GB682936A - Improvements in or relating to welded joints between austenitic and ferritic metal members - Google Patents

Abstract

682,936. Welding by fusion. BABCOCK & WILCOX, Ltd. June 20,1951 [June 20, 1950], No. 14624/51. Class 83 (iv). A welded joint uniting a ferritic alloy member to an austenitic alloy member includes a stabilized ferritic zone intermediate the members. The stabilizer for the ferritic zone may be columbium, titanium, zirconium, cerium, tungsten, boron, tantalum or vanadium. In one embodiment of a joint operating under high pressure and temperature, as for example in a steam generating plant, a pipe of ferritic steel, 2“ per cent Cr, 1 per cent Mo, is welded to an austenitic steel pipe by a deposit of ferritic steel which may have the same composition as that of the ferritic steel pipe but which is stabilized by columbium. In a modification a ferritic steel pipe 10, Fig. 2, is welded by a deposit 15 of non-stabilized ferritic steel to a stabilized ferritic insert 40 which is itself welded to an austenitic pipe 20 of composition 19 per cent Cr-9 per cent Ni stabilized with Cb; 25 per cent Cr, 20 per cent Ni; or 80 per cent Ni, 20 per cent Cr, by an austenitic deposit 25 having a composition similar to that of the pipe 20 but which may be stabilized with columbium. In a further embodiment a ferritic pipe 50, Fig. 4, has deposited thereon a ferritic steel 55 of substantially the same composition as that of the pipe 50 but which is stabilized with columbium. This deposit 55 is bevelled at 56 to form a groove with an austenitic pipe 60 in which groove is deposited austenitic steel 65 which may have a composition the same as that of the pipe 60 but which is preferably stabilized with columbium. Welding may be effected by the process of shielded metal arc, atomic hydrogen, inert gas shielded arc or submerged arc.