Kinetics of methane bubble growth in a 1020 steel

Abstract

A 1020 carbon steel and a sensitive dilatometer have been used to study the changes in the kinetics, and morphology, of methane bubbles with temperature, methane pressure, and bubble size. The transition from roughly spherical bubbles at low methane pressure to lenticular ones at high pressure, as predicted by theory, has been demonstrated along with the predicted change in pressure exponent and activation energy. That is, at high pressures the rate of bubble growth increases as (P _{CH 4} ³ and exhibits an activation energy characteristic of surface diffusion, while at quite low pressures the pressure exponent is about 3/2 with an activation energy between that for grain boundary and lattice diffusion. When the lenticular bubbles grow to a diameter roughly equal to that of the grains, their growth kinetics change to be limited by the power law creep of the matrix.