| 摘要: |
| 采用高功率CO2激光熔覆铁基合金粉末，获得了无裂纹、稀释率低、成形良好的熔覆涂层。利用光学显微镜（OM）、扫描电镜（SEM）、透射电镜（TEM）、X射线衍射（XRD）对熔覆层的显微组织进行了观察与分析，通过硬度测试与拉伸试验考察了涂层的力学性能。结果显示：熔覆层为纳米贝氏体与残余奥氏体的复合组织，均匀分布的贝氏体铁素体板条厚度为50～80 nm，贝氏体板条间为厚度10～30 nm更为细小的残余奥氏体薄膜；熔覆层平均硬度为610 HV，熔覆涂层的抗拉强度为1 280 MPa，延伸率为6.41 %，拉伸断口形貌为韧窝断口。 |
| 关键词: 激光熔覆 纳米贝氏体涂层 微观组织 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目(50971091)；科技部国际科技合作项目(2009DFB50350)；上海市重大技术装备项目(ZX08089） |
|
| Microstructure and Properties of Laser Cladded Nanostructured Bainite Coatings |
|
YUAN Lin, LI Zhu–guo, HUANG Jian, LI Rui–feng
|
|
Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiaotong University
|
| Abstract: |
| A Fe–based coating with cracks–free, low dilution and good forming was deposited by high–power CO2 laser cladding technique. The microstructure of this coating was observed and analyzed by optic microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and X–ray diffraction (XRD), and its mechanical properties were tested by means of hardness tests and tensile tests. The results show that the microstructure of this coating consists of uniformly distributed nanostructured bainite and retained austenite. The plates of bainitic ferrite are 50～80 nm thick, and each plate is separated by an even finer film of retained austenite with a width of 10～30 nm. The average hardness of coatings is about 610 HV, the tensile strength and elongation are 1 280 MPa and 6.41 % respectively. The fracture morphology exhibits the characteristics of ductile fracture with dimples. |
| Key words: laser cladding nanostructured bainite coatings microstructure |
