pressure hydrogen gas to examine the effects of hydrogen accelerated fatigue crack growth. Fatigue crack growth rate (da/dN) vs. stress-intensity factor range (ΔK) relationships were measured for an X52 friction stir welded pipe tested in 21 MPa hydrogen gas at a frequency of 1 Hz and R = 0.5. Tests were performed on three regions: base metal (BM), center of friction stir weld (FSW), and 15 mm off-center of the weld. For all three material regions, tests in hydrogen exhibited accelerated fatigue crack growth rates that exceeded an order of magnitude compared to companion tests in air. Among tests in hydrogen, fatigue crack growth rates were modestly higher in the FSW than the BM and 15 mm off-center tests. Select regions of the fracture surfaces associated with specified ΔK levels were examined which revealed intergranular fracture in the BM and 15 mm off-center specimens but an absence of intergranular features in the FSW specimens. The X52 friction stir weld and base metal tested in hydrogen exhibited fatigue crack growth rate relationships that are comparable to those for conventional arc welded steel pipeline of similar strength found in the literature.
| Original language | English |
|---|---|
| Pages (from-to) | 4259-4268 |
| Number of pages | 10 |
| Journal | International Journal of Hydrogen Energy |
| Volume | 42 |
| Issue number | 7 |
| DOIs | |
| State | Published - Feb 16 2017 |
Funding
The authors would like to acknowledge the support of the Hydrogen Effects on Materials Laboratory team at Sandia National Laboratories. Metallographic samples were prepared and imaged by Andy Gardea and Ryan Nishimoto. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. Friction stir weld was prepared by Oak Ridge National Laboratory, managed by UT-Battle for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. This work was supported by the US Department of Energy Fuel Cell Technologies Office through the Hydrogen Delivery sub-program.
Keywords
- Fatigue crack growth rate
- Friction stir weld
- Hydrogen assisted cracking
- Hydrogen embrittlement