超声表面滚压改善45#钢表层特性及疲劳性能的研究

目的研究超声表面滚压处理(Ultrasonic Surface Rolling Process,USRP)对45#钢表层特性及疲劳性能的影响。方法利用超声表面滚压设备处理45#钢,观察分析处理前后试样的表层特征、状态、微观结构,采用旋转弯曲疲劳试验研究试样疲劳性能,通过升降法测取疲劳极限值。结果 USRP处理后,试样表面形貌显著改善,表面粗糙度由之前的3.2μm降低到0.23μm,显微组织细化,晶粒取向趋于随机分布,表层显微硬度相比心部提高56%左右,强化层厚度可达400μm,残余压应力由-180 MPa提高到-532 MPa,疲劳极限值由296 MPa提高到403 MPa。结论通过USRP处理,试样的表层特性及表面性能得到强化改善。疲劳性能的提高主要归因于USRP处理使材料表面粗糙度降低,晶粒细化,显微硬度与残余压应力提高。

Research on Surface Characteristics and Fatigue Properties of 45# Steel by Ultrasonic Surface Rolling

To study the effect of surface characteristics and fatigue properties of 45#steel by ultrasonic surface rolling processed. The 45#steel was treated by USRP equipment, and the surface characteristics, state and microstructure of the before and after specimens were observed and analyzed by means of the corresponding measurement equipment. The fatigue properties of the specimens were measured by the rotary bending fatigue test, through the bruceton method to obtain the assessment of fa-tigue limits. After USRP treatment, the surface roughness Ra decreased from the previous 3.2 μm to 0.23 μm; grain refinement, the grain orientation tends to random distribution; the micro-hardness of the surface layer was about 56% higher than that of the heart; the thickness of the strengthening layer was up to 400 μm; the maximum residual compressive stress increased from -180 MPa to -532 MPa before the treatment and the fatigue limit of USRP specimens increased from 296 MPa to 403 MPa. Through USRP technology, the surface characteristics and surface properties of the 45#steel specimens were improved. The improvement of fatigue properties was mainly due to the combined effect of low surface roughness, grain refinement, the increase of the mi-crohardness and residual compressive stress.