Use of heavy section austenitic welds for 4-K service

This report covers the weldment properties and materials associated with the Euratom coil for the Large Coil Task development. The material for the casing of this D-shaped coil is a fully austenitic stainless steel made in Germany and similar to AISI 316LN. Construction of the casing requires roughly 50-mm-thick austenitic weldments with an overall weld length in the neighborhood of 100 m. The composition of a number of deposited weld metals and their calculated chromium and nickel equivalents are tabulated. Testing for Charpy impact energy, Vickers hardness, elongation, yield strength, and Young's modulus is performed on these metals, available commercially in the form of electrodes. The results at 4 K were an increase of yield strength of roughly 4% and of ultimate strength of roughly 10% over those properties in the parent metal accompanied by an approximately 35% decrease in brittle fracture toughness. Optimization of the yield strength and toughness level seems to be attainable by the proper balancing of manganese and nickel