The need for alternate energy sources has led to the develop ment of prototype fusion and MHD reactors. Both possible energy systems in current designs usually require the use of magnetic fields for plasma confinement and concentration. For the creation and maintenance of large 5 to 15 tesla magnetic fields, supercon ducting magnets appear more economical. But the high magnetic fields create large forces, and the complexities of the conceptual reactors create severe space restrictions. The combination of re quirements, plus the desire to keep construction costs at a mini mum, has created a need for stronger structural alloys for service at liquid helium temperature (4 K). The complexity of the required structures requires that these alloys be weldable. Furthermore, since the plasma is influenced by magnetic fields and since magnet ic forces from the use of ferromagnetic materials in many configur ations may be additive, the best structural alloy for most applica tions should be nonmagnetic. These requirements have led to consideration of higher strength austenitic steels. Strength increases at low temperatures are achieved by the addition of nitrogen. The stability of the austenitic structure is retained by adding manganese instead of nickel, which is more expensive. Research to develop these higher strength austenitic steels is in process, primarily in Japan and the United States.

Contenu

The Properties of Austenitic Stainless Steel at Cryogenic Temperatures.- Development of Cryogenic Structural Materials for Tokamak Reactor.- Martensitic Transformations in Fe-Cr-Ni Stainless Steels.- The Influence of Martensitic Transformati.on on Strength and Plasticity of Fe-Cr-Ni Alloy Single Crystals.- Austenitic-Steel Elastic Constants.- Temperature Dependence of Flow Strength of Selected Austenitic Stainless Steels.- Cryogenic Properties of Austenitic Stainless Steels for Superconducting Magnet.- Factors Influencing the Low-Temperature Dependence of Yielding in AISI 316 Stainless Steels.- Toughness and Fatigue Properties of Austenitic Steels at Cryogenic Temperature and Their Application in Complex Structures.- Automated Near-Threshold Fatigue Crack Growth Rate Testing of JBK-75 Stainless Steel at Cryogenic Temperatures.- Effects of Magnetic Field on Tensile Behavior at 4 K of Alloys 304 and 310.- Effects of Magnetic Fields on Martensite Transformations and Mechanical Properties of Steels at Low Temperatures.- Effect of EB-Weld and Cold-Rolling on Low Temperature Strength and Toughness of Austenitic Stainless Steels.- The Effect of c-Ferrite upon the Low Temperature Mechanical Properties of Centrifugally Cast Stainless Steels.- The Mechanical Properties of Stainless Steel Castings at 4 K.- Heat Treatments to Desensitize and Remove Delta Ferrite from a 21Cr-6Ni-9Mn Stainless Steel Intended for the Fabrication of Aerofoil Models for Cryogenic Wind Tunnels.- Preliminary Study on Structural Material Selection for Large Superconducting Magnets.- Low Temperature Mechanical and Physical Properties of Age-Hardened Fe-Ni-Cr-Mn Alloys.- Automated Near-Threshold Fatigue Crack Growth Rate Testing of JBK-75 Stainless Steel at Cryogenic Temperatures.- Low Temperature Properties of High-Manganese-Molybdenum Austenitic Iron Alloys.- Structure and Mechanical Properties of High-Alloy Manganese-Aluminum Steels for Cryogenic Applications.- Fracture Properties of a 25Mn Austenitic Steel and Its Welds at 4 K.- The Weldability of 25 Mn Steel.- Instrumented Charpy Impact Tests at Low Temperatures for Several Steels.- Temperatures for Several Steels.- GRI's Research Program on Crack Initiation and Arrest Properties of 9% Nickel Steels Used in LNG Storage Vessels.- Indexes.- List of Contributors.- Alloy Index.