Phenomenon of embrittlement in titanium shells from hydrogen exposure

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

doi:10.1088/1757-899x/537/2/022067

Abstract

Increasing the reliability of equipment used for production, transportation, storage and utilization of hydrogen is directly related to solving the problem of hydrogen embrittlement of metals. Without a fundamental physical theory, it is necessary to predict the bearing capacity of metal structures on the basis of obtained experimental data on the effect which hydrogen have on metal properties. This paper presents a solution (based on the method of discrete orthogonalization proposed by S.K. Godunov) of a physically-nonlinear problem of stress distribution in a titanium shell. Since hydrogen, most notably, reduces plastic properties of metals utilized in structural elements, a critical point was determined where the intensity of shear deformation is maximal. It was found how the intensity changes at a critical point of a shell if the pressure within the device rises to an emergency level. Such a rise of the pressure in the shell could lead to appearance of plastic deformation regions, and hydrogen exposure is manifested in reduced breaking stress and changed fracture pattern.

Highlights

Negative effect which corrosive medium has on mechanical properties of metals used in structural elements is one of the major factors determining designed and remaining service lives of many potentialaccident objects
Most notably, reduces plastic properties of metals utilized in structural elements, a critical point was determined where the intensity of shear deformation is maximal
It was found how the intensity changes at a critical point of a shell if the pressure within the device rises to an emergency level

Summary

Introduction

Negative effect which corrosive medium has on mechanical properties of metals used in structural elements is one of the major factors determining designed and remaining service lives of many potentialaccident objects. It should be reminded that hydrogen interaction with titanium alloys could change their mechanical properties both in a positive and negative manner [4, 5]. It is known that the diffusion equation is completely identical to the heat conduction one [6, 7, 8]. The methods of solving the problems of diffusion and heat conduction are the same. The boundary conditions for the problem in question would be represented by values of hydrogen concentration c, which should be known for a shell surface if one considers certain physical aspects [6]. When Kirchhoff–Love hypothesis are used, an axisymmetric stress state of thin-walled structures is expressed by a system of ordinary differential sixth-order equations [9, 10, 13, 14]

PijY f

Findings

Conclusion