Hydrogen compatibility handbook for stainless steels

Abstract

This handbook compiles data on the effects of hydrogen on the mechanical properties of stainless steels and discusses this data within the context of current understanding of hydrogen compatibility of metals. All of the tabulated data derives from continuing studies of hydrogen effects on materials that have been conducted at the Savannah River Laboratory over the past fifteen years. Supplementary data from other sources are included in the discussion. Austenitic, ferritic, martensitic, and precipitation hardenable stainless steels have been studied. Damage caused by helium generated from decay of tritium is a distinctive effect that occurs in addition to the hydrogen damage from tritium which is the same as for the other hydrogen isotopes protium and deuterium. The handbook defines the scope of our current knowledge of hydrogen effects in stainless steels and serves as a guide to selection of stainless steels for service in hydrogen.

The effects of hydrogen on the fracture toughness properties of upset welded stainless steel

“…This exposure saturated the samples with approximately 9500 atomic parts per million and is typically used to test the susceptibility of a-steel to hydrogen embrittlement (6). The samples were then tested in three-point bending at room temperature in air using an Tnstron Model 1125 Tension-Compression machine.…”

Hydrogen Effects on Fracture Toughness of Type 316L Stainless Steel From 175 K to 425 K

“…Furthermore, another study shows that elongation of non-charged and hydrogen-charged Type 316 stainless steel bar stock increases along with yield strength and ultimate strength at low temperatures [10]. The increase in toughness and elongation with increasing yield strength apparently result from the fact that the plastic deformation behavior of meta-stable austenitic stainless steels changes from slip at high temperature to deformation dominated by martensitic transformation at low temperature [11,12]. This fundamental change in the plastic deformation behavior of Type 316L stainless steel with temperature is the most likely reason for the increase in fracture toughness with decreasing temperature seen in this study.…”

“…Figure 15 indicates that at low temperature the larger voids link up by void sheets; whereas at higher temperature they appear to link up by void growth. Because tensile strength decreases with increasing temperature in Type 316L stainless steels [10, 11,15], the linking up of voids would be easier at higher temperature because the tensile strength of the ligament between growing microvoids would be lower. Crack advance occurs when a significant number of microvoids link up across the crack front.…”

“…1 in hydrogen-exposed Fe-Cr-Ni alloys to the formation of straininduced martensite [1,11]. The less stable alloys were more affected by hydrogen.…”

“…Type 316L stainless steel will transform to martensite under strain at low temperature [11] and the elongated features describe above as enhanced void coalescence might actually be separation along the austenitemartensite interfaces.…”