18 research outputs found
The effects of cold working on sensitization and intergranular corrosion behavior of AISI 304 stainless steel
The effects of prior cold rolling of up to an 80 pct reduction in thickness on the sensitization-desensitization behavior of Type AISI 304 stainless steel and its susceptibility to intergranular corrosion have been studied by electrochemical potentiokinetic reactivation (EPR) and Strauss-test methods. The results indicate that the prior deformation accelerated the sensitization as compared to the undeformed stainless steel. The deformed Type 304 stainless steel experienced desensitization at higher temperatures and times, and it was found to be enhanced by increased cold deformation. This could be attributed to the increased long-range chromium diffusion, possibly brought on by increasing pipe diffusion and vacancies. The role of the deformation-induced martensite (DIM) and texture, introduced by uniaxial cold rolling, on the sensitization-desensitization kinetics has also been discussed. This study could not reveal any systematic relationship between texture and the degree of sensitization (DOS) obtained. The effect of DIM on DOS seems to be pronounced at 500 °C when the steel retained significant amounts of DIM; however, the retained DIM is insignificant at higher sensitization times and temperatures
Variational Approach to the Modulational Instability
We study the modulational stability of the nonlinear Schr\"odinger equation
(NLS) using a time-dependent variational approach. Within this framework, we
derive ordinary differential equations (ODEs) for the time evolution of the
amplitude and phase of modulational perturbations. Analyzing the ensuing ODEs,
we re-derive the classical modulational instability criterion. The case
(relevant to applications in optics and Bose-Einstein condensation) where the
coefficients of the equation are time-dependent, is also examined