PSI - Issue 79

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 79 (2026) 508–516

28th International Conference on Fracture and Structural Integrity - 3rd Mediterranean Conference on Fracture and Structural Integrity

Effects of hydrogen on the mechanical properties of QP1180 AHSS

Giuseppe Macoretta a* , C. M. Belardini a* , B. D. Monelli a , R. Valentini a , M. E. Palmieri b , M. Villa b , L. Tricarico b , S. Bruschi c , M. M. Tedesco d

a Department of Civil and Industrial Engineering, University of Pisa, Largo Lucio Lazzarino 2, 56122, Pisa, Italy b Department of Mechanics, Mathematic and Management, Polytechnic of Bari, Via Edoardo Orabona 4, 70125, Bari Italy

c Department of Industrial Engineering, University of Padova, via Venezia 1, 35131, Padova, Italy d Centro Ricerche Fiat S.c.p.A (CRF) - Stellantis, Corso Giovanni Agnelli 200, 10135, Turin, Italy

Abstract

© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers Multiphase steels enable the exploitation of the optimal characteristics of each microstructural component, resulting in a beneficial blend of mechanical strength and ductility and allowing lightweight design and vehicle emissions reduction. Quenching and Partitioning (QP) steels emerged as 3rd generation Advanced High-Strength Steels (AHSS) for automotive applications. Their microstructure is composed of low-carbon martensite and retained austenite, which provides an outstanding balance of strength and ductility but poses significant questions that currently limit its adoption in the automotive industry, primarily due to their inherent vulnerability to Hydrogen Embrittlement (HE) and delayed fracture. In this study, the interaction between hydrogen (H) and QP1180 AHSS was examined. Hydrogen diffusivity and trap energies were evaluated using Devanathan-Stachurski permeation and Thermal Programmed Desorption (TPD) tests. The as-received material did not present high-temperature peaks, suggesting that RA did not trap significant hydrogen in the measured condition. Tensile Slow Strain Rate Tests (SSRT) were conducted on electrochemically hydrogen-charged smooth specimens, with the effective hydrogen content measured via the hot extraction method for each specimen. Fractographic examinations using scanning electron microscopy revealed the influence of hydrogen on fracture behavior, showing a transition from ductile to predominantly brittle fracture modes at elevated hydrogen concentrations.

Keywords: hydrogen embrittlement; AHSS; SSRT; quenching and partitioning;

* Corresponding author. E-mail address: giuseppe.macoretta@unipi.it, carlomaria.belardini@phd.unipi.it

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers 10.1016/j.prostr.2025.12.363