- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
Due to their attractive combination of high strength along with great ductility, duplex stainless steels (DSS) are often being used as pressure vessels or underwater pipelines. The use of DSS in services combined hydrogen and mechanical load can lead to hydrogen embrittlement. The susceptibility to hydrogen embrittlement is directly related to the interaction between defects (traps) and hydrogen. Hydrogen effects are being studied by a thermal desorption spectrometry (TDS) process. In this research we determine the mechanical properties of DSS with hydrogen at high strain rates. Hydrogen trapping and its effect on the mechanical properties are discussed in details.
4. Summary and conclusions
This study examines the effect of low and high strain rates (10-7 s-1 and 105 s-1, respectively) on hydrogen charged and non-charged LDS. Quasi-static experiments showed an increment of ~20 % in yield strength which was related to the experiment deformation rate; higher deformation rate will not allow for enough time for hydrogen diffusion. This statement is well pronounced at dynamic experiments which did not show any effect of hydrogen on dynamic yield strength, σy.
The hydrogen trapping energies of the quasi-static loaded (~10-7 s-1) sample were ~40 % lower than the nonloaded LDS sample and ~45 % lower than the dynamic loaded sample. At quasi-static loading, hydrogen had enough time to escape from the irreversible trapping site- ı phase, created during gas-phase hydrogen charging. The differences between the activations energies of the rest of the samples were belonged to ı phase density and deformation response which is responsible for hydrogen trapping. The greater deformation which was formed at dynamic experiments caused hydrogen to be trapped deeper in trapping sites (high energy trapping sites). Hydrogen embrittlement model is also seen and valid in the dynamic loaded sample and indicates on the same behaviour of hydrogen at low and high strain rate (10-7 s-1 and 105 s-1 at ~0.5 GPa).