A286 alloy and 304LN stainless steel were chosen for support struts used in the construction of a mirror fusion testing facility, which is subjected to the cryogenic temperature. Electroslag remelting technology (ESR) was adopted to manufacture A286 alloy. A program was initiated to investigate the cryogenic mechanical properties with emphasis on the effect of the grain size of A286 alloy.
The test results revealed that: (1) A286 alloy showed little effect of grain size on the tensile properties, while the fracture toughness properties were affected by the grain size, especially at 4 K; (2) 304LN stainless steel produced almost the same tensile and fracture toughness properties as A286 alloy.
The temperature dependence of the mechanical properties of 304LN stainless steel and A286 alloy also is discussed. The support strut forgings produced excellent quality, and the proof load test results were indicative of the no plastic deformation during applications.