Investigation of cryogenic constructional materials for a fusion reactor

The physical and mechanical properties of 10 alloys have been measured to select the optimum materials for a superconducting magnet frame for fusion reactors. From the results of these measurements, In-625 has the highest value of electrical resistivity and thermal conductivity. Alloy 21-6-9, 2Cr 15 Mn 15 Ni 2N, GH 36 have low magnetic permeabilities at 293 K and 4.2 K (μ<1.005). Alloy 21-6-9 has the highest value of 0.2% proof stress at 4.2 K-1400 MPa, while tensile elongation is beyond 20%. From the results, alloy 21-6-9 is recommended. For decreasing the μ value and enhancing the toughness of the weld metal, a lower C content and a higher Ni content of the welding filler should be used in the welding of this alloy. (orig.)