The changing regularity of mechanical behavior and the creep rupture properties of boiler tubes made from 18-8 type austenitic stainless steel in servicing process have been studied

results show that the tensile strength and the hardness value under room temperature of said boiler tubes in servicing process in general have a rising tendency along with the lengthening of servicing time

but the variation of yield strength isn't remarkable;during the end period of servicing life

the strength and hardness value may suddenly reduce

the specific elongation after rupture

the shrinkage rate of cross-section

and the energy absorbed by impact

in general

have a decreasing tendency along with lengthening of the servicing life;along with lengthening of creep rupture life

the austenitic stainless steel appears sequencially three kinds of creep rupture modes from the grain-penetrating rupture to the along grain rupture.