Hydrogen Embrittlement Susceptibility of Bainitic versus Martensitic High Strength Steels

The objective of this investigation is to systematically quantify and compare the hydrogen embrittlement susceptibility of austempered (bainitic) steels to that of standard quenched and tempered (martensitic) steels used for manufacturing high strength mechanical fasteners. It has been shown that correctly high strength bainitic steels exhibit measurably superior ductility and toughness as compared to martensitic steels of the same chemistry. These improvements in mechanical properties have made bainitic steel a viable and attractive option for making ultrahigh strength fasteners (e.g., 1400 – 1800 MPa tensile strength). Standard tempered martensitic steel fasteners do not exceed 1400 MPa tensile strength. The improved mechanical properties of bainitic steels have led many in the fastener industry to assume that bainitic steels must also exhibit greater resistance to hydrogen embrittlement. However, thus far there have been are no systematic comparisons of both materials at equal strength and/or hardness.

Faculty Supervisor:

Stephen Yue

Student:

Partner:

IBECA Technologies Corp

Discipline:

Engineering

Sector:

Professional, scientific and technical services

University:

McGill University

Program: