Abstract
The paper presents and discusses results of mechanical spectroscopy (MS) tests carried out on a Cr martensitic steel. The study regards the following topics: (i) embrittlement induced by Cr segregation; (ii) interaction of hydrogen with C–Cr associates; (iii) nucleation of Cr carbides. The MS technique permitted characterising of the specific role played by point defects in the investigated phenomena: (i) Cr segregation depends on C–Cr associates distribution in as-quenched material, in particular, a slow cooling rate (~150 K/min) from austenitic field involves an unstable distribution, which leads to Cr concentration fluctuations after tempering at 973 K; (ii) hydrogen interacts with C–Cr associates, and the phenomenon hinders hydrogen attack (HA) because hydrogen atoms bound by C–Cr associates are not able to diffuse towards grain boundaries and dislocation where CH4 bubbles may nucleate, grow, and merge to form the typical HA cracks; (iii) C–Cr associates take part in the nucleation mechanism of Cr7C3 carbides, and specifically these carbides form by the aggregation of C–Cr associates with 1 Cr atom.
Highlights
The role played by point defects is of the utmost relevance in several phenomena occurring in pure metals and alloys
The present paper shows that such apparently anomalous behaviour depends on elementary structures of point defects (C–Cr associates)
1, theofQdifferent vs. temperature spectra of the [27], Cr martensitic steel exhibit complex scenario withinmore position and intensity depending on value E0, exhibits slope changes in correspondence of the Q−1 peaks, indicating that they are exhibit a complex with more peaks of different position and intensity depending on the the quenching ratescenario from austenitic field
Summary
The role played by point defects is of the utmost relevance in several phenomena occurring in pure metals and alloys. Point defects (vacancies, interstitials, substitutional atoms, etc.) alter the elastic constants of a solid, strongly affect diffusion and ordering, and are relevant for irradiation, cold work, and recovery; they have received a lot of attention since the 1960s −1 curves of the steel quenched from 1348 K with cooling rates of 3600 K/min Figure 4. Q−1 curves of the steel quenched from 1348 K with cooling rates of 3600 K/min. The best fit curve the sum of the background curve, sevencurve, peaks corresponding (a) and 150 K/min (b). The best fit is curve is the sum of the background seven peaks to.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
