Influence of Hydrogen Embrittlement on Ductile–Brittle Transition Temperature Determined on Mini-Charpy Specimens Made in X65 Steel

Autor: Pluvinage Guy, Capelle Julien, Apou Martial Kpemou
Rok vydání: 2021
Předmět:
Zdroj: Journal of Failure Analysis and Prevention. 21:2290-2304
ISSN: 1864-1245
1547-7029
Popis: Hydrogen embrittlement is a phenomenon that affects the mechanical properties of steels intended for hydrogen transport. One affected by this embrittlement is the ductile–brittle transition temperature (DBTT). This temperature is conventionally defined and compared to service temperature as an acceptability criterion for codes. Transition temperature does not depend only on the material, but also on specimen geometry, particularly the thickness. This phenomenon is attributed to the plasticity constraint described by several parameters as the effective stress T, the out-of-plane stress Tz and the parameter Ae=0.3% related to the surface covered by plastic strain iso-lines. Generally, the transition temperature is defined for a conservative reason by the Charpy impact test. Standard Charpy specimens are straight beams with a thickness of 10 mm. For thin pipes, it is impossible to extract this type of the standard specimen. One uses in this case mini-Charpy specimens with a reduced thickness due to pipe curvature. This paper aims to quantify the effect of hydrogen embrittlement on the transition temperature of pipe steel (API 5L X65) as well as the effect of Charpy specimen thickness. Three plastic constraint parameters (Teff, Rp, and Ae=0.3%) are computed to get a correlation between plastic constraint and the shift of the transition temperature.
Databáze: OpenAIRE
Externí odkaz: