Effect of Chronium on Hydrogen Environment Embrittlement of Fe-Cr Alloys

Abstract

Tensile properties of Fe Cr alloys of chromium content up to 30 were investigated from 1.1 to 39.3 MPa of hydrogen and in 0.6 MPa of argon at room temperature by using a specially designed equipment. The results obtained are as follows.1. Annealed Fe Cr alloys of Cr content up to 30 Elongation and reduction of area of the annealed alloys decreased with increase in hydrogen pressure, while hydrogen showed no effect on 0.2 proof stress and tensile strength. Hydrogen environment embrittlement (HEE) was minimized at 4～ 8 of chromium content, and HEE increased with increase in chromium content above 12. It is considered that the crack formed by hydrogen on the surface propagated rapidly, when plastic deformation occurred near the maximum load point in stress strain diagram.2. Fe Cr alloys of 16～30Cr content aged at 748 K Hydrogen susceptibility of aged alloys of 16 to 20 chromium content from was larger than that of annealed alloys, and HEE behavior was the same as that of annealed ones. In the aged alloys of 25 to 30 chromium content, the tensile strength, elongation and the reduction of area greatly decreased with increase both in hydrogen pressure and chromium content, while hydrogen showed no effect on 0.2 proof stress. It is considered that the aging at 748 K enhanced the cleavage fracture sensitivity, and a small crack formed by hydrogen with small plastic deformation induced the cleavage fracture easily, thus the aging at 748 K increased the HEE sensitivity.

Influence of high pressure hydrogen environment on tensile and fatigue properties of stainless steels at low temperatures

“…Meta-stable austenitic stainless steel, SUS304L, showed remarkable hydrogen environment embrittlement in relative reduction of area at low temperature around 190 K [7][8][9]11], which is due to the increase of strain-induced martensitic phase during plastic deformation at the temperatures. In SUS304L, the amount of the martensitic phase increased with decreasing temperature at 40 % plastic strain and was almost 100 % below 200 K [13].…”

“…A hydrogen environment causes embrittlement at ambient temperature [6] and low temperatures [7][8][9] down to 80 K under 1.1 MPa gaseous hydrogen. However, no tensile or fatigue data is available neither for the higher pressure hydrogen and low temperature environments nor fatigue properties.…”

Hydrogen Embrittlement Evaluation in Tensile Properties of Stainless Steels at Cryogenic Temperatures

“…A hydrogen environment causes hydrogen environment embrittlement at ambient temperature [6] and low temperatures [7][8][9] down to 80 K under 1.1 MPa gaseous hydrogen. Hydrogen environment embrittlement of the materials which are not hydrogen-charged but are used under high pressure hydrogen environment is of concern.…”

Hydrogen Environment Embrittlement Evaluation in Fatigue Properties of Stainless Steel Sus304l at Cryogenic Temperatures

“…For 20 K fatigue testing it was determined that specimen heating was not an issue when the test frequency was below 3 Hz and thus the 20 K tests reported here are performed at 2 to 3 Hz. Meta-stable austenitic stainless steel, SUS304L, showed remarkable hydrogen environment embrittlement in relative reduction of area at low temperature around 190 K [7][8][9]11], which is due to the increase of strain-induced martensitic phase during plastic deformation at the temperatures. In SUS304L, the amount of the martensitic phase increased with decreasing temperature at 40 % plastic strain and was almost 100 % below 200 K [12].…”