Assessing Gaseous Hydrogen Assisted Fatigue Crack Growth Susceptibility of Pipeline Steel Weld Fusion Zones and Heat Affected Zones

Journal Article · Tue Dec 06 00:00:00 EST 2016 · Materials Performance and Characterization (Online)

DOI:https://doi.org/10.1520/mpc20150057· OSTI ID:1765764

Ronevich, J. A. ^[1]; Somerday, B. P. ^[1]

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1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)

The objective of this work was twofold: (1) measure reliable fatigue crack growth relationships for X65 steel and its girth weld in high-pressure hydrogen gas to enable structural integrity assessments of hydrogen pipelines, and (2) evaluate the hydrogen accelerated fatigue crack growth susceptibility of the weld fusion zone and heat-affected zone relative to the base metal. Fatigue crack growth relationships (da/dN versus ΔK) were measured for girth welded X65 pipeline steel in high pressure hydrogen gas (21 MPa) and in air. Hydrogen assisted fatigue crack growth was observed for the base metal (BM), fusion zone (FZ), and heat-affected zone (HAZ), and was manifested through crack growth rates reaching nearly an order of magnitude acceleration over rates in air. Addditionally, at higher ΔK values, crack growth rates of BM, FZ, and HAZ were coincident; however, at lower ΔK, the fatigue crack growth relationships exhibited some divergence with the fusion zone having the highest crack growth rates. These relative fatigue crack growth rates in the BM, FZ, and HAZ were provisional, however, since both crack closure and residual stress contributed to the crack-tip driving force in specimens extracted from the HAZ. Despite the relatively high applied R-ratio (R = 0.5), crack closure was detected in the heat affected zone tests, in contrast to the absence of crack closure in the base metal tests. Crack closure corrections were performed using the adjusted compliance ratio method and the effect of residual stress on K_max was determined by the crack-compliance method. Crack-tip driving forces that account for closure and residual stress effects were quantified as a weighted function of ΔK and K_max (i.e., K_norm), and the resulting da/dN versus K_norm relationships showed that the HAZ exhibited higher hydrogen accelerated fatigue crack growth rates than the BM at lower K_norm values.

• Research Organization: Sandia National Laboratories (SNL-CA), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Program
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1765764
• Alternate ID(s): OSTI ID: 1331576
• Report Number(s): SAND--2021-0426J; 693363
• Journal Information: Materials Performance and Characterization (Online), Journal Name: Materials Performance and Characterization (Online) Journal Issue: 3 Vol. 5; ISSN 2165-3992
• Publisher: ASTM International
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Fatigue crack growth
embrittlement
hydrogen
pipeline steel
residual stress
weld