Welding of austenitic stainless steel for 4-K service

The objective of the work reported here is to review, develop, and implement high deposition rate welding processes for the fabrication of 4-K superconducting magnets. The processes presented are GTAW, FCAW, GMAW, and SAW. The application of these processes to particular manufacturing projects such as the LCP and the MFTF are given. The filler alloys used to determine such properties as arc deposition rate and utilization factor are 308L and 316L in both transverse and longitudinal applications. It is concluded that FCAW transverse yield strengths over 100 ksi at 4 K make this process both desirable and satisfactory in the current production of magnets. SAW appears to be suitable also for designs with yield strength requirements of 90 ksi at 4 K. Both of these processes are position-limited to flat or horizontal, however; for out-of-position welding, the development of a GMAW process with small diameter wire (0.030-0.063 in) appears to have the most promise