Energy Materials 2017: Materials for Oil and Gas and AMREE Oil & Gas III: Hydrogen Effects on Materials in Energy
Sponsored by: Chinese Society for Metals
Program Organizers: Indranil Roy, Schlumberger; Chengjia Shang, University of Science and Technology Beijing

Tuesday 2:00 PM
February 28, 2017
Room: 14A
Location: San Diego Convention Ctr

Session Chair: Hani Elshahawi, Shell Exploration & Production, Co. ; Partha Ganguly, Baker Hughes

2:00 PM  Keynote
Hydrogen-assisted Failure in Ni-base Superalloy 718 Studied under In-situ Hydrogen Charging: The Role of Localized Deformation in Crack Propagation: Z. Tarzimoghadam1; Dirk Ponge1; J. Klwer2; Dierk Raabe1; 1Max-Planck-Institut fr Eisenforschung GmbH; 2VDM Metals GmbH
    We investigated hydrogen embrittlement (HE) of Ni-base superalloy 718 in different heat treatment conditions by tensile testing at slow strain rate (10-4 s-1) under continuous electrochemical hydrogen charging. Hydrogen-assisted cracking mechanisms were studied via electron backscatter diffraction (EBSD) analysis and electron channeling contrast imaging (ECCI). Fracture in hydrogen-charged samples was dominated by localized deformation. Non-uniform hydrogen concentrations and plastic instabilities arise at the impingement of slip bands on grain boundaries and at intersecting slip lines. Transgranular cracking was caused by shear localization assisted by hydrogen-enhanced localized plasticity (HELP) along {111} slip planes. Intergranular cracking was due to grain boundary triple junction cracking, slip-localization at grain boundaries, and d/g-matrix interface cracking. Observations on the overaged state of alloy 718 with different precipitation conditions for and g phases confirmed that d-phase promotes HE by initializing micro-cracks from d/g interfaces. Moreover, hydrogen-enhanced strain-induced vacancy (HESIV) mechanism also assisted the ductile intergranular and transgranular fracture. The failure mechanism was explained based on hydrogen-enhanced formation of strain-induced vacancies and concurrent nano-void nucleation and coalescence during plastic deformation.

2:30 PM  Invited
Failure Conditions for Individual Grain Boundaries in a Ni-base Alloy Embrittled by H: Michael Demkowicz1; 1Texas A&M University
    Performance predictions for Ni-base alloys used in sour wells may be improved by taking into account microstructure information, such as grain size, texture, or grain boundary (GB) character distribution. I will highlight recent progress towards microstructure-informed lifetime predictions in Ni-base alloys, focusing on the development of a statistical method for inferring the conditions for failure at individual GBs based on data collected from high-throughput experiments. This method minimizes the Kullback-Leibler divergence of fracture probabilities constructed based on hypothesized fracture mechanisms from the experimentally determined fracture probability. We apply this approach to H-assisted crack initiation at coherent twin boundaries in Ni-base alloy 725 and find that the conditions for fracture along these GBs involve simultaneous mode-I loading and slip along the GB plane. Our findings enable improved lifetime predictions for Ni-base alloys that have been embrittled by H.

3:00 PM  
A Combined Micromechanics/Materials Science Approach to Understanding High Temperature Hydrogen Attack: Mohsen Dadfarnia1; May Martin1; Petros Sofronis1; David Moore2; Steve Orwig2; 1University of Illinois Urbana-Champaign; 2BP
    High Temperature Hydrogen Attack (HTHA) of steels plagues higher temperature applications, especially in the petrochemical industry. Focused-ion beam machining allows extraction of samples from site specific locations for subsequent examination in the transmission electron microscope. By using this technique to explore the microstructure immediately ahead of crack tips and along cavitated grain boundaries, a better understanding of the physical processes of the HTHA process can be gained, which can guide the development of models for the degradation process accounting for methane formation and creep cavitation. Based on the underlying deformation and fracture mechanisms, we propose a model for grain boundary failure due to HTHA. The model addresses growth of the pressurized voids on grain boundaries while considering the interaction of the void growth with creep of the surrounding grains under constrained conditions. Effort is made for the model to be simple to use while capturing the underlying chemomechanics.

