磁痕显示对激光强化17-4PH叶片力学性能的影响

Effects of Magnetic Mark Display on Mechanical Properties of Laser-Enhanced 17-4PH Blades

为增强17-4PH钢低压末级叶片的防水蚀性能,对17-4PH叶片进汽边进行激光固溶处理。经过激光固溶处理的末级叶片在后续磁粉探伤过程中,往往会出现明显的磁痕现象。为此,利用光学显微镜、扫描电镜、X射线衍射仪、电子探针等分析手段证明了在激光固溶区域边界处出现磁痕的原因为在边界出现的大量的奥氏体组织,降低了激光固溶边界处的磁导率,从而产生磁痕。利用XRD测定激光固溶叶片的残余应力为压应力,三点弯曲疲劳试验证明通过激光固溶可将17-4PH叶片的R=0.1疲劳极限由原750 MPa提高至860 MPa。

In order to enhance the corrosion resistance of the 17-4PH low-pressure last stage blades,the steam inlet side of the 17-4PH blades needs to be treated with laser-enhanced solid solution.The last stage blades treated with laser solution often show obvious magnetic marks in the subsequent magnetic particle inspection.Optical microscope,scanning electron microscope,X-ray diffractometer,electron probe and other an-alytical means were used to prove that the reason for the appearance of magnetic marks at the boundary of the laser solid solution region was a large number of austenite structures that appeared at the boundary,which reduced the permeability at the boundary of the laser solid solution region.Besides,the residual stress of laser solid solution blade was determined as compressive stress by XRD,and the three-point bending fa-tigue test showed that the R=0.1 fatigue limit of 17-4PH blade could be increased from 750 MPa to 860 MPa by laser-enhanced solid solution.