Effects of Hydrogen Environment on Fatigue Characteristics of 18Cr-8Ni Stainless Steel

2005 ◽  
Vol 482 ◽  
pp. 283-286 ◽  
Author(s):  
Kyohei Kawamoto ◽  
Y. Aoki ◽  
Yasuji Oda ◽  
Takeshi Yoshimura ◽  
Hiroshi Noguchi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Strain Range ◽  
Fatigue Tests ◽  
Hydrogen Gas ◽  
In Situ Observation ◽  
Nitrogen Gas ◽  
Fatigue Characteristics

In order to clarify the effects of hydrogen on the fatigue characteristics of an austenitic stainless steel, bending fatigue tests were conducted in air, in a hydrogen gas and in a nitrogen gas. Main results obtained are as follows. Effects of hydrogen gas environment are not clearly seen on the strain range - fatigue life diagram, because there are opposite effects to crack propagation and to crack initiation; accelerates crack propagation, but retards crack initiation. Striation spacing or in-situ observation confirms the acceleration. The retardation seems to be attributed to the absence of oxygen or water vapor in the hydrogen gas.

Effects of Hydrogen Gas Environment on Non-Propagation Phenomena of a Type 304 Austenitic Stainless Steel

2005 ◽  
Vol 297-300 ◽  
pp. 927-932 ◽  
Author(s):  
Y. Aoki ◽  
T. Matsuyama ◽  
Yasuji Oda ◽  
Kenji Higashida ◽  
Hiroshi Noguchi
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Level ◽  
Fatigue Tests ◽  
Hydrogen Gas ◽  
In Situ Observation ◽  
Nitrogen Gas ◽  
304 Austenitic Stainless Steel ◽  
Type 304

In order to investigate the hydrogen gas effect on non-propagation phenomena of a type 304 austenitic stainless steel, fatigue tests with in-situ observation using a Scanning Laser Microscope were performed in air, in 0.18MPa hydrogen gas and in 0.18MPa nitrogen gas. A nonpropagating crack was observed during the fatigue test in air. At almost the same stress level of non-propagating in air, non-propagating cracks were also observed in fatigue tests in hydrogen and in nitrogen. Stress level of the non-propagation is not sufficiently different in the three environments. However, the process up to non-propagation differs from each other, for example, the crack path and debris.

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