scholarly journals Near-threshold fatigue crack growth of 316L stainless steel at liquid helium temperature.

1989 ◽  
Vol 38 (434) ◽  
pp. 1309-1315 ◽  
Author(s):  
Kenichi SUZUKI ◽  
Junichi FUKAKURA ◽  
Hideo KASHIWAYA
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Liquid Helium ◽  
316L Stainless Steel ◽  
Liquid Helium Temperature ◽  
Helium Temperature ◽  
Near Threshold

Fatigue Crack Growth Properties of a Cryogenic Structural Steel at Liquid Helium Temperature

1996 ◽  
Vol 118 (1) ◽  
pp. 109-113 ◽  
Author(s):  
Shinji Konosu ◽  
Tomohiro Kishiro ◽  
Ogi Ivano ◽  
Yoshihiko Nunoya ◽  
Hideo Nakajima ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Austenitic Stainless Steel ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Liquid Helium ◽  
Liquid Helium Temperature ◽  
Small Scale ◽  
Helium Temperature ◽  
Growth Properties

The structural materials of the coils of superconducting magnets utilized in thermonuclear fusion reactors are used at liquid helium (4.2 K) temperatures and are subjected to repeated thermal stresses and electromagnetic forces. A high strength, high toughness austenitic stainless steel (12Cr-12Ni-10Mn-5Mo-0.2N) has recently been developed for large, thick-walled components used in such environments. This material is non-magnetic even when subjected to processing and, because it is a forging material, it is advantageous as a structural material for large components. In the current research, a large forging of 12Cr-12Ni-10Mn-5Mo-0.2N austenitic stainless steel, was fabricated to a thickness of 250 mm, which is typical of section thicknesses encountered in actual equipment. The tensile fatigue crack growth properties of the forging were examined at liquid helium temperature as function of specimen location across the thickness of the forging. There was virtually no evidence of variation in tensile strength or fatigue crack growth properties attributable to different sampling locations in the thickness direction and no effect of thickness due to the forging or solution treatment associated with large forgings was observed. It has been clarified that there are cases in which small scale yielding (SSY) conditions are not fulfilled when stress ratios are large. ΔJ was introduced in order to achieve unified expression inclusive of these regions and, by expressing crack growth rate accordingly, the following formula was obtained at the second stage (middle range). da/dN = CJ ΔJmJ, CJ = AJ/(ΔJ0)mJ, where, AJ = 1.47 × 10−5 mm/cycle, ΔJ0 = 2.42 × 103N/m.

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