Chipeng Zhang , Wei Li , Shunpeng Zhu , Shengnan Hu , Dapeng Jiang , Jian Chen , Guowei Bo
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引用次数: 0
Abstract
The service life of FB2 steel, a boron-modified 9 % Cr martensitic stainless steel for high-temperature applications, is predominantly governed by its creep-fatigue resistance. Therefore, the stress-controlled cycling loading tests with different dwell time (5, 15, 30 s) at 620 ℃ were employed to study the creep-fatigue behavior of FB2 steel. Meanwhile, two martensitic lath widths of 286 nm (H-FB2 steel) and 568 nm (L-FB2 steel) were tailored for FB2 steel by different heat treatment. Both FB2 variants exhibited pronounced cyclic softening behavior. However, H-FB2 steel showed significantly lower performance than L-FB2 steel, with the latter exhibiting a 64.7 % greater elongation and superior creep-fatigue life improvements of 21.9 %, 14.2 %, and 8.5 % at holding durations of 5 s, 15 s, and 30 s respectively. Further, the BEiT deep learning method achieved an accuracy of 94.4 % for fractographic analysis, by which the fracture mode was identified as brittle and ductile fracture for H-FB2 and L-FB2 steel, respectively. This difference is attributed to the lower initial dislocation density and fine spherical carbides (M23C6 and MX types) in L-FB2 steel, which could accommodate more dislocation and restrict dislocation movement at martensite lath boundaries. This effectively delays both crack initiation and propagation processes, and consequently improves the creep-fatigue resistance.
期刊介绍:
Typical subjects discussed in International Journal of Fatigue address:
Novel fatigue testing and characterization methods (new kinds of fatigue tests, critical evaluation of existing methods, in situ measurement of fatigue degradation, non-contact field measurements)
Multiaxial fatigue and complex loading effects of materials and structures, exploring state-of-the-art concepts in degradation under cyclic loading
Fatigue in the very high cycle regime, including failure mode transitions from surface to subsurface, effects of surface treatment, processing, and loading conditions
Modeling (including degradation processes and related driving forces, multiscale/multi-resolution methods, computational hierarchical and concurrent methods for coupled component and material responses, novel methods for notch root analysis, fracture mechanics, damage mechanics, crack growth kinetics, life prediction and durability, and prediction of stochastic fatigue behavior reflecting microstructure and service conditions)
Models for early stages of fatigue crack formation and growth that explicitly consider microstructure and relevant materials science aspects
Understanding the influence or manufacturing and processing route on fatigue degradation, and embedding this understanding in more predictive schemes for mitigation and design against fatigue
Prognosis and damage state awareness (including sensors, monitoring, methodology, interactive control, accelerated methods, data interpretation)
Applications of technologies associated with fatigue and their implications for structural integrity and reliability. This includes issues related to design, operation and maintenance, i.e., life cycle engineering
Smart materials and structures that can sense and mitigate fatigue degradation
Fatigue of devices and structures at small scales, including effects of process route and surfaces/interfaces.