scope:

This Bulletin reports a two-phase project on the use of low carbon 1-1/4Cr-1/2Mo filler metal to provide a basis for the use of lower hardenability characteristic deposits to enhance weld repair and to evaluate the weld deposit elevated temperature properties with and without PWHT. In Phase I, the efficacy was proven for repair of service exposed components as the testing of jumbo transverse weld specimens did not show rupture in the repair filler metal and rupture times exceeded the ASTM DS50 minimum times when the weld coupons were tested in the creep regime. A Phase II program on filler metal development to enhance the creep properties of the low carbon 1-1/4Cr-1/2Mo deposited weld metal by incorporating tungsten, niobium and vanadium additions. The program was successful in that weld metal creep behavior was improved to a level in excess of that of the base metal and no fabrication difficulties were evident. Thus, the basic work has been accomplished to permit the commercial development of Cr-Mo filler metals, which are fabrication friendly and have elevated temperature properties