【作者】 冯帅；

【导师】 赵秀娟；

【作者基本信息】 大连交通大学 ， 材料学， 2008， 硕士

【摘要】 表面喷丸具有操作简单、耗能少、效率高、适用面广等优点,是金属表面改性技术的有效手段。表面喷丸形成的纳米层能够促进金属在高温氧化过程中氧化物的形核,促进Cr等合金元素在氧化过程中由基体向基体/氧化物界面的扩散,从而提高表层氧化膜中的Cr含量及其致密度,使抗氧化性能得到提高。本文对GH4169高温合金和1Cr17铁素体不锈钢用高能喷丸塑性变形方法制备出纳米结构表层,并进行了耐高温氧化性试验,用X射线衍射仪(XRD)、透射电镜(TEM)、显微硬度、扫描电镜(SEM)及能谱(EDX)对纳米化表层和表层氧化膜组织形态与成分进行了分析,研究结果表明:应用下述喷丸工艺参数:直径Φ1mm的淬火铬钼合金钢丸,弹丸速度为55m/s;喷丸5min实现了GH4169高温合金的表面纳米化,表层晶粒尺寸约58.25nm,随着时间的进一步延长,晶粒逐渐细化,在喷丸180min时,表层晶粒尺寸约为17.83 nm;GH4169经过不同工艺高能喷丸后的样品表面硬度都有显著的提高,未喷丸样品表层的显微硬度为310HV;喷丸180 min样品表层显微硬度可达到610HV,硬化层深度可达约550μm;喷丸30 min样品表层显微硬度也达到了460HV,硬化层深度约230μm;GH4169高温氧化时表面产生的氧化物主要是Cr2O3;未喷丸样品经高温氧化时表面氧化物首先在晶界形核、长大,随着氧化时间的延长或氧化温度的升高,氧化物逐渐覆盖整个表面;纳米化样品经高温氧化时表面氧化物均匀的生长,覆盖整个表面;1Cr17未喷丸样品、纳米化样品和纳米化后退火样品在600℃空气中氧化1min后,表面已经被氧化;纳米化样品和纳米化后退火样品氧化3min时在表面局部观察到极少量、细小的针状氧化物,而未纳米化样品在氧化30min时才能观察到片状氧化物;更多还原

【Abstract】 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.更多还原