High Temperature Strength of Dissimilar Welded Joint

Abstract

The present study was carried out to examine the tensile strength, creep rupture strength and cyclic creep rupture strength of dissimilar metal welded joint. To prepare test pieces, 2 1/4 Cr-1 Mo steel and 18 Cr-8 Ni-Cb steel or 18 Cr-8 Ni-Ti steel plates were welded with Inconel, 50 Ni-10 Cr-2 Mo, 25 Cr-20 Ni, 19 Cr-8 Ni-1 Mo and 16 Cr-8 Ni-2 Mo electrodes. These various dissimilar welded joints were tested as welded and after post heat treatment at 650°C for 3 hours and at 720°C for 1 hour. The results are summarized as follows:
1) The specimen welded with 50 Ni-10 Cr-2 Mo electrode fractures at the weld metal or 21/4 Cr-1 Mo base metal, but those specimens welded with other electrodes fracture at 214 Cr-1 Mo base metal in the tensile test at room temperature and 600°C.
2) Creep rupture strength of an as-welded specimen is higher than that of a post heat treated specimen in a shorter time test at 600°C, but in a longer time test, the creep rupture strength of a post heat treated specimen is higher than that of the as welded specimen.
3) Creep rupture strength of 720°C×1 h post heat treated specimen with Inconel is the highest of all other specimens in long time tests.
4) When temperature and load cycle are imposed in a creep rupture test, the rupture strength of an as-welded specimen is higher than the ordinary creep rupture strength, but the rupture strength of 720°C×1 h post heat treated specimen is lower than the ordinary creep rupture strength.