In connection with the possibility of embrittlement upon extended exposure to temperatures of 500 to 600 C of welds in stainless steel vessels of sodium cooled fast neutron reactors, the behavior of weld deposits from four lots of electrodes was tested. The tests included room temperature ductility determinations after exposure between 10 and 10,000 hr to temperatures of 450 to 900 C and metallographic examination. Data are presented and discussed and extrapolated to 100,000 hr.