Showing papers by "Richard D. Sisson published in 1982"

Importance of stress state on hydrogen embrittlement

Abstract: The accurate assessment of the compatibility of metals and alloys with in-service hydrogen environments requires the ability to extrapolate short term laboratory test data to long term engineering applications. This extrapolation frequently requires the use of tensile and subsized fracture mechanics specimens to predict the behavior of large scale structural components. Both macroscopic and microscopic stress states in the test specimens may be quite different from those in the structural component; thus it is vital to understand the potential roles of stress state in the hydrogen embrittlement process. This paper demonstrates the importance of stress state in the assessment of hydrogen compatibility and shows that for safe, efficient materials utilization design data must be based on the results of several types of mechanical tests.

The effect of surface finish on the deformation characteristics of 1015 steel at 25°c

Abstract: Burst rupture tests performed on preflawed spheriodized 1015 steel discs pressurrized with hydrogen and oxygen gas have shown that hydrogen lowers the failure pressure, decreases fatigue life, promotes failure in a leak-before-burst mode, and changes the microscopic fracture mode Burst tests with unflawed samples of various surface finishes, ranging from 240 grit to 05 μ alumina polish, indicate that surface roughness plays a major role in determining whether samples tested in hydrogen failed by a leak or in a burst mode, rough surfaces promoting the failure by leaking However, no surface effect was seen on the failure mode of samples tested in oxygen