Research On High Temperature Oxidization Property Of GH4169 And 1Cr17 With Nano-sized Surface

Surface peening is one of the effective methods of surface modification technique for metal due to its advantages such as simplicity of operation,energysa-save,efficient and wide-application. The nano-layer formed through surface peening can promote not only the nucleation of oxide during high-temperature oxidization but also the diffusion of alloying agent such as Cr from bulk to interface bulk/oxide so as to increase the content of Cr & density of surface oxidate layer and its anti-oxidation property.In this article, nano-structure surface layer was prepared through high-energy peening plastic formation method on GH4169 high-temperature alloy and 1Cr17 ferrite non-rust steel. then high-temperature resistance oxidization testing was done and the morphology & composition of nano-sized surface layer and surface oxidization layer were analyzed through XRD,TEM,SEM,EDX and micro-hardness.The results indicates that surface nanocrystallization of GH4169 high-temperature alloy was realized and surface layer grain size was 58.25nm approximately using under-mentioned peening processing parameter : quenchedΦ1mm sized Cr-Mo alloy steel shot, 55m/s velocity and peening for 5 min. As the peening time prolong, the grain size decreased gradually, the surface grain size was 17.83nm approximately when peening for 180 min.Hardness of GH4169 sample surface layer was increased significantly through different high energy peening. The micro-hardness of sample surface layer was 310HV without peening and 600HV with peening for 180 min and the depth of harding layer was 550um approximately. Even peening for 30 min, the micro-hardness was 460 HV, the harding layer was 230um.The main surface oxide was Cr2O3 when GH4169 was oxidized at high temperature, surface oxide nucleate and grow at the grain-boundary first when the sample without peening was oxidizated at high temperature, As the oxidizating time prolongs or the oxidizating temperature increases, oxide will cover the whole surface gradually. surface oxide grows evenly then cover the whole surface when peened sample was oxidized at high temperature.When 1Cr17 sample without peening,nano-sized sample and nano-sized annealed sample of 1Cr17 was oxidized 1min under atmosphere at 600℃, the surface has been oxidized. Minute quantity thin acicular oxide can be seen at part of the surface of nano-sized sample and nano-sized annealed sample when oxidized 3 min, while the oxide can only be seen after 30 min oxidization at samples without nanocrystallization.