The effects of solution treatment on the mechanical properties and microstructure of 309 S stainless steel plate were investigated by OM（optical microscopy）

SEM（scanning electron microscopy）

room temperature tensile and micro-hardness test.The results show that the volume fraction of ferrite phase in the 309 Ssteel is obviously reduced from 11.6% to 7.3% after solution treatment.The increase of solution temperature and time can be beneficial for both the dissolution of carbide and austenite grain growth.In addition

strength and micro-hardness of the 309 Sstainless steel are decreased with increasing in hold time.With solution at 1 100℃for 20 min and then water cooling

the yield strength

ultimate tensile strength

micro-hardness and elongation of the 309 Sstainless steel reach 259.71 MPa、575.31 MPa、178.7 HV

0.2

and 58.4%

respectively.The fracture of the specimen is characterized by ductile dimple

and toughness of the specimen after solution treatment is better than that of the hotrolled sheet.