Session: HT-01-01 Joe Kapp Memorial Session: Design and Analysis of High-Pressure Equipment

Paper Number: 61861

Start Time: Wednesday, July 14, 2021, 08:00 PM

61861 - A Model for Stress-Driven Hydrogen Diffusion in Stainless Steels for High-Pressure Applications 

Hydrogen Embrittlement (HE) is a damaging phenomenon potentially affecting the integrity and the durability of stainless steels used in high-pressure applications. Hydrostatic stress gradients, produced by operating loads, are known to significantly affect the migration of the diffusible Hydrogen (H) arising from the environment.  The knowledge of the local H concentration and the consequent mechanical properties’ degradation is fundamental for the strength assessment of industrial components.

This paper deals with the strength assessment of components made in Dual-Phase (DP) stainless steels under typical stress conditions in the presence of diffusible H.

A coupled diffusion-structural model able to evaluate the H distribution is developed and presented. The main parameters driving H migration into this material are included, i.e.: H concentration gradients, hydrostatic stress distribution, and plastic strain. The diffusion properties of the investigated material were measured by permeation tests.

Mechanical tests were carried out on component-like specimens characterized by a uniform initial hydrogen distribution and by geometric discontinuities designed to produce hydrostatic stress gradients. Standard mechanical tests were also performed to investigate the HE of the material in the presence of a uniform H distribution. The presented model was employed to predict the local H concentration and assess the component strength by HE models published in the literature.

Presenting Author: Giuseppe Macoretta Department of Civil and Industrial Engineering - University of Pisa

Authors:

Giuseppe Macoretta Department of Civil and Industrial Engineering - University of Pisa
Francesco Aiello Department of Civil and Industrial Engineering - University of Pisa
Marco Beghini Department of Civil and Industrial Engineering - University of Pisa
Bernardo Disma Monelli Department of Civil and Industrial Engineering - University of Pisa
Renzo Valentini Department of Civil and Industrial Engineering - University of Pisa