| 题名 | 铁基激光熔覆合金设计及微观组织与性能研究 |
| 学位类别 | 博士 |
| 答辩日期 | 2000 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 陈光南 |
| 关键词 | 激光熔覆 铁基合金 微观组织 磨损 强韧性 laser cladding iron-based alloy microstructure wear strengthening and toughening |
| 学位专业 | 工程力学 |
| 中文摘要 | 本文设计并制备了具有优良的强韧性能和高温性能的激光熔覆涂层。利用 SEM、TEMEY X－射线衍射仪等研究了涂层的化学成分、宏微观结构及其转变机制，同时研究了涂层强韧性及耐高温磨损性能及其影响机制。对激光溶覆涂层进行了合金化、微观组织、强韧化机制、加工工艺性能设计。合金系为 Fe-Cr-C-W-Ni，成分配比（质量分数），Fe:52-60%, Cr:24-30%, C:5-6%, W:4.5-7.5%, Ni:5-6%。强化机制为两相强化、亚结构强化及固溶强化，其中强化相为合金碳化物，基体相为合金元素过饱和度极高的韧性奥氏体。亚共晶及过共晶组织的领先凝固相分别为奥氏体及 M_7C_3 合金碳化物，两相共晶组织均为韧性相奥氏体和强化相 M_7C_3 合金碳化物。加工工艺控制领先凝固相的结构、组织演化及力学性能。熔覆组织在高温时效过程中形成大量新的碳化物。在过饱和奥氏体内部，可弥散析出细小的 Mc、M_2C 及 M_(23)C_6碳化物；在奥氏体与 M_7C_3 相界面，亚稳相M_7C_3发生原位转变，形成 M_(23)C_6 及 M_6C碳化物。激光熔覆合金具有较高的综合力学性能，熔覆涂层有高的显微硬度、优良的抗回火稳定性、显著的二次硬化特征、优异的抗磨粒磨损和冲击磨损性能。Fe-Cr-C-W-Ni 激光熔覆合金具有较低的裂纹形成倾向和良好的表面成形性能，这与奥氏体较高的高温韧塑性及合金的低熔点共晶特征密切相关；实验及理论分析表明，通过调整合金成分、激光工艺参数和后续热处理工艺，可获得具有不同强韧性能的熔覆涂层。 |
| 索取号 | 29944 |
| 英文摘要 | The laser cladding coating with high toughness and high-temperature wear resistance was designed and synthesized. The composition, microstructure, and phase evolution were investigated by SEM、TEM、XRD. The mechanical properties and the mechanisms of strengthening and toughening were analysed. The alloying system, Fe-Cr-C-W-Ni was designed in respect of strengthening/toughening, microstructure, laser processing parameters and mechanical properties. The mechanisms of strengthening were two-phase strengthening, seb-grain strengthening and solid solution strengthening. The strengthening phase was alloy carbides. The matrix was austenite, which was non-equilibrium phase with extended solid solution alloy elements and a great deal of fine structures. The primary dendritic phases of hypo-eutectic and hyper-eutectic were austenite and M_7C_3 respectively and both of the interdendritic eutectics consisted of M_7C_3 alloy carbide and austenite. During high temperature aging, a lot of Mc、M_2C and M_(23)C_6 carbides precipitated in austenite and M_7C_3 in situ transformed to M_(23)C_6 and M_6C carbides in the interface of austenite and M_7C_3. The iron-based laser cladding coating revealed high microhardness, excellent tempering-resistance, evident secondary hardening and superior impact wear resistance as compared with S600 high speed steel and the coatings synthesized by laser cladding Ni60 powder. Fe-Cr-C-W-Ni laser cladding coating was free of cracks due to the microstructure characterized by tough austenite phase and low melting point eutectic. Numerical analysis and experiments showed that various coatings with different strength and toughness can be obtained by adjusting the component, laser processing parameters and aging treatment. |
| 语种 | 中文 |
| 学科主题 | 工程力学 |
| 公开日期 | 2009-04-13 ; 2009-08-25 |
| 出处 | [博士论文].北京.中国科学院力学研究所,2000 |
| 内容类型 | 学位论文 |
| 源URL | [http://dspace.imech.ac.cn/handle/311007/24380]  |
| 专题 | 力学研究所_力学所知识产出(1956-2008) |
| 推荐引用方式 GB/T 7714 | . 铁基激光熔覆合金设计及微观组织与性能研究[D]. 北京. 中国科学院研究生院. 2000. |
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