![]() For each steel grade, the lowest fracture stress and highest no-fracture stress are. However, the density of reversible hydrogen traps increased with decreasing amount of PAG boundaries, indicating that PAG boundaries may act as strong hydrogen traps in the investigated steels. tuning-fork specimens are designed to enable accurate str. No correlation was observed between hydrogen diffusivities and different PAG boundary surface areas. Crack propagation was affected by the microstructure alignment of the elongated PAG structure, but the equiaxed structure did not show orientation differences. Equiaxed microstructure exhibits partly intergranular cracking with faster crack propagation rate and hydrogen diffusion. Crack propagation rates were slower with more elongated microstructure, which is linked to transgranular quasi-cleavage crack propagation and slower hydrogen diffusion. The effect of PAG morphology (elongated/equiaxed) on HE susceptibility was studied with steels that had different alloying compositions and with steels that had different PAG morphologies but the same alloying.Īn elongated PAG structure leads to enhanced resistance against HE in comparison to equiaxed PAG structures. ![]() With the addition of a loadcell to the TFT clamping system, a more precise investigation was conducted for 500 HBW steels with various PAG structures. Increasing the strength level leads to lower threshold stress levels and increased susceptibility to HE, especially for steels with over 400 HBW hardness. The first part of the TFT implementation is composed of an evaluation of the HE susceptibility of 300–600 HBW martensitic steels with relative threshold stress levels. Patients or Other Participants: A total of 37 patients (19 males, 18 females) volunteered. Setting: University athletic training room or local orthopaedic center when fractures were suspected. Traditional hydrogen permeation tests with a set-up built within this thesis complement the results. Objective: To determine if the use of a 128-Hz vibrating tuning fork and stethoscope were effective in identifying fractures. The main objectives were to create a simple and fast testing method, which allows ranking of UHSS, and to investigate the effects of prior austenite grain (PAG) structure. ![]() With an isolated tensile stress region, crack initiation is controlled and can be monitored with different clamping arrangements. The testing method utilizes constant displacement for stressing of the tuning-fork specimens by bending, combined with electrochemical hydrogen charging. A novel tuning-fork test (TFT) is developed in this thesis to study HE of UHSS. Hydrogen embrittlement (HE) is a well-recognized issue with ultrahigh-strength steels (UHSS) and an intensively studied subject to minimize the risk of sudden, catastrophic failures in structural applications.
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