Probabilistic Fracture Mechanics Simulation of Stress Corrosion Cracking Using Accelerated Laboratory Testing and Multi-Scale Modeling

Strain gradient plasticity-based modeling of hydrogen environment assisted cracking

“…Three high strength alloys were modeled: (a) an austenitic Ni-Cu superalloy hardened by spherical ' precipitates (Ni3(Al,Ti); 5 nm radius, 0.08-0.1 volume fraction, and 150000 to 190000 precipitates/µm 3 [53]), and (b) two martensitic ultra-high strength steels strengthened by needle-shaped carbide precipitates ((Cr,Mo)2C; 1 nm radius, 5-8 nm length, volume fraction of order 0.03, and about 150000 precipitates/µm 3 [51,54,55]). The heat treatment and microstructure of the superalloy, Monel K-500 (K500; Ni-28.6Cu-2.89Al-0.45Ti-0.166C by wt pct), are described elsewhere [45,50,53] The kinetics of HEAC were measured for K500, AM100, and M54 using precracked fracture mechanics specimens stressed under slow-rising KI while immersed in an aqueous solution of 0.6 M NaCl and as a function of EAPP, as detailed elsewhere [5,[45][46][47][48]. The da/dt versus KI results for each alloy are typical of HEAC in high strength metals [7].…”

Strain Gradient Plasticity-Based Modeling of Damage and Fracture

“…The heat treatment and microstructure of the superalloy, Monel K-500 (Ni-28.6Cu-2.89Al-0.45Ti-0.166C by wt pct), are described elsewhere [102,174]: 0.2% offset yield strength (σ YS ) is 773 MPa, elastic modulus (E) is 183.9 GPa, and ultimate tensile strength (σ UT S ) is 1169 MPa from tensile testing; Ramberg-Osgood flow constants from compression testing (to 2% total strain) are n = 20, α=0.39, E = 185.7 GPa and σ 0 = σ YS = 773 MPa; and plane strain fracture toughness (K IC ) is 200 to 340 MPa √ m. The heat treatment and microstructure of two similar quenched and aged martensitic alloy steels, AerMet T M 100 (Fe-13.4Co-11.1Ni-3.0Cr-1.2-Mo-0.23C by wt pct) and Ferrium T M M54 (Fe-7.0Co-10.1Ni-1.0Cr-2.1Mo-1.3-W-0.1V-0.30C by wt pct), are described elsewhere [92,172,175] The kinetics of HEAC were measured for Monel K-500, AerMet T M 100, and Ferrium T M M54 using precracked fracture mechanics specimens stressed under slow-rising K I while immersed in an aqueous solution of 0.6 M NaCl, as detailed elsewhere [92,102,147,171,172]. The da/dt versus K I results for each alloy, characterized as a function of E APP , are typical of HEAC in high strength alloys [36].…”

“…Interdisciplinary advances in deformation processing [144], fatigue [145], stress corrosion cracking (SCC) [146], and hydrogen embrittlement [147] illustrate this cutting-edge approach. Internal hydrogen and hydrogen environment assisted cracking degrade high toughness alloys in fracture-critical aerospace, ship, energy, and ground transportation structures [133].…”

Loading Rate Effects on the Hydrogen Enhanced Cracking Behavior of Ni- and Co-based Superalloys for Marine Applications

“…Specifically, da/dt vs. K relationships were generated from which the traditional EAC metrics of threshold stress intensity, KTH, and stage II crack growth rate, da/dtII, were established. Such data was then used as inputs for probabilistic LEFM based modeling of crack progression for an idealized component [39].…”

“…Such data is critical to inform LEFM-based component life management tools (e.g. SCCrack [39]) that enable probabilistic management of the environmental cracking behavior of engineering components for a given material, starting crack size, environment, and applied load [39]. Furthermore, these techniques enable targeted testing and mechanistic insights that can lead to material development, informed material selection, and more rigorous structural integrity management.…”