Computer Simulation of Deformation Behavior of 300 Series Stainless Steels in Liquid Hydrogen

Austenitic 304L and 316L steels are important structural materials for containers, tubes and various fields of liquid-hydrogen engineering. But the number of researches on deformation behavior of such steels in liquid hydrogen is much limited comparing to that in liquid helium. Therefore, in the present work, computer simulation of tensile test was carried out for 304L, 316L and 310S steels in liquid hydrogen in order to understand the basic of the deformation of these steels in liquid hydrogen. Tensile tests were conducted under the condition of the constant cross-head speed using round bar specimens. The procedure of computer simulation was almost same as that used in previous works by the present authors. Practical tensile tests did not show serration on the stress-elongation curves of all three steels up to about 40% elongation but thereafter exhibit sudden noticeable serration. However, computer simulation could not reveal such deformation behavior using previous calculation conditions. After discussing the effects of calculation conditions, it was known that the serration which is similar to that observed on the practical stress-elongation curves could be revealed by changing the boiling behavior of liquid hydrogen on the specimen surface. Following such simulation results, it was suggested that the transition from nucleate to film boiling of liquid hydrogen occurs easier than that reported by Brentari et al. The effect of deformation twin on the serration was also discussed, although the details have not been clarified.