关键词: 31608, 超低温；晶粒尺寸；冲击功；断口形貌

Abstract: The ultralow temperature impact tests for S31608 stainless steel(/%:0.065C,16.50Cr,11.80Ni,2.2Mo) Φ168 mm×13 mm extruded seamless pipe (solid-solution-treated at 1060- 1020 ℃ with grain size 50.2- 17.6 μm)at 20 ℃ and-40--269 ℃ are carried out, and the impact fracture is analyzed by scanning electron microscope. The results show that the S31608 steel has high impact energy i.e.290-360Jat-269-20 ℃,and only the grain size of steel has obvious effect on impact energy at -80℃ and- 120 ℃,the impact energy of steel with grain size 25.3-50.2 μm (solid-solution-treated at 1060- 1040℃)at-80℃ and- 120℃ is330-360J,but that of steel with grain size 17.6 μm(solid-solution-treated at1020℃)at-80℃ and- 120℃ is 320-360J.

Key words: S31608, Utra Low Temperature, Grain Size, Impact Energy, Fracture Morphology