Diagram of plastic material transition into brittle state under hydrogen saturation

V I Mironov,O A Lukashuk,I G Emel’Yanov

doi:10.1088/1757-899x/862/2/022020

Abstract

Major progress made in theoretically describing the behavior of a «hydrogen-metal» system still fails to unambiguously explain the phenomenon of hydrogen brittleness in metals. It follows that a phenomenological approach is appropriate to describe the transition of a plastic material into its brittle state with the growth of hydrogen concentration. A diagram for such a transition is plotted on the basis of known experimental data on how hydrogen affects mechanical properties of structural steels. It is intended for the purposes of predicting the behavior of fracture observed in elements of metal structures under peak overloads or normal operation. A post-publication change was made to this article on 11 Jun 2020 to correct the pdf so that it matched the webpage.

Highlights

Hydrogen, as a rule, has a destructive effect on materials of metal structure elements, diminishing both their short-term and long-term mechanical characteristics
It follows that a phenomenological approach is appropriate to describe the transition of a plastic material into its brittle state with the growth of hydrogen concentration
It is intended for the purposes of predicting the behavior of fracture observed in elements of metal structures under peak overloads or normal operation

Summary

Introduction

As a rule, has a destructive effect on materials of metal structure elements, diminishing both their short-term and long-term mechanical characteristics. It remains topical to determine the conditions for transition of an initially plastic material into the brittle state under hydrogen impact. A well-known diagram of A.F. Ioffe defines the conditions for transition of a material from its ductile state into a brittle one due to lowered temperature [7]. The diagram of ductile-brittle transition with the rise of hydrogen concentration in a structural material is considered. 2. Diagram of ductile-brittle transition of 25HNMA steel under electrochemical hydrogen saturation Tensile tests of hydrogen-saturated metal specimens show that when hydrogen concentration grows ultimate and yield strengths change ambiguously. Earlier papers concerning hydrogen impact on mechanical properties of structural steels and alloys note fall in ultimate strength and plasticity indicators, rise in yield strength, insignificant decrease in modulus of elasticity with the growth of hydrogen concentration in a metal.

Published under licence by IOP Publishing Ltd

Conclusion