In　this　paper,　inertia　friction　welding　(IFW)　is　used　to　enable　a　high-quality　and　efficient　joint　between　2205　duplex　stainless　steel　and　316　L　stainless　steel.　Specifically,　stainless　steel　bars　(2205/316　L)　with　a　diameter　of　35　mm　and　length　of　120　mm　are　used.　In　addition,　the　effect　of　IFW　speed　on　the　microstructure　and　properties　of　welded　joints　is　assessed　using　scanning　electron　microscopy,　electron　backscattered　diffraction,　energy　dispersive　X-ray　spectroscopy,　microhardness　test,　and　tensile　tests.　The　results　indicate　that　dynamic　recrystallization　of　the　microstructure　of　joints　occurs　during　IFW　welding,　which　causes　grain　refinement.　The　diffusion　of　Ni　from　the　316　L　base　metal　to　the　2205　base　metal,　as　well　as　the　diffusion　of　Cr　from　the　2205　base　metal　to　the　316　L　base　metal,　results　in　a　strong　metallurgical　bond　between　the　two　materials.　In　addition,　the　microhardness　of　the　welding　area　exceeds　that　of　the　base　metal　(the　closer　to　the　weld　zone,　the　greater　the　microhardness　value).　The　tensile　strength　of　the　joints　initially　increases　with　increasing　IFW　speed,　but　then　it　starts　decreasing　beyond　a　certain　point.　The　optimal　welding　parameters　for　achieving　high-quality　joints　between　2205　duplex　stainless　steel　and　316　L　stainless　steel　are　as　follows:　axial　pressure　=　5　MPa,　rotational　inertia　=　4.17　kg.m(2),　and　IFW　speed　=　2700　r/min.