Materials studies for magnetic fusion energy applications at low temperatures- I

Review of the Mechanical Properties of High-Strength Alloys at Cryogenic Temperatures

“…Significant temperature rise occurs in specimen during cyclic loading at 4.2 K. The magnitude of temperature rise increases with the increase of the test frequency and the strain range. 13,14 In order to suppress the specimen temperature as low as possible, the test frequencies at 4.2 K are chosen as follows: In load-controlled fatigue tests, for tension-tension mode, less than 5 Hz at a stress level of lower than yield strength and less than 1 Hz at a stress level of higher than yield strength; for tension-compression mode, less than 1 Hz at a stress level of lower than yield strength and less than 0.1 Hz at a stress level of higher than yield strength; and in strain-controlled fatigue tests, less than 4 × 10 −3 s −1 at a higher strain level.…”

“…27 Relationship between 0.2 % Proof Stress and Fracture Toughness at 4.2 K The relationship between 0.2 % proof stress and fracture toughness of nitrogen-strengthened austenitic steels at 4.2 K is summarized with the JARI-Box and NIST trend in figure 2. 13,28,29 The NIST trend for 300 series represents this relationship and exhibits a trade-off relationship. High-manganese austenitic stainless steel JK2LB (22Mn-13Cr-9Ni-1Mo-0.12N-0.003B) 30 was chosen as the ITER central solenoid conductor.…”