3:30 PM Break

3:50 PM  
Hydrogen Embrittlement of High Strength Nickel-based Alloys in HP HT Applications: Ramgopal Thodla1; Brandon Rollins1; 1DNV USA
    High strength nickel based alloys are currently being considered for use in high pressure high temperature applications in O&G. While high strength nickel based alloys possess excellent corrosion resistance at elevated temperatures, they are susceptible to hydrogen embrittlement at low temperatures. The FCGR and hydrogen cracking of two high strength nickel based alloys in seawater under cathodic protection will be presented. The role of frequency and K on the FCGR behavior will be presented. The role of different tests methods on assessing the hydrogen cracking behavior of high strength nickel based alloys will also be discussed. The effect of strain rate on the SSR behavior of 718 will be presented. The role of K-rate on the fracture toughness behavior has been investigated and it's influence on the measured threshold will be presented.

4:15 PM  
High Strength Nickel-based Alloys for HPHT Applications: Ramgopal Thodla1; Brandon Rollins1; Jeff Hawk2; Colum Holtam1; 1DNV USA; 2NETL
    Increasing pressures and temperatures in O&G applications there has been a push to use these materials in subsea high pressure high temperature applications. This has led to the need for considering high strength nickel based alloys like 718 and 625+. There are two primary damage modes that are relevant to these conditions, one which is associated with hydrogen embrittlement due to cathodic charging at low temperature and the other associated with SCC at elevated temperatures in chloride containing environments. The role of applied potential on the CGR behavior of 718 and 625+ under cathodic charging conditions will be discussed along with the role of the loading i.e. a comparison between rising displacement and constant K tests. The relationship between the repassivation potential and susceptibility to SCC at elevated temperatures in chloride containing environments will be presented. The differences in the SCC behavior of 718 and 625+ will be discussed.

4:40 PM  
High Strength Alloys for Oil and Gas Drilling Applications: Robert Badrak1; Sergey Kolesov1; William Howie1; 1Weatherford
    The drilling products required to meet today’s harsh operating conditions and environmental considerations have been evolving utilizing alloys with increasing strength levels. The driver for this evolution has been the deeper and further extended reach oilfield drilling applications and the development of smarter more sophisticated tools that require higher performance from the materials of construction. The challenge has been to develop these alloys while maintaining high levels of reliability. The pitfalls that accompany these materials as the strength increases include declining values of impact toughness, fracture resistance, ductility and environmental cracking resistance. This paper presents the chronological development of different classes of alloys that have been developed and used to meet these challenges. Included is a snapshot of some recent developments and a view into the future for these materials.

5:05 PM  
Research on the Pinpoint Controlling of CRA N08028 OCTG Microstructure and Properties: Pan Dong1; Zhiqiang Yu2; Guangwei Fan1; Genshu Zhou2; Pengsheng Yao3; Zhifang Zhang4; 1Technology Center, Shanxi Taigang Stainless Steel Co., Ltd.; 2State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University; 3Shanxi Taigang Stainless Steel Tubes & Pipes Co., Ltd.; 4Shanxi Taigang Stainless Steel Co., Ltd.
    CRA N08028 OCTG pipes and couplings as Cold-Hardened for O&G field down-hole application in H2S environment were prepared by hot extrusion and pilgering. Chemical homogeneity, Sigma phase precipitation, quality of raw pipe precursor, cold deformation, etc. were investigated in detail. By diffusion annealing at 1220 ℃ for 30h, the residual segregation indices of the specified elements were all under 0.2. The raw pipe precursor was solid-solutioned by heating to 1135 ℃ and quenching to clear up the detrimental effect of Sigma phase precipitation. Hot extrusion speed had a remarkable effect on the quality of raw pipe precursor and appropriate parameters could guard against delamination and thickness heterogeneity. The mechanical properties and corrosion-resistance had heavy dependence on cold deformation and ratio of 30-42% would ensure the mechanical properties meet the specifications. The corrosion test results indicated CRA N08028 OCTG by TISCO could be employed in typical sour O&G field globally.