Hydrogen Effects on X80 Steel Mechanical Properties Measured by Tensile and Impact Testing

Author

Xuan Li

Graduation Year

2016

Document Type

Thesis

Degree

M.S.M.E.

Degree Name

MS in Mechanical Engineering (M.S.M.E.)

Degree Granting Department

Mechanical Engineering

Major Professor

Alex A. Volinsky, Ph.D.

Committee Member

Wenjun Cai, Ph.D.

Committee Member

Rasim Guldiken, Ph.D.

Keywords

Hydrogen permeation, Cathodic charging, Hydrogen embrittlement, Slow strain rate tensile (SSRT) test, Charpy impact test

Abstract

The effect of hydrogen charging current density and tensile strain rate on the mechanical properties of X80 pipeline steel were investigated by slow strain rate test (SSRT), Charpy impact test, and scanning electron microscopy (SEM) in this thesis. The results show that both the ultimate tensile strength and elongation to failure of X80 steel were deteriorated significantly after charging with hydrogen. With a strain rate of 5 x 10^-5 s^-1, the relative tensile strength and plasticity loss of X80 steel had no significant change within the range of assumed hydrogen partial pressures at room temperature. At room temperature, X80 steel had no apparent variation in ultimate tensile strength and elongation, except at the strain rate of 10^-6 s^-1. Specimens obtained the greatest relative tensile strength loss and plasticity loss when strained at 10^-6 s^-1 with a current density of 4.6 mA/cm². The fracture morphology of two test groups of X80 steel exhibited significant brittle rupture when tested with dynamic hydrogen charging. The impact energy of X80 was not affected by hydrogen charging. Different current density also had no influence on the results of the impact test.

Scholar Commons Citation

Li, Xuan, "Hydrogen Effects on X80 Steel Mechanical Properties Measured by Tensile and Impact Testing" (2016). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/6110