Abstract:
The mechanical properties of T91/G102 dissimilar steel welded joint on firey side after running for 78 000 h were investigated by room-temperature tensile test, impact test, micro-hardness test and high temperature stress rupture test, and lifespan estimate. The results show that the tensile strengths of the T91 and G102 steel base metals met the requirements, while the tensile strength of welded joint was below the standard value; The impact toughnesses of two base metals were high, but the lowest values were given by the fusion lines in both G102 and T91 steel side ; The micro-hardness of the T91 steel base metal was basically the same as that of a new one, but that of the heat affected zone, weld and G102 steel base metal decreased significantly after running for long times; The lowest value of high temperature stress rupture property was displayed in the heat affected zone on the G102 steel side. Life prediction indicated that the remaining life of the welded joint on firey side could last 27 601 hours. But due to the worse properties of the heat affected zone and the weld seam, the reliability of safe running would be greatly reduced; The type of carbide precipitated in the heat affected zone of the G102 steel side was different from that of the T91 and G102 steel base metals.