A Nitrogen-Strengthened Austenitic Stainless Steel for Cryogenic Magnet Structures

Abstract

The General Klectric Company iK engaged in a major program of dovelopin;',, dcsi};ni"S anc ' ni.TniifacLnri.ng a larf;e riiiporconfluct". inft magnet in support of the Large Coil Program, which if; f mid oil by the U.S. Department of Energy aru! directed by the Oak Ridge Nation^] Laboratory. The: oval: ;!i:iped toroidal, in.ignei; vcighs approximately 'VJ7'kH, with hrirc d iamr-.tor;; of 3.35m and 2.35m; and is designed for a maximum magnetic field of 8T at: 30.65 kA. Limi tat ion:; on naf.net weight and available apace for .structural component;; coupled with extremely large magnetic force.. 1 , presented a major challenge in the selection of a mutable structural material. Detailed considerations of de;;ign and fabrication requirements of the coil resulted in the selection of Type 3161,M stainless stc^ol for major structural components. In support of the magnet development effort, an extensive test program was initiated to verify expected base metal properties, to develop weld processes and to establish weld and base metal design allowables. This paper presents the results of the test program which involved testing and evaluation of 25mm thick Type 316LN plate, shielded metal arc weld (SMAK) deposits selected for structural welds, gas tungsten arc t>/e.ld (GTAU) and gas metal arc weld (GMAW) deposits selected for seal welds. The welding development eEfort including measurements of impact properties at RT and 77K; chemical analyses; measurements of magnetic permeabilities and weld ferrite contents, metallographic and radiographic examinations of welds were performed at the Materials and

Flow and fracture of austenitic stainless steels at cryogenic temperatures

“…Figure B.26: Fracture toughness KJIc versus 0.2% offset yield strength of the material σY S . Comparison of the results obtained in this work for AISI 304L and AISI 316LN with experimental data taken from the works of Shimada et al (1987), Lee et al (1998), Purtscher and Read (1987), Park et al (2019), Morris Jr et al (1992), Murase et al (1993), Nyilas and Mitterbacher (2010), Chan et al (1994), Drexler et al(1994),Krauth and Nyilas (1980),Mazandarany et al (1980),Muster and Elster (1990),Nyilas and Yanagi (1989) andOgata et al (1992). The experiments taken from the literature and the results obtained in this work are represented with empty and filled symbols, respectively.…”

“…For the experiments performed in this work filled and empty symbols represent data points that fall inside and outside the "Region of Qualified Data", respectively, large darker symbols indicate the fracture toughness JQ, solid lines represent the power law regression fitting, and dashed lines correspond to the "construction line" and the "0. (1994), Krauth and Nyilas (1980), Mazandarany et al (1980), Muster and Elster (1990), Nyilas and Yanagi (1989) and Ogata et al (1992).…”

Flow and fracture of austenitic stainless steels at cryogenic temperatures

“…The general trend is that the fracture toughness decreases as the yield strength of the material increases, the data obtained in this paper being in reasonable qualitative agreement with the experiments taken from the literature. Murase et al (1993), Nyilas and Mitterbacher (2010), Chan et al (1994), Drexler et al (1994), Krauth and Nyilas (1980), Mazandarany et al (1980), Muster and Elster (1990), Nyilas and Yanagi (1989) and Ogata et al (1992).…”