Study On The Laves Phase Precipitation Behavior And Its Effect On Toughness Of 10cr-1mo Steel Weld Joint After Thermal Aging

In this paper, the Laves phase precipitation behavior and its effect on toughness of 10Cr-1Mo steel weld joint after different aging time at 600 ?C have been studied. The toughness of the base metal (BM) declined greatly at the first 1000 h aging, while the toughness of the weld metal (WM) kept stable before aged for 1000 h and fell sharply from 1000 h to 4000 h. The severe deterioration in toughness of BM when aged for 1000 h was resulted from the rapid precipitation of dense and small Laves particles. The main reason for the stable toughness of WM before 1000 h could be attributed to only a few Laves particles at this time due to the low nucleation rate of Laves phase during aging, which was related to low content of tungsten in WM. Compared with Laves phase in BM, Laves particles in WM were generally of larger size. In WM, the number of large Laves particles which could induce severe stress concentration increased continually during aging before 8000 h and caused significant decrease of toughness when aged for 4000 h.