后混合水射流喷丸工艺对18CrNiMo7-6渗碳钢表面性能的影响

目的探究不同后混合水射流喷丸工艺对18Cr Ni Mo7-6渗碳钢表面性能的影响。方法运用超景深三维显微系统、三维表面形貌测量系统、X射线残余应力分析仪及HV-1000显微硬度计等,对后混合水射流喷丸前后试样的表面形貌、表面粗糙度、残余应力及显微硬度随层深的变化情况进行分析。结果后混合水射流喷丸时,弹丸和水会对试样表层产生一定的冲蚀、磨损、剪切作用,使试样表面产生新的凹坑。表面粗糙度Ra值随着喷射压力P及喷射靶距H的增加而增大,随着喷嘴移动速度v的增加而减小。试样显微硬度最大值都出现在表面,且随层深的增加,硬度值逐渐减小,喷射压力P=300 MPa时,表面硬度值达到62.8HRC,比试样初始表面硬度值增加了7.35%。试样材料所能引入的残余压应力具有固有最大值σmirs,当引入的残余压应力未达到σmirs时,所产生的最大残余压应力值σmcrs随喷射压力P的增加而增大,但随喷射靶距H和喷嘴移动速度v的改变变化不大。当引入的残余压应力达到σmirs时,所产生的最大残余压应力值σmcrs即为σmirs,不再改变,但是最大残余压应力距表面距离值zm仍会随着喷射压力P的增加而增大。结论后混合水射流喷丸后,试样表面粗糙度变化较大,表层显微硬度有一定提高。残余应力的分布主要与喷射压力P有关,而与喷射靶距H和喷嘴移动速度v关系不大。

Effects of Post-mixed Water Jet Shot Peening Process on Surface Properties of 18CrNiMo7-6 Carburizing Steel

The work aims to explore effects of post-mixed water jet shot peening process on surface properties of 18CrNiMo7-6 carburizing steel. Changes in surface morphology, surface roughness, residual stress and microhardness of the specimen before and after post-mixed water jet shot peening as layer depth varied were analyzed with 3D microscope system, 3D surface morphology measuring system, X-ray residual stress analyzer and HV-1000 micro-hardness meter. During the post-mixed water jet shot peening, projectile and water would have erosion, wear and shearing effects on specimen surface, produces new pits on the surface.The surface roughness Ra increased as injection pressure P and injection target distance H in-creased, and it decreased as nozzle velocity v increased. The maximum microhardness appeared on the specimen surface, and the microhardness decreased as layer depth increased. When the injection pressure P was 300 MPa, the surface microhardness reached 62.8HRC, 7.35% higher than initial surface hardness value of the specimen. Residual compressive stress had a maxi-mum inherent value σmirs. When the introduced residual compressive stress was below σmirs, the maximum residual compressive stress σmcrsincreased as the injection pressure P increased, but changed slightly as jet standoff distance H and nozzle movement speed v varied. However, when the introduced residual compressive stress reached σmirs, the produced maximum residual com-pressive stress σmcrsequaled σmirs, but distance zmbetween the maximum residual compressive stress and the specimen surface still increased as the injection pressure P increased. After post-mixed water jet shot peening, specimen surface roughness changes greatly, microhardness increases to a certain degree, and the distribution of residual stresses is mainly related to the in-jection pressure P instead of jet standoff distance H and nozzle movement speed v.